CN112881810A

CN112881810A - Detection circuit, chip and related electronic device

Info

Publication number: CN112881810A
Application number: CN202110086085.XA
Authority: CN
Inventors: 余倩
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2021-01-22
Filing date: 2021-01-22
Publication date: 2021-06-01
Anticipated expiration: 2041-01-22
Also published as: CN112881810B

Abstract

The application discloses detection circuitry, chip and relevant electron device, detection circuitry include first to fourth input, first to eighth switching circuit and difference integrator circuit. The first to eighth switching circuits are used for charging and discharging the first sensing capacitor and the second sensing capacitor in the detection operation, so as to eliminate the influence of the first mutual capacitance between the first sensing capacitor and the second sensing capacitor on the detection voltage signal in the detection operation, and the differential integration circuit outputs the detection voltage signal related to the approach of the human body according to the sensing capacitance values of the first sensing capacitor and the second sensing capacitor.

Description

Detection circuit, chip and related electronic device

Technical Field

The present disclosure relates to a detection circuit, and more particularly to a capacitance detection circuit, a chip and an electronic device.

Background

In application scenarios such as earphones, mobile phones, vehicle-mounted touch, and the like, the capacitance is often detected to cooperate with a detection algorithm to complete human-computer interaction in various application scenarios based on the capacitance. For example, the wearing state of the earphone is detected according to the capacitance detection result, and whether music is played or not is controlled; for example, the pressure applied by the user on the mobile phone is judged according to the capacitance detection result, and then the gesture of the user and the operation of controlling the mobile phone are judged. However, external interference and temperature variation often cause the sensing capacitance of the sensing capacitor to vary, which results in erroneous determination in application.

In the prior art, a single sensing capacitor is divided into two adjacent sensing capacitors, and sensing is performed in a differential manner to reduce interference of external common mode noise. However, mutual capacitance occurs between adjacent sensing capacitors, and the mutual capacitance can participate in charge transfer during sensing, resulting in misalignment of sensing results. In addition, when a human body approaches or touches the sensing capacitor, the change of the mutual capacitance is opposite to the change of the sensing capacitance, so that the capacitance sensing result is more difficult to interpret. Therefore, how to reduce the external interference such as temperature and the influence of mutual capacitance between the sensing capacitors, so as to make the capacitance sensing more accurate, has become one of the problems to be solved in the art.

Disclosure of Invention

An objective of the present application is to disclose a detection circuit, a chip and a related electronic device, so as to solve the above problems.

An embodiment of the present application provides a detection circuit, which includes first to fourth input terminals, a differential integration circuit, and first to eighth switching circuits. The first input end is coupled to the first end of the first sensing capacitor. The second input terminal is coupled to a second terminal of the first sensing capacitor, the first sensing capacitor has a first intrinsic capacitance, and a sensing capacitance of the first sensing capacitor is changed at least when a human body approaches the first terminal of the first sensing capacitor. The third input terminal is coupled to the first terminal of the second sensing capacitor. The fourth input terminal is coupled to a second terminal of the second sensing capacitor, the second sensing capacitor has a second inherent capacitance, and a sensing capacitance of the second sensing capacitor is changed at least when a human body approaches the first terminal of the second sensing capacitor. The differential integration circuit is used for integrating the voltage of the first internal node and the voltage of the second internal node to generate a detection voltage signal when the detection circuit performs detection operation. The first switching circuit has a first end, a second end and a third end, wherein the first internal node is the first end of the first switching circuit, the second end of the first switching circuit is coupled to the first input end of the detection circuit, and the third end of the first switching circuit is coupled to a ground end, the first switching circuit is configured to turn on or off an electrical connection between the first input end of the detection circuit and the first internal node, and turn on or off an electrical connection between the first input end of the detection circuit and the ground end. The second switching circuit is coupled to the second input terminal of the detection circuit, the first internal node and the ground terminal, and is configured to turn on or off an electrical connection between the second input terminal of the detection circuit and the first internal node, and turn on or off an electrical connection between the second input terminal of the detection circuit and the ground terminal. The third switching circuit is coupled to the first internal node and an operating voltage, and is configured to turn on or off an electrical connection between the first internal node and the operating voltage. The fourth switching circuit is coupled to the first internal node and the ground terminal, and is configured to turn on or off an electrical connection between the first internal node and the ground terminal. The fifth switching circuit has a first terminal, a second terminal and a third terminal, wherein the second internal node is the first terminal of the fifth switching circuit, the second terminal of the fifth switching circuit is coupled to the third input terminal of the detection circuit, the second terminal of the fifth switching circuit is coupled to the ground terminal, and the fifth switching circuit is configured to turn on or off an electrical connection between the third input terminal of the detection circuit and the second internal node, and turn on or off an electrical connection between the third input terminal of the detection circuit and the ground terminal. The sixth switching circuit is coupled to the fourth input terminal, the second internal node, and the ground terminal of the detection circuit, and is configured to turn on or off an electrical connection between the fourth input terminal and the second internal node of the detection circuit, and turn on or off an electrical connection between the fourth input terminal and the ground terminal of the detection circuit. The seventh switching circuit is coupled to the second internal node and the operating voltage, and is configured to turn on or off an electrical connection between the second internal node and the operating voltage. The eighth switching circuit is coupled to the second internal node and the ground terminal, and is configured to turn on or off the electrical connection between the second internal node and the ground terminal.

The first switching circuit, the second switching circuit, the third switching circuit, the fourth switching circuit, the fifth switching circuit, the sixth switching circuit, the seventh switching circuit, and the eighth switching circuit are configured to charge or discharge the first sensing capacitor and the second sensing capacitor in the detection operation to eliminate an influence of a first mutual capacitance between the first sensing capacitor and the second sensing capacitor on the detection voltage signal, so that the differential integration circuit outputs the detection voltage signal related to human body proximity according to sensing capacitance values of the first sensing capacitor and the second sensing capacitor.

Another embodiment of the present application provides a chip including the detection circuit and the detection voltage signal reading circuit for reading the detection circuit output.

Another embodiment of the present application provides an electronic device, including the detection circuit.

The detection circuit, the chip and the related electronic device can reduce the interference of external common-mode signals such as temperature and the like and the interference of mutual capacitance between the sensing capacitors, so that the accuracy of the capacitance signals detected by the detection circuit is improved.

Drawings

FIG. 1 is a schematic diagram of capacitive in-ear detection.

FIG. 2 is another schematic diagram of capacitive in-ear detection.

FIG. 3 is a schematic diagram of a detection circuit according to an embodiment of the present application.

Fig. 4 is a timing diagram of signals received and signals output by the detection circuit of fig. 3 when performing a detection operation.

FIG. 5 is a schematic diagram of a detection circuit according to another embodiment of the present application.

Fig. 6 is a timing diagram of signals received and signals output by the detection circuit of fig. 5 when performing a detection operation.

Fig. 7 is a diagram showing a relationship between the arrangement of the sensing capacitors in fig. 5.

Detailed Description

The following disclosure provides various embodiments or illustrations that can be used to implement various features of the disclosure.

FIG. 1 is a schematic diagram of capacitive in-ear detection. In fig. 1, the self-contained C on the earphone_SFThe first end of the earphone can be an outer polar plate ET on the earphone shell, and the first end of the earphone can be a self-contained C_SFMay be an inner pad IT on the earphone housing. Therefore, when a person wears the earphone, the ear can be contacted with the outside polar plate ET, and the human body equivalent capacitance C of the human body is obtained at the moment_BWill pass through the outer polar plate ET and the self-capacitance C_SFAnd (4) connecting in parallel. In fig. 1, the outer plate ET is connected to the read circuit SC, while the inner plate IT is grounded. At this time, the voltage read by the reading circuit SC can change with the capacitance caused by the outside temperature and the self-capacitance C when the human body approaches_SFParallel human equivalent capacitance C_BTherefore, the voltage read by the reading circuit SC can be used for judging whether a human body approaches the earphone or not, and the in-ear detection is achieved.

In general, the self-capacitance C is read at the reading circuit SC_SFBefore the voltage of the first terminal, the charger in the system will first charge the self-capacitance C_SFHowever, if the charger is disturbed, the ground voltage of the whole system may be disturbed, thereby generating common mode noise. To reduce common mode noise errors, the prior art approach is to use a self-capacitance C_SFSplit into two small self-contained volumes. FIG. 2 is another schematic diagram of capacitive in-ear detection. In FIG. 2, the original self-contained C_SFIs split into two small self-contained cells C_SF1And C_SF2. In this case, if the self-capacitance C is read in a differential manner_SF1And C_SF2The common mode noise caused by the charger interference can be eliminated. However, self-contained C_SF1And C_SF2Will generate mutual capacitance C_mAnd mutual capacitance C when the human body approaches or has temperature change_mAnd self-contained C_SF1And C_SF2The sensing capacitance will have an adverse effect on the read voltage, for example, when the human body is close to the self-capacitance C_SF1And C_SF2In time, self-contained C_SF1And C_SF2The sensing capacitance value of (2) will changeLarge, mutual capacitance C_mIt will be smaller, so that the voltage read by the reading circuit SC is difficult to directly show the variation caused by the approaching human body, and the result of the capacitive ear-entering detection is less accurate.

Fig. 3 is a schematic diagram of a detection circuit 100 according to an embodiment of the present application. In the embodiment of fig. 3, the detection circuit 100 may be coupled to the first sensing capacitor C_S1And a second sensing capacitor C_S2A first sensing capacitor C_S1And a second sensing capacitor C_S2Although the first sensing capacitor C has a fixed capacitance, when a human body approaches or a temperature changes, the first sensing capacitor C sensed by the detection circuit 100_S1And a second sensing capacitor C_S2The sensing capacitance will be changed, so the detection circuit 100 can pass through the first sensing capacitor C_S1And a second sensing capacitor C_S2And detecting the capacitance change to output a corresponding detection voltage signal VOUT.

For example, when a human body approaches the first sensing capacitor C_S1And a second sensing capacitor C_S2Time, human body equivalent capacitance C of human body_BWill interact with the first sensing capacitor C_S1And a second sensing capacitor C_S2In parallel, the first sensing capacitor C_S1And a second sensing capacitor C_S2The sensing capacitance value of the voltage signal VOUT is changed, and the value of the voltage signal VOUT is correspondingly changed. Wherein the human body approaches the first sensing capacitor C_S1And a second sensing capacitor C_S2Comprises a first sensing capacitor C for human body to approach or contact_S1And a second sensing capacitor C_S2。

In addition, the detection circuit 100 of the present application can eliminate the first sensing capacitor C_S1And a second sensing capacitor C_S2Mutual capacitance between C_mThe influence on the detection voltage signal VOUT can be used to more accurately determine whether a human body approaches the first sensing capacitor C_S1And a second sensing capacitor C_S2Therefore, the capacitive touch detection can be performed according to the detection voltage signal VOUT more precisely, and the details thereof are described below.

In fig. 3, the detection circuit 100 may be providedThe detection circuit 100 may be enclosed in a housing (not shown) of the electronic device 10, that is, the housing. In this case, the first sensing capacitor C_S1And a second sensing capacitor C_S2Such as but not limited to a self-capacitance formed by electrodes on at least a portion of the housing, where the electrodes on the housing may be either existing conductive elements on the housing or electrodes specifically located on the housing.

Although the first sensing capacitor C_S1And a second sensing capacitor C_S2It has inherent capacitance, however, when a human body approaches the first sensing capacitor C_S1And a second sensing capacitor C_S2While, the first sensing capacitor C_S1And a second sensing capacitor C_S2The sensing capacitance value will change accordingly. For example, the first sensing capacitor C_S1And a second sensing capacitor C_S2May be located outside at least a portion of the housing, and the first sensing capacitor C_S1And a second sensing capacitor C_S2May be located inside at least a portion of the housing. That is, the first sensing capacitor C_S1And a second sensing capacitor C_S2The first end of (C) may be the outer plate of the casing, and the first sensing capacitor (C)_S1And a second sensing capacitor C_S2May be an inner plate of the housing. Therefore, when a human body approaches the shell, the human body equivalent capacitance C of the human body_BWill interact with the first sensing capacitor C_S1First terminal and second sensing capacitor C_S2Is coupled to the first terminal, so that the first sensing capacitor C_S1And a second sensing capacitor C_S2The sensed capacitance value of (a) changes. In addition, the present application does not limit the first sensing capacitor C_S1And a second sensing capacitor C_S2Is a self-contained, in some other embodiments, the first sensing capacitor C is based on the use of the housing_S1And a second sensing capacitor C_S2Or may be self-contained with other components of the electronic device 10.

The detection circuit 100 may include a first input terminal P1, a second input terminal P2, a third input terminal P3, a fourth input terminal P4, a first switching circuit SW1, a second switching circuit SW2, a third switching circuit SW3, a fourth switching circuit SW4, a fifth switching circuit SW5, a sixth switching circuit SW6, a seventh switching circuit SW7, an eighth switching circuit SW8, and a differential integration circuit 110.

The first input terminal P1 may be coupled to the first sensing capacitor C_S1And the second input terminal P2 may be coupled to the first sensing capacitor C_S1The second end of (a). The third input terminal P3 may be coupled to the second sensing capacitor C_S2And the fourth input terminal P4 may be coupled to the second sensing capacitor C_S2The second end of (a). In the present embodiment, the detection circuit 100 senses the first sensing capacitor C through the first input terminal P1 and the second input terminal P2_S1And the second sensing capacitor C is sensed through the third input terminal P3 and the fourth input terminal P4_S2The sensed capacitance value of (1).

The first switch circuit SW1 has a first terminal, a second terminal and a third terminal, and for convenience of description, the first terminal of the first switch circuit SW1 is further named as a first internal node NS 1. The second terminal of the first switching circuit SW1 may be coupled to the first input terminal P1, the third terminal of the first switching circuit SW1 may be coupled to the ground terminal GND, and the first switching circuit SW1 may turn on or off the electrical connection between the first input terminal P1 and the first internal node NS1, and may turn on or off the electrical connection between the first input terminal P1 and the ground terminal GND.

The second switching circuit SW2 may be coupled to the second input terminal P2, the first internal node NS1 and the ground terminal GND, and the second switching circuit SW2 may turn on or off the electrical connection between the second input terminal P2 and the first internal node NS1, and turn on or off the electrical connection between the second input terminal P2 and the ground terminal GND.

The third switching circuit SW3 may be coupled to the first internal node NS1 and the operating voltage VDD, and the third switching circuit SW3 may turn on or off the electrical connection between the first internal node NS1 and the operating voltage VDD. In the present application, the operating voltage VDD may be greater than the voltage of the ground GND, such as, but not limited to, a supply voltage or a reference voltage provided in a system in which the detection circuit 100 is disposed.

The fourth switching circuit SW4 may be coupled to the first internal node NS1 and the ground GND, and the fourth switching circuit SW4 may turn on or off the electrical connection between the first internal node NS1 and the ground GND.

The fifth switching circuit SW5 has a first terminal, a second terminal and a third terminal, and for convenience of description, the first terminal of the fifth switching circuit SW5 is further named as the second internal node NS 2. The second terminal of the fifth switching circuit SW5 may be coupled to the third input terminal P3, the third terminal of the fifth switching circuit SW5 may be coupled to the ground terminal GND, and the fifth switching circuit SW5 may turn on or off the electrical connection between the third input terminal P3 and the second internal node NS2, and turn on or off the electrical connection between the third input terminal P3 and the ground terminal GND.

The sixth switching circuit SW6 may be coupled to the fourth input terminal P4, the second internal node NS2 and the ground terminal GND, and the sixth switching circuit SW6 may turn on or off the electrical connection between the fourth input terminal P4 and the second internal node NS2, and turn on or off the electrical connection between the fourth input terminal P4 and the ground terminal GND.

The seventh switching circuit SW7 may be coupled to the second internal node NS2 and the operating voltage VDD, and the seventh switching circuit SW7 may turn on or off the electrical connection between the second internal node NS2 and the operating voltage VDD. The eighth switching circuit SW8 may be coupled to the second internal node NS2 and the ground GND, and the eighth switching circuit SW8 may turn on or off the electrical connection between the second internal node NS2 and the ground GND.

The differential integrator circuit 110 has a first input NI1 and a second input NI 2. In fig. 3, the first input NI1 of the differential integration circuit 110 may be coupled to the first internal node NS1, and the second input NI2 of the differential integration circuit 110 may be coupled to the second internal node NS 2. In this way, when the detection circuit 100 performs the detection operation, the differential integration circuit 110 integrates the voltages of the first internal node NS1 and the second internal node NS2 to generate the detection voltage signal VOUT.

In the present embodiment, the differential integration circuit 110 may include a differential amplifier 112, a first capacitor C1, a second capacitor C2, a ninth switching circuit SW9 and a tenth switching circuit SW 10.

The differential amplifier 112 has a first input terminal, a second input terminal, a first output terminal and a second output terminal. In this embodiment, the first input terminal of the differential amplifier 112 may be a positive input terminal, the second input terminal of the differential amplifier 112 may be a negative input terminal, the first output terminal of the differential amplifier 112 may be a positive output terminal and may output a positive output voltage VPO, the second output terminal of the differential amplifier 112 may be a negative output terminal and may output a negative output voltage VNO, and the first output terminal and the second output terminal of the differential amplifier 112 may collectively output the detection voltage signal VOUT.

The first capacitor C1 is coupled between the first input terminal of the differential amplifier 112 and the first output terminal of the differential amplifier 112. The second capacitor C2 is coupled between the second input terminal of the differential amplifier 112 and the second output terminal of the differential amplifier 112.

The ninth switching circuit SW9 may be coupled between the first input terminal of the differential amplifier 112 and the first input terminal NI1 of the differential integration circuit 110, and the ninth switching circuit SW9 may turn on or off the electrical connection between the first input terminal of the differential amplifier 112 and the first input terminal NI1 of the differential integration circuit 110. The tenth switching circuit SW10 may be coupled between the second input terminal of the differential amplifier 112 and the second input terminal NI2 of the differential integration circuit 110, and the tenth switching circuit SW10 may turn on or off the electrical connection between the second input terminal of the differential amplifier 112 and the second input terminal NI2 of the differential integration circuit 110.

In the present embodiment, by controlling the first switching circuit SW1 to the tenth switching circuit SW10, the detection circuit 100 can sense the first sensing capacitor C in a differential manner_S1And a second sensing capacitor C_S2The sensing capacitance value is used for outputting the detection voltage signal VOUT, so that the interference of common mode noise of the external environment to the detection result of the detection voltage signal can be reduced. Further, during the detection operation, by appropriately controlling the first to tenth switching circuits, it is also possible to make the first sensing capacitance C_S1And a second sensing capacitor C_S2In the same charging state, the first internal node NS1 and the second internal node NS2 are at the same voltage, and the first sensing capacitor C is at the same voltage_S1And a second sensing capacitor C_S2Mutual capacitance between C_mThe two terminals of the voltage signal VOUT will be at the same potential, and therefore no charge is stored, so that the detection voltage signal VOUT will not be subjected to mutual capacitance C_mThat is, the detection voltage signal VOUT is not affected by the mutual capacitance C_mThe voltage signal VOUT is detected, so that a more accurate result can be obtained when the capacitance detection is performed according to the detection voltage signal VOUT. The applications of the capacitive detection are many, for example: the capacitive in-ear detection commonly used in the earphones is used for realizing wearing/falling detection of the earphones so as to control whether the earphones perform various operations such as music playing or not, and the capacitive touch detection is used for realizing gesture recognition such as clicking, double clicking and sliding so as to complete man-machine interaction in various application scenes.

However, when the temperature changes, the first sensing capacitor C_S1And a second sensing capacitor C_S2The sensing capacitance value will also change, i.e. the temperature drift phenomenon. In the embodiment, in order to reduce the temperature of the detection voltage signal VOUT and the first sensing capacitor C_S1And a second sensing capacitor C_S2The detection circuit 100 may further include a third capacitor C3, a fourth capacitor C4, and eleventh to eighteenth switching circuits (SW11 to SW18) to offset the first sensing capacitor C3_S1And a second sensing capacitor C_S2The intrinsic capacitance value of the capacitor affects the detection voltage signal VOUT, and offsets the first sensing capacitor C caused by temperature variation_S1And a second sensing capacitor C_S2When the sensing capacitance value is changed, the influence on the detection voltage signal VOUT is caused.

The third capacitor C3 has a first terminal and a second terminal. The eleventh switching circuit SW11 can turn on or off the electrical connection between the first end of the third capacitor C3 and the ground GND. The twelfth switching circuit SW12 can turn on or off the electrical connection between the first end of the third capacitor C3 and the operating voltage VDD. The thirteenth switching circuit S13 can turn on or off the electrical connection between the second terminal of the third capacitor C3 and the ground GND, and turn on or off the electrical connection between the second terminal of the third capacitor C3 and the operating voltage VDD. The fourteenth switching circuit S14 can turn on or off the electrical connection between the first terminal of the third capacitor C3 and the first internal node NS 1.

The fourth capacitor C4 has a first terminal and a second terminal. The fifteenth switching circuit SW15 can turn on or off the electrical connection between the first end of the fourth capacitor C4 and the ground GND. The sixteenth switching circuit SW16 can turn on or off the electrical connection between the first end of the fourth capacitor C4 and the operating voltage VDD. The seventeenth switching circuit SW17 can turn on or off the electrical connection between the second terminal of the fourth capacitor C4 and the ground GND, and turn on or off the electrical connection between the second terminal of the fourth capacitor C4 and the operating voltage VDD. The eighteenth switching circuit SW18 can turn on or off the electrical connection between the first end of the fourth capacitor C4 and the second internal node NS 2.

In the present embodiment, the first switching circuit SW1 may include a first switch S1 and a second switch S2. The first switch S1 has a first terminal, a second terminal and a control terminal, the first terminal of the first switch S1 is coupled to the first input terminal P1, and the second terminal of the first switch S1 is the first internal node NS 1. The second switch S2 has a first terminal, a second terminal and a control terminal, the first terminal of the second switch S2 is coupled to the first input terminal P1, and the second terminal of the second switch S2 is coupled to the ground GND.

The second switching circuit SW2 may include a third switch S3 and a fourth switch S4. The third switch S3 has a first terminal, a second terminal, and a control terminal, the first terminal of the third switch S3 is coupled to the second input terminal P2, and the second terminal of the third switch S3 is coupled to the first internal node NS 1. The fourth switch S4 has a first terminal, a second terminal and a control terminal, the first terminal of the fourth switch S4 is coupled to the second input terminal P2, and the second terminal of the fourth switch is coupled to the ground terminal GND

The fifth switching circuit SW5 includes a fifth switch S5 and a sixth switch S6. The fifth switch S5 has a first terminal, a second terminal and a control terminal, the first terminal of the fifth switch S5 is coupled to the third input terminal P3, and the second terminal of the fifth switch S5 is the second internal node NS 2. The sixth switch S6 has a first terminal, a second terminal, and a control terminal, wherein the first terminal of the sixth switch S6 is coupled to the third input terminal P3, and the second terminal of the sixth switch S6 is coupled to the ground GND.

The sixth switching circuit SW6 includes a seventh switch S7 and an eighth switch S8. The seventh switch S7 has a first terminal, a second terminal, and a control terminal, the first terminal of the seventh switch S7 is coupled to the fourth input terminal P4, and the second terminal of the seventh switch S7 is coupled to the second internal node NS 2. The eighth switch S8 has a first terminal, a second terminal and a control terminal, the first terminal of the eighth switch S8 is coupled to the fourth input terminal P4, and the second terminal of the eighth switch S8 is coupled to the ground GND.

The thirteenth switching circuit SW13 includes a ninth switch S9 and a tenth switch S10. The ninth switch S9 has a first terminal, a second terminal and a control terminal, the first terminal of the ninth switch S9 is coupled to the second terminal of the third capacitor C3, and the second terminal of the ninth switch S9 is coupled to the operating voltage VDD. The tenth switch S10 has a first terminal, a second terminal, and a control terminal, the first terminal of the tenth switch S10 is coupled to the second terminal of the third capacitor C3, and the second terminal of the tenth switch S10 is coupled to the ground GND.

The seventeenth switching circuit SW17 includes an eleventh switch S11 and a twelfth switch S12. The eleventh switch S11 has a first terminal, a second terminal, and a control terminal, the first terminal of the eleventh switch S11 is coupled to the second terminal of the fourth capacitor C4, and the second terminal of the eleventh switch S11 is coupled to the operating voltage VDD. The twelfth switch S12 has a first terminal, a second terminal, and a control terminal, the first terminal of the twelfth switch S12 is coupled to the second terminal of the fourth capacitor C4, and the second terminal of the twelfth switch S12 is coupled to the ground GND.

In addition, the third switching circuit SW3, the fourth switching circuit SW4, the seventh switching circuit SW7, the eighth switching circuit SW8, the ninth switching circuit SW9, the tenth switching circuit SW10, the eleventh switching circuit SW11, the twelfth switching circuit SW12, the fourteenth switching circuit SW14, the fifteenth switching circuit SW15, the sixteenth switching circuit SW16, and the eighteenth switching circuit SW18 may be implemented by a single switch.

The first to eighteenth switching circuits SW1 to SW8 may be used to make the first sensing capacitor C_S1A third capacitor C3, a second sensing capacitor C_S2And the fourth capacitor C4 performs charging, discharging or charge redistribution operations respectively in different periods of time, thereby being more efficient and convenientAdvantageously, the detection operation is performed.

In fig. 3, the first switching circuit SW1, the second switching circuit SW2, the fifth switching circuit SW5 and the sixth switching circuit SW6 can be controlled by a first control signal K1 and a second control signal K2, and the third switching circuit SW3, the seventh switching circuit SW7, the eleventh switching circuit SW11 and the fifteenth switching circuit SW15 can be controlled according to a third control signal K3. The fourth switching circuit SW4, the eighth switching circuit SW8, the twelfth switching circuit SW12 and the sixteenth switching circuit SW16 are controllable according to a fourth control signal K4. The thirteenth switching circuit SW13 can be controlled according to the fifth control signal K5 and the sixth control signal K6, and the seventeenth switching circuit SW17 can also be controlled according to the fifth control signal K5 and the sixth control signal K6. The fourteenth and eighteenth switching circuits SW14 and SW18 are controllable according to the seventh control signal K7, and the ninth and tenth switching circuits SW9 and SW10 are controllable according to the eighth control signal K8.

Fig. 4 is a timing diagram of signals received by the detection circuit 100 when performing a detection operation. In some embodiments, when the control signal K1 is at a high level, the first switching circuit SW1 turns on the electrical connection between the first input terminal P1 and the first internal node NS1, the second switching circuit SW2 turns on the electrical connection between the second input terminal P2 and the ground terminal GND, the fifth switching circuit SW5 turns on the electrical connection between the third input terminal P3 and the ground terminal GND, and the sixth switching circuit SW6 turns on the electrical connection between the fourth input terminal P4 and the second internal node NS 2. When the control signal K2 is at a high level, the first switching circuit SW1 turns on the electrical connection between the first input terminal P1 and the ground GND, the second switching circuit SW2 turns on the electrical connection between the second input terminal P2 and the first internal node NS1, the fifth switching circuit SW5 turns on the electrical connection between the third input terminal P3 and the second internal node NS2, and the sixth switching circuit SW6 turns on the electrical connection between the fourth input terminal P4 and the ground GND.

When the control signal K5 is at a high level, the thirteenth switching circuit SW13 turns on the electrical connection between the second terminal of the third capacitor C3 and the operating voltage VDD, and the seventeenth switching circuit SW17 turns on the electrical connection between the second terminal of the fourth capacitor C4 and the operating voltage VDD. When the control signal K6 is at a high level, the thirteenth switching circuit SW13 turns on the electrical connection between the second terminal of the third capacitor C3 and the ground GND, and the seventeenth switching circuit SW17 turns on the electrical connection between the second terminal of the fourth capacitor C4 and the ground GND.

In addition, the switching circuits SW3, SW4, SW7, SW8, SW9, SW10, SW11, SW12, SW14, SW15 and SW16 are configured to turn on the corresponding electrical connection when the corresponding control signal of the control signals K3, K4, K7 and K8 is at a high potential, and turn off the corresponding electrical connection when the corresponding control signal of the control signals K3, K4, K7 and K8 is at a low potential.

In fig. 4, the detection operation may include a first stage ST1 and a second stage ST2, the first stage ST1 may include a first period TP1, a second period TP2 and a third period TP3, and the second stage ST2 may include a fourth period TP4, a fifth period TP5 and a sixth period TP 6.

In the first stage ST1, the detection circuit 100 may sense the first sensing capacitor C_S1And the third capacitor C3 is charged to the operating voltage VDD respectively, and the first sensing capacitor C is enabled to be charged_S1And a third capacitor C3 coupled to the first internal node NS1 such that the first sensing capacitor C_S1And the internal charge of the third capacitor C3 may be redistributed. At the first sensing capacitor C_S1In the case of matching with the third capacitor C3, the voltage of the first internal node NS1 will only approach the first sensing capacitor C with the human body_S1I.e. the first sensing capacitor C_S1The outer plate of the first sensing capacitor C_S1The first end of the first capacitor is connected in parallel with a human body equivalent capacitor, and the change of a sensing capacitance value caused by temperature is related to the first sensing capacitor C_S1The inherent capacitance thereof is independent of the capacitance of the third capacitor C3, i.e., the voltage at the first internal node NS1 is not induced by the first sensing capacitor C_S1The intrinsic capacitance itself and the capacitance of the third capacitor C3 vary in magnitude. With respect to the first sensing capacitance C_S1The conditions and details of operation matched to the third capacitor C3 will be described later.

Furthermore, in the first stageIn ST1, the detection circuit 100 can sense the second capacitance C_S2And the fourth capacitor C4 is charged to the operating voltage VDD respectively, and the second sensing capacitor C is enabled to be_S2And a fourth capacitor C4 coupled to the second internal node NS2 such that the second sensing capacitor C_S2And the internal charge of the fourth capacitor C4 may be redistributed. Since the third input terminal P3 is continuously coupled to the ground GND in the first stage ST1, the second sensing capacitor C is coupled to the ground GND_S2I.e. the second sensing capacitor C_S2The outer plate of (a) will be in a grounded state. Since the human body is usually in the grounding state, when the human body approaches the second sensing capacitor C_S2Is coupled to the second sensing capacitor C_S2Human body equivalent capacitance C of the first end of_BWill be in a grounded state without causing the second sensing capacitor C_S2Sense a change in capacitance value. In this case, if the second sensing capacitor C_S2Matching the fourth capacitor C4, the voltage at the second internal node NS2 will only be related to the temperature-induced capacitance change and the second sensing capacitor C_S2The inherent capacitance thereof is independent of the capacitance of the fourth capacitor C4, i.e., the voltage at the second internal node NS2 is not induced by the second sensing capacitor C_S2The intrinsic capacitance itself and the capacitance of the fourth capacitor C4 vary in magnitude.

Furthermore, since the differential integrator 110 integrates the voltages of the first and second internal nodes NS1 and NS2 through the first and second capacitors C1 and C2, respectively, the first and second sensing capacitors C and C will have opposite effects on the VOUT signal, so that the first sensing capacitor C will have an opposite effect_S1And a second sensing capacitor C_S2The variation of the sensing capacitance caused by the temperature can be mutually offset, and when the detection voltage signal VOUT is only close to the human body, the first sensing capacitor C_S1Is related to the change in the capacitive sense value.

In the second stage ST2, the detection circuit 100 can sense the first sensing capacitor C_S1Discharging to the ground GND, charging the third capacitor C3 to the operating voltage VDD, and charging the first sensing capacitor C_S1And a third capacitor C3 are commonly coupled to the first internal node NS1,so that the first sensing capacitor C_S1And the internal charge of the third capacitor C3 may be redistributed. In the second stage ST2, since the first input terminal P1 is continuously coupled to the ground GND, the first sensing capacitor C_S1I.e. the first sensing capacitor C_S1The outer electrode plate is grounded, and when a human body approaches the first sensing capacitor C, the human body is grounded_S1Is coupled to the first sensing capacitor C_S1Human body equivalent capacitance C of the first end of_BWill be in a grounded state without causing the first sensing capacitor C_S1Sense a change in capacitance value. In this case, if the first sensing capacitor C_S1Matching the third capacitor C3, the voltage at the first internal node NS1 will only be related to the temperature-induced capacitance change and the first sensing capacitor C_S1The inherent capacitance is independent of the capacitance of the third capacitor C3.

Furthermore, in the second stage ST2, the detection circuit 100 may sense the second sensing capacitance C_S2Discharging to ground, charging the fourth capacitor C4 to the operating voltage VDD, and charging the second sensing capacitor C_S2And a fourth capacitor C4 coupled to the second internal node NS2 such that the second sensing capacitor C_S2And the internal charge of the fourth capacitor C4 may be redistributed. In this case, if the second sensing capacitor C_S2Matching the fourth capacitor C4, the voltage at the second internal node NS2 will only approach the human body to the second sensing capacitor C_S2And a second sensing capacitor C_S2The first end of the first capacitor is connected in parallel with a human body equivalent capacitor, is related to the change of a sensing capacitance value caused by temperature, and is connected with a second sensing capacitor C_S2The inherent capacitance is independent of the capacitance of the fourth capacitor C4.

Furthermore, since the differential integrator 110 integrates the voltages of the first and second internal nodes NS1 and NS2 through the first and second capacitors C1 and C2, respectively, the detected voltage VOUT varies inversely to cause the first sensing capacitor C to sense the voltage VOUT_S1And a second sensing capacitor C_S2The change of the sensing capacitance value caused by temperatureSo as to cancel each other out, and the detection voltage signal VOUT can only be related to the change of the sensing capacitance value caused by the approach of the human body.

In the first stage ST1, the detection circuit 100 may pass through the first sensing capacitor C_S1The effect of the equivalent capacitance of the human body is detected, and in the second stage ST2, the detection circuit 100 can pass through the second sensing capacitor C_S2The influence caused by the equivalent capacitance of the human body is detected. Thus, after the first stage ST1 and the second stage ST2 are completed, the detection voltage signal VOUT output by the detection circuit 100 includes the voltage signal output through the first sensing capacitor C_S1And a second sensing capacitor C_S2The detected human equivalent capacitance changes, so that the change of the human equivalent capacitance can be completely presented, and the touch detection accuracy is improved.

In the first stage ST1, when the first sensing capacitor C_S1And the third capacitor C3 is charged and used as the second sensing capacitor C_S2And the fourth capacitor C4, the first internal node NS1 and the second internal node NS2 are at the same voltage, so the first sensing capacitor C is charged_S1And a second sensing capacitor C_S2Mutual capacitance between C_mWill be at the same potential, in which case the mutual capacitance C_mNo charge is stored. Similarly, in the second stage ST2, when the first sensing capacitor C is turned on_S1And the third capacitor C3 is charged and used as the second sensing capacitor C_S2And the fourth capacitor C4, the first internal node NS1 and the second internal node NS2 are at the same voltage, so that the mutual capacitance C is equal to the voltage of the first internal node NS1_mNo charge is stored. Therefore, the detection voltage signal VOUT output by the detection circuit 100 is hardly subject to mutual capacitance C_mThe influence of (C) and then the detection voltage signal VOUT can be more accurately presented because of the proximity of the human body to the first sensing capacitor C_S1And a second sensing capacitor C_S2The change caused by the capacitance value can be sensed, and a more accurate result can be obtained when touch detection is performed according to the detection voltage signal VOUT.

In addition, in some embodiments, the detection voltage signal VOUT output by the detection circuit 100 is provided to a reading circuit, such as an analog-to-digital converter (analog-to-digital converter) for performing a numerical value interpretation, so that the detection circuit 100 can continuously perform a plurality of detection operations according to the voltage specification required by the analog-to-digital converter, so as to gradually integrate the detection voltage signal VOUT into a predetermined detection range suitable for the operation of the analog-to-digital converter. In some embodiments of the present application, a chip may include the detection circuit 100 and the read circuit.

Furthermore, since the capacitance variation caused by the temperature is automatically offset when the detection circuit 100 outputs the detection voltage signal VOUT, no space is required to be reserved for the influence of the temperature on the detection voltage signal VOUT when the analog-digital conversion circuit is used to perform the subsequent value interpretation, in other words, the whole input range of the analog-digital conversion circuit can be effectively used for interpreting the variation caused by the equivalent capacitance of the human body, thereby increasing the range of the value that can be interpreted effectively and achieving the purpose of increasing the effective sensing range.

In the first period TP1 of fig. 4, the first switching circuit SW1 turns on the electrical connection between the first input terminal P1 and the first internal node NS1, and turns off the electrical connection between the first input terminal P1 and the ground terminal GND. The second switching circuit SW2 turns off the electrical connection between the second input terminal P2 and the first internal node NS1, and turns on the electrical connection between the second input terminal P2 and the ground GND. The third switching circuit SW3 can conduct the electrical connection between the first internal node NS1 and the operating voltage VDD, so that the first sensing capacitor C_S1Is charged to the operating voltage VDD. The fourth switching circuit SW4 can disable the electrical connection between the first internal node NS1 and the ground GND.

The fifth switching circuit SW5 turns off the electrical connection between the third input terminal P3 and the second internal node NS2, and turns on the electrical connection between the third input terminal P3 and the ground GND. The sixth switching circuit SW6 turns on the electrical connection between the fourth input terminal P4 and the second internal node NS2 and turns off the electrical connection between the fourth input terminal P4 and the ground GND. The seventh switching circuit SW7 can conduct the electrical connection between the second internal node NS2 and the operating voltage VDD, so that the second sensing capacitor C_S2Is charged to the operating voltage VDD. The eighth switching circuit SW8 can disable the electrical connection between the second internal node NS2 and the ground GND.

In addition, in the first period TP1, the eleventh switching circuit SW11 may turn on the electrical connection between the first end of the third capacitor C3 and the ground GND. The twelfth switching circuit SW12 can cut off the electrical connection between the first end of the third capacitor C3 and the operating voltage VDD. The thirteenth switching circuit SW13 is capable of turning off the electrical connection between the second terminal of the third capacitor C3 and the ground GND, and turning on the electrical connection between the second terminal of the third capacitor C3 and the operating voltage VDD, so that the second terminal of the third capacitor C3 is charged to the operating voltage VDD. The fourteenth switching circuit SW14 may disable the electrical connection between the first terminal of the third capacitor C3 and the first internal node NS 1.

The fifteenth switching circuit SW15 can turn on the electrical connection between the first end of the fourth capacitor C4 and the ground GND. The sixteenth switching circuit SW16 can cut off the electrical connection between the first end of the fourth capacitor C4 and the operating voltage VDD. The seventeenth switching circuit SW17 is capable of turning off the electrical connection between the second terminal of the fourth capacitor C4 and the ground GND, and turning on the electrical connection between the second terminal of the fourth capacitor C4 and the operating voltage VDD, so that the second terminal of the fourth capacitor C4 is charged to the operating voltage VDD. The eighteenth switching circuit S18 may turn off the electrical connection between the first terminal of the fourth capacitor C4 and the second internal node NS 2.

In addition, in the first period TP1, the ninth switching circuit SW9 may cut off the electrical connection between the first input terminal of the differential amplifier 112 and the first internal node NS1, and the tenth switching circuit SW10 may cut off the electrical connection between the first input terminal of the differential amplifier 112 and the second internal node NS 2.

Then, in a second period TP2 after the first period TP1, the third switching circuit SW3 may cut off the electrical connection between the first internal node NS1 and the operating voltage VDD, and the eleventh switching circuit SW11 may cut off the electrical connection between the first end of the third capacitor C3 and the ground GND. In addition, the fourteenth switching circuit SW14 can turn on the electrical connection between the first end of the third capacitor C3 and the first internal node NS1, and the thirteenth switchThe switch circuit SW13 turns on the electrical connection between the second terminal of the third capacitor C3 and the ground GND, and turns off the electrical connection between the second terminal of the third capacitor C3 and the operating voltage VDD. At this time, the first sensing capacitor C_S1The first terminal of the first sensing capacitor C and the first terminal of the third capacitor C3 are both coupled to the first internal node NS1, so that the first sensing capacitor C_S1And the charge in the third capacitor C3 is redistributed and the voltage Vx of the first internal node NS1₁Can be represented by formula (1).

At the first sensing capacitor C_S1In the case of matching with the third capacitor C3, for example, when the capacitance value of the third capacitor C3 is the inherent capacitance value C of the first sensing capacitor_S1One third of (3), the voltage Vx of the first internal node NS1₁Will be coupled to the first sensing capacitor C_S1The specific capacitance value of (a) is independent of the capacitance value of the third capacitor C3, and equation (1) can be rewritten as equation (2).

That is, the voltage VX of the first internal node NS1₁May be substantially equal to 1/2 times the operating voltage VDD. Similarly, in the second period TP2, the seventh switching circuit SW7 may turn off the electrical connection between the second internal node NS2 and the operating voltage VDD, the fifteenth switching circuit SW15 may turn off the electrical connection between the first end of the fourth capacitor C4 and the ground GND, the eighteenth switching circuit SW18 may turn on the electrical connection between the first end of the fourth capacitor C4 and the second internal node NS2, and the seventeenth switching circuit SW17 may turn on the electrical connection between the second end of the fourth capacitor C4 and the ground GND and turn off the electrical connection between the second end of the fourth capacitor C4 and the operating voltage VDD. At this time, the second sensing capacitor C_S2The first terminal of the second sensing capacitor C4 and the first terminal of the fourth capacitor C4 are both coupled to the second internal node NS2, thereby the second sensing capacitor C_S2And a fourth capacitorThe charge in C4 is redistributed to the second sensing capacitor C_S2In the case of matching with the fourth capacitor C4, for example, when the capacitance value of the fourth capacitor C4 is the second sensing capacitor C_S2One third of the inherent capacitance value of (b), the voltage Vx of the second internal node NS2₂Will be coupled to the second sensing capacitor C_S2The inherent capacitance of the capacitor C4 is independent of the capacitance of the fourth capacitor C4, and the voltage VX is applied₂Can be represented by formula (3).

In some embodiments, since the detection circuit 100 and the housing may be manufactured or designed by different manufacturers, the self-capacitance of the housing may not be known yet when the detection circuit 100 is manufactured, and the first sensing capacitor C cannot be predicted_S1And a second sensing capacitor C_S2Is the magnitude of the inherent capacitance of (a). In this case, the third capacitor C3 may comprise a variable capacitor or a capacitor array, such that the first sensing capacitor C is known to the user_S1According to the magnitude of the inherent capacitance, the first sensing capacitor C can be used_S1And the capacitance value of the variable capacitor or the capacitor array is set by the control signal, so that the third capacitor C3 can be connected with the first sensing capacitor C_S1And (4) matching. Similarly, the fourth capacitor C4 may include a variable capacitor or a capacitor array, and the second sensing capacitor C is known by the user_S2The intrinsic capacitance value can be determined according to the second sensing capacitance C_S2And the capacitance value of the variable capacitance or the capacitance array is set by the control signal, so that the fourth capacitance C4 can be connected with the second sensing capacitance C_S2And (4) matching.

In addition, in FIG. 4, the seventh control signal K7 changes from low to high after the third control signal K3 changes from high to low, and the fifth control signal K5 changes from high to low after the seventh control signal K7 changes from low to high, so as to ensure the first sensing capacitor C_S1A second sensing capacitor C_S2The charges in the third capacitor C3 and the fourth capacitor C4 are not transferred to or from the outside when they are redistributed. However, the present application is not limited thereto, and in some embodiments, the seventh control signal K7 may change from low to high simultaneously when the third control signal K3 changes from high to low, and the fifth control signal K5 may change from high to low simultaneously when the seventh control signal K7 changes from low to high. In addition, in some embodiments, the fifth control signal K5 and the sixth control signal K6 may be complementary control signals, so that the fifth control signal K5 and the sixth control signal K6 synchronously shift potentials.

In a third period TP3 after the second period TP2, the ninth switching circuit SW9 may turn on the electrical connection between the first input terminal of the differential amplifier 112 and the first internal node NS1 for integration through the first capacitor C1, and the tenth switching circuit SW10 may turn on the electrical connection between the first input terminal of the differential amplifier 112 and the second internal node NS2 for integration through the second capacitor C2. In the third period TP3, the duration of the eighth control signal K8 being at the high level is related to the integration time required by the first capacitor C1 and the second capacitor C2, for example, the duration of the eighth control signal K8 being at the high level may be set to be greater than or equal to a duration sufficient for the first capacitor C1 and the second capacitor C2 to complete integration and for the voltage VPO at the first output terminal and the voltage VNO at the second output terminal of the differential amplifier 112 to stabilize.

In an ideal situation, i.e. without temperature change and without human body approaching, the first sensing capacitor C_S1And the third capacitor C3 for the voltage Vx of the first internal node NS1₁Can cancel each other out, so that the voltage Vx of the first internal node NS1₁Will equal 1/2 times VDD to the first sensing capacitance C_S1Is independent of the magnitude of the capacitance of the third capacitor C3. Similarly, the second sensing capacitor C_S2And the fourth capacitor C4 for the voltage Vx of the second internal node NS2₂Can also be cancelled out, so that the voltage Vx of the second internal node NS2₂Will also equal 1/2 times VDDThere is no charge transfer between the first capacitor C1 and the second capacitor C2.

The detection voltage signal VOUT is mainly used for presenting the proximity of a human body to the first sensing capacitor C_S1And a second sensing capacitor C_S2The voltage Vx of the first internal node NS1₁And voltage Vx of second internal node NS2₂And a first sensing capacitor C_S1And a second sensing capacitor C_S2The inherent capacitance of the third capacitor C3 and the capacitance of the fourth capacitor C4 are independent, so that the subsequently generated detection voltage signal VOUT will not be influenced by the first sensing capacitor C_S1A second sensing capacitor C_S2The third capacitor C3 and the fourth capacitor C4 are varied to show the first sensing capacitor C when a human body approaches the sensor simply and precisely_S1And a second sensing capacitor C_S2The change caused by the capacitance value is sensed.

However, when the capacitance value changes due to temperature change and/or a human body approaches, the capacitance change value Δ C due to temperature_T1And equivalent capacitance C of human body_BThe sensed capacitance between the first input terminal P1 and the second input terminal P2 is changed, and the voltage VX of the first internal node NS1 is changed₁And will vary accordingly, resulting in a portion of the charge moving into or out of the first capacitor C1, wherein the amount of charge transferred, Δ QA1, can be expressed as equation (4).

Similarly, the value of the temperature-induced change in capacitance Δ C_T2The capacitance between the third input terminal P3 and the fourth input terminal P4 is also changed, and the voltage VX of the second internal node NS2 is changed₂However, in the first stage ST1, the third input terminal P3 remains coupled to the ground GND, since the human body is usually grounded, when the human body approaches the second sensing capacitor C_S2Is coupled to the second sensing capacitor C_S2Human body equivalence of first end ofCapacitor C_BThe two terminals of the second capacitor C2 are grounded without affecting the sensing capacitance between the third input terminal P3 and the fourth input terminal P4, and the amount of transferred charge Δ QA2 of the second capacitor C2 can be expressed by the formula (5).

Since the first capacitor C1 and the second capacitor C2 are respectively disposed at the positive input terminal and the negative input terminal of the differential amplifier 112, the transferred charge amounts Δ QA1 and Δ QA2 will generate opposite changes in the output voltage of the differential amplifier 112, i.e., the output voltage of the first sensing capacitor C is changed inversely_S1And a second sensing capacitor C_S2Under the condition that the inherent capacitance values are the same, the first sensing capacitor C_S1And the capacitance change value deltaC of the third capacitor C3 caused by temperature drift_T1Will be connected with the second sensing capacitor C_S2And the capacitance change value deltaC of the fourth capacitor C4 caused by temperature_T2Cancel each other out, so the voltage outputted by the differential integrator circuit 110 in the first stage will only be equal to the human body equivalent capacitance C_BThe resulting effect is related to the temperature-induced change in capacitance. For example, if the first capacitor C1 and the second capacitor C2 have the same capacitance, the detection voltage signal VOUT output by the detection circuit 100 in the first stage can be represented by equation (6).

In the fourth period TP4 of the second stage ST2, the first switching circuit SW1 may turn off the electrical connection between the first input terminal P1 and the first internal node NS1 and turn on the electrical connection between the first input terminal P1 and the ground terminal GND, and the second switching circuit SW2 may turn on the electrical connection between the second input terminal P2 and the first internal node NS1 and turn off the electrical connection between the second input terminal P2 and the ground terminal GND. In addition, the third switching circuit SW3 can disable the electrical connection between the first internal node NS1 and the operating voltage VDD, and the fourth switching circuit SWSW4 can conduct the electrical connection between the first internal node NS1 and the ground GND to make the first sensing capacitor C_S1Is discharged to the ground GND.

The fifth switching circuit SW5 turns on the electrical connection between the third input terminal P3 and the second internal node NS2 and turns off the electrical connection between the third input terminal P3 and the ground GND. The sixth switching circuit SW6 turns off the electrical connection between the fourth input terminal P4 and the second internal node NS2, and turns on the electrical connection between the fourth input terminal P4 and the ground GND. The seventh switching circuit SW7 turns off the electrical connection between the second internal node NS2 and the operating voltage VDD, and the eighth switching circuit SW8 turns on the electrical connection between the second internal node NS2 and the ground GND, so that the second sensing capacitor C is connected to the ground GND_S2Is discharged to the ground GND.

The eleventh switching circuit SW11 can turn off the electrical connection between the first end of the third capacitor C3 and the ground GND, and the twelfth switching circuit SW12 can turn on the electrical connection between the first end of the third capacitor C3 and the operating voltage VDD, so that the third capacitor C3 is charged to the operating voltage VDD. The thirteenth switching circuit SW13 turns on the electrical connection between the second terminal of the third capacitor C3 and the ground GND, and turns off the electrical connection between the second terminal of the third capacitor C3 and the operating voltage VDD, and the fourteenth switching circuit SW14 turns off the electrical connection between the first terminal of the third capacitor C3 and the first internal node NS 1.

The fifteenth switching circuit SW15 can turn off the electrical connection between the first end of the fourth capacitor C4 and the ground GND, and the sixteenth switching circuit SW16 can turn on the electrical connection between the first end of the fourth capacitor C4 and the operating voltage VDD, so that the fourth capacitor C4 is charged to the operating voltage VDD. The seventeenth switching circuit SW17 turns on the electrical connection between the second terminal of the fourth capacitor C4 and the ground GND, and turns off the electrical connection between the second terminal of the fourth capacitor C4 and the operating voltage VDD, and the eighteenth switching circuit SW18 turns off the electrical connection between the first terminal of the fourth capacitor C4 and the second internal node NS 2.

In addition, in the fourth period TP4, the ninth switching circuit SW9 may cut off the electrical connection between the first input terminal of the differential amplifier 112 and the first internal node NS1, and the tenth switching circuit SW10 may cut off the electrical connection between the first input terminal of the differential amplifier 112 and the second internal node NS 2.

Then, in a fifth period TP5 after the fourth period TP4, the fourth switching circuit SW4 may cut off the electrical connection between the first internal node NS1 and the ground terminal GND, the eighth switching circuit SW8 may cut off the electrical connection between the second internal node NS2 and the ground terminal GND, the twelfth switching circuit SW12 may cut off the electrical connection between the first end of the third capacitor C3 and the operating voltage VDD, and the sixteenth switching circuit SW16 may cut off the electrical connection between the first end of the fourth capacitor C4 and the operating voltage VDD. The fourteenth switching circuit SW14 can switch on the electrical connection between the first end of the third capacitor C3 and the first internal node NS1, so that the first sensing capacitor C is connected to the first sensing capacitor C_S1Redistribute the charges in the third capacitor C3, and the eighteenth switching circuit SW18 can conduct the electrical connection between the first end of the fourth capacitor C4 and the second internal node NS2, so that the second sensing capacitor C is connected to the second sensing capacitor C_S2And the charge in the fourth capacitor C4. The thirteenth switching circuit SW13 turns off the electrical connection between the second terminal of the third capacitor C3 and the ground GND, and turns on the electrical connection between the second terminal of the third capacitor C3 and the operating voltage VDD. The seventeenth switching circuit SW17 turns off the electrical connection between the second terminal of the fourth capacitor C4 and the ground terminal, and turns on the electrical connection between the second terminal of the fourth capacitor C4 and the operating voltage VDD. At this time, since the second terminal of the third capacitor C3 is raised to the operating voltage VDD, the voltage of the first terminal of the third capacitor C3 is also raised to twice the operating voltage 2VDD at the first sensing capacitor C_S1After the charge in the third capacitor C3 is completely redistributed, the voltage Vx of the first internal node NS1₁Can be represented by formula (7).

At the first sensing capacitor C_S1In the case of matching with the third capacitor C3, for example, when the capacitance value of the third capacitor C3 is the first sensing capacitor C_S1When the capacitance value is one third of the intrinsic capacitance value, the formula (7) can be rewritten to the formula (8).

Similarly, at the second sensing capacitance C_S2In the case of matching with the fourth capacitor C4, for example, when the capacitance value of the fourth capacitor C4 is the second sensing capacitor C_S2One third of the inherent capacitance value of (b), the voltage Vx of the second internal node NS2₂May be represented by formula (9).

In the fifth period TP5 of FIG. 4, the seventh control signal K7 changes from low to high after the fourth control signal K4 changes from high to low to ensure the first sensing capacitor C_S1A second sensing capacitor C_S2The charges in the third capacitor C3 and the fourth capacitor C4 are not transferred to or from the outside when they are redistributed. However, in some embodiments, when the fourth control signal K4 changes from high to low, the seventh control signal K7 may also change from low to high simultaneously. In addition, the fifth control signal K5 can be changed from low to high after the seventh control signal K7 is changed from low to high, so as to ensure that the second terminals of the third capacitor C3 and the fourth capacitor C4 are further increased in potential during the process of redistributing charges.

In a sixth time period TP6 after the fifth time period TP5, the ninth switching circuit SW9 may turn on the electrical connection between the first input terminal of the differential amplifier 112 and the first internal node NS1 for integration through the first capacitor C1, and the tenth switching circuit SW10 may turn on the electrical connection between the second input terminal of the differential amplifier 112 and the second internal node NS2 for integration through the second capacitor C2, at which time the first output terminal and the second output terminal of the differential amplifier 112 may also output the detection voltage signal VOUT.

According to the equations (8) and (9), it can be seen that, in an ideal situation, the first sensing capacitor C_S1The inherent capacitance and the capacitance of the third capacitor C3 for the voltage VX of the first internal node NS1₁Can cancel each other out, and the second sensing capacitor C_S2The inherent capacitance and the capacitance of the fourth capacitor C4 for the voltage VX of the second internal node NS2₂Can also cancel each other out, so that the voltage Vx of the first internal node NS1₁And a voltage Vx of a second internal node NS2₂Is equal to 1/2 times VDD, there will be no charge transfer in the first capacitor C1 and the second capacitor C2.

However, when there is a temperature change, the first sensing capacitor C_S1And the capacitance change value deltaC of the third capacitor C3 due to temperature_T1The capacitance between the first input terminal P1 and the second input terminal P2 is still changed, and the voltage VX of the first internal node NS1 is changed₁And will vary accordingly, resulting in a portion of the charge moving into or out of the first capacitor C1. In addition, since the first input terminal P1 is continuously coupled to the ground GND in the second stage ST2, even when a human body approaches the first sensing capacitor C_S1Is coupled to the first sensing capacitor C_S1Human body equivalent capacitance C of the first end of_BThe two ends of the capacitor are grounded without affecting the capacitance, and the amount of transferred charge Δ QB1 can be represented by equation (10).

In contrast, since the eighth switching circuit SW8 turns off the electrical connection between the third input terminal P3 and the ground terminal GND during the fifth period TP5, a human body approaches the second sensing capacitor C_S2Time, equivalent capacitance C of human body_BWill pass through the second sensing capacitor C_S2First terminal and second sensing capacitor C_S2In parallel, the capacitance between the third input terminal P3 and the fourth input terminal P4 is affected. In addition, when there is a temperature change, the second sensing circuit senses electricityContainer C_S2And the capacitance change value deltaC of the fourth capacitor C4 due to temperature_T2The capacitance between the third input terminal P3 and the fourth input terminal P4 is also changed, so that the voltage VX of the second internal node NS2 is changed₂This in turn results in a partial charge transfer into or out of the second capacitor C2, wherein the amount of charge transferred Δ QB2 can be expressed as in equation (11).

In the equations (10) and (11), since the influence of the variation of the sensing capacitance due to the temperature exists in the form of common mode noise, the output voltage of the differential amplifier 112 is not influenced, so that the variation of the sensing voltage signal VOUT in the second stage ST2 is only equal to the detected human body equivalent capacitance C_BIt is related. That is, in the first stage ST1, the detection circuit 100 passes through the first sensing capacitor C_S1To detect the equivalent capacitance C of the human body_BThe influence on the capacitance between the first input terminal P1 and the second input terminal P2 is determined by the detection circuit 100 passing through the second sensing capacitor C during the second stage ST2_S2To detect the equivalent capacitance C of the human body_BThe influence on the capacitance between the third input terminal P3 and the fourth input terminal P4 is that the detection voltage signal VOUT can pass through the first sensing capacitor C after the first stage ST1 and the second stage ST2 of the detection operation are completed_S1And a second sensing capacitor C_S2Detected human body equivalent capacitance C_BChange to completely present the equivalent capacitance C of the human body_BAnd ensure the accuracy of touch detection.

Furthermore, a first sensing capacitor C_S1And a second sensing capacitor C_S2Although mutual capacitance C may be generated between them_mHowever, in the first phase ST1 of the sensing operation, the first internal node NS1 and the second internal node NS2 are also charged to the operating voltage VDD, and in the second phase ST2, the first internal node NS1 and the second internal node NS2 are also discharged to the ground GND, so that during the sensing operation,mutual capacitance C_mWill remain at approximately the same voltage without storing charge. Thus, the mutual capacitance C can be reduced_mThe influence on the detection voltage signal VOUT can also obtain more accurate results when the touch detection is carried out according to the detection voltage signal VOUT.

In addition, in fig. 3, the differential integration circuit 110 may further include a first reset switch RSW1 and a second reset switch RSW 2. The first reset switch RSW1 may be coupled to the first input terminal of the differential amplifier 112 and the first output terminal of the differential amplifier 112, and the first reset switch RSW1 may conduct the electrical connection between the first input terminal of the differential amplifier 112 and the first output terminal of the differential amplifier 112 during the reset operation to perform the discharge reset on the first capacitor C1. The second reset switch RSW2 may be coupled to the second input terminal of the differential amplifier 112 and the second output terminal of the differential amplifier 112, and the second reset switch RSW2 may conduct the electrical connection between the second input terminal of the differential amplifier 112 and the second output terminal of the differential amplifier 112 during the reset operation to perform the discharge reset on the second capacitor C2.

In addition, in the detecting operation, the first reset switch RSW1 may cut off the electrical connection between the first input terminal of the differential amplifier 112 and the first output terminal of the differential amplifier 112, and the second reset switch RSW2 may cut off the electrical connection between the second input terminal of the differential amplifier 112 and the second output terminal of the differential amplifier 112, so that the differential integration circuit 110 can perform integration through the first capacitor C1 and the second capacitor C2.

Since the first reset switch RSW1 and the second reset switch RSW2 can discharge and reset the first capacitor C1 and the second capacitor C2, the differential integrator circuit 110 is not affected by the previous detection operation during integration, thereby improving the accuracy and stability of the detection circuit 100.

In the embodiment of fig. 3, the detection circuit 100 removes the first sensing capacitor C through the third capacitor C3 and the fourth capacitor C4_S1And a second sensing capacitor C_S2The influence of the intrinsic capacitance value on the detection voltage signal VOUTAnd removing the first sensing capacitor C caused by temperature_S1And a second sensing capacitor C_S2The error caused by the change of the sensed capacitance value. In some embodiments, the third capacitor C3 and the fourth capacitor C4 may be replaced by external sensing capacitors to save the area required by the detection circuit.

Fig. 5 is a schematic diagram of a detection circuit 200 according to another embodiment of the present application, and the detection circuit 200 has a similar structure to the detection circuit 100 and can operate according to a similar principle. However, the detection circuit 200 may further include a fifth input terminal P5, a sixth input terminal P6, a seventh input terminal P7, an eighth input terminal P8, a nineteenth switching circuit SW19, a twentieth switching circuit SW20, a twenty-first switching circuit SW21, a twenty-second switching circuit SW22, a twenty-third switching circuit SW23, a twenty-fourth switching circuit SW24, a twenty-fifth switching circuit SW25, a twenty-sixth switching circuit SW26, a twenty-seventh switching circuit SW27, and a twenty-eighth switching circuit SW 28.

In fig. 5, the fifth input terminal P5 may be coupled to the third sensing capacitor C_S3The sixth input terminal P6 may be coupled to the third sensing capacitor C_S3The seventh input terminal P7 may be coupled to the fourth sensing capacitor C_S4And the eighth input terminal P8 may be coupled to the fourth sensing capacitor C_S4The second end of (a). First sensing capacitor C_S1A second sensing capacitor C_S2A third sensing capacitor C_S3And a fourth sensing capacitor C_S4Although the first sensing capacitor C has a fixed capacitance, when a human body approaches or a temperature changes, the first sensing capacitor C sensed by the detection circuit 200_S1A second sensing capacitor C_S2A third sensing capacitor C_S3And a fourth sensing capacitor C_S4The sensing capacitance will be changed, so the detection circuit 200 can pass through the first sensing capacitor C_S1A second sensing capacitor C_S2A third sensing capacitor C_S3And a fourth sensing capacitor C_S4And detecting the capacitance change to output a corresponding detection voltage signal VOUT.

In this embodiment, the third sensing capacitor C_S3And a fourth sensing capacitor C_S4And a first sensing capacitor C_S1And a second sensing capacitor C_S2Similarly, it may be a self-contained enclosure formed by at least a portion of the housing of the electronic device 20 housing the detection circuit 200. For example, the third sensing capacitor C_S3First terminal and fourth sensing capacitor C_S4May be located outside at least a portion of the housing, and the third sensing capacitor C_S3Second terminal and fourth sensing capacitor C_S4May be located inside at least a portion of the housing. Thus, when a human body approaches the shell, the equivalent capacitance C of the human body_BWill be coupled to the first sensing capacitor C_S1First terminal, second sensing capacitor C_S2First terminal, third sensing capacitor C_S3First terminal and fourth sensing capacitor C_S4Is coupled to the first end of the first sensing capacitor C_S1A second sensing capacitor C_S2A third sensing capacitor C_S3And a fourth sensing capacitor C_S4The sensed capacitance value of (a) changes.

FIG. 7 shows a first sensing capacitor C according to an embodiment of the present application_S1A second sensing capacitor C_S2A third sensing capacitor C_S3And a fourth sensing capacitor C_S4The setting relationship diagram of (1). In FIG. 7, the first sensing capacitor C_S1And a second sensing capacitor C_S2Are adjacently arranged, a second sensing capacitor C_S2And a third sensing capacitor C_S3Are adjacently arranged, and the third sensing capacitor C_S3And a fourth sensing capacitor C_S4Are adjacently disposed, so that the first sensing capacitor C_S1And a second sensing capacitor C_S2Will generate mutual capacitance C_m1A second sensing capacitor C_S2And a third sensing capacitor C_S3Will generate mutual capacitance C_m2Third sensing capacitor C_S3And a fourth sensing capacitor C_S4Will generate mutual capacitance C_m3。

Since the detection circuit 200 can use the self-capacitance of the external housing as the third sensing capacitor C_S3And a fourth sensing capacitor C_S4To cancel the first sensing capacitor C_S1And a second sensing capacitor C_S2The influence of the intrinsic capacitance value on the detection voltage signal VOUTFirst sensing capacitor C for sounding and counteracting temperature_S1And a second sensing capacitor C_S2Can eliminate the first mutual capacitance C_m1A second mutual capacitance C_m2And a third mutual capacitance C_m3The influence on the sense voltage VOUT can be eliminated by replacing the third capacitor C3 and the fourth capacitor C4 in the sensing circuit 100, thereby reducing the circuit area required by the sensing circuit 200.

In fig. 5, the nineteenth switching circuit SW19 may be coupled to the first internal node NS1 and the first input NI1 of the differential integration circuit 210, and the nineteenth switching circuit SW19 may turn on or off the electrical connection between the first internal node NS1 and the first input NI1 of the differential integration circuit 210. The twentieth switching circuit SW20 may be coupled to the second internal node NS2 and the second input NI2 of the differential integration circuit 210, and the twentieth switching circuit SW20 may turn on or off the electrical connection between the second internal node NS2 and the second input NI2 of the differential integration circuit 210. As a result, when the detection circuit 200 performs the detection operation, the differential integration circuit 210 is coupled to the first internal node NS1 and the second internal node NS2 through the nineteenth switching circuit SW19 and the twentieth switching circuit SW20, and integrates the voltages of the first internal node NS1 and the second internal node NS2 to generate the detection voltage signal VOUT.

The twenty-first switching circuit SW21 can turn on or off the electrical connection between the first input NI1 of the differential integration circuit 210 and the ground GND. The twenty-second switching circuit SW22 can turn on or off the electrical connection between the first input NI1 of the differential integration circuit 210 and the operating voltage VDD. The twenty-third switching circuit SW23 can turn on or off the electrical connection between the fifth input terminal P5 and the ground GND, and turn on or off the electrical connection between the fifth input terminal P5 and the first input terminal NI1 of the differential integration circuit 210. The twenty-fourth switching circuit SW24 can turn on or off the electrical connection between the sixth input terminal P6 and the ground GND, and turn on or off the electrical connection between the sixth input terminal P6 and the first input terminal NI1 of the differential integration circuit 210.

The twenty-fifth switching circuit SW25 can turn on or off the electrical connection between the second input NI2 of the differential integration circuit 210 and the operating voltage VDD. The twenty-sixth switching circuit SW26 can turn on or off the electrical connection between the second input NI2 of the differential integration circuit 210 and the ground GND. The twenty-seventh switching circuit SW27 can turn on or off the electrical connection between the seventh input terminal P7 and the ground GND, and turn on or off the electrical connection between the seventh input terminal P7 and the second input terminal NI2 of the differential integration circuit 210. The twenty-eighth switching circuit SW28 can turn on or off the electrical connection between the eighth input terminal P8 and the ground GND, and turn on or off the electrical connection between the eighth input terminal P8 and the second input terminal NI2 of the differential integration circuit 210.

In the present embodiment, the twenty-third switching circuit SW23 includes a thirteenth switch S13 and a fourteenth switch S14. The thirteenth switch S13 has a first terminal, a second terminal and a control terminal, the first terminal of the thirteenth switch S13 is coupled to the fifth input terminal P5, and the second terminal of the thirteenth switch S13 is coupled to the first input terminal NI1 of the differential integration circuit 210. The fourteenth switch S14 has a first terminal, a second terminal and a control terminal, the first terminal of the fourteenth switch S14 is coupled to the fifth input terminal P5, and the second terminal of the fourteenth switch S14 is coupled to the ground GND.

The twenty-fourth switching circuit SW24 includes a fifteenth switch S15 and a sixteenth switch S16, the fifteenth switch S15 has a first terminal, a second terminal and a control terminal, the first terminal of the fifteenth switch S15 is coupled to the sixth input terminal P6, and the second terminal of the fifteenth switch S15 is coupled to the first input terminal NI1 of the differential integrator circuit 210. The sixteenth switch S16 has a first terminal, a second terminal and a control terminal, the first terminal of the sixteenth switch S16 is coupled to the sixth input terminal P6, and the second terminal of the sixteenth switch S16 is coupled to the ground GND.

The twenty-seventh switching circuit SW27 includes a seventeenth switch S17 and an eighteenth switch S18. The seventeenth switch S17 has a first terminal, a second terminal and a control terminal, the first terminal of the seventeenth switch S17 is coupled to the seventh input terminal P7, and the second terminal of the seventeenth switch S17 is coupled to the second input terminal NI2 of the differential integrator circuit 210. The eighteenth switch S18 has a first terminal, a second terminal and a control terminal, the first terminal of the eighteenth switch S18 is coupled to the seventh input terminal P7, and the second terminal of the eighteenth switch S18 is coupled to the ground GND.

The twenty-eighth switching circuit SW28 includes a nineteenth switch S19 and a second time switch S20, the nineteenth switch S19 has a first terminal, a second terminal and a control terminal, the first terminal of the nineteenth switch S19 is coupled to the eighth input terminal P8, and the second terminal of the nineteenth switch S19 is coupled to the second input terminal NI2 of the differential integrator circuit 210. The twentieth switch S20 has a first terminal, a second terminal and a control terminal, the first terminal of the twentieth switch S20 is coupled to the eighth input terminal P8, and the second terminal of the twentieth switch S20 is coupled to the ground GND.

In addition, the twenty-first switching circuit SW21, the twenty-second switching circuit SW22, the twenty-fifth switching circuit SW25, and the twenty-sixth switching circuit SW26 may be implemented by a single switch.

In fig. 5, the first switching circuit SW1, the second switching circuit SW2, the fifth switching circuit SW5, the sixth switching circuit SW6, the twenty-third switching circuit SW23, the twenty-fourth switching circuit SW24, the twenty-seventh switching circuit SW27 and the twenty-eighth switching circuit SW28 can be electrically connected or disconnected according to the first control signal K1 and the second control signal K2, and the third switching circuit SW3, the seventh switching circuit SW7, the twenty-first switching circuit SW21 and the twenty-fifth switching circuit SW25 can be electrically connected or disconnected according to the third control signal K3. The fourth switching circuit SW4, the eighth switching circuit SW8, the twenty-second switching circuit SW22 and the twenty-sixth switching circuit SW26 can be electrically connected or disconnected according to the fourth control signal K4. The nineteenth switching circuit SW19 and the twentieth switching circuit SW20 can be electrically connected or disconnected according to the ninth control signal K9, and the ninth switching circuit SW9 and the tenth switching circuit SW10 can be electrically connected or disconnected according to the eighth control signal K8.

Fig. 6 is a timing diagram of signals received by the detection circuit 200 when performing a detection operation. In this embodiment, when the control signal K1 is at a high level, the first switching circuit SW1 turns on the electrical connection between the first input terminal P1 and the first internal node NS1, the second switching circuit SW2 turns on the electrical connection between the second input terminal P2 and the ground terminal GND, the fifth switching circuit SW5 turns on the electrical connection between the third input terminal P3 and the first internal node NS1, the sixth switching circuit SW6 turns on the electrical connection between the fourth input terminal P4 and the ground terminal GND, the twenty-third switching circuit SW23 turns on the electrical connection between the fifth input terminal P5 and the ground terminal GND, the twenty-fourth switching circuit SW24 turns on the electrical connection between the sixth input terminal P6 and the first input terminal 1 of the differential integration circuit 210, the twenty-seventh switching circuit SW27 turns on the electrical connection between the seventh input terminal P7 and the ground terminal GND, and the eighth switching circuit SW28 turns on the electrical connection between the eighth input terminal P8 and the second input terminal P2 of the differential integration circuit 210.

When the control signal K2 is at a high level, the first switching circuit SW1 turns on the electrical connection between the first input terminal P1 and the ground GND, the second switching circuit SW2 turns on the electrical connection between the second input terminal P2 and the first internal node NS1, the fifth switching circuit SW5 turns on the electrical connection between the third input terminal P3 and the ground GND, the sixth switching circuit SW6 turns on the electrical connection between the fourth input terminal P4 and the first internal node NS1, the twenty-third switching circuit SW23 turns on the electrical connection between the fifth input terminal P5 and the first input terminal NI1 of the differential integrating circuit 210, the twenty-fourth switching circuit SW24 turns on the electrical connection between the sixth input terminal P6 and the ground GND, the twenty-seventh switching circuit SW27 turns on the electrical connection between the seventh input terminal P7 and the second input terminal NI2 of the differential integrating circuit 210, and the twenty-eighth switching circuit SW28 turns on the electrical connection between the ground terminal P8 and the ground GND.

In addition, the switching circuits SW3, SW4, SW7, SW8, SW21, SW22, SW25, SW26, SW19, SW20, SW9 and SW10 are configured to turn on the corresponding electrical connection when the corresponding control signal of the control signals K3, K4, K8 and K9 is at a high potential, and turn off the corresponding electrical connection when the corresponding control signal of the control signals K3, K4, K8 and K9 is at a low potential.

In fig. 6, the detection operation may include a first stage ST1 and a second stage ST2, the first stage ST1 may include a first period TP1, a second period TP2 and a third period TP3, and the second stage ST2 may include a fourth period TP4, a fifth period TP5 and a sixth period TP 6.

In the first stage ST1, the detection circuit 200 may sense the first sensing capacitor C_S1Charging to the operating voltage VDD and making the third sensing capacitor C_S3Discharging to the ground terminal GND, and making the first sensing capacitor C_S1And a third sensing capacitor C_S3Is redistributed. In addition, since the fifth input terminal P5 is coupled to the third sensing capacitor C_S3The first terminal of the third sensing capacitor C is continuously coupled to the ground terminal GND_S3I.e. the third sensing capacitor C_S3The outer plate of (a) will be in a grounded state. Since the human body is usually in the grounding state, when the human body approaches the third sensing capacitor C_S3Is coupled to the third sensing capacitor C_S3Human body equivalent capacitance C of the first end of_BWill be in a grounded state without causing the third sensing capacitor C_S3Sense a change in capacitance value. Therefore, in the first sensing capacitor C_S1And a third sensing capacitor C_S3In a matched condition, the voltage at the first internal node NS1 will only be equal to the voltage at the first sensing capacitor C when a human body approaches the first input terminal P1_S1Parallel human equivalent capacitance C_BThe changes are relevant. With respect to the first sensing capacitance C_S1And a third sensing capacitor C_S3The matching conditions and operation details will be described later.

In addition, in the first stage ST1, the detection circuit 200 may sense the second sensing capacitor C_S2Discharging to the ground GND and making the fourth sensing capacitor C_S4Charging to the operation voltage VDD and then enabling the second sensing capacitor C_S2And a fourth sensing capacitor C_S4Is redistributed. In addition, since the seventh input terminal P7 is coupled to the fourth sensing capacitor C_S4And is continuously coupled to the ground GND, so that the fourth sensing capacitor C_S4I.e. the fourth sensing capacitor C_S4The outer plate of (a) will be in a grounded state. In this case, when the human body approaches the fourth sensing capacitor C_S4Is coupled to the fourth sensing capacitor C_S4Human body equivalent capacitance C of the first end of_BWill be in a grounded state without causing the fourth sensing capacitor C_S4Sense a change in capacitance value. At this time, if the second sensing capacitor C_S2And a fourth sensing capacitor C_S4If the voltage at the second internal node NS2 is matched with the voltage at the second sensing capacitor C when the human body approaches the third input terminal P3_S2Parallel human equivalent capacitance C_BThe changes are relevant. With respect to the second sensing capacitance C_S2And a fourth sensing capacitor C_S4The matching conditions and operation details will be described later.

Furthermore, since the differential integrator 210 integrates the voltages of the first internal node NS1 and the second internal node NS2 through the first capacitor C1 and the second capacitor C2, respectively, the voltages of the first internal node NS1 and the second internal node NS2 will generate an opposite change in the detection voltage signal VOUT, so that after the first stage ST1 is over, the change in the detection voltage signal VOUT will cause the first sensing capacitor C to generate an equivalent capacitance with the human body_S1And a second sensing capacitor C_S2Is detected.

In the second stage ST2, the detection circuit 200 may sense the first sensing capacitor C_S1Discharging to the ground GND and making the third sensing capacitor C_S3Charging to the operation voltage VDD and then making the first sensing capacitor C_S1And a third sensing capacitor C_S3Is redistributed. In the second stage ST2, the first input terminal P1 is coupled to the first sensing capacitor C_S1The first terminal of the first sensing capacitor C is continuously coupled to the ground GND, so that if the first sensing capacitor C is connected to the ground GND_S1And a third sensing capacitor C_S3If the voltage at the first internal node NS1 is matched, the voltage at the first internal node NS1 will only approach the third sensing capacitor C with the human body_S3Time and third sensing capacitor C_S3Parallel human equivalent capacitance C_BThe changes are relevant.

Furthermore, in the second stage ST2, the detection circuit 200 may sense the second sensing capacitance C_S2Charging to the operating voltage VDD and making the fourth sensing capacitor C_S4Discharging to the ground GND, and making the second sensing capacitor C_S2And a fourth sensing capacitor C_S4Is redistributed. In thatIn the second stage ST2, the third input P3 is coupled to the second sensing capacitor C_S2The first terminal of the second sensing capacitor C is continuously coupled to the ground GND, so that if the second sensing capacitor C is used_S2And a fourth sensing capacitor C_S4If the voltage at the second internal node NS2 is matched, the voltage at the second internal node NS2 will only approach the fourth sensing capacitor C with the human body_S4Time and fourth sensing capacitor C_S4Parallel human equivalent capacitance C_BIt is related.

Furthermore, since the differential integrator 210 integrates the voltages of the first internal node NS1 and the second internal node NS2 through the first capacitor C1 and the second capacitor C2, respectively, the voltages of the first internal node NS1 and the second internal node NS2 will generate an opposite change in the sense voltage signal VOUT, so that after the second stage ST2 is over, the change in the sense voltage signal VOUT will be equal to the change in the body equivalent capacitor C_BResulting in a third sensing capacitance C_S3And a fourth sensing capacitor C_S4Is related to a change in the sensed capacitance value.

That is, in the first stage ST1, the detection circuit 200 may pass through the first sensing capacitor C_S1And a second sensing capacitor C_S2The influence of the equivalent capacitance of the human body is detected, and in the second stage ST2, the detection circuit 200 can pass through the third sensing capacitor C_S3And a fourth sensing capacitor C_S4The influence caused by the equivalent capacitance of the human body is detected. In this way, after the first stage ST1 and the second stage ST2 are finished, the detection voltage signal VOUT outputted by the detection circuit 200 will completely represent the human body equivalent capacitance C_BFor the first sensing capacitor C_S1A second sensing capacitor C_S2A third sensing capacitor C_S3And a fourth sensing capacitor C_S4The capacitance value is sensed to improve the accuracy of touch detection according to the detection voltage signal VOUT.

However, in the first and second stages ST1 and ST2, the second sensing capacitor C_S2And a third sensing capacitor C_S3Mutual capacitance between C_m2The two terminals of the detection circuit 200 are at the same voltage, so that no charge is stored, and the detection result of the detection circuit 200 is not affected. Furthermore, the first sensingCapacitor C_S1And a second sensing capacitor C_S2Mutual capacitance between C_m1And a third sensing capacitor C_S3And a fourth sensing capacitor C_S4Mutual capacitance between C_m3Will be in an opposite charging state and therefore mutually capacitive C_m1And C_m3The influence of the difference is cancelled out in the differential integration process, and therefore, the detection voltage signal VOUT output by the detection circuit 200 is not influenced.

In the detection circuit 200, a first sensing capacitor C_S1And a third sensing capacitor C_S3The influence of the sensing capacitance variation and the self-fixed capacitance on the detection voltage signal VOUT due to the temperature can be mutually cancelled, and the second sensing capacitance C_S2And a fourth sensing capacitor C_S4Since the sensing capacitance variation caused by temperature and the influence of the self-fixed capacitor on the detection voltage signal VOUT can be mutually cancelled, the detection circuit 200 has automatically eliminated the first sensing capacitor C when outputting the detection voltage signal VOUT_S1A second sensing capacitor C_S2A third sensing capacitor C_S3And a fourth sensing capacitor C_S4Inherent capacitance itself and errors in the change in sensed capacitance due to temperature. Therefore, when the analog-digital conversion circuit is used for carrying out numerical value judgment subsequently, the influence of the reserved space on the temperature on the detection voltage signal VOUT is not needed, in other words, the whole input range of the analog-digital conversion circuit can be effectively used for judging the change caused by the human equivalent capacitance, so that the range of the numerical value which can be effectively judged is enlarged, and the purpose of improving the effective sensing range is achieved.

In the first period TP1 of FIG. 6, the first switch circuit SW1, the second switch circuit SW2, the third switch circuit SW3 and the fourth switch circuit SW4 enable the first sensing capacitor C to be turned on_S1Is charged to the operating voltage VDD. The fifth switching circuit SW5, the sixth switching circuit SW6, the seventh switching circuit SW7 and the eighth switching circuit SW8 enable the second sensing capacitor C to be sensed_S2Is discharged to the ground GND.

A twenty-first switching circuit SW21, a twenty-second switching circuit SW22, a twenty-third switching circuit SW23 and a twenty-fourth switching circuitWay SW24 allows third sensing capacitor C to be used_S3Will be discharged to ground GND. The twenty-fifth switching circuit SW25, the twenty-sixth switching circuit SW26, the twenty-seventh switching circuit S27 and the twenty-eighth switching circuit SW28 enable the fourth sensing capacitor C to be_S4Is charged to the operating voltage VDD.

In addition, the nineteenth switching circuit SW19 may disable the electrical connection between the first internal node NS1 and the first input NI1 of the differential integration circuit 210, and the twentieth switching circuit SW20 may disable the electrical connection between the second internal node NS2 and the second input NI2 of the differential integration circuit 210. The ninth switching circuit SW9 can cut off the electrical connection between the first input terminal of the differential amplifier 212 and the first input terminal NI1 of the differential integration circuit 210, and the tenth switching circuit SW10 can cut off the electrical connection between the second input terminal of the differential amplifier 212 and the second input terminal NI2 of the differential integration circuit 210.

Then, in a second period TP2 after the first period TP1, the third switching circuit SW3 may cut off the electrical connection between the first internal node NS1 and the operating voltage VDD, and the twenty-first switching circuit SW21 may cut off the electrical connection between the first input NI1 of the differential integration circuit 210 and the ground GND. In addition, the nineteenth switching circuit SW19 can turn on the electrical connection between the first internal node NS1 and the first input terminal NI1 of the differential integration circuit 210, so that the first sensing capacitor C is connected to the first input terminal NI1 of the differential integration circuit 210_S1And a third sensing capacitor C_S3And the voltage VX of the first internal node NS1₁Can be represented by formula (12).

At the first sensing capacitor C_S1And a third sensing capacitor C_S3In the case of matching, e.g. when the first sensing capacitor C_S1And a third sensing capacitor C_S3The voltage VX of the first internal node NS1 with the same inherent capacitance₁Will be coupled to the first sensing capacitor C_S1And a third sensing capacitor C_S3The specific capacitance value of (2) is not dependent, and equation (12) can be rewritten as equation (13).

That is, the voltage VX of the first internal node NS1₁May be substantially equal to 1/2 times the operating voltage VDD. Similarly, during the second period TP2, the eighth switching circuit SW8 may turn off the electrical connection between the second internal node NS2 and the ground GND, the twenty-fifth switching circuit SW25 may turn off the electrical connection between the second input NI2 of the differential integration circuit 210 and the operating voltage VDD, and the twentieth switching circuit SW20 may turn on the electrical connection between the second internal node NS2 and the first input NI1 of the differential integration circuit 210, so that the second sensing capacitor C is connected to the second sensing capacitor C_S2And a fourth sensing capacitor C_S4Charge redistribution in (c). At the second sensing capacitor C_S2And a fourth sensing capacitor C_S4In the matched condition, the voltage VX of the second internal node NS2₂Will be able to communicate with the second sensing capacitor C_S2And a fourth sensing capacitor C_S4Is independent of the capacitance value of (a). For example, if the second sensing capacitor C_S2And a fourth sensing capacitor C_S4Having the same inherent capacitance value, the voltage VX₂Can be represented by formula (14).

In a third period TP3 after the second period TP2, the ninth switching circuit SW9 may turn on the electrical connection between the first input terminal of the differential amplifier 212 and the first input terminal NI1 of the differential integrating circuit 210 for integration through the first capacitor C1, and the tenth switching circuit SW10 may turn on the electrical connection between the second input terminal of the differential amplifier 212 and the second input terminal NI2 of the differential integrating circuit 210 for integration through the second capacitor C2.

According to the equation (12), the first sensing capacitor C_S1And a third sensing capacitor C_S3With the same capacitance, the intrinsic capacitance of the two and the temperature-induced capacitanceThe changes in the sensed capacitance cancel each other out, so that the voltage VX at the first internal node NS1 is not close to the human body₁Will equal 1/2 times VDD. Similarly, the second sensing capacitor C_S2And a fourth sensing capacitor C_S4The intrinsic capacitance and the sensing capacitance due to temperature can also cancel each other out, so the voltage VX of the second internal node NS2₂And is equal to 1/2 times VDD, there is no charge transfer between the first capacitor C1 and the second capacitor C2.

However, when a human body approaches, the equivalent capacitance C of the human body_BThe capacitance between the first input terminal P1 and the second input terminal P2 is changed, and the voltage VX of the first internal node NS1 is changed₁And will vary accordingly, resulting in a portion of the charge moving into or out of the first capacitor C1, and the amount of charge transferred, Δ QA1, can be expressed as equation (15). In addition, since the fifth input terminal P5 is continuously coupled to the ground GND in the first stage ST1, the third sensing capacitor C_S3The first terminal is also coupled to the ground GND, so that the first terminal is coupled to the third sensing capacitor C_S3Human body equivalent capacitance C of the first end of_BWithout affecting the sensing capacitance between the fifth input terminal P5 and the sixth input terminal P6.

Similarly, when a human body approaches, the equivalent capacitance C of the human body_BWill be connected to the second sensing capacitor C_S2So that the sensing capacitance between the third input terminal P3 and the fourth input terminal P4 changes, when the voltage VX at the second internal node NS2 is applied₂And will vary accordingly, resulting in a portion of the charge moving into or out of the second capacitor C2, wherein the amount of charge transferred, Δ QA2, can be expressed as equation (16). In addition, since the seventh input terminal P7 is continuously coupled to the ground GND in the first stage ST1, the body-equivalent capacitor C is connected to the ground GND_BThe sensing capacitance between the seventh input terminal P7 and the eighth input terminal P8 is not affected.

Since the first capacitor C1 and the second capacitor C2 are respectively disposed at the positive input end and the negative input end of the differential amplifier 212, the transferred charge amounts Δ QA1 and Δ QA2 generate opposite changes to the output voltage of the differential amplifier 212, and therefore, the detection voltage VOUT output by the differential integration circuit 210 can be represented by the formula (17) when the first capacitor C1 and the second capacitor C2 have the same capacitance value.

In the first period TP1 of the first stage ST1, the first internal node NS1 is at the operating voltage VDD, and the second internal node NS2 is at the ground GND. In contrast, the first input NI1 of the differential integration circuit 210 is at the ground GND, and the second input NI2 of the differential integration circuit 210 is at the operating voltage VDD, so that the mutual capacitance C_m1And C_m3The charging directions of the two charging circuits are opposite to each other, and the influence of the two charging circuits can be mutually counteracted, so that the detection operation is not influenced. In addition, mutual capacitance C_m2Not shown in FIG. 5, but due to mutual capacitance C_m2Both ends of the first and second electrodes are coupled to the ground GND, so that charges are not stored and the detection operation is not affected.

In a fourth period TP4 of the second stage ST2 after the first stage ST1, the first, second, third, and fourth switching circuits SW1, SW2, SW3, and SW4 may cause the first sensing capacitance C to be a capacitance C_S1Is discharged to the ground GND. The fifth switching circuit SW5, the sixth switching circuit SW6, the seventh switching circuit SW7 and the eighth switching circuit SW8 enable the second sensing capacitor C to be connected to the first sensing capacitor C_S2Is charged to the operating voltage VDD.

The twenty-first switching circuit SW21, the twenty-second switching circuit SW22, the twenty-third switching circuit and the twenty-fourth switching circuit SW24 enable the third sensing capacitor C to be_S3Is charged to the operating voltage VDD.

The twenty-fifth switching circuit SW25, the twenty-sixth switching circuit SW26, the twenty-seventh switching circuit SW27 and the twenty-eighth switching circuit SW28 enable the fourth sensing capacitor C to be_S4Is discharged to ground.

In addition, the nineteenth switching circuit SW19 may disable the electrical connection between the first internal node NS1 and the first input NI1 of the differential integration circuit 210, the twentieth switching circuit SW20 may disable the electrical connection between the second internal node NS2 and the second input NI2 of the differential integration circuit 210, the ninth switching circuit SW9 may disable the electrical connection between the first input NI1 of the differential amplifier 212 and the first input NI1 of the differential integration circuit 210, and the tenth switching circuit SW10 may disable the electrical connection between the second input NI2 of the differential amplifier 212 and the second input NI2 of the differential integration circuit 210.

Then, in a fifth period TP5 after the fourth period TP4, the fourth switching circuit SW4 may turn off the electrical connection between the first internal node NS1 and the ground GND, the twenty-second switching circuit SW22 may turn off the electrical connection between the first input NI1 of the differential integrator 210 and the operating voltage VDD, and the nineteenth switching circuit SW19 may turn on the electrical connection between the first internal node NS1 and the first input NI1 of the differential integrator 210, so that the first sensing capacitor C is electrically connected to the first sensing capacitor C_S1And a third sensing capacitor C_S3And the voltage VX of the first internal node NS1₁Can be represented by formula (18).

At the first sensing capacitor C_S1And a third sensing capacitor C_S3In the case of matching, e.g. when the first sensing capacitor C_S1And a third sensing capacitor C_S3The voltage VX of the first internal node NS1 with the same inherent capacitance₁Will be coupled to the first sensing capacitor C_S1And a third sensing capacitor C_S3The specific capacitance value of (1) is not dependent on the specific capacitance value of (18), and the formula (19) can be rewritten.

That is, the voltage VX of the first internal node NS1₁May be substantially equal to 1/2 times the operating voltage VDD. Similarly, in the fifth period TP5, the seventh switching circuit SW7 may turn off the electrical connection between the second internal node NS2 and the operating voltage VDD, the twenty-sixth switching circuit SW26 may turn off the electrical connection between the second input terminal NI2 of the differential integration circuit 210 and the ground terminal GND, and the twentieth switching circuit SW20 may turn on the electrical connection between the second internal node NS2 and the second input terminal NI2 of the differential integration circuit 210, so that the second sensing capacitor C is connected to the second sensing capacitor C_S2And a fourth sensing capacitor C_S4Charge redistribution in (c). At the second sensing capacitor C_S2And a fourth sensing capacitor C_S4In the matched condition, the voltage VX of the second internal node NS2₂Will be able to communicate with the second sensing capacitor C_S2And a fourth sensing capacitor C_S4Is independent of the capacitance value of (a). For example, if the second sensing capacitor C_S2And a fourth sensing capacitor C_S4Having the same inherent capacitance value, the voltage VX₂Can be represented by formula (20).

In a sixth time period TP6 after the fifth time period TP5, the ninth switching circuit SW9 may turn on the electrical connection between the first input terminal of the differential amplifier 212 and the first input terminal NI1 of the differential integration circuit 210 for integration through the first capacitor C1, the tenth switching circuit SW10 may turn on the electrical connection between the second input terminal of the differential amplifier 212 and the second input terminal NI2 of the differential integration circuit 210 for integration through the second capacitor C2, and the first output terminal and the second output terminal of the differential amplifier 212 may output the detection voltage signal VOUT.

According to the equation (18), the first sensing capacitor C_S1And a third sensing capacitor C_S3When they have the same capacitance value, the inherent capacitance values of the two andsince the changes in the sensed capacitance due to temperature cancel each other out, the voltage VX at the first internal node NS1 is not close to the human body₁Will equal 1/2 times VDD. Similarly, the second sensing capacitor C_S2And a fourth sensing capacitor C_S4The intrinsic capacitance and the change of the sensing capacitance due to the temperature can also be cancelled, so the voltage Vx of the second internal node NS2₂And is equal to 1/2 times VDD, there is no charge transfer between the first capacitor C1 and the second capacitor C2.

However, when a human body approaches, the equivalent capacitance C of the human body_BWill be connected to the third sensing capacitor C_S3In parallel, the sensing capacitance between the fifth input terminal P5 and the sixth input terminal P6 changes, and the voltage VX of the first internal node NS1 at this time₁And will vary accordingly, resulting in a portion of the charge moving into or out of the first capacitor C1, and the amount of charge transferred, Δ QA1, can be expressed as equation (21). In addition, since the first input terminal P1 is continuously coupled to the ground GND in the second stage ST2, the body-equivalent capacitor C is connected to the ground GND_BThe sensing capacitance between the first input terminal P1 and the second input terminal P2 is not affected.

Similarly, when a human body approaches, the equivalent capacitance C of the human body_BWill be connected with the fourth sensing capacitor C_S4In parallel, the sensing capacitance between the seventh input terminal P7 and the eighth input terminal P8 changes, and the voltage VX of the second internal node NS2 at this time₂And will vary accordingly, resulting in a portion of the charge moving into or out of the second capacitor C2, wherein the amount of charge transferred, Δ QA2, may be represented by equation (22). In addition, since the third input terminal P3 is continuously coupled to the ground GND in the second stage ST2, the body-equivalent capacitor C is connected to the ground GND_BThe sensing capacitance between the third input terminal P3 and the fourth input terminal P4 is not affected.

Since the first capacitor C1 and the second capacitor C2 are respectively disposed at the positive input end and the negative input end of the differential amplifier 212, the transferred charge amounts Δ QA1 and Δ QA2 cause inverse changes to the output voltage of the differential amplifier 212, and the detection voltage VOUT output by the differential integration circuit 210 can be represented by equation (23) if the first capacitor C1 and the second capacitor C2 have the same capacitance value.

In the first period TP1 of the second stage ST2, the first internal node NS1 is at the ground GND, and the second internal node NS2 is at the operation voltage VDD. In contrast, the first input NI1 of the differential integration circuit 210 is at the operating voltage VDD, and the second input NI2 of the differential integration circuit 210 is at the ground GND, so that the mutual capacitance C_m1And C_m3The charging directions of the two charging circuits are opposite to each other, and the influence of the two charging circuits on the detection operation can be mutually counteracted. In addition, mutual capacitance C_m2Both ends of the first and second electrodes are coupled to the operation voltage VDD, so that charges are not stored and the detection operation is not affected.

To sum up, the detection circuit provided by the embodiment of the application can enable mutual capacitance between different sensing capacitors to be mutually offset or not to generate an effect by controlling the switching circuit, so that the accuracy of the detection circuit can be improved. In addition, the detection circuit of the application can also utilize different sensing capacitors to offset errors caused by external common-mode interference such as temperature and the like, so that the detection voltage signal is only related to the equivalent capacitance of the human body, the range of effective interpretation numerical values is enlarged, and the purpose of improving the effective sensing range is achieved.

The application also provides a chip and an electronic device, such as an earphone. The voltage detection signals generated by the detection circuits in the chip and the electronic device can accurately show the change of the sensing capacitance value when a human body approaches, and cannot be interfered by temperature change and mutual capacitance, so that the chip and the electronic device can be used for capacitive touch detection, capacitive ear detection, capacitive pressure detection and the like.

The foregoing description has set forth briefly the features of certain embodiments of the present application so that those skilled in the art may more fully appreciate the various aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should understand that they can still make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.

Claims

1. A detection circuit, characterized in that the detection circuit comprises:

a first input end coupled to a first end of the first sensing capacitor;

a second input terminal coupled to a second terminal of the first sensing capacitor, wherein the first sensing capacitor has a first intrinsic capacitance, and a sensing capacitance of the first sensing capacitor is changed at least when a human body approaches the first sensing capacitor;

a third input terminal coupled to the first terminal of the second sensing capacitor;

a fourth input terminal coupled to a second terminal of the second sensing capacitor, wherein the second sensing capacitor has a second inherent capacitance, and a sensing capacitance of the second sensing capacitor is changed at least when a human body approaches the second sensing capacitor;

a differential integration circuit for performing differential integration according to a voltage of the first internal node and a voltage of the second internal node to generate a detection voltage signal when the detection circuit performs a detection operation;

a first switching circuit having a first end, a second end and a third end, wherein the first end of the first switching circuit is the first internal node, the second end of the first switching circuit is coupled to the first input end of the detection circuit, the third end of the first switching circuit is coupled to a ground end, and the first switching circuit is configured to turn on or off an electrical connection between the first input end of the detection circuit and the first internal node and turn on or off an electrical connection between the first input end of the detection circuit and the ground end;

a second switching circuit, coupled to the second input terminal of the detection circuit, the first internal node and the ground terminal, for turning on or off an electrical connection between the second input terminal of the detection circuit and the first internal node, and turning on or off an electrical connection between the second input terminal of the detection circuit and the ground terminal;

a third switching circuit coupled to the first internal node and an operating voltage, the third switching circuit being configured to turn on or off an electrical connection between the first internal node and the operating voltage;

a fourth switching circuit, coupled to the first internal node and the ground terminal, for turning on or off an electrical connection between the first internal node and the ground terminal;

a fifth switching circuit having a first end, a second end and a third end, the first end of the fifth switching circuit being the second internal node, the second end of the fifth switching circuit being coupled to the third input end of the detection circuit, and the third end of the fifth switching circuit being coupled to the ground end, the fifth switching circuit being configured to turn on or off an electrical connection between the third input end of the detection circuit and the second internal node, and to turn on or off an electrical connection between the third input end of the detection circuit and the ground end;

a sixth switching circuit, coupled to the fourth input terminal of the detection circuit, the second internal node, and the ground terminal, for turning on or off an electrical connection between the fourth input terminal of the detection circuit and the second internal node, and turning on or off an electrical connection between the fourth input terminal of the detection circuit and the ground terminal;

a seventh switching circuit, coupled to the second internal node and the operating voltage, for turning on or off an electrical connection between the second internal node and the operating voltage; and

an eighth switching circuit, coupled to the second internal node and the ground terminal, for turning on or off an electrical connection between the second internal node and the ground terminal;

wherein:

the first switching circuit, the second switching circuit, the third switching circuit, the fourth switching circuit, the fifth switching circuit, the sixth switching circuit, the seventh switching circuit, and the eighth switching circuit are configured to charge and discharge the first sensing capacitor and the second sensing capacitor in the detection operation, so as to eliminate an influence of a first mutual capacitance between the first sensing capacitor and the second sensing capacitor on the detection voltage signal in the detection operation, so that the differential integration circuit outputs the detection voltage signal related to human body proximity according to sensing capacitance values of the first sensing capacitor and the second sensing capacitor.

2. The detection circuit of claim 1, wherein the first switching circuit comprises:

a first switch having a first terminal, a second terminal, and a control terminal, the first terminal of the first switch being coupled to the first input terminal of the detection circuit, the second terminal of the first switch being the first internal node; and

a second switch having a first end, a second end and a control end, wherein the first end of the second switch is coupled to the first input end of the detection circuit, and the second end of the second switch is coupled to the ground end.

3. The detection circuit of claim 1, wherein the second switching circuit comprises:

a third switch having a first end, a second end and a control end, the first end of the third switch being coupled to the second input end of the detection circuit, the second end of the third switch being coupled to the first internal node; and

a fourth switch having a first end, a second end and a control end, wherein the first end of the fourth switch is coupled to the second input end of the detection circuit, and the second end of the fourth switch is coupled to the ground end.

4. The detection circuit of claim 1, wherein the fifth switching circuit comprises:

a fifth switch having a first terminal, a second terminal, and a control terminal, the first terminal of the fifth switch being coupled to the third input terminal of the detection circuit, the second terminal of the fifth switch being the second internal node; and

a sixth switch having a first end, a second end, and a control end, wherein the first end of the sixth switch is coupled to the third input end of the detection circuit, and the second end of the sixth switch is coupled to the ground end.

5. The detection circuit of claim 1, wherein the sixth switching circuit comprises:

a seventh switch having a first terminal, a second terminal, and a control terminal, the first terminal of the seventh switch being coupled to the fourth input terminal of the detection circuit, the second terminal of the seventh switch being coupled to the second internal node; and

an eighth switch having a first end, a second end, and a control end, wherein the first end of the eighth switch is coupled to the fourth input end of the detection circuit, and the second end of the eighth switch is coupled to the ground end.

6. The detection circuit of any one of claims 1 to 5, wherein the differential integration circuit has a first input and a second input, and the differential integration circuit comprises:

a differential amplifier having a first input terminal, a second input terminal, a first output terminal and a second output terminal, wherein the first output terminal and the second output terminal of the differential amplifier are used for outputting the detection voltage signal;

a first capacitor having a first end and a second end, the first end of the first capacitor being coupled to the first input end of the differential amplifier, and the second end of the first capacitor being coupled to the first output end of the differential amplifier;

a second capacitor having a first end and a second end, the first end of the second capacitor being coupled to the second input end of the differential amplifier, and the second end of the second capacitor being coupled to the second output end of the differential amplifier;

a ninth switching circuit for turning on or off electrical connection between the first input terminal of the differential amplifier and the first input terminal of the differential integrating circuit; and

a tenth switching circuit for turning on or off electrical connection between the second input terminal of the differential amplifier and the second input terminal of the differential integrating circuit.

7. The detection circuit of claim 6, further comprising:

a third capacitor having a first end and a second end;

an eleventh switching circuit for turning on or off the electrical connection between the first end of the third capacitor and the ground terminal;

a twelfth switching circuit for turning on or off the electrical connection between the first end of the third capacitor and the operating voltage;

a thirteenth switching circuit for turning on or off the electrical connection between the second end of the third capacitor and the ground terminal, and turning on or off the electrical connection between the second end of the third capacitor and the operating voltage;

a fourteenth switching circuit for turning on or off the electrical connection between the first end of the third capacitor and the first internal node;

a fourth capacitor having a first end and a second end;

a fifteenth switching circuit for turning on or off the electrical connection between the first end of the fourth capacitor and the ground terminal;

a sixteenth switching circuit, configured to turn on or off an electrical connection between the first end of the fourth capacitor and the operating voltage;

a seventeenth switching circuit for turning on or off an electrical connection between the second terminal of the fourth capacitor and the ground terminal, and turning on or off an electrical connection between the second terminal of the fourth capacitor and the operating voltage; and

an eighteenth switching circuit for turning on or off the electrical connection between the first end of the fourth capacitor and the second internal node;

wherein the first input of the differential integrator circuit is coupled to the first internal node and the second input of the differential integrator circuit is coupled to the second internal node.

8. The detection circuit of claim 7, wherein the detection operation comprises a first stage and a second stage in sequence, the first stage comprising:

charging the first and third sensing capacitances, redistributing charge in the first and third capacitances so that the voltage at the first internal node is independent of the first intrinsic capacitance value of the first sensing capacitance and the capacitance value of the third capacitance;

charging the second sensing capacitor and the fourth capacitor, redistributing charges in the second sensing capacitor and the fourth capacitor so that the voltage of the second internal node is independent of the second intrinsic capacitance value of the second sensing capacitor and the capacitance value of the fourth capacitor; and

the differential integration circuit differentially integrates the voltage of the first internal node and the voltage of the second internal node after the charge in the first sensing capacitor and the third capacitor is redistributed and after the charge in the second sensing capacitor and the fourth capacitor is redistributed;

wherein, in the first phase, the third input terminal of the detection circuit is coupled to ground, such that the voltage of the second internal node is related to capacitance change caused by temperature and is unrelated to capacitance change caused by human body approaching the second sensing capacitor, and the voltage of the first internal node is related to capacitance change caused by human body approaching the first sensing capacitor and temperature;

the second stage comprises:

the differential integration circuit differentially integrates the voltage of the first internal node and the voltage of the second internal node after charge in the first sensing capacitor, the third capacitor, the second sensing capacitor, and the fourth capacitor is redistributed;

in the second phase, the first input terminal of the detection circuit is coupled to ground, so that the voltage of the first internal node is related to capacitance change caused by temperature and is unrelated to capacitance change caused by human body approaching to the first sensing capacitor, and the voltage of the second internal node is related to capacitance change caused by temperature and human body approaching to the second sensing capacitor.

9. The detection circuit of claim 8, wherein:

in the first phase, when the first sensing capacitor and the third capacitor are charged and when the second sensing capacitor and the fourth capacitor are charged, the first internal node and the second internal node are at the same potential, so that two ends of the first mutual capacitance are at the same potential, and the first mutual capacitance does not store charges; and

in the second phase, when the first sensing capacitor and the third capacitor are charged and when the second sensing capacitor and the fourth capacitor are charged, the first internal node and the second internal node are at the same potential, so that two ends of the first mutual capacitance are at the same potential, and the first mutual capacitance does not store charges.

10. The detection circuit of claim 7, wherein the capacitance value of the third capacitance is one third of the first intrinsic capacitance value of the first sensing capacitance, and the capacitance value of the fourth capacitance is one third of the second intrinsic capacitance value of the second sensing capacitance.

11. The detection circuit of claim 10, wherein:

the third capacitor comprises a first variable capacitor or a first capacitor array, wherein a capacitance value of the first variable capacitor or the first capacitor array can be changed according to an inherent capacitance value of the first sensing capacitor through a first control signal; and

the fourth capacitor comprises a second variable capacitor or a second capacitor array, wherein a capacitance value of the second variable capacitor or the second capacitor array can be changed according to an inherent capacitance value of the second sensing capacitor through a second control signal.

12. The detection circuit of claim 7, wherein the thirteenth switching circuit comprises:

a ninth switch having a first end, a second end, and a control end, the first end of the ninth switch being coupled to the second end of the third capacitor, the second end of the ninth switch being coupled to the operating voltage; and

a tenth switch having a first end, a second end, and a control end, wherein the first end of the tenth switch is coupled to the second end of the third capacitor, and the second end of the tenth switch is coupled to the ground end.

13. The detection circuit of claim 7, wherein the seventeenth switching circuit comprises:

an eleventh switch having a first end, a second end, and a control end, wherein the first end of the eleventh switch is coupled to the second end of the fourth capacitor, and the second end of the eleventh switch is coupled to the operating voltage; and

a twelfth switch having a first end, a second end, and a control end, wherein the first end of the twelfth switch is coupled to the second end of the fourth capacitor, and the second end of the twelfth switch is coupled to the ground end.

14. The detection circuit of claim 6, further comprising:

a nineteenth switching circuit for turning on or off electrical connection between the first internal node and the first input terminal of the differential integrating circuit; and

a twentieth switching circuit for turning on or off electrical connection between the second internal node and the second input terminal of the differential integrating circuit.

A fifth input terminal coupled to the first terminal of the third sensing capacitor;

a sixth input terminal coupled to a second terminal of the third sensing capacitor, wherein the third sensing capacitor has a third inherent capacitance value, and a sensing capacitance value of the third sensing capacitor is changed at least when a human body approaches the third sensing capacitor;

a seventh input terminal coupled to the first terminal of the fourth sensing capacitor;

an eighth input terminal coupled to a second terminal of the fourth sensing capacitor, wherein the fourth sensing capacitor has a fourth inherent capacitance, and a sensing capacitance of the fourth sensing capacitor is changed at least when a human body approaches the fourth sensing capacitor;

a twenty-first switching circuit for turning on or off the electrical connection between the first input terminal of the differential integration circuit and the ground terminal;

a twenty-second switching circuit for turning on or off the electrical connection between the first input terminal of the differential integration circuit and the operating voltage;

a twenty-third switching circuit for turning on or off the electrical connection between the fifth input terminal and the ground terminal, and turning on or off the electrical connection between the fifth input terminal and the first input terminal of the differential integrating circuit;

a twenty-fourth switching circuit for turning on or off the electrical connection between the sixth input terminal and the ground terminal, and turning on or off the electrical connection between the sixth input terminal and the first input terminal of the differential integrating circuit;

a twenty-fifth switching circuit for turning on or off an electrical connection between the second input terminal of the differential integration circuit and the operating voltage;

a twenty-sixth switching circuit for turning on or off the electrical connection between the second input terminal of the differential integration circuit and the ground terminal;

a twenty-seventh switching circuit for turning on or off an electrical connection between the seventh input terminal and the ground terminal, and turning on or off an electrical connection between the seventh input terminal and the second input terminal of the differential integrating circuit; and

and a twenty-eighth switching circuit for turning on or off the electrical connection between the eighth input terminal and the ground terminal, and turning on or off the electrical connection between the eighth input terminal and the second input terminal of the differential integrating circuit.

15. The detection circuit of claim 14, wherein the detection operation comprises a first stage and a second stage in sequence, the first stage comprising:

charging the first sensing capacitor, discharging the third sensing capacitor, and redistributing charges in the first sensing capacitor and the third sensing capacitor so that the voltage of the first internal node is independent of capacitance changes caused by the first intrinsic capacitance value of the first sensing capacitor, the third intrinsic capacitance value of the third sensing capacitor, and temperature;

charging the fourth sensing capacitor, discharging the second sensing capacitor, and redistributing charges in the second sensing capacitor and the fourth sensing capacitor such that the voltage of the second internal node is independent of capacitance changes caused by the second intrinsic capacitance value of the second sensing capacitor, the fourth intrinsic capacitance value of the fourth sensing capacitor, and temperature; and

the differential integration circuit differentially integrates the voltage of the first internal node and the voltage of the second internal node after charge in the first sensing capacitor and the third sensing capacitor is redistributed and after charge in the second sensing capacitor and the fourth sensing capacitor is redistributed;

wherein, in the first phase, the fifth input terminal and the seventh input terminal of the detection circuit are coupled to ground, so that the voltage of the first internal node is related to a capacitance change caused by a human body approaching the first sensing capacitor and is unrelated to a capacitance change caused by a human body approaching the third sensing capacitor, and the voltage of the second internal node is related to a capacitance change caused by a human body approaching the second sensing capacitor and is unrelated to a capacitance change caused by a human body approaching the fourth sensing capacitor;

the second stage comprises:

charging the third sensing capacitor, discharging the first sensing capacitor, and redistributing charges in the first and third sensing capacitors such that the voltage of the first internal node is independent of capacitance changes caused by the first intrinsic capacitance value of the first sensing capacitor, the third intrinsic capacitance value of the third sensing capacitor, and temperature;

charging the second sensing capacitor, discharging the fourth sensing capacitor, and redistributing charges in the second sensing capacitor and the fourth sensing capacitor so that the voltage of the second internal node is independent of capacitance changes caused by the second intrinsic capacitance value of the second sensing capacitor, the fourth intrinsic capacitance value of the fourth sensing capacitor, and temperature; and

the differential integration circuit differentially integrates the voltage of the first internal node and the voltage of the second internal node after the charge in the first sensing capacitor and the third sensing capacitor is redistributed and after the charge in the second sensing capacitor and the fourth sensing capacitor is redistributed;

in the second phase, the first input terminal and the third input terminal of the detection circuit are coupled to ground, so that the voltage of the first internal node is related to a capacitance change caused by a human body approaching the third sensing capacitor and is unrelated to a capacitance change caused by a human body approaching the first sensing capacitor, and the voltage of the second internal node is related to a capacitance change caused by a human body approaching the fourth sensing capacitor and is unrelated to a capacitance change caused by a human body approaching the second sensing capacitor.

16. The detection circuit of claim 15, wherein during the detection operation, two ends of a second mutual capacitance between the second sensing capacitor and the third sensing capacitor are at the same potential, and a third mutual capacitance between the third sensing capacitor and the fourth sensing capacitor and the first mutual capacitance have a mutually cancelling effect on the detection voltage signal, such that the detection voltage signal is independent of the first mutual capacitance, the second mutual capacitance and the third mutual capacitance.

17. The detection circuit of claim 14, wherein the twenty-third switching circuit comprises:

a thirteenth switch having a first terminal, a second terminal, and a control terminal, the first terminal of the thirteenth switch being coupled to the fifth input terminal of the detection circuit, the second terminal of the thirteenth switch being coupled to the first input terminal of the differential integration circuit; and

a fourteenth switch having a first end, a second end and a control end, wherein the first end of the fourteenth switch is coupled to the fifth input end of the detection circuit, and the second end of the fourteenth switch is coupled to the ground end.

18. The detection circuit of claim 14, wherein the twenty-fourth switching circuit comprises:

a fifteenth switch having a first end, a second end and a control end, the first end of the fifteenth switch being coupled to the sixth input end of the detection circuit, the second end of the fifteenth switch being coupled to the first input end of the differential integration circuit; and

a sixteenth switch having a first end, a second end, and a control end, wherein the first end of the sixteenth switch is coupled to the sixth input end of the detection circuit, and the second end of the sixteenth switch is coupled to the ground end.

19. The detection circuit of claim 14, wherein the twenty-seventh switching circuit comprises:

a seventeenth switch having a first end, a second end, and a control end, the first end of the seventeenth switch being coupled to the seventh input end of the detection circuit, the second end of the seventeenth switch being coupled to the second input end of the differential integration circuit; and

an eighteenth switch having a first end, a second end, and a control end, the first end of the eighteenth switch being coupled to the seventh input end of the detection circuit, the second end of the eighteenth switch being coupled to the ground end.

20. The detection circuit of claim 14, wherein the twenty-eighth switching circuit comprises:

a nineteenth switch having a first terminal, a second terminal, and a control terminal, the first terminal of the nineteenth switch being coupled to the eighth input terminal of the detection circuit, the second terminal of the nineteenth switch being coupled to the second input terminal of the differential integration circuit; and

a twentieth switch having a first end, a second end, and a control end, wherein the first end of the twentieth switch is coupled to the eighth input end of the detection circuit, and the second end of the twentieth switch is coupled to the ground end.

21. The detection circuit of claim 6, wherein the differential integration circuit further comprises:

a first reset switch for turning on an electrical connection between the first input terminal of the differential amplifier and the first output terminal of the differential amplifier in a reset operation, and turning off the electrical connection between the first input terminal of the differential amplifier and the first output terminal of the differential amplifier in the detection operation; and

a second reset switch for turning on an electrical connection between the second input terminal of the differential amplifier and the second output terminal of the differential amplifier in a reset operation, and for turning off the electrical connection between the second input terminal of the differential amplifier and the second output terminal of the differential amplifier in the detection operation.

22. A chip comprising the detection circuit of any one of claims 1-21 and a reading circuit for reading a detection voltage signal output by the detection circuit.

23. An electronic device, comprising:

the detection circuit of any one of claims 1-21.