KR102445540B1 - A low noise and high sensitivity touch sensing circuit and system - Google Patents

Abstract

The present invention proposes a low-noise high-sensitivity touch sensing circuit that can remove a low-frequency noise generated inside a circuit, and a low-noise high-sensitivity processing sensing system. The low-noise high-sensitivity touch sensing circuit comprises: an amplifier; a second chopper stabilization circuit; a third chopper stabilization circuit; a positive SC input part; a positive feedback circuit; a negative SC input part; a negative feedback circuit; and a voltage regulation circuit.

Description

{A low noise and high sensitivity touch sensing circuit and system}

The present invention relates to a touch sensing circuit, and more particularly, to a low-noise and high-sensitivity touch sensing system capable of removing low-frequency noise generated inside the circuit, and to a low-noise and high-sensitivity touch sensing circuit.

In various electronic devices, the use of a touch panel is increasing as a means for a user to input a command to an electronic device along with a screen output. Among the technologies for detecting a touch when a touch is made on the touch panel, a method of detecting a change in capacitance is most used, and for this, a touch sensing circuit for detecting a change in capacitance is used.

1 is a conceptual diagram of a touch sensing system.

FIG. 2 is a specific embodiment of the touch sensing system shown in FIG. 1 .

1 and 2 , the touch sensing system 100 includes an amplifier 110 , a positive SC input unit 120 , a positive feedback circuit 130 , a negative SC input unit 140 , a negative feedback circuit 150 , The amplifier input stage includes a voltage adjustment circuit 160 (hereinafter referred to as a voltage adjustment circuit), an ADC 170 and a timing control circuit 180 .

Hereinafter, FIGS. 1 and 2 are combined and described. In addition, for convenience of description, the touch sensing system 100 is divided into a touch sensing circuit and a signal processing unit, and the touch sensing circuit includes an amplifier 110, a positive SC input unit 120, a positive feedback circuit 130, It is assumed that the negative SC input unit 140 , the negative feedback circuit 150 , and the voltage adjustment circuit 160 are included, and the signal processing unit includes the ADC 170 and the timing control circuit 180 .

Referring to FIG. 2 , the touch sensing system 100 performs initialization in which the switch control signal pi 0 (zero, Φ0) is activated, that is, after discharging the two feedback capacitors CFp & CFn, the subsequent pi 0 becomes a logic It can be seen that two switch control signals pi 1 ( .phi.1) and pi 2 ( .phi.2) that do not overlap each other are used in the inactive time period to be in the low state.

FIG. 3 is a signal diagram of pi 1 and pi 2 shown in FIG. 2 .

Referring to FIG. 3 , it can be seen that the period in which pi 1 is activated (ON) and the period in which pi 2 is activated (ON) do not overlap each other. The reason for such a signal is that, when the period in which pi 1 is activated and the period in which pi 2 is activated overlap each other, the first power supply VDD is applied to one terminal of the first input terminal capacitor CIp and the second input terminal capacitor CIn. ) and the second power source GND may be simultaneously connected.

Hereinafter, for convenience of explanation, when the logic value of the switch control signal is in a high state, that is, in the activation section, the corresponding switch is turned on (ie, short-circuited), and when the logic low state, the corresponding switch is turned off (ie, open). Assume and explain

FIG. 4 shows the connection state of the high-sensitivity touch sensing circuit according to the present invention according to the switch control signal shown in FIG. 2 .

The left side of FIG. 4 shows the connection state of the touch sensing circuit when pi 1 is activated, and the right side of FIG. 4 shows the connection state of the touch sensing circuit when pi 2 is activated.

Hereinafter, the reason why the touch sensing circuit according to the present invention can determine whether the user touches the device regardless of the value of the parasitic capacitor Cp will be described together with the connection state of FIG. 4 .

As shown on the left side of FIG. 4, when pi 1 (Φ1) is in a logic high state, the amount of charge QP charged in the positive-side capacitor and the amount of charge QN charged in the negative-side capacitor are shown on the right side of FIG. As such, when pi 2 (Φ2) is in a logic high state, the charge amount QP charged in the positive-side capacitor and the charge amount QN charged in the negative-side capacitor can be expressed as Equation 1 below.

According to the charge conservation law, since the total charge at pi 1 and the total charge at pi 2 must be the same, Equation 1 can be summarized as Equation 2 below.

In Equation 2, the parasitic capacitor CP and the internal offset capacitor CO have the same capacitance, the first input terminal capacitor CIp and the second input terminal capacitor CIn have the same capacitance, and the first feedback capacitor ( When it is assumed that the capacitances of CFp) and the second feedback capacitor CFn are also equal to each other, and it is assumed that the first feedback capacitor CFp and the second feedback capacitor CFn are CF, the difference between the two expressions in Equation 2 can be expressed as in Equation 3 below.

를 더 한 값을 가지게 된다. 즉, 수학식 3을 참조하면, 터치에 의해 증가하는 이득

는 CT의 크기에 의해서만 결정되며, CP와는 전혀 상관없다는 것을 확인할 수 있다.In Equation 3, since VOUTP'- VOUTN' is the output value integrated in the previous step, the output value VOUTP- VOUTN at pi 2 is the output value integrated in the previous step.

has a value added to . That is, referring to Equation 3, the gain increased by the touch

It can be confirmed that is determined only by the size of the CT and has nothing to do with the CP.

Although not shown in FIGS. 1 and 2 , in the process of processing the output signal of the conventional touch sensing circuit by the signal processing unit, for example, a step of removing high-frequency noise using a SUM filter or an average filter is performed. do. In particular, peak noise can also be removed by using a moving average filter.

The conventional touch sensing circuit also has a disadvantage in that low-frequency noise is generated by itself.

5 is a result of measuring 1/f noise of a conventional touch sensing circuit.

6 is a result of filtering 1/f noise of a conventional touch sensing circuit.

7 is a result of measuring thermal noise of a conventional touch sensing circuit.

8 is a result of filtering the thermal noise of the conventional touch sensing circuit.

The low-frequency noise shown in FIGS. 5 to 8 cannot be removed by using a conventional high-frequency filter. In order to remove the low-frequency noise generated in the conventional touch sensing circuit, it is possible to apply a method of increasing the size of the transistor constituting the touch sensing circuit, that is, the ratio of the width and length of the channel, but it is possible to increase the size of the chip. Since there are disadvantages, an effective method for removing low-frequency noise generated from the touch sensing circuit itself is required.

US Published Patent: US 2020/0220543 A1 (July 09, 2020)

The technical problem to be solved by the present invention is to propose a low-noise, high-sensitivity touch sensing circuit capable of removing low-frequency noise generated inside the circuit.

Another technical problem to be solved by the present invention is to propose a low-noise, high-sensitivity treatment sensing system capable of removing low-frequency noise generated inside a circuit.

A low-noise and high-sensitivity touch sensing circuit according to the present invention for achieving the above technical problem is an amplifier, a second chopper stabilization circuit, a third chopper stabilization circuit, a positive SC input unit, a positive feedback circuit, a negative SC input unit, a negative feedback circuit, and a voltage adjustment includes a circuit. The second chopper stabilizing circuit chops the input signals applied to the two input terminals in response to the switch control signals pi 3 and pi 4 to the two input terminals of the amplifier. The third chopper stabilizing circuit chops the two outputs of the amplifier applied to the two input terminals in response to the pi 3 and the pi 4 to the two output terminals. The positive SC input unit charges a predetermined amount of charge in the first input terminal capacitor included therein using one of the first voltage source and the second voltage source in response to the switch control signals pi 1 and pi 2, and then the second chopper It is transmitted to one input terminal of the stabilization circuit. The positive feedback circuit is installed between one input terminal of the second chopper stabilization circuit and one output terminal of the third chopper stabilization circuit, and discharges a first feedback capacitor included therein in response to the switch control signal pi 0 or an amount of charge in response to the amount of charge applied from the positive SC input unit is charged to the first feedback capacitor. The negative SC input unit charges a predetermined amount of charge in a second input terminal capacitor included therein by using one of the first voltage source and the second voltage source in response to the pi 1 and the pi 2, and then the second chopper It is transmitted to the other input terminal of the stabilization circuit. The negative feedback circuit is installed between the other input terminal of the second chopper stabilization circuit and the other output terminal of the third chopper stabilization circuit, and discharges a second feedback capacitor included therein in response to the pi 0. Alternatively, an amount of charge in response to the amount of charge applied from the negative SC input unit is charged to the second feedback capacitor. The voltage regulation circuit generates two paths connected to the first voltage source, and each time the pi 2 is activated in response to the switch control signals pi 3' and pi 4', one path is connected to the first input terminal capacitor. The other terminal and the second input terminal are connected to one of the other terminals of the capacitor, and the other path is connected to the other terminal.

The low-noise and high-sensitivity touch sensing system according to the present invention for achieving the above other technical problem includes the low-noise and high-sensitivity touch sensing circuit according to claim 6, an ADC that converts an analog signal output from the low-noise and high-sensitivity touch sensing circuit into a digital signal, and and a timing control circuit generating the pi 0, the pi 1, the pi 2, the pi 3, the pi 3', the pi 4, and the pi 4'.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. will be able

As described above, in the low-noise and high-sensitivity touch sensing system and the low-noise and high-sensitivity touch sensing circuit according to the present invention, low-frequency noise such as flicker noise generated inside the circuit is modulated into high-frequency noise using a chopper stabilization circuit, and then is already used in the system. There is an advantage in that the low-frequency noise can be removed without adding a low-noise filter by allowing the removal using the existing high-frequency noise filter.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art from the following description. will be.

1 is a conceptual diagram of a touch sensing system.
FIG. 2 is a specific embodiment of the touch sensing system shown in FIG. 1 .
FIG. 3 is a signal diagram of pi 1 and pi 2 shown in FIG. 2 .
FIG. 4 shows the connection state of the high-sensitivity touch sensing circuit according to the present invention according to the switch control signal shown in FIG. 2 .
5 is a result of measuring 1/f noise of a conventional touch sensing circuit.
6 is a result of filtering 1/f noise of a conventional touch sensing circuit.
7 is a result of measuring thermal noise of a conventional touch sensing circuit.
8 is a result of filtering the thermal noise of the conventional touch sensing circuit.
9 is an embodiment of a low-noise and high-sensitivity touch sensing system according to the present invention.
FIG. 10 is an example of a switch control signal for driving the low-noise and high-sensitivity touch sensing system shown in FIG. 9 .
11 is a detailed circuit diagram of a low-noise and high-sensitivity touch sensing system according to an embodiment of the present invention.
12 is an example of a circuit of the chopper stabilization circuit shown in FIG.
13 is a comparison of noise levels according to whether or not the chopper stabilization circuit according to the present invention is used.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings describing exemplary embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings. Like reference numerals in each figure indicate like elements.

9 is an embodiment of a low-noise and high-sensitivity touch sensing system according to the present invention.

Referring to FIG. 9 , the low-noise and high-sensitivity touch sensing system 900 according to the present invention includes an amplifier 910 , a positive SC input unit 920 , a positive feedback circuit 930 , a negative SC input unit 940 , and a negative feedback circuit 950 . ), a first chopper stabilization circuit (not shown), the amplifier input stage voltage adjusting circuit 960 (hereinafter referred to as voltage adjusting circuit), the second chopper stabilization circuit CS2, the third chopper stabilization circuit CS3, and the ADC 170. and a timing control circuit 180 .

The second chopper stabilization circuit CS2 chops the input signal applied to the two input terminals in response to pi 3 (Φ3) and pi 4 (Φ4) to the two input terminals (+, -) of the amplifier 910 ( chopping). Here, chopping means that two input signals are switched to two output terminals as they are or crossed in response to two different switch control signals, and a detailed circuit will be described later.

The third chopper stabilization circuit CS3 converts two output signals VOUTP' & VOUTN' of the amplifier 910 applied to two input terminals in response to pi 3 and pi 4 to two output signals VOUTP & VOUTN. chop with

The positive SC input unit 920 uses one of the first voltage source VDD and the second voltage source GND in response to pi 1 and pi 2 to the first input terminal capacitor CIp (not shown) included therein. After charging a certain amount of charge, it is transferred to one input terminal A2 of the second chopper stabilization circuit CS2.

The positive feedback circuit 930 is installed between one input terminal A2 of the second chopper stabilization circuit CS2 and one output terminal VOUTP of the third chopper stabilization circuit CS3, and in response to pi 0 It performs a function of discharging the first feedback capacitor CFp (not shown) included in the , or charging the first feedback capacitor CFp with an amount of charge in response to the amount of charge applied from the positive SC input unit 920 .

The negative SC input unit 940 uses one of the first voltage source VDD and the second voltage source GND in response to pi 1 and pi 2 to the second input terminal capacitor CIn (not shown) included therein. After charging a certain amount of charge, it is transferred to the other input terminal B2 of the second chopper stabilization circuit CS2.

The negative feedback circuit 950 is installed between the other input terminal B2 of the second chopper stabilization circuit CS2 and the other output terminal VOUTN of the third chopper stabilization circuit CS3, and in response to pi 0 A function of discharging the second feedback capacitor CFn (not shown) included therein or charging the second feedback capacitor CFn with an amount of charge in response to the amount of charge applied from the negative SC input unit 940 is performed.

The voltage regulation circuit 960 generates two paths connected to the first voltage source VDD, and alternates the two paths whenever pi 2 is activated in response to pi 3' and pi 4', and the positive SC input unit 920 ) and the negative SC input unit 940 .

The ADC 170 converts the analog signal output from the two output terminals VOUTP VOUTN of the third chopper stabilization circuit CS3 into a digital signal.

The timing control circuit 180 generates switch control signals pi 0, pi 1, pi 2, pi 3, pi 3', pi 4 and pi 4'.

FIG. 10 is an example of a switch control signal for driving the low-noise and high-sensitivity touch sensing system shown in FIG. 9 .

Referring to FIG. 10 , pi 0 is used to initialize the low-noise and high-sensitivity touch sensing system 900 , and pi 1 to pi 4' are used for the integration process performed by the low-noise and high-sensitivity touch sensing system 900 .

Just as pi 1 and pi 2 do not overlap each other, so pi 3 and pi 4 are signals that do not overlap each other, pi 3 is equal to, for example, a signal with the frequency of pi 1 halved, and pi 4 is It is the same as the signal with pi 3 delayed by half.

Pi 3' has the same frequency as Pi 3 and is active for about 50% of the second half of Pi 3's activation period. Pi 4' has the same frequency as Pi 4 and is active for about 50% of the second half of Pi 4's activation period.

In the first integration interval (1'st INTEGRATION), pi 3 and pi 3' are activated, and in the second integration interval (2'nd INTEGRATION), pi 4 and pi 4' are activated, and this switching process is repeated continuously. it can be seen that

The switch control signal proposed by the present invention has a characteristic that during the period in which pi 2 is activated, a pair of pi 3 and pi 3' and a pair of pi 4 and pi 4' are alternately activated.

11 is a detailed circuit diagram of a low-noise and high-sensitivity touch sensing system according to an embodiment of the present invention.

Referring to FIG. 11 , it can be seen that the first chopper stabilization circuit CS1 , the second chopper stabilization circuit CS2 , and the ALC third chopper stabilization circuit CS3 are added to the conventional circuit shown in FIG. 2 .

A detailed configuration of the circuit 900 of the low-noise and high-sensitivity touch sensing system according to the present invention will be described with reference to FIGS. 9 and 11 .

In the following description, it is assumed that the switch is turned on when the plurality of switch control signals pi 0 to pi 4' are in a logic high state, that is, the two terminals are short-circuited. Conversely, when it is in a logic low state, it is assumed that the corresponding switch is turned off, that is, two terminals are opened.

In the following description, the fifth switch sw5 and the tenth switch sw10 switch in response to pi 0, and the second switch sw2 , the third switch sw3 , the seventh switch sw7 and the eighth switch sw7 It is assumed that the switch sw8 switches in response to pi 1 , and the first switch sw1 , the fourth switch sw4 , the sixth switch sw6 , and the ninth switch sw9 switch in response to the pi 2 . do.

The voltage adjustment circuit 960 includes a first resistor R1 having one terminal connected to the first voltage source VDD, a second resistor R2 having one terminal connected to the first voltage source VDD, and a first resistor R1. and a first chopper stabilizing circuit CS1 connecting the other terminal of the , and the other terminal of the second resistor R2. The first chopper stabilization circuit CS1 connects the other terminal of the first resistor R1 and the second resistor R2 respectively connected to the two input terminals A1 and B1 in response to pi 3' and pi 4' to 2 Switching is performed to the other terminal of the first input terminal capacitor CIp connected to the output terminals C1 and D1, respectively, and the other terminal of the second input terminal capacitor CIn.

The positive SC input unit 920 is connected to a first switch sw1, pi 1 for switching the first voltage source VDD to one end of the first input stage capacitor CIp in response to the first input stage capacitor CIp, pi 2 A second switch sw2 for switching the second voltage source GND to one end of the first input terminal capacitor CIp in response, and the second voltage source GND in response to pi 1 to the other end of the first input terminal capacitor CIp A third switch sw3 for switching to the terminal and a fourth switch for switching the other terminal of the first input terminal capacitor CIp to one input terminal A2 of the second chopper stabilization circuit CS2 in response to pi 2 ( sw4).

The positive feedback circuit 930 has one terminal connected to one input terminal A2 of the second chopper stabilization circuit CS2 and the other terminal connected to one output terminal C3 of the third chopper stabilization circuit CS3. and a first feedback capacitor CFp and a fifth switch sw5 for switching both ends of the first feedback capacitor CFp in response to the pi 0 signal.

The negative SC input unit 940 includes a sixth switch sw6 for switching the first voltage source VDD to one end of the second input terminal capacitor CIn in response to pi 2, and a second voltage source GND in response to pi 1 a seventh switch sw7 for switching to one end of the second input terminal capacitor CIn, an eighth switch for switching the other terminal of the second input terminal capacitor CIn to a second voltage source GND in response to pi 1 ( sw8) and a ninth switch sw9 for switching the other terminal of the second input terminal capacitor CIn to the other terminal B2 of the second chopper stabilization circuit CS2 in response to pi 2 .

The negative feedback circuit 750 has one terminal connected to the other input terminal B2 of the second chopper stabilization circuit CS2, and the other terminal is connected to the other output terminal D3 of the third chopper stabilization circuit CS3. and a second feedback capacitor CFn connected thereto and a tenth switch sw10 for switching both ends of the second feedback capacitor CFn in response to a pi 0 signal.

Since the connection relationship between the second chopper stabilization circuit CS2 and the third chopper stabilization circuit CS3 and the amplifier 910 has already been described with reference to FIG. 9 , a description thereof will be omitted.

12 is an example of a circuit of the chopper stabilization circuit shown in FIG.

A first chopper stabilization circuit CS1 is shown on the left side of FIG. 12 , and a second chopper stabilization circuit CS2 and a third chopper stabilization circuit CS3 are shown on the right side, and three chopper stabilization circuits CS1 to The interior of CS3) is the same.

The first chopper stabilization circuit CS1 connects one input terminal A1 to two output terminals ( C1 and D1) are alternately connected, and at the same time, the other input terminal (B1) is connected to an unconnected output terminal among the two output terminals (C1, D1).

The configuration and operation characteristics of the second chopper stabilization circuit CS2 and the third chopper stabilization circuit CS3 are different from the first chopper stabilization circuit CS1 in that the names of the switches are sw15 to sw18, and the switch control signal is pi 3' and pi 4' to pi 3 and pi 4 are the same except that they are the same, and thus a description thereof will be omitted.

The input signal is modulated by the chopper stabilization circuits CS1 and CS2, and the modulated input signal is amplified together with low-frequency noise in the amplifier 910, and the amplified low-frequency noise and the modulated input signal are generated by the third chopper stabilization circuit. It is demodulated by (CS3). At this time, the modulated input signal is demodulated into the original signal, but the modulated low-frequency noise is changed to a high frequency during the modulation process, so it can be removed using a low-pass filter or a ripple rejection loop. .

13 is a comparison of noise levels according to whether or not the chopper stabilization circuit according to the present invention is used.

Referring to FIG. 13 , it can be seen that the magnitude of low-frequency noise included in the signal when the chopper shown above is not used is significantly larger than the magnitude of low-frequency noise included in the signal when the chopper shown at the bottom is used. .

In the above, the technical idea of the present invention has been described together with the accompanying drawings, but this is an exemplary description of a preferred embodiment of the present invention and does not limit the present invention. In addition, it is a clear fact that any person skilled in the art to which the present invention pertains can make various modifications and imitations without departing from the scope of the technical spirit of the present invention.

910: amplifier
920: positive SC input
930: positive feedback circuit
940: negative SC input
950: negative feedback circuit
960: amplifier input stage voltage adjustment circuit
CS2: second chopper stabilization circuit
CS3: 3rd chopper stabilization circuit
170: ADC
180: timing control circuit

Claims (7)

amplifier;
a second chopper stabilizing circuit for chopping input signals applied to two input terminals to two input terminals of the amplifier in response to switch control signals pi 3 and pi 4;
a third chopper stabilizing circuit for chopping two outputs of the amplifier applied to two input terminals to two output terminals in response to the pi 3 and the pi 4;
One input of the second chopper stabilization circuit after charging a predetermined amount of charge in the first input terminal capacitor included therein using one of the first voltage source and the second voltage source in response to the switch control signals pi 1 and pi 2 a positive SC input that transmits to the terminal;
Installed between one input terminal of the second chopper stabilization circuit and one output terminal of the third chopper stabilization circuit, in response to the switch control signal pi 0, the first feedback capacitor included therein is discharged or the positive SC a positive feedback circuit for charging an amount of charge in response to the amount of charge applied from the input unit to the first feedback capacitor;
Another operation of the second chopper stabilization circuit after charging a predetermined amount of charge to a second input terminal capacitor included therein using one of the first voltage source and the second voltage source in response to the pi 1 and the pi 2 a negative SC input unit for transmitting to the input terminal;
It is installed between the other input terminal of the second chopper stabilization circuit and the other output terminal of the third chopper stabilization circuit, and in response to the pi 0, the second feedback capacitor included therein is discharged or the negative SC input unit a negative feedback circuit for charging an amount of charge in response to the amount of charge applied from the second feedback capacitor; and
Generates two paths connected to the first voltage source, and each time Pi 2 is activated in response to switch control signals pi 3' and pi 4', one path is connected to the other terminal of the first input terminal capacitor and the A voltage regulating circuit connected to one of the other terminals of the second input terminal capacitor and the other path is connected to the other terminal.
Low-noise and high-sensitivity touch sensing circuitry. The method of claim 1, wherein the voltage regulating circuit comprises:
a first resistor having one terminal connected to the first voltage source;
a second resistor having one terminal connected to the first voltage source; and
In response to the switch control signals pi 3' and pi 4', the first path generated by the first resistor and the second path generated by the second resistor are alternately connected to the positive SC input unit and the negative SC input unit The first chopper stabilization circuit
Low-noise and high-sensitivity touch sensing circuitry. The method of claim 2, wherein the first chopper stabilization circuit comprises:
an eleventh switch for switching one input terminal of the first chopper stabilization circuit to an output terminal of the first chopper stabilization circuit in response to the pi 3';
a twelfth switch for switching one input terminal of the first chopper stabilization circuit to the other output terminal of the first chopper stabilization circuit in response to the pi 4';
a thirteenth switch for switching the other input terminal of the first chopper stabilization circuit to an output terminal of the first chopper stabilization circuit in response to the pi 4'; and
a fourteenth switch for switching the other input terminal of the first chopper stabilization circuit to the other output terminal of the first chopper stabilization circuit in response to the pi 3';
Low-noise and high-sensitivity touch sensing circuitry. The method of claim 1, wherein the second chopper stabilization circuit comprises:
a fifteenth switch for switching an input terminal of the second chopper stabilization circuit to an output terminal of the second chopper stabilization circuit in response to the pi 3;
a 16th switch for switching one input terminal of the second chopper stabilization circuit to the other output terminal of the second chopper stabilization circuit in response to the pi 4;
a seventeenth switch for switching the other input terminal of the second chopper stabilization circuit to an output terminal of the second chopper stabilization circuit in response to the pi 4; and
an eighteenth switch for switching the other input terminal of the second chopper stabilization circuit to the other output terminal of the second chopper stabilization circuit in response to the pi 3;
Low-noise and high-sensitivity touch sensing circuitry. The method of claim 1, wherein the third chopper stabilization circuit comprises:
a fifteenth switch for switching an input terminal of the third chopper stabilization circuit to an output terminal of the third chopper stabilization circuit in response to the pi 3;
a 16th switch for switching one input terminal of the third chopper stabilization circuit to the other output terminal of the third chopper stabilization circuit in response to the pi 4;
a seventeenth switch for switching the other input terminal of the third chopper stabilization circuit to an output terminal of the third chopper stabilization circuit in response to the pi 4; and
an eighteenth switch for switching the other input terminal of the third chopper stabilization circuit to the other output terminal of the third chopper stabilization circuit in response to the pi 3;
Low-noise and high-sensitivity touch sensing circuitry. In claim 3,
The pi 0 is used for initialization of the low-noise and high-sensitivity touch sensing circuit,
The pi 1, the pi 2, the pi 3, the pi 3', the pi 4 and the pi 4' are used for an integration process performed in the low-noise and high-sensitivity touch sensing circuit in the inactive state of the pi 0,
The period in which the pi 1 and the pi 2 are activated do not overlap each other,
The sections in which pi 3 and pi 4 are activated do not overlap each other,
The pi 3 is the same as the signal obtained by reducing the frequency of the pi 1 by half,
The pi 4 is the same as the signal obtained by delaying the pi 3 by half,
The pi 3' has the same frequency as the pi 3 and is a signal that is activated in a part of the period in which the pi 3 is activated,
The pi 4' has the same frequency as that of the pi 4 and is a low-noise and high-sensitivity touch sensing circuit that is a signal that is activated in a part of the period in which the pi 4 is activated. The low-noise and high-sensitivity touch sensing circuit according to claim 6;
an ADC for converting an analog signal output from the low-noise and high-sensitivity touch sensing circuit into a digital signal; and
a timing control circuit for generating the pi 0, the pi 1, the pi 2, the pi 3, the pi 3', the pi 4 and the pi 4';
A low-noise, high-sensitivity touch sensing system that includes.

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