KR101535131B1 - Method and apparatus for removal charge noise in touuch panel driver - Google Patents

Abstract

The present invention relates to removal of charge noise and, more particularly, to an apparatus for removing charge noise in a touch panel driving apparatus which sufficiently responds with respect to the charge noise caused by a ground mismatch between a sensor system in an electrostatic method and a human body, and enables to minimize loss of sensitivity, and a method thereof. According to the present invention, the apparatus comprises: an electric charge sensing unit including a capacitor in which a value is changed by a change in electric charges; an electric charge amplification unit for amplifying and outputting basic noise applied from the outside when a TX signal is turned-on, and amplifying and outputting an amount of the change in the electric charges received from the electric charge sensing unit when the TX signal is turned-off; a sampling unit having a first signal (vsnh_sig) for sampling the amount of the change in the electric charges received from the electric charge amplification unit and a second signal (vsnh_ref) for sampling the basic noise to be separated and outputted; an analog-to-digital conversion unit for converting a third signal (V_diff) which removes common noise from the first signal (vsnh_sig) and the second signal (vsnh_ref) received from the sampling unit (130), into a digital signal in order to output the same; a driving control unit for driving the TX signal to be turned-on or off; and a switching generator (150) for generating various control signals (sw, smp_sig, smp_ref, adc_ena) which control the driving of the electric charge amplification unit (120), the sampling unit (130), and the analog-to-digital conversion unit (140).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power noise canceling apparatus,

More particularly, the present invention relates to a touch panel driving apparatus capable of sufficiently responding to power noise caused by a ground mismatch between an electrostatic sensor system and a human body and minimizing loss of sensitivity And more particularly, to a power noise canceling apparatus and method.

The principle of the electrostatic sensor is a structure that senses a change in the amount of charge input to the sensor. The change of the charge amount can be changed in various ways, and a typical device for applying the change is a device for inducing a change of the charge amount by the touch.

FIG. 1 is a circuit diagram of a conventional mutual capacitance type electrostatic sensor, and FIG. 2 is a driving waveform diagram of the conventional mutual capacitance type electrostatic sensor of FIG.

1, in the conventional panel driving apparatus, a sum of a fixed capacitor between TX and RX metal and a capacitor formed in a magnetic field between TX and RX on the touch panel 1 is referred to as a mutual capacitance (Cm) The voltage according to the capacitance change of the capacitor Cm connected to the TX and RX enters the input of the single output amplifier 2 and outputs as one amplified voltage.

At this time, the output voltage vout is expressed by the following Equation 1.

Where VTX is the voltage of each of TX0 through TX4 in FIG. 1, and Cfb is the feedback capacitor connected between the (-) input and output of the amplifier.

Referring to FIG. 2, a TX pulse is inputted to the touch panel, and the output voltage Vout of the amplifier 2 is derived from Equation (1). The output voltage shows vsnh waveform through the sampling unit 3. The difference in the amount of change such as dV in FIG. 2 is caused by the amount of change of the mutual capacitance Cm at the time of touch, and the final analog- (4) to be output as a digital value of dV_code.

FIG. 3 is a circuit diagram modeling one channel of the touch panel of FIG. 1, and FIG. 4 is a waveform diagram showing an output signal of the amplifier according to noise.

Referring to FIG. 3, C1 is equal to Cm and C2 is equal to Cfb. FIG. 3 shows the modeling of the parasitic capacitors of the touch panel, the resistance, and the input paths of noise between the TX and C1 capacitor nodes, RX and C1 capacitor nodes.

Referring to FIG. 4, the cause of power noise (charge noise or power noise) is caused by a mismatch of ground. For example, the virtual ground vss2 of the touch panel modeling and the ground vss1 of the sensor amplifier 2 are represented differently when a finger is touched to the touch panel, noise of several tens Hz to several hundreds of kHz is input, As shown in Fig. 1, it is amplified by C2 (= Cfb).

The vout output by noise has a frequency of external noise and oscillates with a very large width. As a result, the change amount dV is greatly reduced as compared with FIG. 2, and as a result, the margin of the output sensitivity becomes very small as shown in FIG.

FIG. 5 is a circuit diagram of an electrostatic sensor having a noise canceling function according to the related art, FIG. 6 is a view for explaining a driving waveform of the electrostatic sensor having a noise canceling function shown in FIG. 5, Fig. 8 is a waveform diagram showing an output signal for a noise input.

An electrostatic sensor having a noise elimination function according to the related art includes a charge amount sensing unit 10, a charge amplification unit 20, a sampling unit 30, and an analog-to-digital converter (ADC) 40 as shown in FIG. . A driving control unit (not shown) for generating a voltage TX applied to the capacitors included in the charge amount sensing unit 10 and various control signals for controlling the driving of the sampling unit 30 and the analog / digital conversion unit 40 (Not shown).

The charge sensing unit 10 includes a first capacitor c1 whose charge value is fixed and a second capacitor c2 whose value changes by a change in the amount of charge and the first capacitor c1 and the second capacitor c2, c2 and detects the change of the charge amount by the interaction of the first capacitor c1 and the second capacitor c2 when the TX signal is on and the switch sw is on by the drive control unit, And the capacitor c4. The charge amount sensing unit 10 is grounded by the capacitor c4.

The charge amplifying unit 20 includes an amplifier 21 for amplifying and outputting a fundamental noise vn applied from the outside and a change amount of the charge input from the charge amount sensing unit 10, And a switch sw1 for connecting both ends of the feedback capacitor c3 and the feedback capacitor c3 connected between the feedback capacitor c3 and the feedback capacitor c3.

When the switch SW1 is turned off while the TX signal is turned on by the drive control unit, the amplifier 21 and the feedback capacitor c3 amplify the basic noise vn applied from the outside by the amplifying action of the amplifier 21 and the feedback capacitor c3 When the TX signal is turned off by the drive control unit in a state where the switch sw1 is off, the charge amount sensing unit 10 is controlled by the amplifying action of the amplifier 21 and the feedback capacitor c3, And outputs the amplified amount of change.

At this time, the fundamental noise vn applied from the outside by the feedback operation of the amplifier 21 is absorbed by the amplifier 21, so that the noise vn is not observed. Then, the switch sw1 is turned off while the TX signal is on to amplify and output the fundamental noise vn externally applied by the amplifying action of the amplifier 21 and the feedback capacitor c3, the amplifier 21 and the feedback capacitor c3 amplify the change amount of the charge input from the charge amount sensing unit 10 when the TX signal is turned off with the switch sw1 off, .

The sampling unit 30 includes a first sampling unit 31 for sampling a variation amount of charges received from the charge amplification unit 20 according to the first control signal smp_sig and outputting a first signal vsnh_sig, And a second sampling unit 32 for sampling the fundamental noise received from the charge amplification unit 20 according to the control signal smp_ref and outputting a second signal (vsnh_ref).

At this time, the first sampling unit 31 samples the change amount of the charge by the first control signal smp_sig in the state where the TX signal is turned off by the drive control unit and outputs the first signal (vsnh_sig) 2 sampling unit 32 samples the basic noise by the second control signal smp_ref of the drive control unit in the TX signal on state by the drive control unit and outputs the sampled basic noise as the second signal vsnh_ref.

For example, when a signal for controlling the driving of the sampling unit 30 is input by the drive control unit in the ON state of the TX signal, the basic noise vn is sampled to output the second signal (vsnh_ref). Here, the second signal refers to a reference. After the output of the second signal (vsnh_ref), the TX control signal is turned off by the drive control unit. When a signal for controlling the driving of the sampling unit 30 is inputted, the change amount of the charge is sampled, (vsnh_sig). Here, the first signal refers to a signal.

The drive control unit calculates and outputs a third signal V_diff which is a difference between the first signal (vsnh_sig) received from the sampling unit 30 and the second signal (vsnh_ref). Specifically, the third signal V_diff is a component obtained by subtracting the second signal (vsnh_ref) from the first signal (vsnh_sig).

The analog-to-digital converter (ADC) 40 converts the received third signal V_diff into a digital signal ADC_OUT and outputs it.

However, in this conventional technique, even if the same noise level is applied to the first signal and the second reference, since the first signal amplification is amplified based on the relative second reference, the noise level of the reference signal becomes relatively invisible and as a result, only the noise of the first signal is visible as shown in FIG. Therefore, there is a problem that the output sensitivity is attenuated and the input range of the analog-to-digital converter (ADC) becomes out of order, resulting in an error code of the analog-to-digital converter (ADC).

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the conventional art and it is an object of the present invention to provide an apparatus and method for detecting an external power noise signal for a power noise caused by a ground mismatch between an electrostatic sensor system and a human body, There is provided an apparatus and method for removing power noise in a touch panel driving apparatus capable of enhancing sensitivity by eliminating a common noise component by applying a common noise to a touch panel driving apparatus, There is a purpose.

According to an aspect of the present invention, there is provided an apparatus for removing power noise in a touch panel driving apparatus including: a charge amount sensing unit including a capacitor whose value changes according to a change in a charge amount; A charge amplification unit for amplifying and outputting a fundamental noise applied from the outside when the TX signal is on and amplifying a change amount of the charge input from the charge amount sensing unit when the TX signal is off; A sampling unit for separately outputting a first signal (vsnh_sig) obtained by sampling a change amount of the charge received from the charge amplification unit and a second signal (vsnh_ref) sampled from the fundamental noise; An analog-to-digital converter for converting a first signal (vsnh_sig) received from the sampling unit and a third signal (V_diff) obtained by removing common noise from the second signal (vsnh_ref) into a digital signal and outputting the digital signal; A drive control unit for driving a TX signal on and off; And a switching generator for generating various control signals (sw, smp_sig, smp_ref, adc_ena) for controlling the driving of the charge amplifying part, the sampling part and the analog / digital converting part.

Here, the charge amplifying unit includes: an amplifier for amplifying and outputting a change amount of charge inputted from the external noise source and the charge amount sensing unit; A feedback capacitor connected between the inverting input terminal and the output terminal of the amplifier; And a switch connecting both ends of the feedback capacitor. When the TX signal is on, the switch is turned off to amplify and output the basic noise applied from the outside by the amplifying action of the amplifier and the feedback capacitor When the TX signal is turned off when the switch is off, it is preferable to amplify and output the change amount of the charge input from the charge amount sensing unit by the amplifying action of the amplifier and the feedback capacitor.

The charge sensing unit includes a first capacitor having a fixed charge value and a second capacitor having a variable value according to a change in the amount of charge. The charge sensing unit senses a change in the amount of charge due to an interaction between the first capacitor and the second capacitor. It is preferable to initialize the first capacitor and the second capacitor in a state where the signal is on and the switch is on.

On the other hand, the charge amplifying unit includes: an amplifier for amplifying and outputting a change amount of charge inputted from the external noise source and the basic noise; A first variable capacitor connected between the inverting input terminal and the output terminal of the amplifier; A first switch connecting both ends of the first variable capacitor; A second variable capacitor connected to one end of the first switch; And a second switch for connecting the other end of the first switch and the second variable capacitor. When sensing a basic reference, only the first variable capacitor is operated, and the change amount of the charge is sensed the first variable capacitor c5 and the second variable capacitor c6 operate or vice versa to adjust the magnitude of the charge and the basic noise of the charge signal to determine the final sensitivity .

The charge amount sensing unit may include a first capacitor having a fixed charge value and a second capacitor having a value varying according to a change in the amount of charge. The charge amount sensing unit senses a change in the amount of charge due to an interaction between the first capacitor and the second capacitor, It is preferable to initialize the first capacitor and the second capacitor when the TX signal is on, the first switch is on, and the second switch is off.

Here, the sampling unit includes: a first sampling unit for sampling a fundamental noise received from the charge amplification unit according to a first control signal and outputting a first signal; And a second sampling unit for sampling a change amount of the charge received from the charge amplification unit according to the second control signal and outputting a second signal, wherein the first sampling unit is configured to output the first control signal when the TX signal is off And the second sampling unit samples the basic noise by the second control signal and outputs the second signal when the TX signal is on.

The analog-to-digital converter preferably converts the third signal into a digital signal according to the third control signal while the TX signal is off, and outputs the digital signal.

The present invention has the following effects.

First, a change in driving operation is applied to the input noise signal, noise is commonly applied to a reference and a signal, and then the common noise component is removed by a differential method, thereby improving the touch sensitivity have.

Second, the algorithm for eliminating the power supply noise is processed at the analog end of the ADC so that problems such as reduction in operating speed, increase in current, and increase in area can be solved.

1 is a circuit diagram of a conventional mutual capacitance type electrostatic sensor.
2 is a driving waveform diagram of the conventional mutual capacitance type electrostatic sensor of FIG.
3 is a circuit diagram modeling one channel of the touch panel of Fig.
4 is a waveform diagram showing an output signal of the amplifier according to noise.
5 is a circuit diagram of an electrostatic sensor having a noise canceling function according to the related art.
6 is a diagram for explaining a drive waveform of the electrostatic sensor having the noise canceling function shown in FIG.
7 is a waveform diagram showing an output signal for the noise input of FIG.
8 is a view for explaining a power noise removing device in the touch panel driving apparatus according to the first embodiment of the present invention.
FIG. 9 is a diagram for explaining driving waveforms of the power noise removing apparatus in the touch panel driving apparatus according to the first embodiment of the present invention shown in FIG.
10 is a diagram for explaining an output signal for the noise input of FIG.
11 is a view for explaining a power noise removing apparatus in a touch panel driving apparatus according to a second embodiment of the present invention.
FIG. 12 is a diagram for explaining driving waveforms of a power noise removing apparatus in a touch panel driving apparatus according to a second embodiment of the present invention shown in FIG. 11;

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

In addition, although the term used in the present invention is selected as a general term that is widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, since the meaning is described in detail in the description of the relevant invention, It is to be understood that the present invention should be grasped as a meaning of a term that is not a name of the present invention. Further, in describing the embodiments, descriptions of technical contents which are well known in the technical field to which the present invention belongs and which are not directly related to the present invention will be omitted. This is for the sake of clarity of the present invention without omitting the unnecessary explanation.

In the present invention, since the TX signal and various signals have phases, the present invention is also applicable to the case where the phases of the signals are opposite to each other, and it is obvious that they belong to the scope of the present invention.

8 is a view for explaining a power noise removing device in the touch panel driving apparatus according to the first embodiment of the present invention.

8, the apparatus for removing power supply noise in the touch panel driving apparatus according to the first embodiment of the present invention includes a charge quantity sensing unit 110, a charge amplification unit 120, a sampling unit 130, an analog-digital conversion unit ADC) 140 and a switching generator 150.

The switching generator 150 generates various control signals (sw, smp_sig, smp_ref, adc_ena) for controlling the driving of the charge amplification unit 120, the sampling unit 130 and the analog / digital conversion unit 140.

In addition, the power supply noise removing apparatus of the present invention controls the driving (on / off) of the voltage TX applied to the capacitors included in the charge amount sensing unit 110 and controls various control signals sw, smp_sig, smp_ref, and a drive control unit (not shown) for controlling the generation and timing of the signals.

The charge quantity can be varied by various methods. Typically, the amount of charge can be changed by a touch, but the present invention can be applied to all devices in which the amount of charges other than the touch can change.

The charge amount sensing unit 110 includes a capacitor c2 whose value changes according to a change in the amount of charge. Preferably, it may be implemented by a mutual capacitance method.

The charge amplification unit 120 amplifies and outputs the fundamental noise vn applied from the outside when the TX signal is turned on in the drive control unit and outputs the amplified basic noise vn, Amplifies and outputs the change amount of the charge.

The sampling unit 130 separates the first signal (vsnh_sig) sampled by the amount of change in charge and the second signal (vsnh_ref) sampled from the basic noise vn received from the charge amplification unit 120 and outputs the separated signal.

Specifically, when the signal (smp_ref) for controlling the driving of the sampling unit 130 is input from the switching generator 150 in a state where the TX signal is turned on by the drive control unit, the fundamental noise vn is sampled, . The second signal is a reference. The TX signal is switched to the off state by the drive control unit and the signal smp_sig for controlling the driving of the sampling unit 130 is inputted from the switching generator 150. Then, And outputs a first signal. The first signal is a signal.

The analog-to-digital converter (ADC) 140 converts the received first signal (vsnh_sig) received from the sampling unit 130 and a third signal V_diff from which the common noise is removed from the second signal (vsnh_ref) ADC_OUT).

The switching generator 150 generates various control signals (sw, smp_sig, smp_ref, adc_ena) for controlling the driving of the charge amplification unit 120, the sampling unit 130 and the analog / digital conversion unit 140.

[First Embodiment]

FIG. 8 is a circuit diagram of an apparatus for removing power supply noise in a touch panel driving apparatus according to a first embodiment of the present invention, FIG. 9 is a circuit diagram of a power noise removing apparatus in the touch panel driving apparatus according to the first embodiment of the present invention, And FIG. 10 is a waveform diagram for explaining the output of the noise input in the touch panel driving apparatus according to the first embodiment of the present invention.

8 and 9, the charge amplification unit 120 includes an amplifier 121 for amplifying and outputting a fundamental noise vn applied from the outside and a change amount of the charge input from the charge amount sensing unit 110, A feedback capacitor c3 connected between an inverting input terminal and an output terminal of the feedback capacitor c1 and a switch sw connecting both ends of the feedback capacitor c3.

When the switching signal is turned off by the switching generator 150 while the TX signal is turned on by the driving control unit, the amplifying operation of the amplifier 121 and the feedback capacitor c3 causes the base The amplifier 121 and the feedback capacitor c3 amplify and output the noise vn by turning off the TX signal by the drive control unit while the switch sw is off, And amplifies and outputs the change amount of the charge input from the charge amount sensing unit 110. [

The charge amount sensing unit 110 includes a first capacitor c1 whose charge value is fixed and a second capacitor c2 whose value changes by a change in the amount of charge. The charge amount sensing unit 110 includes a first capacitor c1 and a second capacitor c2, c2 and detects the change of the amount of charge by the interaction of the first capacitor c1 and the second capacitor c1 when the TX signal is turned on by the drive control unit and the switch sw is turned on by the switching generator 150, The second capacitor c2, and the capacitor c4. The charge amount sensing unit 110 is grounded by the capacitor c4.

At this time, the fundamental noise vn applied from the outside by the feedback operation of the amplifier 121 is absorbed by the amplifier 121, so that the noise vn is not observed. Then, in the ON state of the TX signal, the switch sw is turned off to amplify and output the fundamental noise vn externally applied by the amplifying action of the amplifier 121 and the feedback capacitor c3, the amplifier 121 and the feedback capacitor c3 amplify the change amount of the charge input from the charge amount sensing unit 110 by the amplification action of the amplifier 121 and the feedback capacitor c3 when the TX signal is turned off, Output.

The sampling unit 130 samples a variation amount of the charge received from the charge amplification unit 120 according to the first control signal smp_sig from the switching generator 150 and outputs a first signal Which outputs a second signal (vsnh_ref) by sampling the fundamental noise received from the charge amplification section 120 in accordance with the second control signal smp_ref from the sampling section 131 and the switching generator 150, ) Sampling unit 132. The sampling unit 132 includes a sampling unit 132,

The first sampling unit 131 samples the change amount of the charge by the first control signal smp_sig from the switching generator 150 in the state where the TX signal is turned off by the drive control unit and outputs the first signal vsnh_sig, . The second sampling unit 132 samples the basic noise by the second control signal smp_ref from the switching generator 150 while the TX signal is turned on by the drive control unit and outputs the second signal vsnh_ref do.

The analog-to-digital converter (ADC) 150 receives the third control signal adc_ena from the sampling unit 130 according to the third control signal adc_ena from the switching generator 150 in the state that the TX signal is off by the drive control unit. The third signal V_diff is calculated by calculating a third signal V_diff which is a difference between the first signal vsnh_sig and the second signal vsnh_ref and converts the third signal V_diff into a digital signal ADC_OUT.

When noises are applied to the outside, the switching generator 150 drives it as shown in FIG.

The first control signal c1, the second capacitor c2 and the capacitor c4 are initialized when the switch generator 150 turns on the switch sw in the period in which the TX signal is high by the drive control unit . At this time, the fundamental noise vn is absorbed by the amplifier 121 by the feedback operation of the amplifier 121, so that no noise is observed. At this time, when the switching generator 150 turns off the switch sw, basic noise is amplified by the amplification action of the feedback capacitor c3 and the amplifier 121, and is output as vout. And samples it with the second signal (vsnh_ref) by the second control signal smp_ref. Up to this point, the change amount of the charge of the second capacitor c2 has not yet been outputted as vout.

Then, when the switch sw is turned on for the second time, the capacitor c4 and the first capacitor c1 and the second capacitor c2 are initialized again, and the drive control unit drives the TX signal to low, 2 capacitor c2 is transferred to the amplifier 121, the amplifier 121 amplifies the change amount of the second capacitor c2 by the feedback capacitor c3 and outputs the amplified voltage to the output terminal vout. At this time, sampling is performed with the first signal (vsnh_sig) using the first control signal (smp_sig) from the switching generator 150.

The second signal (vsnh_ref) and the first signal (vsnh_sig) are subjected to the same noise that varies due to external noise and the third signal V_diff, which is the difference between the two signals, (ADC) 140, the common noise components of the two signals are removed and only the signal components pass through the analog-to-digital converter (ADC) 140 as shown in FIG. 10, resulting in an increase in the dV_code which is the sensitivity of the system.

[Second Embodiment]

FIG. 11 is a circuit diagram of an apparatus for removing power supply noise in a touch panel driving apparatus according to a second embodiment of the present invention. FIG. 12 is a circuit diagram of a power noise removing apparatus in a touch panel driving apparatus according to a second embodiment of the present invention. Fig.

11 and 12, an apparatus for removing power supply noise in a touch panel driving apparatus according to a second embodiment of the present invention includes a charge amount sensing unit 110, a sampling unit 130, and an analog-to-digital converter (ADC) 140 are the same as those of the first embodiment.

Particularly, the difference is the charge amplification part 120 and the switching generator 160, and therefore, the description will focus on this point.

The charge amplifying unit 120 includes an amplifier 121 for amplifying and outputting a basic noise vn and an amount of change of charges input from the charge amount sensing unit 110 and an inverting input terminal and an output terminal of the amplifier 121, A first switch sw1 connecting both ends of the first variable capacitor c5, a second variable capacitor c6 connected to one end of the first switch sw1, and a second variable capacitor c5 connected to one end of the first switch sw1. 1 switch (sw1) and a second switch (sw2) connecting the other end of the switch (sw1) and the second variable capacitor (c6).

The switching generator 160 generates various control signals (sw1, sw2, smp_sig, smp_ref, adc_ena) for controlling the driving of the charge amplification unit 120, the sampling unit 130 and the analog-

When the first switch sw1 and the second switch sw2 are turned off under the control of the switching generator 160 while the TX signal is turned on by the drive control unit, the amplifier 121 and the first variable Amplifies and outputs the basic noise vn applied from the outside by the amplifying action of the capacitor c5 and turns off the TX signal by the drive control unit when the first switch sw1 is off, When the second switch sw2 is turned on in the generator 160, the amplification operation of the amplifier 121, the first variable capacitor c5 and the second variable capacitor c6 causes the charge amount detection unit 110 And amplifies and outputs the amount of change of the input charge.

The charge amount sensing unit 110 includes a first capacitor c1 whose charge value is fixed and a second capacitor c2 whose value changes by a change in the amount of charge. The charge amount sensing unit 110 includes a first capacitor c1 and a second capacitor c2, c2 and the TX signal is turned on by the drive control unit and the first switch sw1 is turned on and the second switch sw2 is turned on by the switching generator 160, Initialize the first capacitor c1 and the second capacitor c2 in the off state. And the charge amount sensing unit 10 is grounded by the capacitor c4.

At this time, the fundamental noise vn applied from the outside by the feedback operation of the amplifier 121 is absorbed by the amplifier 121, so that the noise vn is not observed.

Then, in a state in which the TX signal is on, the switching generator 160 turns off the first switch sw1 and the second switch sw2 to perform the amplifying operation of the amplifier 121 and the first variable capacitor c5 Amplifies and outputs the basic noise vn applied from the outside by the switching generator 160 and turns off the TX signal in a state where the first switch sw1 is turned off by the switching generator 160, When the second switch sw2 is turned on by the first variable capacitor c5 and the second variable capacitor c6 by the amplifying function of the amplifier 121, the first variable capacitor c5 and the second variable capacitor c6, And outputs the amplified change amount.

Details of the other components are the same as those of the first embodiment, and thus will not be described.

12, the operation of the TX signal and the switch of the electrostatic-type sensor described in the second embodiment and the driving of various control signals for controlling the sampling unit 130 and the analog-to-digital converter (ADC) You can see the waveform.

When external noise is applied, the switching generator 160 drives as shown in FIG.

The level of noise in the sensing operation due to the external noise and the driving time may change the amount of charge and the reference noise. In this case, when sensing a basic reference using the first variable capacitor c5 and the second variable capacitor c6 as shown in FIG. 11, only the first variable capacitor c5 operates and the amount of change the first variable capacitor c5 and the second variable capacitor c6 operate or vice versa to sense a change in the amount of charge and a basic reference The size can be tuned and the final sensitivity can be improved.

According to the present invention, there is an effect that noise is commonly applied to reference and signal by changing a driving operation with respect to an input noise signal, and sensitivity is improved by removing a common noise component by a differential method.

Also, it is possible to process the algorithm that eliminates the charge noise at the analog end of the ADC, which can be processed at the downstream end of the ADC, to solve the problems such as decrease in operation speed, increase in current, There is an effect.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. Obviously, such modifications are intended to be within the scope of the claims.

110: charge amount sensing unit 120: charge amplification unit
121: Amplifier 130: Sampling unit
140: analog-to-digital converter (ADC) 150, 160: switching generator

Claims (7)

A charge amount sensing unit including a capacitor whose value changes according to a change in a charge amount;
A charge amplification unit for amplifying and outputting a fundamental noise applied from the outside when the TX signal is on and amplifying a change amount of the charge input from the charge amount sensing unit when the TX signal is off;
A sampling unit for separately outputting a first signal (vsnh_sig) obtained by sampling a change amount of the charge received from the charge amplification unit and a second signal (vsnh_ref) sampled from the basic noise;
An analog-to-digital converter converting the first signal (vsnh_sig) received from the sampling unit 130 and the third signal (V_diff) obtained by removing the common noise from the second signal (vsnh_ref) into a digital signal and outputting the digital signal;
A driving control unit for driving the TX signal on and off; And
And a switching generator 150 for generating various control signals (sw, smp_sig, smp_ref, adc_ena) for controlling the driving of the charge amplification part 120, the sampling part 130 and the analog / digital conversion part 140 Wherein the power supply noise canceling device comprises:
The method according to claim 1,
Wherein the charge amplification unit comprises:
An amplifier for amplifying and outputting a basic noise applied from the outside and a variation amount of the charge input from the charge amount sensing unit;
A feedback capacitor connected between the inverting input terminal and the output terminal of the amplifier; And
And a switch connecting both ends of the feedback capacitor,
When the TX signal is on, amplifying and outputting a fundamental noise applied from the outside by the amplifying action of the amplifier and the feedback capacitor when the switch is turned off, and when the switch is off, And amplifies and outputs a change amount of the charge input from the charge amount sensing unit by an amplification action of the amplifier and the feedback capacitor when the TX signal is off.
3. The method of claim 2,
Wherein the charge amount sensing unit includes a first capacitor having a fixed charge value and a second capacitor having a value varying according to a change in the amount of charge, the charge amount sensing unit sensing a change in the amount of charge due to an interaction between the first capacitor and the second capacitor,
Wherein the first and second capacitors are initialized in a state where the TX signal is on and the switch is on. The method according to claim 1,
Wherein the charge amplification unit comprises:
An amplifier for amplifying and outputting a basic noise applied from the outside and a variation amount of the charge input from the charge amount sensing unit;
A first variable capacitor connected between an inverting input terminal and an output terminal of the amplifier;
A first switch connecting both ends of the first variable capacitor;
A second variable capacitor connected to one end of the first switch; And
And a second switch connecting the other end of the first switch and the second variable capacitor,
When sensing the basic reference, only the first variable capacitor operates. When sensing a charge change signal, the first variable capacitor c5 and the second variable capacitor c6 operate or vice versa to improve the final sensitivity by programmatically adjusting the magnitude of a charge of a charge and a reference noise. .
5. The method of claim 4,
Wherein the charge amount sensing unit includes a first capacitor having a fixed charge value and a second capacitor having a value varying according to a change in the amount of charge, the charge amount sensing unit sensing a change in the amount of charge due to an interaction between the first capacitor and the second capacitor,
Wherein the first and second capacitors are initialized when the TX signal is on, the first switch is on, and the second switch is off. Power noise cancellation device.
The method according to claim 2 or 4,
Wherein the sampling unit comprises:
A first sampling unit for sampling a fundamental noise received from the charge amplification unit according to a first control signal and outputting a first signal; And
And a second sampling unit for sampling a variation amount of the charge received from the charge amplification unit according to a second control signal and outputting a second signal,
Wherein the first sampling unit samples a change amount of the charge by the first control signal and outputs a first signal when the TX signal is off,
Wherein the second sampling unit samples the fundamental noise by the second control signal and outputs a second signal when the TX signal is on.
The method according to claim 1,
Wherein the analog-to-digital converter converts the third signal into a digital signal and outputs the digital signal according to a third control signal when the TX signal is off.

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