Capacitance detection circuit, touch chip and electronic device

Abstract

The application discloses a kind of capacitance detection circuit, touch chip and electronic equipment, the capacitance detection circuit includes: detection capacitance, the detection capacitance is used to detect external sensing signal, and corresponding capacitance value is output;Drive circuit, the drive circuit is used to generate and output driving signal;Capacitance-voltage conversion circuit, the first input end of the capacitance-voltage conversion circuit is connected with the detection capacitance, the second input end of the capacitance-voltage conversion circuit is connected with the output end of the drive circuit, and the capacitance-voltage conversion circuit is used to output corresponding total voltage signal according to the capacitance value of the detection capacitance and the driving signal;Signal processing circuit, the receiving end of the signal processing circuit is connected with the output end of the capacitance-voltage conversion circuit, and the signal processing circuit is also used to signal processing to the total voltage signal, to obtain the capacitance variation of the detection capacitance.The application can improve the sensitivity of capacitance detection circuit.

Description

Technical Field

[0001] This invention relates to the field of capacitance detection technology, and in particular to a capacitance detection circuit, a touch chip, and an electronic device. Background Technology

[0002] Traditional switch-controlled discrete capacitance detection circuits sample interference noise on the capacitance sensor when the switch is activated. Since the frequency of the switch action is much lower than the frequency of the interference noise, according to the Nyquist sampling theorem, the interference noise will be aliased into the useful signal bandwidth, thereby increasing the noise energy in the useful signal bandwidth and reducing the sensitivity of the capacitance detection circuit. Summary of the Invention

[0003] The main objective of this invention is to provide a capacitance detection circuit that aims to improve the sensitivity of the capacitance detection circuit.

[0004] To achieve the above objectives, the present invention provides a capacitance detection circuit comprising:

[0005] A detection capacitor is used to detect external sensing signals and output the corresponding capacitance value.

[0006] The driving circuit is used to generate and output driving signals;

[0007] A capacitor-to-voltage circuit is provided, wherein the first input terminal of the capacitor-to-voltage circuit is connected to the detection capacitor, and the second input terminal of the capacitor-to-voltage circuit is connected to the output terminal of the driving circuit. The capacitor-to-voltage circuit is used to output a corresponding total voltage signal according to the capacitance value of the detection capacitor and the driving signal.

[0008] The signal processing circuit has its receiving end connected to the output end of the capacitor-to-voltage circuit. The signal processing circuit is also used to process the total voltage signal to obtain the capacitance change of the detection capacitor.

[0009] Optionally, the capacitance detection circuit further includes:

[0010] A programmable gain amplifier is provided, wherein the positive input terminal of the programmable gain amplifier is connected to the output terminal of the capacitor-to-voltage circuit, and the output terminal of the programmable gain amplifier is connected to the receiving terminal of the signal processing circuit. The programmable gain amplifier is used to amplify the total voltage signal and output it to the signal processing circuit so that the signal processing circuit can obtain the capacitance change of the detection capacitor based on the total voltage signal.

[0011] Optionally, the capacitance detection circuit further includes:

[0012] A voltage cancellation circuit is connected to the inverting input terminal of the programmable gain amplifier. The voltage cancellation circuit is used to output a cancellation signal to the programmable gain amplifier so that the programmable gain amplifier cancels the basic voltage signal according to the cancellation signal and converts the total voltage signal into a corresponding voltage change signal before outputting it.

[0013] The signal processing circuit is also used to process the voltage change signal to obtain the change in the detection capacitor.

[0014] Optionally, the detection capacitor is also used to output a base capacitance value when no external sensing signal is detected;

[0015] The capacitor-to-voltage circuit is also used to output a corresponding base voltage signal based on the base capacitance value of the detection capacitor and the driving signal.

[0016] The amplitude, frequency, and phase of the cancellation signal are the same as those of the base voltage signal.

[0017] Optionally, the voltage cancellation module includes:

[0018] A cancellation signal generating circuit, wherein the cancellation signal generating circuit is used to generate and output a cancellation signal;

[0019] A digital-to-analog converter (DAC) is provided, wherein the input terminal of the DAC is connected to the output terminal of the cancellation signal generation circuit, and the output terminal of the DAC is connected to the inverting input terminal of the programmable gain amplifier. The DAC is used to perform digital-to-analog conversion processing on the cancellation signal and then output it to the programmable gain amplifier.

[0020] Optionally, the driving circuit includes:

[0021] A drive signal generation circuit, wherein the drive signal generation circuit is used to generate and output a drive signal;

[0022] A digital-to-analog converter (DAC) is provided, wherein the input terminal of the DAC is connected to the output terminal of the drive signal generation circuit, and the output terminal of the DAC is connected to the second input terminal of the capacitor-to-voltage circuit. The DAC is used to perform digital-to-analog conversion processing on the drive signal and then output it to the capacitor-to-voltage circuit.

[0023] Optionally, the signal processing circuit includes:

[0024] An analog-to-digital converter (ADC) is provided, the input of which is connected to the output of the programmable gain amplifier. The ADC is used to convert the total voltage signal output by the capacitor-to-voltage circuit into an analog-to-digital signal and then output it.

[0025] A signal processor, the input of which is connected to the output of the analog-to-digital converter, is used to process the total voltage signal output by the analog-to-digital converter to obtain the capacitance change of the detection capacitor.

[0026] Optionally, the driving signal is one of a sine wave, a square wave, a triangular wave, and a sawtooth wave.

[0027] The present invention also proposes a touch chip, which includes the above-described capacitance detection circuit.

[0028] The present invention also proposes an electronic device, which includes the touch chip described above; or, includes the capacitance detection circuit described above.

[0029] In this invention, a driving circuit is used to generate continuous driving signals. Upon receiving the driving signal, the capacitor-to-voltage circuit converts the capacitance of the detected capacitor into a voltage, allowing the signal processing circuit to obtain the capacitance change of the detected capacitor from the voltage signal output by the capacitor-to-voltage circuit. This invention uses continuous driving signals, avoiding the sampling problems inherent in switched capacitor circuits. Therefore, it effectively avoids noise aliasing caused by sampling and improves the capacitance detection sensitivity under interference noise conditions. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0031] Figure 1 This is a functional module diagram of an embodiment of the capacitance detection circuit of the present invention;

[0032] Figure 2 This is a functional module schematic diagram of another embodiment of the capacitance detection circuit of the present invention;

[0033] Figure 3 This is a schematic diagram of the circuit structure of an embodiment of the capacitance detection circuit of the present invention.

[0034] Explanation of icon numbers:

[0035] label name label name 10 Detection capacitor 60 Voltage cancellation circuit 20 drive circuit DAC1, DAC2 Digital-to-analog converter 30 Capacitor-to-voltage circuit ADC Analog-to-digital converter 40 Signal processing circuit DSP Digital Signal Processor 50 Programmable gain amplifier

[0036] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0039] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0040] This invention proposes a capacitance detection circuit.

[0041] Currently, traditional switch-controlled discrete capacitance detection circuits sample interference noise on the capacitance sensor when the switch is activated. Since the frequency of the switch action is much lower than the frequency of the interference noise, according to the Nyquist sampling theorem, the interference noise will be aliased into the useful signal bandwidth, thereby increasing the noise energy in the useful signal bandwidth and reducing the sensitivity of the capacitance detection circuit.

[0042] To solve the above problems, refer to Figures 1 to 3 In one embodiment, the capacitance detection circuit includes:

[0043] The detection capacitor 10 is used to detect external sensing signals and output the corresponding capacitance value.

[0044] Drive circuit 20, which is used to generate and output drive signals;

[0045] A capacitor-to-voltage circuit 30 is provided, wherein the first input terminal of the capacitor-to-voltage circuit 30 is connected to the detection capacitor 10, and the second input terminal of the capacitor-to-voltage circuit 30 is connected to the output terminal of the driving circuit 20. The capacitor-to-voltage circuit 30 is used to output a corresponding total voltage signal according to the capacitance value of the detection capacitor 10 and the driving signal.

[0046] The signal processing circuit 40 has its receiving end connected to the output end of the capacitor-to-voltage circuit 30. The signal processing circuit 40 is also used to obtain the capacitance change of the detection capacitor 10 based on the total voltage signal.

[0047] In this embodiment, the detection capacitor 10 can be implemented using a variable capacitor, such as a variable-gap capacitor, a variable-area capacitor, or a variable-dielectric capacitor. According to the capacitance formula C = εA / δ, where ε is the dielectric constant of the two electrodes, A is the area covered by the electrodes, and δ is the distance between the electrodes, when the dielectric constant and area are constant, the smaller the distance between the electrodes, the larger the capacitance; conversely, the larger the distance, the smaller the capacitance. Thus, when the detection capacitor 10 receives external sensing signals, such as sound, pressure, or vibration, the pressure-sensitive film will displace, causing a change in the distance between the pressure-sensitive film and the substrate electrodes, thereby altering the capacitance between them and achieving the detection of the sensing signal.

[0048] The driver circuit 20 can be implemented using a microprocessor and a digital-to-analog converter (DAC) to generate and output the drive signal, while the capacitor-to-voltage circuit 30 can be implemented using a comparator. (See reference...) Figure 3 , Figure 3 This is a schematic diagram of a circuit structure for an embodiment of a capacitance detection circuit. The capacitance-to-voltage circuit 30 in the diagram is implemented using a comparator. The positive input terminal of the comparator is connected to the drive circuit 20 to receive the drive signal, while the negative input terminal is connected to the detection capacitor 10. Thus, the comparator can output a corresponding voltage signal based on the drive signal and the capacitance value of the detection capacitor 10, that is, convert the capacitance of the detection capacitor 10 into a voltage value and output it. The drive signal generated by the drive circuit 20 can be a sine wave, square wave, triangle wave, sawtooth wave, etc. The following explanation uses a sine wave as an example.

[0049] The drive circuit 20 generates a sine wave with amplitude B1 and frequency f:

[0050] V in =B1sin(2πft)

[0051] After passing through capacitor-to-voltage converter 30, the output is:

[0052]

[0053] in:

[0054]

[0055] Thus, when the signal processing circuit 40 receives the total voltage signal output by the capacitor-to-voltage circuit 30, it can obtain the capacitance change value of the detection capacitor 10 by means of table lookup, quadrature demodulation and Fourier transform, and thus obtain the sensing signal or other parameters detected by the detection capacitor 10 based on the capacitance change value of the detection capacitor 10.

[0056] Understandably, existing capacitance detection circuits are typically switched capacitor circuits. In practical applications, a sampling process is unavoidable. When the capacitance value Ctp of the detection capacitor 10 is relatively large, the switching frequency cannot be very high. Furthermore, in practical applications, the capacitance value Ctp of the detection capacitor 10 is often affected by noise interference. When the interference noise is greater than half the switching frequency, according to the Nyquist sampling theorem, the interference noise will be aliased into the useful signal bandwidth, thereby increasing the noise energy within the useful signal bandwidth and reducing the sensitivity of the capacitance detection circuit.

[0057] Therefore, in the technical solution of this invention, a driving circuit 20 is used to generate a continuous driving signal to replace the switch for driving. This allows the capacitor-to-voltage circuit 30 to convert the capacitance of the detection capacitor 10 into a voltage value upon receiving the driving signal, enabling the signal processing circuit 40 to obtain the capacitance change of the detection capacitor 10 through the voltage value. This invention uses a continuous driving signal, eliminating the need for a switch to control the detection capacitor for sampling. This avoids the switching sampling problem present in switched capacitor circuits. Thus, in the presence of interference noise, the interference noise will not be superimposed into the useful signal bandwidth due to switching sampling. Therefore, noise aliasing caused by sampling can be effectively avoided, thereby improving the purity of the useful signal and increasing the capacitance detection sensitivity in the presence of interference noise.

[0058] Reference Figures 1 to 3 In one embodiment, the capacitance detection circuit further includes:

[0059] A programmable gain amplifier 50 is provided, with its positive input terminal connected to the output terminal of the capacitor-to-voltage circuit 30 and its output terminal connected to the receiving terminal of the signal processing circuit 40. The programmable gain amplifier 50 is used to amplify the total voltage signal and output it to the signal processing circuit 40, so that the signal processing circuit 40 can obtain the capacitance change of the detection capacitor 10 based on the total voltage signal.

[0060] In this embodiment, a programmable gain amplifier 50 is selected to amplify the voltage signal output from the capacitor-to-voltage circuit 30. Alternatively, other amplifiers or amplification circuits can be used to achieve the signal amplification effect. (Refer to...) Figure 3 , Figure 3 This is a schematic diagram of the circuit structure of an embodiment of the capacitance detection circuit. The positive input terminal of the programmable gain amplifier 50 is connected to the output terminal of the capacitor-to-voltage circuit 30, which is used to amplify the total voltage signal output by the capacitor-to-voltage circuit 30 and then output it to the signal processing circuit 40.

[0061] Optionally, the capacitance detection circuit further includes:

[0062] A voltage cancellation circuit 60 is connected to the inverting input terminal of the programmable gain amplifier 50. The voltage cancellation circuit 60 is used to output a cancellation signal to the programmable gain amplifier 50, so that the programmable gain amplifier 50 cancels the basic voltage signal according to the cancellation signal and converts the total voltage signal into a corresponding voltage change signal before outputting it.

[0063] The signal processing circuit 40 is also used to obtain the change in the detection capacitor 10 based on the voltage change signal.

[0064] In this embodiment, the voltage cancellation circuit 60 can be implemented using a microprocessor and a digital-to-analog converter (DAC) to generate and output a cancellation signal. (Refer to...) Figure 3 , Figure 3 This is a schematic diagram of a circuit structure for one embodiment of a capacitance detection circuit. The inverting input of the programmable gain amplifier 50 is connected to the voltage cancellation circuit 60 to receive the cancellation signal, while the non-inverting input of the programmable gain amplifier 50 is connected to the output of the capacitance-to-voltage conversion circuit 30. Thus, the programmable gain amplifier 50 can cancel out the basic voltage signal portion representing the basic capacitance value of the detection capacitor 10 from the received cancellation signal and the total voltage signal, and then amplify and output the remaining voltage change signal after cancellation.

[0065] Optionally, the detection capacitor 10 is also used to output a base capacitance value when no external sensing signal is detected;

[0066] The capacitor-to-voltage circuit 30 is also used to output a corresponding base voltage signal based on the base capacitance value of the detection capacitor 10 and the driving signal.

[0067] The amplitude, frequency, and phase of the cancellation signal are the same as those of the base voltage signal.

[0068] Understandably, when the sensing capacitor 10 does not detect an external sensing signal, that is, when the capacitance value of the sensing capacitor 10 does not change, the capacitor-to-voltage circuit 30 will output a base voltage signal. This base voltage signal represents the base capacitance value of the sensing capacitor 10. Therefore, by simply having the voltage cancellation circuit 60 output a cancellation signal with the same amplitude, frequency, and phase as the base voltage signal, the base voltage signal can be canceled out. With this configuration, when the capacitance of the sensing capacitor 10 does not change, that is, when the sensing capacitor 10 does not detect an external sensing signal, the voltage output by the programmable gain amplifier 50 after cancellation by the cancellation signal is zero. When the capacitance of the detection capacitor 10 changes, that is, when the detection capacitor 10 detects an external sensing signal, the electrical signal output by the programmable gain amplifier 50 after cancellation by the cancellation signal is a voltage change signal representing the change in capacitance of the detection capacitor 10. This allows the signal processing circuit 40 to obtain the change in capacitance of the detection capacitor 10 through table lookup, quadrature demodulation, and Fourier transform, thereby obtaining the sensing signal or other parameters detected by the detection capacitor 10 based on the change in capacitance. The driving signal is denoted as V. in =B1sin(2πft) is used as an example.

[0069] The drive circuit 20 generates a sine wave with amplitude B1 and frequency f:

[0070] V in =B1sin(2πft)

[0071] After passing through capacitor-to-voltage converter 30, the output is:

[0072]

[0073] in:

[0074]

[0075] Based on the voltage signal output by the capacitor-to-voltage circuit 30, the voltage cancellation circuit 60 generates a voltage signal that is inversely proportional to V. out A sinusoidal wave of the same amplitude, frequency, and phase cancels it out, thus reducing the capacitance value C of the detection capacitor 10. tp When there is no change, the voltage signal output by the programmable gain amplifier is:

[0076] V out,pga =0

[0077] When the capacitance C tp Change to C tp +ΔC tp At that time, the output of the programmable gain amplifier is approximately:

[0078]

[0079] The above formula can convert the change in capacitance into a change in voltage. Thus, when the signal processing circuit 40 receives the voltage change signal output by the programmable gain amplifier 50, it can obtain the change in capacitance of the detection capacitor 10 by means of table lookup, quadrature demodulation and fast Fourier transform, and thus obtain the sensing signal or other parameters detected by the detection capacitor 10 based on the change in capacitance of the detection capacitor 10.

[0080] In the technical solution of the present invention, by setting a programmable gain amplifier 50 and a voltage cancellation circuit 60, and using the voltage cancellation circuit 60 to generate a cancellation signal to cancel the base voltage signal representing the base capacitance value of the detection capacitor 10, the programmable gain amplifier 50 can directly output a voltage conversion signal representing the capacitance change value of the detection capacitor 10, thereby enabling the signal processing circuit 40 to obtain the capacitance change value of the detection capacitor 10 based on the voltage change signal, thus improving the processing speed of the signal processing circuit 40.

[0081] Reference Figures 1 to 3 In one embodiment, the voltage cancellation module includes:

[0082] A cancellation signal generating circuit, wherein the cancellation signal generating circuit is used to generate and output a cancellation signal;

[0083] The digital-to-analog converter (DAC) has its input terminal connected to the output terminal of the cancellation signal generation circuit, and its output terminal connected to the inverting input terminal of the programmable gain amplifier 50. The DAC is used to perform digital-to-analog conversion processing on the cancellation signal and then output it to the programmable gain amplifier 50.

[0084] In this embodiment, the voltage cancellation circuit 60 is implemented using a cancellation signal generation circuit and a digital-to-analog converter (DAC) to generate and output a cancellation signal. The cancellation signal generation circuit can be a microprocessor within the signal processing circuit 40, or it can be a separate microprocessor dedicated to outputting the cancellation signal. This configuration uses a microprocessor and a DAC to output the cancellation signal to cancel the base voltage signal, without using a conventional cancellation capacitor. Compared to a cancellation capacitor, the DAC has a much smaller area. Therefore, this invention uses a cancellation signal for voltage cancellation, avoiding the use of a cancellation capacitor, thereby effectively reducing the chip area, lowering the overall size of the capacitance detection circuit, and improving the practicality and stability of the capacitance detection circuit.

[0085] Reference Figures 1 to 3 In one embodiment, the driving circuit 20 includes:

[0086] A drive signal generation circuit, wherein the drive signal generation circuit is used to generate and output a drive signal;

[0087] The digital-to-analog converter (DAC) has its input terminal connected to the output terminal of the drive signal generation circuit, and its output terminal connected to the second input terminal of the capacitor-to-voltage circuit 30. The DAC is used to perform digital-to-analog conversion processing on the drive signal and then output it to the capacitor-to-voltage circuit 30.

[0088] In this embodiment, the driving circuit 20 employs a driving signal generation circuit and a digital-to-analog converter (DAC) to generate and output a driving signal. The driving signal generation circuit can be the microprocessor in the signal processing circuit 40, or it can be a separate microprocessor dedicated to outputting the driving signal. This configuration uses a continuous driving signal, avoiding the sampling problem present in switched capacitor circuits. Therefore, it effectively avoids noise aliasing caused by sampling and improves the capacitance detection sensitivity in the presence of interference noise. Furthermore, the cancellation signal generation circuit in the voltage cancellation circuit 60, the driving signal generation circuit in the driving circuit 20, and the microprocessor in the signal processing circuit 40 can be integrated into the same chip, saving the layout area of ​​the capacitance detection circuit, reducing the overall size of the capacitance detection circuit, and improving the practicality and stability of the capacitance detection circuit.

[0089] Reference Figures 1 to 3 In one embodiment, the signal processing circuit 40 includes:

[0090] An analog-to-digital converter (ADC) is provided, the input of which is connected to the output of the programmable gain amplifier 50. The ADC is used to convert the total voltage signal output by the capacitor-to-voltage circuit 30 into an analog-to-digital signal and then output it.

[0091] A signal processor, the input of which is connected to the output of the analog-to-digital converter (ADC), is used to obtain the capacitance change of the detection capacitor 10 based on the total voltage signal output by the ADC.

[0092] In this embodiment, the signal processing circuit 40 can be implemented using an analog-to-digital converter (ADC) and a signal processor. The ADC converts the analog signal output from the programmable gain amplifier 50 into a digital signal and outputs it to the signal processor. The signal processor can be implemented using a microprocessor such as a microcontroller, FPGA, or CPLD. The signal processor can obtain the capacitance change of the detection capacitor 10 based on the voltage change signal output from the programmable gain amplifier 50 through methods such as table lookup, quadrature demodulation, and fast Fourier transform. The signal processor can also generate drive signals and cancellation signals, and convert the generated drive signals and cancellation signals into analog signals through a digital-to-analog converter (DAC) before outputting them to complete the driving and cancellation functions. This saves the layout area of ​​the capacitance detection circuit, reduces the overall size of the capacitance detection circuit, and improves the practicality and stability of the capacitance detection circuit.

[0093] Reference Figures 1 to 3 In one embodiment, the driving signal is one of a sine wave, a square wave, a triangular wave, and a sawtooth wave.

[0094] In this embodiment, the driving signal can be one of a sine wave, square wave, triangle wave, and sawtooth wave. Correspondingly, the cancellation signal can also be one of a sine wave, square wave, triangle wave, and sawtooth wave. The cancellation signal only needs to be selected according to the signal type corresponding to the driving signal. The signal types of the driving signal and the cancellation signal can be selected according to user needs or the electronic equipment being used. In this way, it can meet the diverse application needs of users and improve the applicability and practicality of the capacitance detection circuit.

[0095] The present invention also proposes a touch chip, which includes the above-described capacitance detection circuit. The specific structure of the capacitance detection circuit is as described in the above embodiments. Since the present touch chip adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0096] The present invention also proposes an electronic device, wherein the touch chip includes the touch chip described above, or includes the capacitance detection circuit described above. The specific structure of the capacitance detection circuit and the touch chip is as described in the above embodiments. Since the electronic device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0097] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A capacitance detection circuit, characterized by, The capacitive detection circuit comprises: a detection capacitor configured to detect an external sensing signal and output a corresponding capacitance value; a driving circuit configured to generate and output a continuous driving signal; a capacitance-to-voltage conversion circuit, a first input terminal of which is connected to the detection capacitor, a second input terminal of which is directly coupled to an output terminal of the driving circuit, and which is configured to output a corresponding total voltage signal according to the capacitance value of the detection capacitor and the driving signal; a signal processing circuit, a receiving terminal of which is connected to an output terminal of the capacitance-to-voltage conversion circuit, and which is further configured to perform signal processing on the total voltage signal to obtain a capacitance change amount of the detection capacitor.

2. The capacitance detection circuit of claim 1, wherein, The capacitive detection circuit further comprises: a programmable gain amplifier, a positive input terminal of which is connected to the output terminal of the capacitance-to-voltage conversion circuit, and an output terminal of which is connected to the receiving terminal of the signal processing circuit, and which is configured to output the total voltage signal after amplification processing to the signal processing circuit, so that the signal processing circuit obtains the capacitance change amount of the detection capacitor according to the total voltage signal.

3. The capacitance detection circuit of claim 2, wherein, The capacitive detection circuit further comprises: a voltage offset circuit, which is connected to a negative input terminal of the programmable gain amplifier, and which is configured to output an offset signal to the programmable gain amplifier, so that the programmable gain amplifier converts the total voltage signal into a corresponding voltage change signal after offsetting a basic voltage signal according to the offset signal and then outputs the voltage change signal; the signal processing circuit is further configured to perform signal processing on the voltage change signal to obtain the change amount of the detection capacitor.

4. The capacitance detection circuit of claim 3, wherein, The detection capacitor is further configured to output a basic capacitance value when no external sensing signal is detected; the capacitance-to-voltage conversion circuit is further configured to output a corresponding basic voltage signal according to the basic capacitance value of the detection capacitor and the driving signal; the amplitude, frequency and phase of the offset signal are the same as those of the basic voltage signal.

5. The capacitance detection circuit of claim 3, wherein, The voltage offset circuit comprises: an offset signal generation circuit configured to generate and output an offset signal; a digital-to-analog converter, an input terminal of which is connected to an output terminal of the offset signal generation circuit, and an output terminal of which is connected to the negative input terminal of the programmable gain amplifier, and which is configured to output the offset signal after digital-to-analog conversion processing to the programmable gain amplifier.

6. The capacitance detection circuit of claim 1, wherein, The driving circuit comprises: a driving signal generation circuit configured to generate and output a driving signal; a digital-to-analog converter, an input terminal of which is connected to an output terminal of the driving signal generation circuit, and an output terminal of which is connected to the second input terminal of the capacitance-to-voltage conversion circuit, and which is configured to output the driving signal after digital-to-analog conversion processing to the capacitance-to-voltage conversion circuit.

7. The capacitance detection circuit of claim 2, wherein, The signal processing circuit comprises: An analog-to-digital converter, an input end of the analog-to-digital converter being connected with an output end of the programmable gain amplifier, the analog-to-digital converter being configured to output a total voltage signal output by the capacitance-to-voltage circuit after analog-to-digital conversion processing; A signal processor, an input end of the signal processor being connected with an output end of the analog-to-digital converter, the signal processor being configured to perform signal processing on the total voltage signal output by the analog-to-digital converter to obtain a capacitance change amount of the detection capacitor.

8. The capacitance detection circuit of claim 1, wherein, The driving signal is one of a sine wave, a square wave, a triangle wave and a sawtooth wave.

9. A touch chip, comprising: The capacitive detection circuit according to any one of claims 1-8.

10. An electronic device, comprising: The touch chip according to claim 9; or the capacitive detection circuit according to any one of claims 1-8.

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