Touch signal-to-noise ratio enhancement circuit, chip and electronic device

Abstract

The embodiment of the present application provides a touch signal-to-noise ratio increasing circuit, chip and electronic device. The touch signal-to-noise ratio increasing circuit is provided with a first bias resistor and a first-stage operational amplifier module after the output end of the touch sensor, the first end of the first bias resistor is connected to a preset voltage, the second end of the first bias resistor is connected to the output end of the touch sensor, and is connected to the in-phase input end of the first-stage operational amplifier. In this way, the electrical signal output by the electrical signal receiving module of the touch sensor can be amplified in-phase based on voltage, and the traditional current-based amplification method is abandoned. The noise gain will not increase with the increase of the load capacitance, thereby reducing the attenuation of the signal output by the touch sensor due to the change of the cathode plate, reducing the influence of the increase in the size of the capacitive screen on the SNR signal-to-noise ratio, increasing the SNR of the capacitive screen, and improving the signal accuracy of the touch sensor of the capacitive screen.

Description

Technical Field

[0001] The present application relates to the technical field of display screens, and in particular to a touch signal-to-noise ratio increasing circuit, chip and electronic device. Background Art

[0002] Capacitive screen is a screen that uses touch sensors to obtain the induced current when the human body touches the screen, and further determines the user's touch position. With the development of capacitive screen technology, capacitive screens are gradually widely used in various display scenarios, and the size of capacitive screens is getting larger and larger.

[0003] However, the increase in the size of the capacitive screen will increase the size of the cathode plate built into the capacitive screen, and the increase in the size of the capacitive screen will also make the distance between the cathode plate and the touch sensor closer and closer, resulting in an increasing capacitance between the plates, which may cause more and more charge to flow away from the cathode plate. This will further reduce the SNR (Signal Noise Ratio) of the capacitive screen, thereby affecting the signal accuracy of the touch sensor of the capacitive screen.

[0004] In this application, the capacitance between the plates is collectively referred to as the load capacitance of the touch sensor. How to improve the SNR of a capacitive screen with a large size and a large load capacitance has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] In view of this, the present application provides a touch signal-to-noise ratio increasing circuit, chip and electronic device to improve the SNR of a capacitive screen with a large size and a large load capacitance.

[0006] In a first aspect, the present application provides a touch signal-to-noise ratio increasing circuit, the touch signal-to-noise ratio increasing circuit comprising:

[0007] A first bias resistor, a first-stage inverting input resistor, and a first-stage operational amplifier module; wherein the first-stage operational amplifier module is a non-inverting amplifier module;

[0008] The first end of the first bias resistor is connected to a preset voltage, the second end of the first bias resistor is connected to an output end of the touch sensor, and the second end of the first bias resistor is connected to a non-inverting input end of the first-stage operational amplifier module;

[0009] If the touch signal-to-noise ratio increasing circuit is powered by a single power supply, the first end of the first-stage inverting input resistor is connected to the inverting input end of the first-stage operational amplifier module, and the second end of the first-stage inverting input resistor is grounded; or, if the touch signal-to-noise ratio increasing circuit is powered by a dual power supply, the first end of the first-stage inverting input resistor is connected to the inverting input end of the first-stage operational amplifier module, and the second end of the first-stage inverting input resistor is connected to the preset voltage.

[0010] In some possible implementations, the touch signal-to-noise ratio increasing circuit further includes: a first bias capacitor, wherein:

[0011] A first end of the first bias capacitor is connected to the preset voltage, and a second end of the first bias capacitor is connected to the non-inverting input end of the first-stage operational amplifier module.

[0012] In some possible implementations, the touch signal-to-noise ratio increasing circuit further includes: a filter, wherein:

[0013] The filter is connected to the output end of the first-stage operational amplifier module, and is used to output a target filtering result based on the output result of the first-stage operational amplifier module.

[0014] In some possible implementations, the touch signal-to-noise ratio increasing circuit further includes: an analog-to-digital conversion module, wherein:

[0015] The analog-to-digital conversion module is connected to the output end of the filter and is used to convert the target filtering result into a target digital signal.

[0016] In some possible implementations, the first-stage operational amplifier module is a buffer, and the touch signal-to-noise ratio increasing circuit further includes:

[0017] A second-stage operational amplifier module, a second-stage non-inverting input resistor, and a second-stage inverting input resistor, wherein the output end of the buffer is connected to the first end of the second-stage non-inverting input resistor, and the second end of the second-stage non-inverting input resistor is connected to the non-inverting input end of the second-stage operational amplifier module;

[0018] The first end of the second-stage inverting input resistor is connected to the inverting input end of the second-stage operational amplifier module, and the second end of the second-stage inverting input resistor is grounded.

[0019] In some possible implementations, the first-stage operational amplifier module is a buffer, and the touch signal-to-noise ratio increasing circuit further includes:

[0020] The second stage operational amplifier module, the second stage non-inverting input resistor, the second stage inverting input resistor, where:

[0021] The in-phase output terminal of the buffer is connected to the first end of the in-phase input resistor of the second stage, and the second end of the in-phase input resistor of the second stage is connected to the in-phase input terminal of the second stage operational amplifier module;

[0022] The inverting output terminal of the buffer is connected to the first terminal of the second-stage inverting input resistor, and the second terminal of the second-stage inverting input resistor is connected to the inverting input terminal of the second-stage operational amplifier module.

[0023] In some possible implementations, the common-phase amplifier module includes: a common-phase amplifier and a first-stage amplification feedback resistor, wherein the first end of the first-stage amplification feedback resistor is connected to the output end of the common-phase amplifier, and the second end of the first-stage amplification feedback resistor is connected to the inverting input end of the common-phase amplifier.

[0024] In some possible implementations, the touch signal-to-noise ratio increasing circuit further includes:

[0025] The second stage operational amplifier module, the second stage non-inverting input resistor, the second stage inverting input resistor, and the filter, among which:

[0026] A first end of the second-stage in-phase input resistor is connected to the output end of the in-phase amplification module, and a second end of the second-stage in-phase input resistor is connected to the in-phase input end of the second-stage operational amplification module;

[0027] The first end of the second-stage inverting input resistor is connected to the inverting input end of the second-stage operational amplifier module, and the second end of the second-stage inverting input resistor is grounded;

[0028] The output end of the second-stage operational amplifier module is connected to the filter.

[0029] In some possible implementations, a gain of the in-phase amplification module is less than a preset gain threshold.

[0030] In some possible implementations, the touch signal-to-noise ratio increasing circuit further includes: a second-stage in-phase input resistor, a second-stage inverting input resistor, and a second-stage operational amplifier module, wherein:

[0031] The in-phase output terminal of the first-stage operational amplifier module is connected to the first terminal of the second-stage in-phase input resistor, and the second terminal of the second-stage in-phase input resistor is connected to the in-phase input terminal of the second-stage operational amplifier module;

[0032] The inverting output terminal of the first-stage operational amplifier module is connected to the first terminal of the second-stage inverting input resistor, and the second terminal of the second-stage inverting input resistor is connected to the inverting input terminal of the second-stage operational amplifier module.

[0033] In some possible implementations, the touch signal-to-noise ratio increasing circuit further includes:

[0034] A first control switch, a second control switch, a first differential connection resistor, and a second differential connection resistor, wherein:

[0035] The first end of the first control switch is connected to the second end of the second-stage in-phase input resistor of the i-th RX channel, the second end of the first control switch is connected to the first end of the first differential connection resistor, and the second end of the first differential connection resistor is connected to the second end of the second-stage inverting input resistor of the (i+1)-th RX channel;

[0036] The first end of the second control switch is connected to the second end of the second-stage inverting input resistor of the i-th RX channel, the second end of the second control switch is connected to the first end of the second differential connection resistor, and the second end of the second differential connection resistor is connected to the second end of the second-stage non-inverting input resistor of the (i+1)-th RX channel;

[0037] The i-th RX channel and the i+1-th RX channel are two adjacent channels among the multiple RX channels; and the RX channel is a touch signal-to-noise ratio increasing circuit corresponding to the RX electrode.

[0038] In some possible implementations, when the first control switch is closed, the in-phase output end in the i-th RX channel and the inverting output end in the i+1-th RX channel are adjacently differentially performed; when the second control switch is closed, the inverting output end in the i-th RX channel and the in-phase output end in the i+1-th RX channel are adjacently differentially performed to obtain a target differential result.

[0039] In some possible implementations, the touch sensor further includes a reference channel; the reference channel includes: a first bias resistor, a first-stage inverting input resistor, and a first-stage operational amplifier module; wherein the first-stage operational amplifier module is a non-inverting amplifier module,

[0040] The first end of the first bias resistor is connected to a preset voltage, the second end of the first bias resistor is connected to the touch sensor, and the second end of the first bias resistor is connected to the non-inverting input end of the first-stage operational amplifier module;

[0041] The first end of the first-stage inverting input resistor is connected to the inverting input end of the first-stage operational amplifier module, and the second end of the first-stage inverting input resistor is connected to the preset voltage.

[0042] In some possible implementations, the second-stage non-inverting input resistor includes: a first second-stage non-inverting input resistor and a second second-stage non-inverting input resistor, and the second-stage inverting input resistor includes: a first second-stage inverting input resistor and a second second-stage inverting input resistor, wherein:

[0043] The first end of the first second stage in-phase input resistor in the i-th RX channel is connected to the in-phase output end of the first stage operational amplifier module, and the second end of the first second stage in-phase input resistor is connected to the second end of the second second stage in-phase input resistor in the i-th RX channel and the in-phase input end of the second stage operational amplifier module in the i-th RX channel;

[0044] The first end of the second second-stage non-inverting input resistor in the i-th RX channel is connected to the first end of the second second-stage non-inverting input resistor in each of the RX channels and the inverting output end of the reference channel;

[0045] The first end of the first second stage inverting input resistor in the i-th RX channel is connected to the inverting output end of the first stage operational amplifier module, and the second end of the first second stage inverting input resistor is connected to the second end of the second second stage inverting input resistor in the i-th RX channel and the inverting input end of the second stage operational amplifier in the i-th RX channel;

[0046] The first end of the second second-stage inverting input resistor in the i-th RX channel is connected to the first end of the second second-stage inverting input resistor in each of the RX channels and the in-phase output end of the reference channel;

[0047] The in-phase output end of the i-th RX channel is subtracted from the inverting output end of the reference channel, and the inverting output end of the i-th RX channel is subtracted from the in-phase output end of the reference channel to obtain a target differential result; the RX channel is a touch signal-to-noise ratio increasing circuit corresponding to the RX electrode, and the reference channel is a touch signal-to-noise ratio increasing circuit corresponding to the reference electrode.

[0048] In some possible implementations, the touch signal-to-noise ratio increasing circuit further includes a mean value generating channel;

[0049] The mean value generation channel includes: a mean non-inverting input resistor, a mean inverting input resistor, a second-stage operational amplifier module, a filter, and a sample-and-hold device. The mean value generation channel is used to collect the average value of the output results of each RX channel.

[0050] In some possible implementations, the second-stage non-inverting input resistor includes: a first second-stage non-inverting input resistor and a second second-stage non-inverting input resistor, and the second-stage inverting input resistor includes: a first second-stage inverting input resistor and a second second-stage inverting input resistor;

[0051] The second end of the mean non-inverting input resistor is connected to the non-inverting input end of the second-stage operational amplifier module, the second end of the mean inverting input resistor is connected to the inverting input end of the second-stage operational amplifier module, the output end of the second-stage operational amplifier module is connected to the input end of the filter, and the output end of the filter is connected to the input end of the sample and hold device;

[0052] Each of the RX channels and the mean value generation channel includes: a first input resistor, a second input resistor, a first input capacitor, and a second input capacitor, wherein:

[0053] The first end of the first-second-stage non-inverting input resistor in the i-th RX channel is connected to the non-inverting output end of the first-stage operational amplifier module of the i-th channel and the first end of the first input resistor, and the second end of the first-second-stage non-inverting input resistor of the i-th RX channel is connected to the second end of the second-second-stage non-inverting input resistor of the i-th RX channel and the non-inverting input end of the second-stage operational amplifier module of the i-th RX channel;

[0054] The first end of the second second stage in-phase input resistor of the i-th RX channel is connected to the first end of the second second stage in-phase input resistor of each RX channel and the inverting output end of the second stage operational amplifier module of the mean value generating channel;

[0055] The first end of the first and second stage inverting input resistors of the i-th RX channel is connected to the inverting output end of the first stage operational amplifier module of the i-th channel and the first end of the second input resistor; the second end of the first and second stage inverting input resistors of the i-th RX channel is connected to the second end of the second second stage inverting input resistor of the i-th RX channel and the inverting input end of the second stage operational amplifier of the i-th RX channel;

[0056] The first end of the second second-stage inverting input resistor of the i-th RX channel is connected to the first end of the second second-stage inverting input resistor of each RX channel and the in-phase output end of the second-stage operational amplifier module of the mean value generating channel;

[0057] The second end of the first input resistor is connected to the first end of the average in-phase input resistor and the first end of the first input capacitor; the second end of the first input capacitor is grounded;

[0058] The second end of the second input resistor is connected to the first end of the mean inverting input resistor and the first end of the second input capacitor; the second end of the second input capacitor is grounded;

[0059] The in-phase output end of the i-th RX channel is subtracted from the inverting output end of the mean generation channel, and the inverting output end of the i-th RX channel is subtracted from the in-phase output end of the mean generation channel to obtain a target differential result.

[0060] In a second aspect, the present application provides a capacitive screen, wherein the capacitive screen includes any touch signal-to-noise ratio increasing circuit described in the first aspect.

[0061] In a third aspect, the present application provides a chip, wherein the chip includes the touch signal-to-noise ratio increasing circuit described in any one of the first aspects.

[0062] In a fourth aspect, the present application provides an electronic device, wherein the electronic device includes the chip described in the third aspect.

[0063] Compared with the prior art, the beneficial effects of the embodiments of the present application are:

[0064] The embodiment of the present application provides a touch signal-to-noise ratio increasing circuit, chip and electronic device. The touch signal-to-noise ratio increasing circuit is provided with a first bias resistor and a first-stage operational amplifier module after the output end of the touch sensor, the first end of the first bias resistor is connected to a preset voltage, the second end of the first bias resistor is connected to the output end of the touch sensor, and is connected to the in-phase input end of the first-stage operational amplifier. In this way, the electrical signal output by the electrical signal receiving module of the touch sensor can be amplified in-phase based on voltage, and the traditional current-based amplification method is abandoned. The noise gain will not increase with the increase of the load capacitance, thereby reducing the attenuation of the signal output by the touch sensor due to the change of the cathode plate, reducing the influence of the increase in the size of the capacitive screen on the SNR signal-to-noise ratio, increasing the SNR of the capacitive screen, and improving the signal accuracy of the touch sensor of the capacitive screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Further details, features and advantages of the present application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0066] Figure 1 A circuit diagram of a touch sensor electrical signal amplifying circuit commonly used in the prior art is shown;

[0067] Figure 2 A circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0068] Figure 3 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0069] Figure 4Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0070] Figure 5 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0071] Figure 6 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0072] Figure 7 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0073] Figure 8 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0074] Fig. 9 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0075] Fig.10 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0076] Fig.11 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0077] Fig.12 Another circuit diagram of a touch signal-to-noise ratio enhancement circuit provided in an embodiment of the present application is shown;

[0078] Fig.13 A schematic diagram showing the technical effect of the measured SNR of the touch signal-to-noise ratio increasing circuit provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0079] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be construed as being limited to the embodiments described herein. Instead, these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the drawings and embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0080] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments". Relevant definitions of other terms will be given in the description below. It should be noted that the concepts of "first", "second", etc. mentioned in this application are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0081] It should be noted that the modifications of "one" and "plurality" mentioned in the present application are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0082] In the field of capacitive screens, mutual capacitance detection of capacitive screens regards the capacitive screen as a sensing matrix constructed by multiple RX electrodes and TX electrodes. The touch sensor identifies the RX electrodes and TX electrodes where the touch occurs, and determines the area where the finger touches to achieve touch recognition.

[0083] Specifically, in a capacitive screen, the TX electrode can be called a driving electrode, and the RX electrode can be called a sensing electrode. A coupling capacitor is formed between the TX electrode and the RX electrode. When the capacitive screen is touched, such as when a finger touches it, the touch of the finger causes the coupling capacitor to change. The touch sensor determines the area where the touch occurs by identifying the changed capacitance value.

[0084] Therefore, the circuit set inside the capacitive screen can be composed of the following circuits:

[0085] Part 1: Get the touch sensor of the user's touch operation. The touch sensor can be equivalent to Figure 1 The circuit shown is composed of a cross-coupling capacitor Cm, a self-capacitance Cr1 between the TX electrode and the cathode plate, a self-capacitance Cr2 between the RX electrode and the cathode plate, and a wiring impedance Rr. One end of the touch sensor is connected to the TX electrode, and the other end is connected to the RX electrode. When the mutual capacitance of the TX electrode and the RX electrode is detected, an excitation signal is input to the TX electrode, and after the cross-coupling capacitor and the self-capacitance in the touch sensor work together, a response signal is output from the RX electrode end.

[0086] Part 2: An amplifier circuit for amplifying the response signal output by the touch sensor. The amplifier circuit commonly used in the prior art can be as follows: Figure 1As shown, the current is amplified by the first-stage current amplification module, a trans-impedance amplifier (TIA), to obtain an amplified response signal.

[0087] Part 3: A signal processing circuit that filters and performs analog-to-digital conversion on the amplified response signal to obtain the final target digital signal.

[0088] Among them, in the circuit of the second part, the transimpedance amplifier commonly used in the prior art acts to convert the input current into a proportional output voltage, that is, the transimpedance amplifier is essentially an inverting amplifier. In addition, as described in the background technology, when the size of the capacitive screen gradually increases, the size of the cathode plate also gradually increases, and the load capacitance of the touch sensor also gradually increases, which causes more and more charge signals to flow away from the cathode plate, and then causes the amount of charge entering the transimpedance amplifier to gradually decrease, which easily causes the output voltage signal obtained by the transimpedance amplifier to become smaller, and then causes the SNR of the capacitive screen circuit to gradually decrease, reducing the signal accuracy of the touch sensor.

[0089] In view of this, the present application provides a touch signal-to-noise ratio increasing circuit, chip and electronic device for increasing the SNR signal-to-noise ratio of a capacitive screen circuit and improving the accuracy of a touch sensor.

[0090] In some embodiments, the touch signal-to-noise ratio enhancement circuit provided by the embodiments of the present application may be a comprehensive circuit of the above three partial circuits, or may be an amplifier circuit of the second part, or any combination circuit of the amplifier circuit and the other two partial circuits.

[0091] In some embodiments, the capacitive screen signal-to-noise ratio enhancement circuit provided in the present application can be as follows: Figure 2 As shown, it specifically includes the following parts:

[0092] A first bias resistor Rb1, a first-stage inverting input resistor R12, and a first-stage operational amplifier module, wherein the first-stage operational amplifier module is a non-inverting amplifier module.

[0093] Specifically, in some embodiments, the first-stage operational amplifier module can be as follows: Figure 2 As shown, it includes: a first stage operational amplifier, a first feedback resistor Rf1 and a first feedback capacitor Cf1. The connection relationship between the first feedback resistor Rf1 and the first feedback capacitor Cf1 is as follows: Figure 2 As shown, the two are connected in parallel between the inverting input terminal (-) and the non-inverting output terminal (+) of the first stage operational amplifier.

[0094] like Figure 2 As shown, the connection relationship between the various components of the touch signal-to-noise ratio enhancement circuit provided in the embodiment of the present application can be:

[0095] A first end of the first bias resistor Rb1 is connected to a preset voltage, a second end of the first bias resistor Rb1 is connected to an output end of the touch sensor, and a second end of the first bias resistor Rb1 is connected to a non-inverting input end (+) of the first-stage operational amplifier module;

[0096] If the touch signal-to-noise ratio enhancement circuit is powered by a single power supply, the first end of the first-stage inverting input resistor R12 is connected to the inverting input terminal (-) of the first-stage operational amplifier module, and the second end of the first-stage inverting input resistor R12 is grounded.

[0097] Among them, in some embodiments, since the touch sensor is equivalent to a capacitor during the mutual capacitance detection process, and since the capacitor has the characteristic of only passing AC signals but not DC signals, the DC signal generated during the mutual capacitance detection process cannot enter the amplifier circuit through the touch sensor, and the amplifier circuit requires positive and negative power supplies. Based on this, in the embodiment of the present application, by adding a preset voltage after the touch sensor, the preset voltage is essentially a DC bias power supply, which is used to provide a single power supply for the circuit, and a DC bias is added to the response signal without DC bias transmitted from the touch sensor, so that the response signal output by the touch sensor can smoothly enter the amplifier circuit for amplification.

[0098] As an implementation mode, the preset voltage is VCMI (Voltage Control Mode Input, common mode voltage input), and the voltage value of the VCMI may be 1 / 2 of the power supply voltage of the first stage operational amplifier. Preferably, the preset voltage VCMI is within the range of 1-2V.

[0099] Since the preset voltage is connected after the touch sensor, there is no impedance between the preset voltage VCMI and the first-stage operational amplifier module. At this time, the response signal output by the touch sensor can easily short-circuit from the preset voltage VCMI and flow out without entering the first-stage operational amplifier module. Based on this, in an embodiment of the present application, a first bias resistor Rb1 is added between the preset voltage VCMI and the output end of the touch sensor. The first bias resistor should be a high-impedance resistor, which is required to prevent the response signal output by the touch sensor from flowing out from the preset voltage VCMI. As an implementation method, the resistance range of the first bias resistor Rb1 is 2KΩ~50KΩ. Preferably, the resistance value of the first bias resistor Rb1 is 10KΩ.

[0100] It can be seen that compared with Figure 1It is common to input the response signal output by the touch sensor into an inverting amplifier for current amplification. The touch signal-to-noise ratio increasing circuit provided in the embodiment of the present application inputs the response signal output by the touch sensor into the non-inverting input terminal (+) of the first-stage operational amplifier module. When the capacitive screen is single-ended, the DC bias is increased by means of a preset voltage. When the load capacitance of the touch sensor increases, the attenuation of the charge or the amount of charge flowing away from the cathode plate due to the increase in the size of the cathode plate is reduced, thereby reducing the influence of the increase in the size of the capacitive screen on the signal-to-noise ratio SNR, increasing the SNR of the capacitive screen, and improving the signal accuracy of the touch sensor of the capacitive screen.

[0101] In some embodiments, the touch signal-to-noise ratio increasing circuit provided in the embodiments of the present application can also be as follows: Figure 3 As shown, the preset voltage VCMI and the first stage operational amplifier include not only the first bias resistor Rb1 but also the first bias capacitor Cb1. The first end of the first bias capacitor Cb1 is connected to the preset voltage, and the second end of the first bias capacitor Cb1 is connected to the non-inverting input terminal (+) of the first stage operational amplifier module. That is, the first bias resistor Rb1 and the first bias capacitor Cb1 are connected in parallel between the touch sensor output terminal and the preset voltage output terminal, and the first bias resistor Rb1 and the first bias capacitor Cb1 are connected in parallel between the non-inverting input terminal (+) of the first stage operational amplifier module and the preset voltage output terminal.

[0102] Since the capacitive screen detects whether a touch has occurred by monitoring the capacitance change between the TX / RX electrodes, and then detects the specific coordinate changes where the touch has occurred. And because the distance between the touch sensor and the display layer is very close, when there is a touch on the display layer, the display layer is prone to interfere with the capacitance change between the TX / RX electrodes, resulting in errors in the touch sensor detection. In this application, the interference caused by the display layer to the capacitance change between the TX / RX electrodes is determined as display interference, and the signal amplitude of the display interference usually far exceeds the amplitude of the touch signal detected by the touch sensor.

[0103] Based on this, an embodiment of the present application is selected, a first bias capacitor Cb1 is connected in parallel to the first bias resistor Rb1, and a low-pass filter is formed by combining the first bias capacitor Cb1 and the first bias resistor Rb1, so that the high-amplitude display interference signal flows out from the first bias capacitor Cb1 without entering the first-stage operational amplifier. In this way, the display interference signal and the common-mode interference signal entering the first-stage operational amplifier module can be effectively reduced, and the conversion accuracy of the first-stage operational amplifier module can be further improved. As an implementation method, the capacitance value of the first bias capacitor Cb1 ranges from 0.5pf to 20pf, and preferably, the capacitance value of the first bias capacitor Cb1 is 10pf.

[0104] In some embodiments, if the capacitive screen circuit is powered by dual power supplies, based on the dual power supply situation, the touch signal-to-noise ratio enhancement circuit provided in the present application is adaptively adjusted. The specific adjustment circuit structure diagram is as follows: Figure 4 As shown, the second end of the first-stage inverting input resistor R12 is adjusted from being grounded to being connected to a preset voltage VCMI, and other adjustments are not made.

[0105] In the embodiment of the present application, when the capacitive screen is powered by dual power supplies, one of the power supplies is connected to the preset voltage VCMI connected to the first bias resistor Rb1, and the other power supply is connected to the preset voltage VCMI connected to the first-stage inverting input resistor R12. In this way, the touch signal-to-noise ratio increasing circuit provided by the present application is not only applicable to the capacitive screen powered by a single power supply, but also to the capacitive screen powered by dual power supplies.

[0106] In some embodiments, the power supply of the capacitive screen is divided into two types: analog power supply and digital power supply, wherein the voltage range of the analog power supply is: 2.6V ~ 3.6V, and the voltage range of the digital power supply is: 1.8V ~ 3.3V. The specific power supply depends on the capacitive screen motherboard. If either the analog power supply or the digital power supply is selected for power supply, it is a single power supply, and if both the analog power supply and the digital power supply are used for power supply, it is a dual power supply.

[0107] In some embodiments, it is also possible to Figure 5 As shown, the touch signal-to-noise ratio enhancement circuit provided in the present application may further include: a filter. The filter is connected to the output end of the first-stage operational amplifier module and is used to output a target filtering result based on the output result of the first-stage operational amplifier module.

[0108] in, Figure 5 The internal circuit structure of the filter and the connection relationship of the internal components can be referred to Figure 6 The circuit structure diagram shown in FIG. Specifically, the internal components of the filter include: a filter amplifier, a first filter input resistor, a second filter input resistor, a filter input capacitor, a filter feedback resistor, and a filter feedback capacitor. The connection relationship between the components is as follows:

[0109] The first end of the filter input capacitor is connected to the first end of the first filter input resistor and the inverting output end (-) of the first-stage operational amplifier module, and the second end of the filter input capacitor is connected to the first end of the second filter input resistor and the non-inverting output end (+) of the first-stage operational amplifier module.

[0110] The second end of the first filter input resistor is connected to the non-inverting input terminal (+) of the filter amplifier. The second end of the second filter input resistor is connected to the inverting input terminal (-) of the filter amplifier.

[0111] Among them, one end of a filter feedback resistor is connected to the first end of the first filter input resistor, and the other end is connected to the first filter output end (-) of the filter amplifier; one end of a filter feedback capacitor is connected to the second end of the first filter input resistor, and the other end is connected to the first filter output end (-) of the filter amplifier; one end of another filter feedback resistor is connected to the first end of the second filter input resistor, and the other end is connected to the second filter output end (+) of the filter amplifier; one end of a filter feedback capacitor is connected to the second end of the second filter input resistor, and the other end is connected to the second filter output end (+) of the filter amplifier. The specific electrical signal conversion process can refer to the introduction of the working principles of other filters.

[0112] In some embodiments, the touch signal-to-noise ratio increasing circuit may further include an analog-to-digital conversion ADC module based on the existence of a filter, wherein the analog-to-digital conversion ADC module is connected to the output end of the filter and is used to convert the target filtering result into a target digital signal.

[0113] In the present application, the first-stage operational amplifier module in the touch signal-to-noise ratio enhancement circuit provided in the embodiment of the present application is essentially a common-phase amplifier module, that is, a voltage amplifier circuit that increases input impedance through negative feedback, and its type can be a buffer with a common-phase amplification function or a common-phase amplifier with a common-phase amplification function. Among them, the common-phase amplifier type can be an ordinary single-power common-phase amplifier, or a dual-power common-phase amplifier, or a fixed-gain common-phase amplifier, or a gain-adjustable PGA (Programmable Gain Amplifier).

[0114] In some embodiments, when the first-stage operational amplifier module is a buffer with a common-mode amplification function, and the buffer outputs a single-ended signal, the circuit structure of the touch signal-to-noise ratio enhancement circuit provided in the embodiment of the present application can be as follows: Figure 7 As shown, it also includes:

[0115] The second stage operational amplifier module, the second stage in-phase input resistor R21, and the second stage inverting input resistor R22. The connection relationship between the circuit components is as follows: Figure 7 As shown:

[0116] The output end of the buffer is connected to the first end of the first and second stage in-phase input resistor R21, and the second end of the first and second stage in-phase input resistor R21 is connected to the in-phase input end (+) of the second stage operational amplifier module;

[0117] The first end of the first and second stage inverting input resistor R22 is connected to the inverting input terminal (-) of the second stage operational amplifier module, and the second end of the first and second stage inverting input resistor R22 is grounded.

[0118] In some embodiments, the first-stage operational amplifier module is a buffer with a common-mode amplification function, and the buffer outputs a fully differential signal. The circuit structure of the touch signal-to-noise ratio enhancement circuit provided in the embodiment of the present application can be as follows: Figure 8 As shown, it also includes:

[0119] The second stage operational amplifier module, the first and second stage in-phase input resistors R21, and the first and second stage inverting input resistors R22. The connection relationship between the circuit elements is as follows: Figure 8 As shown:

[0120] The in-phase output terminal of the buffer is connected to the first end of the first and second stage in-phase input resistor R21, and the second end of the first and second stage in-phase input resistor R21 is connected to the in-phase input terminal (+) of the second stage operational amplifier module;

[0121] The inverting output terminal of the buffer is connected to the first end of the first and second stage inverting input resistors R22, and the second ends of the first and second stage inverting input resistors R22 are connected to the inverting input terminal (-) of the second stage operational amplifier module.

[0122] in, Figure 7 and Figure 8 The second-stage operational amplifier module in the figure is shown in the figure, which is composed of a second-stage operational amplifier, two sets of second feedback resistors Rf2 and second feedback capacitors Cf2, wherein the connection relationship between the internal components of the second-stage operational amplifier module is:

[0123] One set of second feedback resistors Rf2 and second feedback capacitors Cf2 are connected in parallel between the inverting input terminal (-) and the non-inverting output terminal (+) of the second-stage operational amplifier, and another set of second feedback resistors Rf2 and second feedback capacitors Cf2 are connected in parallel between the non-inverting input terminal (+) and the non-inverting output terminal (-) of the second-stage operational amplifier. The values ​​of the two sets of second feedback resistors Rf2 and second feedback capacitors Cf2 can be the same or different, and can be flexibly adjusted according to actual needs, and this application does not make strict restrictions.

[0124] Since the gain of the buffer may be fixed, there may be a situation where the amplification gain of the buffer is insufficient to amplify the response signal output by the touch sensor to meet the filter input voltage requirement. In the embodiment of the present application, a second-stage operational amplifier module is connected to the output end of the buffer, and the second-stage operational amplifier module performs a second amplification on the response signal amplified by the first-stage operational amplifier module, so that the response signal output by the touch sensor can be amplified to meet the filter input voltage requirement.

[0125] In some embodiments, the touch signal-to-noise ratio increasing circuit provided in the embodiments of the present application can also be as follows: Fig. 9As shown, the first stage operational amplifier module (part of the circuit in the dashed box on the left side of the figure) is composed of a simple common-mode amplifier AMP and a first feedback resistor Rf1. Fig. 9 As shown, the touch signal-to-noise ratio increasing circuit provided in the embodiment of the present application may also include:

[0126] The second stage operational amplifier module, the first and second stage in-phase input resistors R21, the first and second stage inverting input resistors R22, wherein the connection relationship between the components can be as follows: Fig. 9 As shown:

[0127] A first end of the first feedback resistor Rf1 is connected to the output end of the common-phase amplifier AMP, and a second end of the first feedback resistor Rf1 is connected to the inverting input end (-) of the common-phase amplifier AMP.

[0128] The first end of the first and second stage common-phase input resistor R21 is connected to the output end of the common-phase amplifier AMP, and the second end of the first and second stage common-phase input resistor R21 is connected to the common-phase input end (+) of the second stage operational amplifier module.

[0129] The first end of the first and second stage inverting input resistor R22 is connected to the inverting input terminal (-) of the second stage operational amplifier module, and the second end of the first and second stage inverting input resistor R22 is grounded.

[0130] The output end of the second-stage operational amplifier module is connected to the filter.

[0131] In some embodiments, when the gain of the buffer or the gain of the common-phase amplifier AMP is sufficient to amplify the response signal output by the touch sensor to the input voltage requirement of the filter, the second-stage operational amplifier module and the corresponding second-stage common-phase input resistor and second-stage inverting input resistor may be omitted, and the first-stage operational amplifier module is directly connected to the filter, and the amplified response signal is directly input into the filter for filtering to obtain the target filtered signal.

[0132] If the gain of the buffer or the gain of the common-mode amplifier AMP is less than the preset gain threshold, a second-stage operational amplifier module is added between the first-stage operational amplifier module and the filter. The second-stage operational amplifier module performs secondary amplification on the amplified response signal, and then inputs the secondary amplified signal into the filter for filtering to obtain the target filtered signal.

[0133] Among them, in some embodiments, the second-stage operational amplifier module can also be a programmable gain amplifier, and the amplification gain of the second-stage operational amplifier module can be adjusted by software, so that the amplification gain of the amplifier circuit obtained by combining the first-stage operational amplifier module and the second-stage operational amplifier module meets the requirements.

[0134] Since the mutual capacitance detection of the capacitive screen regards the capacitive screen as a sensing matrix constructed by multiple RX electrodes and TX electrodes, the touch sensor determines the specific touch coordinates of the touch point triggered by the user based on the difference in the response signals output by the TX electrode and the RX electrode under the action of the excitation signal. Based on this, in order to improve the SNR of the entire capacitive screen, the touch signal-to-noise ratio increase circuit provided in the embodiment of the present application can be connected to each RX electrode. As another implementation method, the touch signal-to-noise ratio increase circuit provided in the embodiment of the present application can be selectively connected to some RX electrodes, and the specific number of connections can be flexibly selected based on actual operations.

[0135] The touch signal-to-noise ratio amplification circuit in the present application can increase the signal-to-noise ratio of touch detection to improve the sensitivity of touch detection. Based on this, in some embodiments, the signal-to-noise ratio amplification circuit of each channel is of the same type. Each RX channel can also flexibly select a different signal-to-noise ratio amplification circuit based on the difference of each output signal.

[0136] When the capacitive screen is touched, the coupling capacitance between the TX electrode and the RX electrode will change. During the capacitive screen touch detection process, the specific touch location is determined by determining the change in the coupling capacitance. In this application, by setting a reference capacitance as a comparison benchmark, the difference between the coupling capacitance and the reference capacitance is determined to determine whether the coupling capacitance has changed and the size of the change. This method of capacitive screen touch detection based on the difference between the coupling capacitance and the reference capacitance is a differential detection method.

[0137] Based on the application scenario of the differential detection method, that is, in the scenario where the touch sensor is used for differential detection, the touch signal-to-noise ratio increasing circuit provided in the present application can be as follows: Figure 10 to Figure 12 As shown, the touch signal-to-noise ratio increasing circuit corresponding to each RX electrode specifically includes a preset voltage VCMI, a first bias resistor Rb1, a first-stage operational amplifier module, first and second-stage in-phase input resistors R21, first and second-stage inverting input resistors R22, a second-stage operational amplifier module, a filter, and a sample-and-hold device.

[0138] Among them, in the connection relationship of each component of the touch signal-to-noise ratio increasing circuit corresponding to each RX electrode, the connection relationship between the preset voltage VCMI, the first bias resistor Rb1 and the cross-coupling capacitor Cm is the same as the connection relationship between the preset voltage VCMI, the first bias resistor Rb1 and the touch sensor mentioned above, wherein the cross-coupling capacitor Cm is a coupling capacitor formed between each RX electrode and each TX electrode.

[0139] The first stage operational amplifier module can be Figure 2 to Figure 9 The first-stage operational amplifier module shown in any figure, wherein Figure 10 to Figure 12 The first stage operational amplifier module circuit shown in the left dashed box is Figure 2 For example, the first-stage operational amplifier module in is a common-mode amplifier module composed of a first-stage operational amplifier AMP, a first feedback resistor Rf1, and a first feedback capacitor Cf1, wherein the first feedback resistor Rf1 and the first feedback capacitor Cf1 are connected in parallel to the negative feedback circuit of the first-stage operational amplifier.

[0140] The connection relationship between the components in the touch signal-to-noise ratio enhancement circuit can be as follows: Figure 10 to Figure 12 As shown:

[0141] The in-phase output terminal of the first stage operational amplifier module is connected to the first end of the first and second stage in-phase input resistors R21, and the second ends of the first and second stage in-phase input resistors R21 are connected to the in-phase input terminal (+) of the second stage operational amplifier module.

[0142] The inverting output terminal of the first stage operational amplifier module is connected to the first end of the first and second stage inverting input resistors R22, and the second ends of the first and second stage inverting input resistors R22 are connected to the inverting input terminal (-) of the second stage operational amplifier module.

[0143] The inverting output terminal (-) of the second-stage operational amplifier module is connected to the non-inverting input terminal (+) of the filter, the non-inverting output terminal (+) of the second-stage operational amplifier module is connected to the inverting input terminal (-) of the filter, the first filter output terminal (-) of the filter is connected to the first input terminal (Vin1) of the sample holder, and the second filter output terminal (+) of the filter is connected to the second input terminal (Vin2) of the sample holder.

[0144] Among them, the first sampling output end of the sample holder in the touch signal-to-noise ratio increasing circuit corresponding to each RX electrode is connected to the in-phase input end (+) of the analog-to-digital conversion buffer, and the second sampling output end of the sample holder in the touch signal-to-noise ratio increasing circuit corresponding to each RX electrode is connected to the inverting input end (-) of the analog-to-digital conversion buffer.

[0145] Among them, the sample and hold Figure 10 to Figure 12 As shown, it is composed of a sampling and holding capacitor C1, a sampling and holding capacitor C2 and switches S1 to S4. The first end of the switch S1 is connected to the first filter output end of the filter, the second end of the switch S1 is connected to the first end of the sampling and holding capacitor C1 and the first end of the switch S3, the second end of the sampling and holding capacitor C1 is grounded, and the second end of the switch S3 is connected to the second end of the switch S3 of the sampling and holding device of the other RX channel and the non-inverting input end (+) of the analog-to-digital conversion buffer.

[0146] A first end of the switch S2 is connected to the second filter output end of the filter, a second end of the switch S2 is connected to the first end of the sampling and holding capacitor C2 and the first end of the switch S4, a second end of the sampling and holding capacitor C2 is grounded, and a second end of the switch S4 is connected to the second end of the switch S4 of the sampling and holding device of the other RX channel and the inverting input end (-) of the analog-to-digital conversion buffer.

[0147] The switches S1 to S4 are closed or opened based on the high and low levels of the sampling clock. Specifically, as an implementation, when the sampling clock is at a high level, the switch is closed, and when the sampling clock is at a low level, the switch is opened. The specific control method can be flexibly set according to actual needs, and this application does not strictly limit it.

[0148] When switch S1 and switch S3 are closed, the in-phase output signal of the filter output enters the sample-and-hold device and is sampled. When switch S1 and switch S3 are disconnected, the sample-and-hold device keeps outputting the in-phase output signal. Similarly, when switch S2 and switch S4 are closed, the inverted output signal of the filter output enters the sample-and-hold device and is sampled. When switch S2 and switch S4 are disconnected, the sample-and-hold device keeps outputting the inverted output signal. The specific signal holding and signal output principles of the sample-and-hold device can be referred to the technical documents of the relevant sample-and-hold device, which will not be described here.

[0149] In the present application, the naming of the in-phase output terminal and the inverting output terminal of each component can be replaced with other naming forms, but it is necessary to ensure that the signal polarity of the touch signal-to-noise ratio increase circuit corresponding to each RX electrode output to the in-phase input terminal (+) of the analog-to-digital conversion buffer remains consistent, and to ensure that the signal polarity of each RX channel output to the inverting input terminal (-) of the analog-to-digital conversion buffer remains consistent.

[0150] The inverting output terminal (-) of the analog-to-digital buffer is connected to the first input terminal (Vin1) of the analog-to-digital conversion module ADC, and the non-inverting output terminal (+) of the analog-to-digital conversion buffer is connected to the second input terminal (Vin2) of the analog-to-digital conversion module ADC. The analog-to-digital buffer is essentially a non-inverting amplified follower, which is used to indirectly provide a transient current for the analog-to-digital conversion module ADC to prevent the ADC from obtaining current from the sample-and-hold device, thereby causing inaccurate analog-to-digital conversion results.

[0151] In the embodiment of the present application, the second-stage operational amplifier module may also be a PGA amplifier, which is used when the gain of the first-stage operational amplifier module is less than a preset gain threshold. When the gain of the first-stage operational amplifier module meets the preset gain threshold condition, the PGA amplifier may not be used. Among them, the preset gain threshold condition may be that the voltage amplitude of the output signal amplified by the first-stage operational amplifier module meets the filtered input voltage amplitude of the filter. The specific threshold may be set according to actual experience or according to experimental test results, and the present application does not make a strict limitation.

[0152] Since the types of differential detection are divided into many types, such as adjacent differential detection, reference channel differential detection, average value differential detection, etc. Among them, adjacent differential detection determines the touch area by the change difference between the coupling capacitances of adjacent RX electrodes. Based on this, for the case of adjacent differential detection, the touch signal-to-noise ratio increase circuit corresponding to each RX electrode includes a preset voltage VCMI, a first bias resistor Rb1, a first-stage inverting input resistor R12, a first-stage operational amplifier module, a second-stage positive input resistor R21, a first- and second-stage inverting input resistors R22, a second-stage operational amplifier module, a filter, a sample holder, and an analog-to-digital conversion buffer and an analog-to-digital conversion module ADC shared in the touch signal-to-noise ratio increase circuit corresponding to each RX electrode. The touch signal-to-noise ratio increase circuit under adjacent differential detection provided in the present application can be as follows Fig.10 As shown, the touch signal-to-noise ratio increasing circuit provided in the embodiment of the present application further includes:

[0153] A first control switch K1, a second control switch K2, a first differential connection resistor R1, and a second differential connection resistor R2.

[0154] For the convenience of description, the touch signal-to-noise ratio enhancement circuit corresponding to the RX electrode is collectively referred to as the "RX channel" in the following text of this application.

[0155] Among them, the connection relationship between the components between adjacent RX channels is as follows: Fig.10 As shown:

[0156] A first end of the first control switch K1 is connected to a second end of the first and second stage in-phase input resistor R21 of the i-th RX channel, a second end of the first control switch K1 is connected to a first end of the first differential connection resistor R1, and a second end of the first differential connection resistor R1 is connected to a second end of the first and second stage inverting input resistor R22 of the i+1-th RX channel;

[0157] A first end of the second control switch K2 is connected to a second end of the first-second stage inverting input resistor R22 of the i-th RX channel, a second end of the second control switch K2 is connected to a first end of the second differential connection resistor R2, and a second end of the second differential connection resistor R2 is connected to a second end of the first-second stage inverting input resistor R21 of the i+1-th RX channel;

[0158] The principle of differential detection is to detect whether the coupling capacitance Cm of the RX channel has changed compared to the reference channel. If it has changed, it indicates that the capacitive screen has been touched. In other words, if the capacitive screen has not been touched, the difference between the coupling capacitance Cm of the adjacent channels should remain stable. If the difference between the coupling capacitance Cm of the adjacent channels has changed, it indicates that one of the adjacent RX electrodes has been touched.

[0159] Based on this, in the embodiment of the present application, when the first control switch K1 is closed, the in-phase output result of the first-stage operational amplifier module of the i-th RX channel is input to the inverting input terminal of the second-stage operational amplifier module of the i+1-th RX channel. Since the in-phase output result of the i-th RX channel and the inverting output result of the i+1-th RX channel are in opposite phase, an addition operation is performed on the two, which is equivalent to taking a difference between the two to obtain a result of the difference, that is, whether there is a difference between adjacent RX channels. If there is a difference, it indicates that a touch has occurred in one of the RX electrodes. Based on the result obtained by the difference, it can be further determined which specific channel of the adjacent channels has been touched.

[0160] Similarly, when the second control switch K2 is closed, the inverting output result of the first-stage operational amplifier module of the i-th RX channel is adjacently subtracted from the inverting output result of the first-stage operational amplifier module of the i+1-th RX channel, and based on the result obtained by the subtraction, it is further determined which channel of the adjacent RX electrodes is touched.

[0161] As an implementation method, the first control switch K1 and the second control switch K2 can be closed simultaneously based on the control signal clock, which can help to simultaneously determine the coupling capacitance difference between adjacent RX electrodes and further more accurately determine which RX electrode is touched.

[0162] The difference results of each RX channel with other adjacent channels enter the second-stage operational amplifier module PGA, which performs secondary amplification on the adjacent difference results. Then, through the sample-and-hold device and the analog-to-digital conversion buffer, the adjacent difference results enter the analog-to-digital conversion module ADC to output the digital signal matrix of the difference results of each RX channel. According to the value of each element in the digital signal matrix, the coordinates of the corresponding touch position can be determined.

[0163] By using the embodiment of the present application, multi-channel adjacent differential detection can be realized. Specifically, during adjacent differential detection, the adjacent differential detection result can be obtained by subtracting the conversion results between adjacent channels. In addition, since the two signal lines form a differential signal line after the switch K1 and the switch K2 are closed at the same time, when there is display interference noise, the display interference noise will be coupled to the two differential signal lines at the same time. When adjacent differences are made between adjacent RX channels, this display interference noise is common mode noise and will be completely offset, thereby reducing the interference of display interference on the target differential result, and further improving the output result accuracy of the touch signal-to-noise ratio enhancement circuit.

[0164] Among them, in the embodiment of the present application, when the first control switch K1 and the second control switch K2 between each RX channel are both disconnected, the capacitive screen touch detection used between each RX channel is single-channel touch detection, rather than differential detection. By selecting the embodiment of the present application, the touch detection method can be flexibly selected by controlling whether the first control switch K1 and the second control switch K2 between each RX channel are closed at the same time.

[0165] Based on the principle of adjacent channel differential detection, the output result of each channel needs to be calculated continuously RX(i+1)-RX(i), which requires a large amount of calculation and the algorithm processing is relatively complicated. In order to save the complexity of the algorithm processing, in some embodiments, the complexity of the algorithm processing is reduced by reducing the circuit of the reference channel differential detection. Fig.11 As shown, the reference channel includes: a first bias resistor Rb1, a first-stage inverting input resistor R12, and a first-stage operational amplifier module; wherein the first-stage operational amplifier module is a non-inverting amplifier module,

[0166] A first end of the first bias resistor Rb1 is connected to a preset voltage VCMI, a second end of the first bias resistor Rb1 is connected to the touch sensor, and a second end of the first bias resistor Rb1 is connected to a non-inverting input terminal (+) of the first-stage operational amplifier module;

[0167] A first end of the first-stage inverting input resistor R12 is connected to the inverting input terminal (-) of the first-stage operational amplifier module, and a second end of the first-stage inverting input resistor R12 is connected to a preset voltage VCMI.

[0168] On this basis, as an implementation method, the touch signal-to-noise ratio increasing circuit for the case of differential detection with subtracted reference channels in the embodiment of the present application can be as follows: Fig.11 As shown:

[0169] In addition to the preset voltage, the first bias resistor Rb1, the first-stage operation module, the filter, the sample and hold, and the possible second-stage operation amplifier module included in each RX channel, the second-stage in-phase input resistor in the touch signal-to-noise ratio increase circuit corresponding to each RX electrode of the differential detection of the subtracted reference channel includes two second-stage in-phase input resistors (R21, R23) and two second-stage inverting input resistors (R22, R24).

[0170] The first stage operational amplifier module is as follows Fig.11 The first stage operational amplifier shown in the dotted box is a common-mode amplifier module composed of a first feedback resistor Rf1 and a first feedback capacitor Cf1. Similarly, the first feedback resistor Rf1 and the first feedback capacitor Cf1 are connected in parallel to the negative feedback circuit of the first stage operational amplifier.

[0171] The second stage operational amplifier module is also selected according to the gain of the first stage operational amplifier module. If the second stage operational amplifier module is not needed, the second stage non-inverting input resistor and the second stage inverting input resistor are directly connected to the filter.

[0172] As a connection method, the connection relationship of each component in the capacitive screen signal-to-noise ratio circuit under the condition of subtracting the reference channel differential detection is as follows: Fig.11 As shown:

[0173] The first end of the first second stage common-phase input resistor R21 in the i-th RX channel is connected to the common-phase output end of the first stage operational amplifier module, and the second end of the first second stage common-phase input resistor R21 is connected to the second end of the second second stage common-phase input resistor R23 of the i-th RX channel and the common-phase input end (+) of the i-th second stage operational amplifier module.

[0174] The first end of the second second stage in-phase input resistor R23 of the i-th RX channel and the first ends of the second second stage in-phase input resistors R23 of other RX channels are connected to the inverting output end of the reference channel.

[0175] The first end of the first-second-stage inverting input resistor R22 of the i-th RX channel is connected to the inverting output end of the first-stage operational amplifier module, and the second end of the first-second-stage inverting input resistor R22 is connected to the second end of the second-second-stage inverting input resistor R24 ​​of the i-th RX channel and the inverting input end (-) of the i-th second-stage operational amplifier.

[0176] The first end of the second second-stage inverting input resistor R24 ​​of the i-th RX channel is connected to the first end of the second second-stage inverting input resistor R24 ​​of each RX channel and the in-phase output end of the reference channel.

[0177] The in-phase output terminal of the i-th RX channel is subtracted from the inverting output terminal of the reference channel, and the inverting output terminal of the i-th RX channel is subtracted from the in-phase output terminal of the reference channel to obtain the target differential result.

[0178] Specifically, the reference channel is a touch signal-to-noise ratio increasing circuit corresponding to a reference electrode, wherein the reference electrode may be an RX electrode, which may be a target channel selected from RX0 to RXn, or an external electrode, such as a preset test point around a capacitive screen, or a cathode plate.

[0179] If adjacent differential detection is based on the difference between the coupling capacitances of adjacent channels to determine whether there is a touch, then the fixed channel minus or reference channel minus differential detection is based on detecting the difference between the coupling capacitance of each RX channel and the coupling capacitance of the fixed channel to determine whether there is a touch in each RX channel. Based on this, in an embodiment of the present application, each RX channel subtracts the in-phase output result of the first-stage operational amplifier module from the inverted output result of the reference channel, and subtracts the inverted output result of the first-stage operational amplifier module from the in-phase output result of the reference channel to determine whether the coupling capacitance of each RX channel has changed compared to the coupling capacitance of the reference channel, and then passes the subtraction results of each channel through the second-stage operational amplifier module, filter, sample holder, analog conversion buffer and analog-to-digital conversion module to output the digital signal matrix of each RX channel, and based on the value of each element in the digital signal matrix, the area where the touch occurs can be determined.

[0180] In the embodiment of the present application, adjacent channels are not subtracted from each other. Instead, a reference channel RXm is introduced. The output result of each channel can be obtained by subtracting the signal of RXm from the signal of each channel. That is, RX0-RXm, RX1-RXm... are used to achieve the effect of differential detection. In this way, each channel only needs to be subtracted from the reference channel to obtain its own result. The calculation process is simpler and the implementation difficulty is lower.

[0181] In some embodiments, whether a touch occurs on each RX channel of the capacitive screen can be detected by subtracting the average value from the differential detection. Specifically, as an implementation, the touch signal-to-noise ratio increasing circuit under subtracting the average value from the differential detection provided in the embodiment of the present application can be as follows: Fig.12 As shown, on the basis of each RX channel, a mean generation channel is also included, and the mean generation channel includes: a mean non-inverting input resistor RS1, a mean inverting input resistor RS2, a second-stage operational amplifier module PGA, a filter, and a sample and hold device. The mean generation channel is used to collect the output results of each RX channel and calculate the average value of the output results.

[0182] Among them, for each RX channel, the second-stage common-phase input resistor also includes a first second-stage common-phase input resistor R21 and a second second-stage common-phase input resistor R23, and the second-stage inverting input resistor also includes a first second-stage inverting input resistor R22 and a second second-stage inverting input resistor R24.

[0183] like Fig.12 As shown, between each RX channel and the mean value generation channel, there are: a first input resistor RA1, a second input resistor RA2, a first input capacitor CA1, and a second input capacitor CA2.

[0184] like Fig.12As shown, the connection relationship between the components in the touch signal-to-noise ratio enhancement circuit under the mean-subtracted differential detection is as follows:

[0185] The second end of the mean non-inverting input resistor RS1 is connected to the non-inverting input terminal (+) of the second-stage operational amplifier module, the second end of the mean inverting input resistor RS2 is connected to the inverting input terminal (-) of the second-stage operational amplifier module, the output terminal of the second-stage operational amplifier module is connected to the input terminal of the filter, and the output terminal of the filter is connected to the input terminal of the sample and hold.

[0186] The first end of the first-second-stage common-phase input resistor R21 in the i-th RX channel is connected to the common-phase output end of the first-stage operational amplifier module of the i-th channel and the first end of the input first input resistor RA1, and the second end of the first-second-stage common-phase input resistor R21 of the i-th RX channel is connected to the second end of the second-second-stage common-phase input resistor R23 of the i-th RX channel and the common-phase input end (+) of the second-stage operational amplifier module of the i-th RX channel.

[0187] The first end of the second second stage in-phase input resistor R23 of the i-th RX channel is connected to the first end of the second second stage in-phase input resistor R23 of each RX channel and the inverting output end (-) of the second stage operational amplifier module of the mean generation channel.

[0188] The first end of the first and second stage inverting input resistor R22 of the i-th RX channel is connected to the inverting output end of the first stage operational amplifier module of the i-th channel and the first end of the second input resistor RA2; the second end of the first and second stage inverting input resistor R22 of the i-th RX channel is connected to the second end of the second and second stage inverting input resistor R24 ​​of the i-th RX channel and the inverting input end (-) of the second stage operational amplifier of the i-th RX channel.

[0189] The first end of the second second-stage inverting input resistor R24 ​​of the i-th RX channel is connected to the first end of the second second-stage inverting input resistor R24 ​​of each RX channel and the non-inverting output end (+) of the second-stage operational amplifier module of the mean generation channel.

[0190] The second end of the first input resistor RA1 is connected to the first end of the mean in-phase input resistor RS1 and the first end of the first input capacitor CA1; the second end of the first input capacitor CA1 is grounded.

[0191] The second end of the second input resistor RA2 is connected to the first end of the mean inverting input resistor RS2 and the first end of the second input capacitor CA2; the second end of the second input capacitor CA2 is grounded.

[0192] The in-phase output terminal of the i-th RX channel is subtracted from the inverting output terminal of the mean generation channel, and the inverting output terminal of the i-th RX channel is subtracted from the in-phase output terminal of the mean generation channel to obtain the target differential result.

[0193] The mean value generation channel is equivalent to an adding circuit, which accumulates the output values ​​of all channels, and then uses the input resistor RA to set the gain to achieve the effect of dividing by the number of channels to obtain an output mean value. The first input capacitor CA1 and the second input capacitor CA2 added to the mean value generation channel circuit are used to filter out high-frequency interference signals in the average value signal.

[0194] Similar to adjacent differential detection and reference channel differential detection, in an embodiment of the present application, after the in-phase output end and the inverted output of each RX channel are input to the second-stage operational amplifier module of the mean generation channel, the mean is calculated, and the in-phase output result mean and the inverted output result mean of each RX channel are output. Then the in-phase output result mean and the inverted output result mean are subtracted from the in-phase output result and the inverted output result of each RX channel. Specifically, the in-phase output result of each RX channel is subtracted from the inverted output result mean of the mean generation channel, and the inverted output result of each RX channel is subtracted from the in-phase output result mean of the mean generation channel, and the difference between the coupling capacitance of each RX channel and the coupling capacitance change mean of each RX channel is obtained to determine which specific RX channel has been touched.

[0195] By selecting an embodiment of the present application, the output results of all RX channels are collected by the mean generation channel and the average value is obtained. Then, when outputting, the output result of each RX channel is subtracted from the mean value. There is no need for differential restoration, which can effectively reduce the problem of noise accumulation caused by the introduction of white noise in the differential restoration process.

[0196] Compared with the touch signal-to-noise ratio increasing circuit of adjacent differential detection, the touch signal-to-noise ratio increasing circuit of mean-subtracted channel differential detection has a module output method similar to that of a single-ended signal in terms of circuit engineering implementation. The wiring on the circuit board does not need to be strictly arranged according to a fixed wiring sequence, thus saving design and processing costs.

[0197] In a second aspect, the present application further proposes a capacitive screen, which includes the above-mentioned touch signal-to-noise ratio increasing circuit.

[0198] In the third aspect, the present application also proposes a chip, which includes the above-mentioned touch signal-to-noise ratio increasing circuit. The chip (Integrated Circuit, IC) is also called a chip, which can be but not limited to a SOC (System on Chip) chip or a SIP (system in package) chip. The chip can effectively solve the problem of reduced signal-to-noise ratio as the size of the capacitive screen increases due to the touch signal-to-noise ratio increasing circuit set inside.

[0199] Specifically, the touch signal-to-noise ratio increasing circuit is connected to each RX channel of the capacitive screen through each pin of the chip. For the case where RX is a single-ended output, the touch signal-to-noise ratio increasing circuit after each RX channel can be the same or different. For the case where RX is a differential output, a flexible selection can be made based on the three embodiments of differential detection, which is not strictly limited in this application.

[0200] Among them, the touch signal-to-noise ratio increasing circuit of the high impedance input voltage amplification type is as follows Fig.13 The measured SNR curve results shown in the figure show that when the size of the capacitive screen increases, the touch signal-to-noise ratio enhancement circuit provided by the present application is a new solution, and the measured SNR obtained is better than the measured SNR of the original current amplification solution. Specifically, it can be clearly seen from the following formula that the capacitive screen signal-to-noise ratio provided by the present application is better than the traditional solution:

[0201] Combination Figure 1 The circuit diagram shown can be used to deduce that the signal gain of the original solution satisfies the following formula 1) through circuit theory:

[0202] Signal Gain≈sC M R f Formula 1)

[0203] Where s is the signal, and C in the formula M is the capacitance of the input capacitor, R f is the resistance of the feedback resistor.

[0204] The noise gain of the original solution satisfies the following formula 2):

[0205] Noise Gain≈1+sC r R f Formula 2)

[0206] Among them, C in the formula r is the capacitance of the input capacitor, R f is the resistance of the feedback resistor.

[0207] According to formula 1) and formula 2), it can be seen that the noise gain and signal gain are positively correlated with the resistance of the feedback resistor and the capacitance of the input capacitor. The greater the change in the capacitance of the input capacitor, the greater the noise gain, and the lower the signal-to-noise ratio.

[0208] According to the application provided Figure 2 The touch signal-to-noise ratio increasing circuit shown in the figure can be deduced through circuit theory that the signal gain of the new solution satisfies the following formula 3):

[0209] Signal Gain≈(1+R f / RG1)(s C M R b / 1+s C r R b )Formula 3)

[0210] Where s is the signal, C M is the capacitance of the input capacitor, R f is the resistance of the feedback resistor, R b is the resistance value of the first bias resistor, and RG1 is the resistance value of the first grounding resistor.

[0211] The noise gain of the new solution satisfies the following formula 4):

[0212] Noise Gain≈1+R f / RG1 formula 4)

[0213] According to formula 3) and formula 4), it can be seen that the noise gain of the new solution is independent of the input capacitance. Therefore, changes in the input capacitance will not affect the noise gain, and thus will not introduce noise, reducing noise interference. Secondly, the noise gain is only positively correlated with the ratio between the resistance value of the feedback resistor and the resistance value of the grounding resistor. By selecting the appropriate magnitude of the grounding resistor and the feedback resistor, the noise gain can be controlled.

[0214] By selecting the embodiment of the present application, the built-in signal-to-noise ratio increasing circuit of the capacitive screen can be flexibly selected according to actual needs, thereby reducing display interference and common-mode interference, and improving the signal response effect and display effect of the capacitive screen.

[0215] In the fourth aspect, the present application also proposes an electronic device including a touch signal-to-noise ratio increasing circuit. Specifically, the electronic device includes a device body and a chip as described above provided in the device body. The electronic device may be, but is not limited to, any electronic device including a display screen, such as a smart TV, a display, a mobile phone, a smart tablet, etc. The electronic device can effectively solve the problem of reduced signal-to-noise ratio due to the increasing size of the capacitive screen through the touch signal-to-noise ratio increasing circuit provided inside.

[0216] The above are only preferred embodiments of the present application, and are not intended to limit the present application in any form. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technical personnel in the field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present application. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A touch signal-to-noise ratio increasing circuit, It is characterized in that The touch signal-to-noise ratio increasing circuit comprises: A first bias resistor, a first-stage inverting input resistor, and a first-stage operational amplifier module; wherein the first-stage operational amplifier module is a non-inverting amplifier module; The first end of the first bias resistor is connected to a preset voltage, the second end of the first bias resistor is connected to the touch sensor, and the second end of the first bias resistor is connected to the non-inverting input end of the first-stage operational amplifier module; If the touch signal-to-noise ratio increasing circuit is powered by a single power supply, the first end of the first-stage inverting input resistor is connected to the inverting input end of the first-stage operational amplifier module, and the second end of the first-stage inverting input resistor is grounded; or, if the touch signal-to-noise ratio increasing circuit is powered by a dual power supply, the first end of the first-stage inverting input resistor is connected to the inverting input end of the first-stage operational amplifier module, and the second end of the first-stage inverting input resistor is connected to the preset voltage; The first-stage operational amplifier module is a buffer, and the touch signal-to-noise ratio increasing circuit further includes: A second-stage operational amplifier module, a second-stage non-inverting input resistor, and a second-stage inverting input resistor, wherein the output end of the buffer is connected to the first end of the second-stage non-inverting input resistor, and the second end of the second-stage non-inverting input resistor is connected to the non-inverting input end of the second-stage operational amplifier module; The first end of the second-stage inverting input resistor is connected to the inverting input end of the second-stage operational amplifier module, and the second end of the second-stage inverting input resistor is grounded; or, The first-stage operational amplifier module is a buffer, and the touch signal-to-noise ratio increasing circuit further includes: The second stage operational amplifier module, the second stage non-inverting input resistor, the second stage inverting input resistor, where: The in-phase output terminal of the buffer is connected to the first end of the in-phase input resistor of the second stage, and the second end of the in-phase input resistor of the second stage is connected to the in-phase input terminal of the second stage operational amplifier module; The inverting output terminal of the buffer is connected to the first terminal of the second-stage inverting input resistor, and the second terminal of the second-stage inverting input resistor is connected to the inverting input terminal of the second-stage operational amplifier module; or, The touch signal-to-noise ratio increasing circuit further includes: a second-stage in-phase input resistor, a second-stage inverting input resistor, and a second-stage operational amplifier module, wherein: The in-phase output terminal of the first-stage operational amplifier module is connected to the first terminal of the second-stage in-phase input resistor, and the second terminal of the second-stage in-phase input resistor is connected to the in-phase input terminal of the second-stage operational amplifier module; The inverting output terminal of the first-stage operational amplifier module is connected to the first terminal of the second-stage inverting input resistor, and the second terminal of the second-stage inverting input resistor is connected to the inverting input terminal of the second-stage operational amplifier module.

2. The touch signal-to-noise ratio increasing circuit according to claim 1, It is characterized in that The touch signal-to-noise ratio increasing circuit further includes: a first bias capacitor, wherein: A first end of the first bias capacitor is connected to the preset voltage, and a second end of the first bias capacitor is connected to the non-inverting input end of the first-stage operational amplifier module.

3. The touch signal-to-noise ratio increasing circuit according to claim 1, It is characterized in that The touch signal-to-noise ratio increasing circuit further includes: a filter, wherein: The filter is connected to the output end of the first-stage operational amplifier module, and is used to output a target filtering result based on the output result of the first-stage operational amplifier module.

4. The touch signal-to-noise ratio increasing circuit according to claim 3, It is characterized in that The touch signal-to-noise ratio increasing circuit further includes: an analog-to-digital conversion module, wherein: The analog-to-digital conversion module is connected to the output end of the filter and is used to convert the target filtering result into a target digital signal.

5. The touch signal-to-noise ratio increasing circuit according to claim 1, It is characterized in that The common-phase amplifier module includes: a common-phase amplifier and a first-stage amplification feedback resistor, wherein the first end of the first-stage amplification feedback resistor is connected to the output end of the common-phase amplifier, and the second end of the first-stage amplification feedback resistor is connected to the inverting input end of the common-phase amplifier.

6. The touch signal-to-noise ratio increasing circuit according to claim 5, It is characterized in that The touch signal-to-noise ratio increasing circuit further includes: The second stage operational amplifier module, the second stage non-inverting input resistor, the second stage inverting input resistor, and the filter, among which: A first end of the second-stage in-phase input resistor is connected to the output end of the in-phase amplification module, and a second end of the second-stage in-phase input resistor is connected to the in-phase input end of the second-stage operational amplification module; The first end of the second-stage inverting input resistor is connected to the inverting input end of the second-stage operational amplifier module, and the second end of the second-stage inverting input resistor is grounded; The output end of the second-stage operational amplifier module is connected to the filter.

7. The touch signal-to-noise ratio increasing circuit according to claim 6, It is characterized in that The gain of the in-phase amplification module is less than a preset gain threshold.

8. The touch signal-to-noise ratio increasing circuit according to claim 1, It is characterized in that The touch signal-to-noise ratio increasing circuit further includes: A first control switch, a second control switch, a first differential connection resistor, and a second differential connection resistor, wherein: The first end of the first control switch is connected to the second end of the second-stage in-phase input resistor of the i-th RX channel, the second end of the first control switch is connected to the first end of the first differential connection resistor, and the second end of the first differential connection resistor is connected to the second end of the second-stage inverting input resistor of the (i+1)-th RX channel; The first end of the second control switch is connected to the second end of the second-stage inverting input resistor of the i-th RX channel, the second end of the second control switch is connected to the first end of the second differential connection resistor, and the second end of the second differential connection resistor is connected to the second end of the second-stage non-inverting input resistor of the (i+1)-th RX channel; The i-th RX channel and the i+1-th RX channel are two adjacent channels among the multiple RX channels; and the RX channel is a touch signal-to-noise ratio increasing circuit corresponding to the RX electrode.

9. The touch signal-to-noise ratio increasing circuit according to claim 8, It is characterized in that When the first control switch is closed, the in-phase output terminal in the i-th RX channel and the inverting output terminal in the (i+1)-th RX channel are adjacent to each other and are differentially connected; When the second control switch is closed, the inverting output terminal in the i-th RX channel and the non-inverting output terminal in the (i+1)-th RX channel are adjacently differentially obtained to obtain a target differential result.

10. The touch signal-to-noise ratio increasing circuit according to claim 1, It is characterized in that The touch sensor further includes a reference channel; the reference channel includes: a first bias resistor, a first-stage inverting input resistor, and a first-stage operational amplifier module; wherein the first-stage operational amplifier module is a non-inverting amplifier module, The first end of the first bias resistor is connected to a preset voltage, the second end of the first bias resistor is connected to the touch sensor, and the second end of the first bias resistor is connected to the non-inverting input end of the first-stage operational amplifier module; The first end of the first-stage inverting input resistor is connected to the inverting input end of the first-stage operational amplifier module, and the second end of the first-stage inverting input resistor is connected to the preset voltage.

11. The touch signal-to-noise ratio increasing circuit according to claim 10, It is characterized in that The second-stage common-phase input resistor includes: a first second-stage common-phase input resistor and a second second-stage common-phase input resistor, and the second-stage inverting input resistor includes: a first second-stage inverting input resistor and a second second-stage inverting input resistor, wherein: The first end of the first second stage in-phase input resistor in the i-th RX channel is connected to the in-phase output end of the first stage operational amplifier module, and the second end of the first second stage in-phase input resistor is connected to the second end of the second second stage in-phase input resistor in the i-th RX channel and the in-phase input end of the second stage operational amplifier module in the i-th RX channel; The first end of the second second-stage non-inverting input resistor in the i-th RX channel is connected to the first end of the second second-stage non-inverting input resistor in each of the RX channels and the inverting output end of the reference channel; The first end of the first second stage inverting input resistor in the i-th RX channel is connected to the inverting output end of the first stage operational amplifier module, and the second end of the first second stage inverting input resistor is connected to the second end of the second second stage inverting input resistor in the i-th RX channel and the inverting input end of the second stage operational amplifier in the i-th RX channel; The first end of the second second-stage inverting input resistor in the i-th RX channel is connected to the first end of the second second-stage inverting input resistor in each of the RX channels and the in-phase output end of the reference channel; The in-phase output end of the i-th RX channel is subtracted from the inverting output end of the reference channel, and the inverting output end of the i-th RX channel is subtracted from the in-phase output end of the reference channel to obtain a target differential result; the RX channel is a touch signal-to-noise ratio increasing circuit corresponding to the RX electrode, and the reference channel is a touch signal-to-noise ratio increasing circuit corresponding to the reference electrode.

12. The touch signal-to-noise ratio increasing circuit according to claim 8, It is characterized in that The touch signal-to-noise ratio increasing circuit also includes a mean value generating channel; The mean value generation channel includes: a mean non-inverting input resistor, a mean inverting input resistor, a second-stage operational amplifier module, a filter, and a sample-and-hold device. The mean value generation channel is used to collect the average value of the output results of each RX channel.

13. The touch signal-to-noise ratio increasing circuit according to claim 12, It is characterized in that The second-stage common-phase input resistor includes: a first second-stage common-phase input resistor and a second second-stage common-phase input resistor, and the second-stage inverting input resistor includes: a first second-stage inverting input resistor and a second second-stage inverting input resistor; The second end of the mean non-inverting input resistor is connected to the non-inverting input end of the second-stage operational amplifier module, the second end of the mean inverting input resistor is connected to the inverting input end of the second-stage operational amplifier module, the output end of the second-stage operational amplifier module is connected to the input end of the filter, and the output end of the filter is connected to the input end of the sample and hold device; Each of the RX channels and the mean value generation channel includes: a first input resistor, a second input resistor, a first input capacitor, and a second input capacitor, wherein: The first end of the first-second-stage non-inverting input resistor in the i-th RX channel is connected to the non-inverting output end of the first-stage operational amplifier module of the i-th channel and the first end of the first input resistor, and the second end of the first-second-stage non-inverting input resistor of the i-th RX channel is connected to the second end of the second-second-stage non-inverting input resistor of the i-th RX channel and the non-inverting input end of the second-stage operational amplifier module of the i-th RX channel; The first end of the second second stage in-phase input resistor of the i-th RX channel is connected to the first end of the second second stage in-phase input resistor of each RX channel and the inverting output end of the second stage operational amplifier module of the mean value generating channel; The first end of the first and second stage inverting input resistors of the i-th RX channel is connected to the inverting output end of the first stage operational amplifier module of the i-th channel and the first end of the second input resistor; the second end of the first and second stage inverting input resistors of the i-th RX channel is connected to the second end of the second second stage inverting input resistor of the i-th RX channel and the inverting input end of the second stage operational amplifier of the i-th RX channel; The first end of the second second-stage inverting input resistor of the i-th RX channel is connected to the first end of the second second-stage inverting input resistor of each RX channel and the in-phase output end of the second-stage operational amplifier module of the mean value generating channel; The second end of the first input resistor is connected to the first end of the average in-phase input resistor and the first end of the first input capacitor; the second end of the first input capacitor is grounded; The second end of the second input resistor is connected to the first end of the mean inverting input resistor and the first end of the second input capacitor; the second end of the second input capacitor is grounded; The in-phase output end of the i-th RX channel is subtracted from the inverting output end of the mean generation channel, and the inverting output end of the i-th RX channel is subtracted from the in-phase output end of the mean generation channel to obtain a target differential result.

14. A capacitive screen, It is characterized in that The capacitive screen includes the touch signal-to-noise ratio increasing circuit according to any one of claims 1 to 13.

15. A chip, It is characterized in that The chip includes the touch signal-to-noise ratio increasing circuit according to any one of claims 1 to 13.

16. An electronic device, It is characterized in that The electronic device comprises the chip according to claim 15.

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