Signal processing circuit and related touch control circuit, chip and touch device
Patent Information
- Application Number
- CN202110271022.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-03-12
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2041-03-12
AI Technical Summary
The prior art is difficult to reduce the complexity of signal processing circuits while maintaining high accuracy in touch detection, especially in avoiding pixel array interference and frequency matching problems, resulting in increased design complexity and cost.
Bandpass triangular integral analog-to-digital converter is used to dynamically adjust its central frequency to the coded signal frequency, and signal processing is performed through in-phase orthogonal demodulator and digital filter, and demodulation and filtering are used to reduce the Circuit complexity.
High-precision signal conversion and reduced circuit design complexity, reducing hardware implementation costs, while avoiding additional bandpass filters and sampling point storage requirements.
Smart Images
Figure CN113131937B_ABST
Abstract
Description
Technical Field
[0001] The present application relates to a signal processing circuit, and more particularly to a signal processing circuit for touch detection. Background Art
[0002] In order to provide users with a better experience, current smart devices often have a touch panel disposed above a display pixel array so that users can perform human-computer interaction in a touch-controlled manner. Figure 1 is a schematic diagram of a touch panel TP1. The touch panel TP1 includes a plurality of transmitting electrodes GL1 to GLM and a plurality of receiving electrodes DL1 to DLN, wherein M and N are positive integers greater than 1. When performing touch detection, the transmitting electrodes GL1 to GLM receive specific coding signals. Figure 1 In the embodiment, the transmitting electrodes GL1 to GLM can be arranged in parallel, and each transmitting electrode GL1 to GLM is perpendicular to the receiving electrodes DL1 to DLN, so the coding signal transmitted on the transmitting electrodes GL1 to GLM will be coupled to the receiving electrodes DL1 to DLN, so the sensing signal will be generated correspondingly on the receiving electrodes DL1 to DLN. When a finger touches the touch panel, the capacitance between the transmitting electrode and the receiving electrode near the finger touch point will change, causing the sensing signal on the receiving electrodes DL1 to DLN to change. Therefore, based on the change of the sensing signal on the receiving electrodes DL1 to DLN, the position of the finger touching the panel can be inferred.
[0003] Generally speaking, the prior art often uses a Nyquist analog-to-digital converter to convert the sensing signal into a digital signal, and then processes the digital signal to detect the change of the sensing signal. Since the change of the sensing signal caused by a touch event is very small, a higher accuracy is required when performing analog-to-digital conversion, such as 12-bit to 14-bit accuracy. However, such a high accuracy requirement will greatly increase the design complexity of the Nyquist analog-to-digital converter.
[0004] In addition, since the touch panel is usually arranged adjacent to the pixel array for displaying images, in order to prevent the sensing signal from being interfered with by the driving signal of the pixel array, the controller of the touch panel will change the frequency of the coding signal according to the use of the pixel array to prevent the frequencies of the coding signal and the driving signal from being too close and interfering with each other. However, when the frequency of the coding signal changes, since the sampling frequency of the Nyquist analog-to-digital converter remains fixed, there is no fixed ratio relationship between the frequency of the coding signal and the sampling frequency of the Nyquist analog-to-digital converter, resulting in the need for the processing circuit of the digital signal to reselect a suitable sampling point after the Nyquist analog-to-digital converter generates a digital signal, thereby increasing the complexity of the processing circuit. Therefore, how to achieve the accuracy required by the system and reduce the complexity of the circuit design to reduce the implementation cost has become a problem to be solved. Summary of the invention
[0005] One of the purposes of the present application is to disclose a signal processing circuit and a related touch control circuit, chip and touch device that can maintain accuracy and reduce circuit complexity, so as to solve the above-mentioned problems.
[0006] One embodiment of the present application provides a signal processing circuit. The signal processing circuit is coupled to a touch panel, the touch panel receives a coding signal and correspondingly couples to generate a sensing signal, the signal processing circuit is used to receive the sensing signal sent by the touch panel, and convert the sensing signal into an in-phase value and an orthogonal value to assist in determining a touch event on the touch panel. The signal processing circuit includes an amplifier, a bandpass delta-sigma analog-to-digital converter, an in-phase orthogonal demodulator, and a digital filter. The amplifier is used to amplify the sensing signal to generate an amplified sensing signal. The bandpass delta-sigma analog-to-digital converter is used to convert the amplified sensing signal into a digital sensing signal, and the center frequency of the bandpass delta-sigma analog-to-digital converter is dynamically adjusted to be close to the frequency of the coding signal. The in-phase orthogonal demodulator is used to demodulate the digital sensing signal into a plurality of in-phase sampling values and a plurality of orthogonal sampling values. The digital filter is used to filter the high-frequency noise in the plurality of in-phase sampling values and the plurality of orthogonal sampling values.
[0007] Another embodiment of the present application provides a touch control circuit, which includes a plurality of signal processing circuits, which are used to correspondingly receive a plurality of sensing signals transmitted from a plurality of receiving electrodes in the touch panel and convert the plurality of sensing signals into a plurality of in-phase values and a plurality of orthogonal values.
[0008] Another embodiment of the present application provides a chip, including the touch control circuit. Another embodiment of the present application provides a touch device, including the touch control circuit and the touch panel.
[0009] The signal processing circuit and related touch control circuit, chip and touch device of the present application can use a bandpass delta-sigma analog-to-digital converter with narrow bandwidth performance to perform analog-to-digital conversion on the sensing signal, thereby achieving a higher conversion accuracy. In addition, the bandpass delta-sigma analog-to-digital converter can make the center frequency and the sampling frequency have a fixed multiplication factor, so that the in-phase orthogonal demodulator can use a fixed sampling point for demodulation, thereby reducing the complexity of the circuit design. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 is a schematic diagram of a touch panel.
[0011] Figure 2 FIG. 4 is a schematic diagram of a touch device according to an embodiment of the present application.
[0012] Figure 3 FIG. 4 is a schematic diagram of a bandpass delta-sigma analog-to-digital converter according to an embodiment of the present invention.
[0013] Figure 4 FIG. 4 is a schematic diagram of a touch device according to another embodiment of the present invention. DETAILED DESCRIPTION
[0014] The following disclosure provides a variety of implementations or illustrations that can be used to implement different features of the present disclosure. The specific examples of components and configurations described below are used to simplify the present disclosure. As can be imagined, these descriptions are only illustrative and are not intended to limit the present disclosure. For example, in the description below, forming a first feature on or above a second feature may include certain embodiments in which the first and second features are directly in contact with each other; and may also include certain embodiments in which additional components are formed between the above-mentioned first and second features, so that the first and second features may not be in direct contact. In addition, the present disclosure may reuse component symbols and / or labels in multiple embodiments. Such repetition is based on the purpose of simplicity and clarity, and does not itself represent the relationship between the different embodiments and / or configurations discussed.
[0015] Furthermore, spatially relative terms such as "below," "below," "below," "above," and the like may be used herein to facilitate description of the relationship between one component or feature shown in the figure relative to another or more components or features. These spatially relative terms are intended to encompass a variety of different orientations of the device during use or operation in addition to the orientation shown in the figure. The device may be placed in other orientations (e.g., rotated 90 degrees or in other orientations), and these spatially relative descriptive terms should be interpreted accordingly.
[0016] Although the numerical ranges and parameters used to define the broader scope of the present application are approximate values, the relevant numerical values in the specific embodiments have been presented as accurately as possible. However, any numerical value inherently inevitably contains standard deviations due to individual testing methods. Here, "about" generally refers to the actual value within plus or minus 10%, 5%, 1% or 0.5% of a specific value or range. Alternatively, the term "about" means that the actual value falls within the acceptable standard error of the mean value, depending on the consideration of a person with ordinary knowledge in the technical field to which the present application belongs. It should be understood that, except for the experimental examples, or unless otherwise explicitly stated, all ranges, quantities, values and percentages used herein (for example, to describe the amount of material used, the length of time, temperature, operating conditions, quantitative ratios and the like) are modified by "about". Therefore, unless otherwise stated to the contrary, the numerical parameters disclosed in this specification and the attached patent scope are all approximate values and can be changed as needed. At least these numerical parameters should be understood as the number of significant digits indicated and the values obtained by applying the general rounding method. Herein, numerical ranges are expressed from one endpoint to another endpoint or between two endpoints; unless otherwise stated, the numerical ranges described herein include the endpoints.
[0017] Figure 2 FIG. 1 is a schematic diagram of a touch control device 10 according to an embodiment of the present application. The touch control device 10 may include a touch control circuit 12 and a touch panel 14. In this embodiment, the touch panel 14 may be connected to Figure 1 The touch panel TP1 has the same structure and can operate according to the same principle. In addition, the touch control circuit 12 may include a controller U1 and signal processing circuits 1001 to 100N, where N is a positive integer greater than 1. In some embodiments, the touch control circuit 12 may be implemented as a chip.
[0018] In this embodiment, the controller U1 can send the coding signal SIG in sequence T1 to the corresponding transmitting electrodes GL1 to GLM, and the coding signal SIG on the transmitting electrodes GL1 to GLM T1 will be coupled to the receiving electrodes DL1 to DLN of the touch panel 14, so the receiving electrodes DL1 to DLN will generate coupled sensing signals SIG R1 To SIG RN .
[0019] The signal processing circuits 1001 to 100N may be respectively coupled to corresponding receiving electrodes DL1 to DLN in the touch panel 14. The signal processing circuit 1001 may receive the sensing signal SIG R1 , and the sensing signal SIG R1 The in-phase value and the quadrature value are converted to enable the touch control circuit 12 to determine the touch event on the touch panel 14 accordingly.
[0020] In this embodiment, the signal processing circuits 1001 to 100N may have the same structure and may operate according to the same principle. For example, the signal processing circuit 1001 may be coupled to the receiving electrode DL1 and may receive the sensing signal SIG. R1 The signal processing circuit 1001 may include an amplifier 110 , a bandpass delta-sigma analog-to-digital converter 120 , an in-phase quadrature demodulator 130 , and a digital filter 140 .
[0021] The amplifier 110 can convert the sensing signal SIG R1 Amplify to generate an amplified sensing signal SIG A1 , and the bandpass delta-sigma analog-to-digital converter 120 can amplify the sensing signal SIG A1 Converted into digital sensing signal SIG DA1 The center frequency of the bandpass delta-sigma analog-to-digital converter 120 can be dynamically adjusted, and the bandpass delta-sigma analog-to-digital converter 120 can perform analog-to-digital conversion on a signal with a frequency close to the center frequency. Since the bandpass delta-sigma analog-to-digital converter 120 has a narrow bandwidth performance focusing on the center frequency, when the center frequency of the bandpass delta-sigma analog-to-digital converter 120 is close to the coding signal SIG T1 When the frequency of the bandpass delta-sigma analog-to-digital converter 120 is the same as that of the coding signal SIG T1 The sensing signal SIG with similar frequency R1 High-precision analog-to-digital conversion is performed. In contrast, the Nyquist analog-to-digital converter of the prior art performs analog-to-digital conversion on signals within the entire Nyquist frequency range. Therefore, if one wants to use the Nyquist analog-to-digital converter to achieve the same accuracy as the bandpass delta-sigma analog-to-digital converter 120, the design complexity of the Nyquist analog-to-digital converter will increase, thereby greatly increasing the cost of hardware implementation.
[0022] In this embodiment, the center frequency of the bandpass delta-sigma analog-to-digital converter 120 can be dynamically adjusted to the frequency f of the coding signal. TX similar, for example, the frequency difference between the two is within the coding signal frequency f TX For example, Figure 2 In the embodiment, the controller U1 can provide a clock signal SIG CLK , and the bandpass delta-sigma analog-to-digital converter 120 can be based on the clock signal SIG CLK The sampling frequency is f, that is, the sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120 s Will be with the clock signal SIG CLK The frequency of the controller U1 is the same as that of the clock signal SIGCLK To control the sampling frequency of the bandpass delta-sigma analog-to-digital converter 120. In this case, when the controller U1 changes the frequency f of the coding signal TX When the controller U1 can synchronously adjust the clock signal SIG CLK The frequency of the bandpass delta-sigma analog-to-digital converter 120 is adjusted accordingly to obtain the sampling frequency f s In this embodiment, since the sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120 is s The center frequency f of the bandpass delta-sigma analog-to-digital converter 120 c There is a fixed ratio relationship between them, so by adjusting the sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120 s The center frequency f of the bandpass delta-sigma analog-to-digital converter 120 is adjusted accordingly. c Therefore, the controller U1 can be based on the sampling frequency f s With the center frequency f c The ratio relationship between the clock signal SIG CLK The frequency of the bandpass delta-sigma analog-to-digital converter 120 is set to c Can maintain the same frequency f as the coding signal TX In this way, the sensing signal SIG can be detected more accurately. R1 Perform analog-to-digital conversion to generate a digital sensing signal SIG DA1 .
[0023] Figure 3 FIG. 1 is a schematic diagram of a bandpass delta-sigma analog-to-digital converter 120 according to an embodiment of the present invention. Figure 3 In the embodiment, the bandpass delta-sigma analog-to-digital converter 120 may include a resonator loop filter 122, a multibit quantizer 124, a dynamic element matching (DEM) module 126, and a digital analog converter (DAC) 128. The digital analog converter 128 may convert the digital sensing signal SIG output by the bandpass delta-sigma analog-to-digital converter 120 into a digital sensing signal SIG. DA1 Converted into analog signal as feedback signal SIG FB , and the dynamic element matching (DEM) module 126 can reduce the impact of non-ideal components in the digital-to-analog converter 128. Then, the bandpass delta-sigma analog-to-digital converter 120 amplifies the sensing signal SIG A1 And feedback signal SIGFB The subtraction is performed, and the signal is filtered by the resonant loop filter 122 to generate a delta-sigma modulation signal, which is then quantized by the multi-bit quantizer 124 to generate a digital sensing signal SIG DA1 .
[0024] In this embodiment, the center frequency f of the bandpass delta-sigma analog-to-digital converter 120 is c is the resonant frequency of the resonant loop filter 122. The sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120 is s It can be designed as its center frequency f c X times, so that the bandpass delta-sigma analog-to-digital converter 120 has a bandpass characteristic. Figure 3 In the embodiment, the resonant loop filter 122 may use a second-order transfer function To perform delta-sigma modulation, the coefficient α and the center frequency f c and sampling frequency f s The relationship can be expressed as formula (1).
[0025]
[0026] That is to say, by appropriately selecting the value of the coefficient α, the center frequency f can be determined accordingly. c and sampling frequency f s For example, if the value of α is cos(π / 4), the center frequency f of the bandpass delta-sigma analog-to-digital converter 120 can be c Set its sampling frequency to f s One eighth of .
[0027] Then, the in-phase and quadrature demodulator 130 can convert the digital sensing signal SIG DA1 The in-phase and quadrature demodulator 130 can sequentially demodulate the sensing signal SIG into a plurality of in-phase sampling values and a plurality of quadrature sampling values. DA1 The digital sensing signal SIG is multiplied by a plurality of sampling points on the sinusoidal signal to generate a plurality of in-phase sampling values, and the digital sensing signal SIG can be sequentially converted into DA1 Multiplying multiple sampling points on the cosine signal to generate multiple orthogonal sampling values.
[0028] Generally speaking, the sampling point required by the in-phase orthogonal demodulator 130 will be different from the frequency f of the coded signal. TX and the sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120 s For example, the in-phase sampling points required by the in-phase quadrature demodulator 130 can be expressed as Where x is a positive integer. In this case, if the frequency f of the coding signal TX With sampling frequency f sare mutually prime, then when the value of x increases from 1 to more than the sampling frequency f s When f is taken from the sinusoidal signal, the same sampling point will be obtained. s After sampling points, the same sampling points will be taken out. In this case, the in-phase quadrature demodulator 130 actually only needs f s sampling points, and x can be from 1 to f s Any integer in (the value of x can include 1 and f s ). However, if the sampling frequency f s is the frequency of the coding signal f TX When the value of x increases from 1 to more than X, the same sampling points will be obtained. In this case, the in-phase orthogonal demodulator 130 actually only needs X sampling points, and x can be any integer from 1 to X (the value of x can include 1 and X).
[0029] According to the above description, it can be seen that at the frequency f of the coding signal TX With sampling frequency f s When there is no fixed ratio relationship between them, when the frequency f of the coding signal TX When the in-phase quadrature demodulator 130 changes, it is also necessary to obtain new in-phase sampling points and quadrature sampling points accordingly. In some embodiments, the touch control circuit 12 may further include a sine signal generator or a cosine signal generator to generate a sine signal or a cosine signal, so as to extract the required sampling points from the sine signal or the cosine signal. However, this will increase the area and hardware required for the in-phase quadrature demodulator 130.
[0030] However, in the signal processing circuit 1001, the sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120 is s With the center frequency f c The ratio between them can be fixed to X, and when the frequency of the coding signal f TX When the sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120 changes, s will also change accordingly, so that the center frequency f of the bandpass delta-sigma analog-to-digital converter 120 c The frequency f of the coding signal TX In this case, even if the coding signal SIG T1 The frequency f TX The sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120 changes. s It will also change to the coding signal frequency f TX Therefore, the in-phase and quadrature demodulator 130 still only needs to use the same X in-phase sampling points and X quadrature sampling points to complete the demodulation.
[0031] In this embodiment, X may be an integer greater than 2, and may be a power of 2, such as but not limited to 8. In this case, the eight sinusoidal sampling points on the sinusoidal signal may be eight sampling points evenly distributed over 360 degrees, for example and in is any real number between -π and π, and the phase difference between any two adjacent sine sampling points is 45 degrees. Similarly, the eight cosine sampling points on the cosine signal can be eight sampling points evenly distributed over 360 degrees, for example and At this time, the phase difference between any two adjacent cosine sampling points is 45 degrees.
[0032] Since the cosine signal and the sine signal are two sets of signals with the same waveform but a phase difference of 90 degrees, in this embodiment, the signal processing circuit 1001 can store eight sine sampling points in advance, and can deduce the other eight cosine sampling points based on the eight sine sampling points without having to store eight cosine sampling points. For example, the signal processing circuit 1001 can further include a demodulation sampling register 160, which can store eight sine sampling points. and In addition, the signal processing circuit 1001 can cyclically shift the sinusoidal sequence to the right by two sampling points, that is, to obtain a sampling point sequence with a phase difference of 90 degrees with the original sinusoidal sequence. and As the cosine sequence, the signal processing circuit 1001 can obtain eight sampling points in the cosine sequence from the sine sequence without storing the sampling points of the cosine signal separately, thereby reducing the hardware area required by the signal processing circuit 1001.
[0033] Get digital sensing signal SIG DA1 After the multiple in-phase sampling values and the multiple orthogonal sampling values are obtained, the digital filter 140 can filter out the high-frequency noise in the multiple in-phase sampling values and the multiple orthogonal sampling values. Figure 2 In the embodiment of the present invention, the signal processing circuit 1001 may further include a downsampling unit 150. The downsampling unit 150 may generate an in-phase value ID1 and a quadrature value QD1 according to a plurality of in-phase sampling values and a plurality of quadrature sampling values. For example, the downsampling unit 150 may accumulate a plurality of in-phase sampling values and multiply them by a specific weight value to obtain the in-phase value ID1, and may accumulate a plurality of quadrature sampling values and multiply them by a specific weight value to obtain the quadrature value QD1.
[0034] In this embodiment, the signal processing circuits 1001 to 100N may process the sensing signal SIG R1 To SIG RN Amplification, analog-to-digital conversion, quadrature demodulation and downsampling are performed to obtain the corresponding in-phase values ID1 to IDN and quadrature values QD1 to QDN. Then, the controller U1 can sense the signal SIG. R1 To SIG RN The in-phase values ID1 to IDN and the quadrature values QD1 to QDN are used to estimate the sensing signal SIG. R1 To SIG RN The amplitude of the sensing signal SIG R1 To SIG RN The amplitude of is used to determine whether a touch event occurs on the touch panel 14, and when a touch event occurs, further determine the touched position on the touch panel 14.
[0035] In addition, since the operation of the bandpass delta-sigma analog-to-digital converter 120 causes the quantization noise to be moved to a high frequency and generate out-of-band quantization noise, generally speaking, in order to filter out the out-of-band quantization noise, a bandpass filter is disposed after the bandpass delta-sigma analog-to-digital converter 120 to eliminate the out-of-band quantization noise. However, in the present embodiment, the out-of-band quantization noise generated by the bandpass delta-sigma analog-to-digital converter 120 is filtered out after passing through the in-phase quadrature demodulator 130, the digital filter 140 and the down-sampling unit 150, so there is no need to additionally dispose a bandpass filter in the signal processing circuits 1001 to 100N.
[0036] However, during the sampling process of the bandpass delta-sigma analog-to-digital converter 120, some frequencies are greater than the sampling frequency f s The noise signal will become low-frequency aliasing noise after folding, resulting in a decrease in the signal-to-noise ratio of the sampling result and affecting the signal quality. Therefore, in some embodiments, the amplified sensing signal SIG A1 Before sampling, a filter is used to filter out the high-frequency signal to reduce the generation of aliasing noise.
[0037] Figure 4 1 is a schematic diagram of a touch device 20 according to another embodiment of the present invention. The touch device 20 may include a touch control circuit 22 and a touch panel 14. The touch control circuit 22 may include a controller U1 and signal processing circuits 2001 to 200N. The signal processing circuits 2001 to 200N may have similar structures to the signal processing circuits 1001 to 100N and may operate according to similar principles, but each signal processing circuit 2001 to 200N may also include a low-pass filter 270.
[0038] In this case, the low pass filter 270 can filter the amplified sensing signal SIG A1 The frequency is greater than or equal to the sampling frequency f of the bandpass delta-sigma analog-to-digital converter 120. s signal to reduce the aliasing noise generated during the sampling process of the bandpass delta-sigma analog-to-digital converter 120.
[0039] It should be noted that the low-pass filter 270 must allow the coding signal SIG T1 Signals with similar frequencies can pass through, so if the value of X is small, for example, less than or equal to 4, the design complexity of the low-pass filter 270 may be increased because the frequencies of the signal to be retained and the signal to be filtered are closer. In addition, if a larger value of X is selected to facilitate the implementation of the low-pass filter 270, more sampling points need to be stored in the in-phase quadrature demodulator 130. For example, if X is 16, the in-phase quadrature demodulator 130 needs 16 sine sampling points and 16 cosine sampling points. In other words, the larger the value of X, the more sampling points the signal processing circuit 2001 needs to store. Therefore, the designer can avoid the design of the low-pass filter 270 being too complicated and avoid the number of sampling points that the signal processing circuit 2001 needs to store being too large by appropriately selecting the value of X.
[0040] In summary, the signal processing circuit and related touch control circuit, chip and touch device provided by the embodiments of the present application can use a bandpass delta-sigma analog-to-digital converter to perform analog-to-digital conversion on the sensing signal. Since the bandpass delta-sigma analog-to-digital converter has a narrow bandwidth performance focusing on the center frequency, the bandpass delta-sigma analog-to-digital converter can achieve a higher conversion accuracy when the center frequency is close to the frequency of the coding signal. In addition, the bandpass delta-sigma analog-to-digital converter can make the center frequency and the sampling frequency have a fixed multiplier, so even if the frequency of the coding signal changes, the in-phase orthogonal demodulator can still use the same sampling point for orthogonal demodulation, thereby reducing the design complexity of the signal processing circuit and the hardware implementation cost.
[0041] The above description briefly presents the features of certain embodiments of the present application, so that those with ordinary knowledge in the technical field to which the present application belongs can more fully understand the various aspects of the present disclosure. Those with ordinary knowledge in the technical field to which the present application belongs should understand that they can easily use the present disclosure as a basis to design or change other processes and structures to achieve the same purpose and / or achieve the same advantages as the embodiments described herein. Those with ordinary knowledge in the technical field to which the present application belongs should understand that these equal embodiments still belong to the spirit and scope of the present disclosure, and they can be variously changed, replaced and modified without departing from the spirit and scope of the present disclosure.
Claims
1. A signal processing circuit, characterized in that: Coupled to a touch panel, the touch panel receives a coding signal and generates a coupled sensing signal accordingly, the signal processing circuit is used to receive the sensing signal sent by the touch panel, and convert the sensing signal into an in-phase value and an orthogonal value to assist in determining a touch event on the touch panel, the signal processing circuit includes: an amplifier, used to amplify the sensing signal to generate an amplified sensing signal; A bandpass delta-sigma analog-to-digital converter, used for converting the amplified sensing signal into a digital sensing signal, wherein the center frequency of the bandpass delta-sigma analog-to-digital converter is dynamically adjusted to a frequency close to the coding signal; an in-phase and quadrature demodulator, used for demodulating the digital sensing signal into a plurality of in-phase sampling values and a plurality of quadrature sampling values; and The digital filter is used to filter high frequency noise in the plurality of in-phase sampling values and the plurality of orthogonal sampling values.
2. The signal processing circuit according to claim 1, characterized in that The ratio between the sampling frequency of the bandpass sigma-delta analog-to-digital converter and the center frequency is fixed to X, where X is an integer greater than 2.
3. The signal processing circuit according to claim 2, characterized in that The in-phase and quadrature demodulator multiplies the digital sensing signal with X sampling points on a sine signal to generate the multiple in-phase sampling values, and multiplies the digital sensing signal with X sampling points on a cosine signal to generate the multiple quadrature sampling values.
4. The signal processing circuit according to claim 2, wherein: X is 8; The in-phase orthogonal demodulator multiplies the digital sensing signal by eight sinusoidal sampling points on the sinusoidal signal to generate the multiple in-phase sampling values, and the phase difference between every two adjacent sinusoidal sampling points in the eight sinusoidal sampling points is 45 degrees; and The in-phase quadrature demodulator multiplies the digital sensing signal by eight cosine sampling points on the cosine signal to generate the multiple quadrature sampling values, and the phase difference between every two adjacent cosine sampling points in the eight cosine sampling points is 45 degrees.
5. The signal processing circuit according to claim 4, characterized in that include: A demodulation sampling register, used for storing the eight sinusoidal sampling points; The in-phase orthogonal demodulator obtains a cosine sequence by cyclically shifting the sine sequence formed by sequentially arranging the eight sine sampling points to the right by two sampling points, and sequentially extracts eight sampling points from the cosine sequence as the eight cosine sampling points.
6. The signal processing circuit according to claim 1, characterized in that: A low-pass filter is also included to filter the signal in the amplified sensing signal whose frequency is greater than or equal to the sampling frequency of the band-pass delta-sigma analog-to-digital converter.
7. The signal processing circuit according to claim 1, characterized in that: A down-sampling unit is further included, which is used to generate the in-phase value according to the multiple in-phase sampling values and to generate the orthogonal value according to the multiple orthogonal sampling values.
8. A touch control circuit, characterized in that: include: A plurality of signal processing circuits as claimed in any one of claims 1 to 6 are used to correspondingly receive a plurality of sensing signals transmitted from a plurality of receiving electrodes in the touch panel, and convert the plurality of sensing signals into a plurality of in-phase values and a plurality of orthogonal values.
9. The touch control circuit as claimed in claim 8, further comprising: The controller is used for determining a plurality of amplitudes of the plurality of sensing signals according to the plurality of in-phase values and the plurality of orthogonal values, and determining a touch event on the touch panel according to the plurality of amplitudes.
10. The touch control circuit according to claim 9, characterized in that The controller is further used for sending a coding signal to a plurality of corresponding transmitting electrodes on the touch panel, and the coding signal is coupled to the plurality of receiving electrodes through the plurality of transmitting electrodes to generate the plurality of sensing signals accordingly.
11. The touch control circuit according to claim 10, characterized in that The controller is further used to adjust the center frequencies of a plurality of bandpass delta-sigma analog-to-digital converters in the plurality of signal processing circuits to be close to the frequency of the coding signal.
12. A chip, characterized in that: include: The touch control circuit according to any one of claims 8 to 11.
13. A touch device, characterized in that: include: The touch control circuit according to any one of claims 8 to 11; and The touch panel.