Active pen signal receiving circuit and method based on adjacent channel difference offset

Abstract

The invention specifically provides an active pen signal receiving circuit and receiving method based on adjacent channel difference offset, and the circuit comprises a signal channel processing link which comprises an induction channel, a transimpedance amplification module, and a signal shaping module; the sensing channels in two adjacent signal channel processing links are respectively used as a reference channel and a signal channel; a transimpedance amplification module in a signal channel processing link corresponding to the signal channel is used for receiving a first noise signal output by the reference channel and a second noise signal output by the signal channel, and after a common-mode noise signal in the second noise signal is counteracted based on the first noise signal, the denoised signal is amplified to obtain a target signal; and the signal shaping module is used for shaping the amplified target signal to generate a digital square wave signal which can be used for demodulation. According to the invention, the space adjacent channel is used as a noise reference source, the precision and effect of noise suppression are improved, efficient real-time noise cancellation can be carried out at the analog front end, and the processing delay is reduced.

Description

Technical Field

[0001] This invention relates to the field of data communication technology, and in particular to an active pen signal receiving circuit and receiving method based on differential cancellation of adjacent channels. Background Technology

[0002] In active pen touch systems, high-voltage signals (such as 10V square waves) emitted from the pen tip using digital modulation methods like DBPSK (Differential Binary Phase Shift Keying) need to be coupled to the large self-capacitance of the touchscreen through the extremely small parasitic capacitance between the pen tip and the screen sensing electrodes. This significant capacitance ratio causes the signal to attenuate to the microvolt (μV) level. Simultaneously, the large-amplitude common-mode noise generated by the touchscreen itself is directly superimposed on the same sensing node, completely drowning out the useful signal.

[0003] Existing touch control solutions are mainly designed for detecting capacitance changes. Their front-end circuits and post-processing are not optimized for restoring high-fidelity digital modulation waveforms. When dealing with strong common-mode interference that is in the same frequency as the signal, it is difficult to guarantee the integrity of the modulation information. Summary of the Invention

[0004] This invention provides an active pen signal receiving circuit and receiving method based on adjacent channel differential cancellation, which improves the efficiency and real-time performance of common-mode noise cancellation.

[0005] This invention provides an active pen signal receiving circuit based on adjacent channel differential cancellation, comprising: The signal channel processing link includes a sensing channel, a transimpedance amplification module, and a signal shaping module; The sensing channels within two adjacent signal channel processing links serve as a reference channel and a signal channel, respectively. The transimpedance amplifier module within the signal channel processing link corresponding to the signal channel is used to receive the first noise signal output by the reference channel and the second noise signal output by the signal channel. Based on the first noise signal canceling the common-mode noise signal in the second noise signal, the denoised signal is amplified to obtain the target signal. The signal shaping module is used to shape the amplified target signal to generate a digital square wave signal that can be demodulated.

[0006] Furthermore, the reference channel is used to sense an initial sensed signal containing a common-mode noise signal and convert it into a first noise signal; The signal channel is used to sense an initial sensing signal containing a common-mode noise signal and an active pen modulation signal, and convert it into a second noise signal.

[0007] Furthermore, the sensing channel includes: a self-capacitance, a current transmitter, and an integrating capacitor; The self-capacitance is used to sense the initial sensing signal and input the initial sensing signal into the current transmitter; The current transmitter outputs a current signal proportional to the initial induced signal into the integrating capacitor; The integrating capacitor is used to convert the current signal into a voltage signal and then input it into the transimpedance amplifier module.

[0008] Furthermore, the signal channel processing link also includes a common-mode feedback circuit; One end of the common-mode feedback circuit is connected to the output of the reference channel and the signal channel, and the other end is connected to the input of the transimpedance amplifier module. The common-mode feedback circuit is used to stabilize the DC operating points of the reference channel and the signal channel within a preset voltage range.

[0009] Furthermore, the transimpedance amplification module includes a transimpedance amplifier; The first noise signal and the second noise signal are respectively connected to the non-inverting input terminal and the inverting input terminal of the transimpedance amplifier; The transimpedance amplifier is used to cancel the common-mode noise signal in the second noise signal and amplify the denoised signal to obtain the target signal.

[0010] Furthermore, it also includes a first feedback network; The first feedback network is located between the output terminal and the inverting input terminal of the transimpedance amplifier, and is used to stabilize the gain linearity of the transimpedance amplifier, suppress noise higher than the active pen signal frequency, and preserve the waveform integrity of the target signal.

[0011] Furthermore, it also includes DC blocking capacitors; The DC blocking capacitor receives the target signal and performs AC coupling on the target signal.

[0012] Furthermore, it also includes capacitively coupled amplifiers; The non-inverting input of the capacitively coupled amplifier is connected to the first noise signal, and the inverting input is connected to an AC coupling signal generated based on the target signal. The capacitively coupled amplifier outputs an AC signal that matches the frequency of the active pen.

[0013] Furthermore, it also includes a second feedback network; The second feedback network is located between the output terminal and the inverting input terminal of the capacitively coupled amplifier, and is used to stabilize the gain linearity of the capacitively coupled amplifier, suppress out-of-band interference, and preserve the waveform integrity of the AC signal.

[0014] Furthermore, the signal shaping module includes: a comparator; The non-inverting input of the comparator is connected to the first noise signal, and the inverting input is connected to the AC signal. The comparator outputs the digital square wave signal that can be used for demodulation.

[0015] On the other hand, this invention discloses an active pen signal receiving method based on adjacent channel differential cancellation, the method comprising: The reference channel and the signal channel in the processing link of two adjacent signal channels respectively acquire the first noise signal and the second noise signal; After cancelling the common-mode noise signal in the second noise signal with the first noise signal, the second noise signal is amplified to obtain the target signal; The amplified target signal is shaped to generate a digital square wave signal that can be used for demodulation.

[0016] Compared with the prior art, the present invention has at least the following technical effects: This invention employs a hardware differential architecture to achieve real-time common-mode noise cancellation. This noise cancellation process occurs in the first stage of amplification in the analog front-end, specifically at the transimpedance amplification module. The transimpedance amplification module directly cancels out the common-mode noise components. Since this process is implemented entirely with analog hardware circuitry, eliminating the need for analog-to-digital conversion and digital computation, it exhibits extremely low processing latency, resulting in real-time signal processing performance superior to traditional digital post-processing schemes. Furthermore, this invention utilizes spatially adjacent channels as noise reference sources. Because adjacent sensing channels are physically close together, the common-mode noise signals they receive exhibit extremely high spatial correlation in amplitude, phase, and waveform. This highly correlated noise sample allows the differential cancellation process to accurately eliminate common-mode interference components, improving the accuracy and effectiveness of noise suppression. Attached Figure Description

[0017] Figure 1 This is a simplified schematic diagram of the active pen signal receiving circuit based on differential cancellation of adjacent channels in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the waveforms of each node in the active pen signal receiving circuit based on differential cancellation of adjacent channels in Embodiment 1 of the present invention. Figure 3 This is a simplified flowchart illustrating the active pen signal receiving method based on differential cancellation of adjacent channels in Embodiment 2 of the present invention. Detailed Implementation

[0018] The following description, with reference to schematic diagrams, illustrates the active pen signal receiving circuit and receiving method based on adjacent channel differential cancellation of the present invention, which shows preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0019] The invention is described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0020] Example 1 Please refer to Figure 1 This embodiment discloses an active pen signal receiving circuit based on differential cancellation of adjacent channels, comprising: The signal channel processing link includes a sensing channel, a transimpedance amplification module, and a signal shaping module. The sensing channels in two adjacent signal channel processing links serve as reference channel B and signal channel A, respectively.

[0021] The transimpedance amplifier module in the signal channel processing link corresponding to signal channel A is used to receive the first noise signal VB output by reference channel B and the second noise signal VA output by signal channel A. After canceling the common-mode noise signal in the second noise signal VA based on the first noise signal VB, the denoised signal is amplified to obtain the target signal VAMP1.

[0022] The signal shaping module is used to shape the amplified target signal to generate a digital square wave signal VOUT that can be used for demodulation.

[0023] In this embodiment, a hardware differential architecture is used to achieve real-time common-mode noise cancellation. This noise cancellation process occurs in the first stage of amplification in the analog front-end, namely the transimpedance amplification module. The transimpedance amplification module directly cancels out the common-mode noise components. Since this process is implemented entirely with analog hardware circuitry, without the need for analog-to-digital conversion and digital computation, it has extremely low processing latency, and the real-time performance of signal processing is superior to traditional digital post-processing schemes. Simultaneously, this invention utilizes spatially adjacent channels as noise reference sources. Because adjacent sensing channels are physically close together, the common-mode noise signals they receive have extremely high spatial correlation in amplitude, phase, and waveform. This highly correlated noise sample enables the differential cancellation process to accurately eliminate common-mode interference components, improving the accuracy and effectiveness of noise suppression.

[0024] In this embodiment, the common-mode noise signal is an interference signal generated during the operation of the touchscreen itself, including liquid crystal display driving signals, power ripple signals, and other environmental electromagnetic interference signals. The amplitude of this type of noise signal can typically reach hundreds of millivolts. The active pen modulation signal is a digital modulation signal emitted by the active pen tip and coupled to the touchscreen via the parasitic capacitance between the pen tip and the screen sensing electrode. Its modulation method includes DBPSK (Differential Binary Phase Shift Keying) modulation, and the signal amplitude is reduced to the microvolt level after coupling attenuation. The purpose of this invention is to recover the weak active pen modulation signal from the strong common-mode noise background and shape it into a regular square wave that can be used by the back-end digital demodulation module.

[0025] In this embodiment, the application scenario targeted by the present invention is a capacitively coupled active pen touch system, which is particularly suitable for application environments where the touch screen generates strong common-mode noise interference during operation. In the touch screen's sensing channel array, when the pen tip approaches or contacts a certain sensing channel, that channel is defined as signal channel A, and the signal it receives simultaneously includes the active pen modulation signal and the common-mode noise signal. The channel spatially adjacent to signal channel A and far from the pen tip is defined as reference channel B, and the signal it receives mainly contains the common-mode noise signal and essentially no active pen modulation signal. Through this dynamic channel role allocation, the pairing relationship between signal channel A and reference channel B can be flexibly determined according to the actual position of the active pen.

[0026] In this embodiment, the number of signal channel processing links is determined based on the size of the touchscreen sensing channel array and the requirements for parallel processing capabilities. In practical applications, touchscreens typically have multiple sensing channels, and the number of signal channel processing links can correspond to the number of sensing channels. Alternatively, some channels can be selected for configuration based on system resources and performance requirements. This invention does not impose specific limitations on this.

[0027] As can be seen, the pairing mode between signal channel A and reference channel B can be replicated and extended across the entire channel array. Through this scalable architecture design, the present invention can achieve large-scale parallel real-time noise suppression at the front end, meeting the requirements of high-resolution touchscreens for simultaneous processing of multiple channels, while ensuring the independence and consistency between each processing unit.

[0028] In this embodiment, the reference channel B is used to sense an initial sensing signal containing common-mode noise and convert it into a first noise signal VB. The signal channel A is used to sense an initial sensing signal containing both common-mode noise and active pen modulation signals and convert it into a second noise signal VA.

[0029] Specifically, the sensing channel includes: self-capacitance Cs, current transmitter 1, and integrating capacitor C1.

[0030] The self-capacitor Cs is used to sense the initial sensing signal and input the initial sensing signal into the current transmitter 1. The current transmitter 1 outputs a current signal proportional to the initial sensing signal into the integrating capacitor C1. The integrating capacitor C1 is used to convert the current signal Iout into a voltage signal (that is, into a first noise signal VB and a second noise signal VA) and then input it into the transimpedance amplifier module.

[0031] In this embodiment, the initial sensing signal is converted into current and initially integrated through a sensing channel. Specifically, the self-capacitor Cs serves as the sensing electrode of the touchscreen, sensing the composite voltage signal superimposed on it and inputting it to the current transmitter 1. Due to its low input impedance, the current transmitter 1 can quickly respond to changes in charge on the self-capacitor, converting the voltage signal into a proportional current signal output. This current signal is then injected into the integrating capacitor C1, which completes the current-to-voltage conversion and simultaneously achieves a preliminary low-pass filtering effect, providing a pre-processed voltage signal for the subsequent transimpedance amplification module.

[0032] In a specific example, the circuit connection of the sensing channel is as follows: One end of the self-capacitor Cs is connected to the parasitic capacitor Cf, and the other end is connected to the inverting input terminal of the current transmitter 1; the non-inverting input terminal of the current transmitter 1 is connected to the reference voltage VCM, the inverting input terminal is connected to the output terminal of the self-capacitor Cs, the output terminal of the current transmitter 1 is connected to one end of the integrating capacitor C1, one end of the integrating capacitor C1 is also connected to one end of the common-mode feedback circuit, and the other end of the integrating capacitor C1 is grounded.

[0033] Furthermore, the signal channel processing link also includes a common-mode feedback circuit.

[0034] One end of the common-mode feedback circuit is connected to the output terminals of the reference channel B and the signal channel A, and the other end is connected to the input terminal of the transimpedance amplifier module. The common-mode feedback circuit is used to stabilize the DC operating points of the reference channel B and the signal channel A within a preset voltage range.

[0035] In this embodiment, a common-mode feedback circuit is used to achieve stable control of the DC operating point in a differential architecture referenced by dynamically adjacent channel signals. This common-mode feedback circuit continuously monitors the DC level of the current transmitter 1's output node and stabilizes this level near a preset operating point through a negative feedback mechanism. This design ensures that subsequent circuit modules, such as the transimpedance amplifier 2, maintain good linear operation over a wide input signal range, avoiding signal distortion or circuit saturation caused by DC offset, thereby improving the reliability of the entire signal processing chain.

[0036] In this embodiment, the preset voltage range is selected based on the input common-mode voltage range of the subsequent transimpedance amplifier 2 and the power supply voltage of the circuit. It is usually set near the midpoint of the power supply voltage to obtain the maximum dynamic margin. Those skilled in the art can adjust it according to the specific circuit parameters, and no specific restrictions are made here.

[0037] In this embodiment, the transimpedance amplification module includes a transimpedance amplifier 2.

[0038] The first noise signal VB and the second noise signal VA are respectively connected to the non-inverting input terminal and the inverting input terminal of the transimpedance amplifier 2. The transimpedance amplifier 2 is used to cancel the common-mode noise signal in the second noise signal VA and amplify the denoised signal to obtain the target signal VAMP1.

[0039] Please refer to Figure 2 The differential cancellation principle is explained using signal channel A and reference channel B as examples. The current transmitter 1 of signal channel A outputs current IA, and the current transmitter 1 of reference channel B outputs current IB. Both current signals are connected to the differential input of the transimpedance amplifier 2 corresponding to signal channel A, with IB connected to the non-inverting input and IA connected to the inverting input. Since signal channel A and reference channel B are spatially adjacent, the environmental common-mode noise they receive is highly correlated; therefore, IA and IB both contain nearly identical common-mode noise components (Inoise). The active pen modulation signal Ipen is coupled only through the parasitic capacitance Cf between the pen tip and the sensing electrode of signal channel A; therefore, the active pen modulation signal exists only in IA. Based on the differential amplification principle, the target signal VAMP1 output by transimpedance amplifier 2 is proportional to IB-IA.

[0040] That is, VAMP1∝(IB-IA)=(Inoise)-(Inoise+Ipen)=-Ipen.

[0041] Thus, the common-mode noise components Inoise cancel each other out in the differential operation, and the output of transimpedance amplifier 2 retains only the voltage component proportional to the active pen modulation signal. The common-mode noise is simulated and canceled out in real time in the first stage of the signal chain amplification, and the signal-to-noise ratio is significantly improved for the first time in this stage, laying a good foundation for subsequent filtering and shaping processing.

[0042] Furthermore, in this embodiment, a first feedback network is also included.

[0043] In this embodiment, the first feedback network is configured to have low-pass filtering characteristics, with a cutoff frequency set above the pen signal frequency to suppress noise higher than the active pen signal frequency. Furthermore, the aforementioned first feedback network can also be used to stabilize the gain linearity of the transimpedance amplifier 2 and preserve the waveform integrity of the target signal VAMP1.

[0044] In a specific example, the first feedback network includes a first feedback resistor R1 and a first feedback capacitor C2, and the specific connection method of the first feedback network is as follows: The first feedback resistor R1 is connected between the inverting input terminal and the output terminal of the transimpedance amplifier 2, and the first feedback capacitor C2 is connected in parallel across the first feedback resistor R1.

[0045] In the specific example above, the transimpedance gain of the transimpedance amplifier 2 is determined by setting the first feedback resistor R1, which improves the linearity of the current-to-voltage conversion; by setting the first feedback capacitor C2 in parallel with the first feedback resistor R1, a bypass path is formed in the high-frequency band, so that the first feedback network exhibits low-pass filtering characteristics, effectively suppressing noise components higher than the active pen signal frequency, while avoiding high-frequency oscillation, and ensuring that the denoised target signal VAMP1 maintains complete waveform characteristics.

[0046] Furthermore, the active pen signal receiving circuit also includes a DC blocking capacitor C4. The DC blocking capacitor C4 receives the target signal VAMP1 and AC couples the target signal VAMP1.

[0047] Furthermore, the active pen signal receiving circuit also includes a capacitively coupled amplifier 3. The non-inverting input terminal of the capacitively coupled amplifier 3 is connected to the first noise signal VB, and the inverting input terminal is connected to the denoised AC coupling signal. The capacitively coupled amplifier 3 outputs an AC signal VAMP2 that matches the frequency of the active pen.

[0048] In this embodiment, a second feedback network is also included. The second feedback network is located between the output terminal and the inverting input terminal of the capacitively coupled amplifier 3, and is used to stabilize the gain linearity of the capacitively coupled amplifier 3, suppress out-of-band interference, and preserve the waveform integrity of the AC signal VAMP2.

[0049] In a specific example, the second feedback network includes a second feedback resistor R2 and a second feedback capacitor C3. The specific connection method of the second feedback network is as follows: The second feedback resistor R2 is connected between the inverting input terminal and the output terminal of the capacitively coupled amplifier 3, and the second feedback capacitor C3 is connected in parallel across the two ends of the second feedback resistor R2.

[0050] In this embodiment, the configuration of the second feedback network is similar to that of the first feedback network. The voltage gain of the capacitively coupled amplifier 3 is set by the second feedback resistor R2, and a high-frequency bypass is formed by the second feedback capacitor C3 to further suppress out-of-band residual noise, so that the output AC signal VAMP2 waveform is pure and regular.

[0051] In this embodiment, the DC blocking capacitor C4 and the second feedback network together constitute a bandpass filter. Specifically, the DC blocking capacitor C4 and the input impedance of the capacitively coupled amplifier 3 form a high-pass filter characteristic, which can effectively block DC components and low-frequency drift signals, determining the lower cutoff frequency of the bandpass filter; while the second feedback capacitor C3 and the second feedback resistor R2 in the second feedback network form a low-pass filter characteristic, determining the upper cutoff frequency of the bandpass filter. Together, they form a bandpass filter centered on the active pen signal frequency. This bandpass filter only allows signals within the active pen's operating frequency band to pass through, while effectively suppressing low-frequency drift interference and high-frequency spurious noise. This bandpass filter design further improves the signal-to-noise ratio, making the output AC signal VAMP2 cleaner and the waveform more regular, creating favorable conditions for the accurate decision of the subsequent comparator.

[0052] Furthermore, in this embodiment, the signal shaping module includes a comparator 4.

[0053] The non-inverting input of the comparator 4 is connected to the first noise signal VB, the inverting input is connected to the AC signal VAMP2, and the comparator outputs the digital square wave signal VOUT that can be demodulated.

[0054] In this embodiment, to maintain the consistency of the processing reference throughout the entire link, the node voltage VB after the current transmitter 1 of reference channel B is simultaneously fed to the non-inverting input of the capacitively coupled amplifier 3 of signal channel A and the non-inverting reference of the comparator. Through this reference reference transfer mechanism, the entire signal processing link performs differential processing and threshold decision based on the same dynamic noise reference, avoiding signal distortion or decision errors caused by inconsistent reference levels at each stage, and ensuring the consistency of processing from noise cancellation to signal shaping.

[0055] Please refer to Figure 2 The signal recovery effect of this invention can be intuitively demonstrated through the waveform diagrams of each node.

[0056] The pen tip transmits a signal that is a regular square wave with a high amplitude, and its phase carries DBPSK (Differential Two-Phase Phase Shift Keying) modulation information.

[0057] Analog front-end received signal: The signal actually received on the self-capacitance Cs. For example... Figure 2 As shown, the weak pen tip signal is completely drowned out by strong common-mode noise (such as liquid crystal interference) on the order of hundreds of millivolts, resulting in an extremely low signal-to-noise ratio.

[0058] The transimpedance amplifier output, i.e. the target signal VAMP1, shows that most of the noise components common to the reference channel B have been canceled out, and the outline of the pen tip signal (sine wave envelope) has emerged from the noise background, resulting in a significant improvement in the signal-to-noise ratio for the first time.

[0059] The output of the capacitively coupled amplifier, after further processing by a subsequent bandpass filter, becomes the AC signal VAMP2. Out-of-band residual noise is effectively filtered out, resulting in a cleaner and more regular signal waveform, approaching an ideal sine wave shape, thus creating favorable conditions for digital decision-making.

[0060] Demodulation algorithm output: The final digital square wave signal VOUT is shaped and demodulated by comparator 4 and then restored. The output is a clear digital square wave, and its phase transition is completely consistent with the DBPSK modulation information transmitted from the pen tip, proving that the circuit of this invention can reliably recover digital communication signals under extreme noise environments.

[0061] As can be seen, the above waveform evolution process fully verifies the effectiveness of the technical path of adjacent channel differential cancellation, bandpass filtering, and dynamic threshold comparison proposed in this embodiment.

[0062] Example 2 Please refer to Figure 3 Based on the same inventive concept, this embodiment discloses an active pen signal receiving method based on differential cancellation of adjacent channels, which is implemented using the active pen signal receiving circuit based on differential cancellation of adjacent channels disclosed in Embodiment 1. The method includes: S1. Reference channel B and signal channel A in the processing links of two adjacent signal channels respectively collect the first noise signal VB and the second noise signal VA; S2. Based on the first noise signal VB canceling the common-mode noise signal in the second noise signal VA, the second noise signal VA is amplified to obtain the target signal VAMP1; S3. Shape the amplified target signal to generate a digital square wave signal VOUT that can be used for demodulation.

[0063] It is understood that the above-described active pen signal receiving method and the active pen signal receiving circuit disclosed in Embodiment 1 are based on the same technical design principle, and both can achieve the same technical purpose. The effect that the active pen signal receiving circuit can achieve has been described in detail in Embodiment 1, so it will not be repeated here.

[0064] Various modifications and variations are possible without departing from the spirit and scope of the invention. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. An active pen signal receiving circuit based on differential cancellation of adjacent channels, characterized in that, include: The signal channel processing link includes a sensing channel, a transimpedance amplification module, and a signal shaping module; The sensing channels within two adjacent signal channel processing links serve as a reference channel and a signal channel, respectively. The transimpedance amplifier module within the signal channel processing link corresponding to the signal channel is used to receive the first noise signal output by the reference channel and the second noise signal output by the signal channel. Based on the first noise signal canceling the common-mode noise signal in the second noise signal, the denoised signal is amplified to obtain the target signal. The signal shaping module is used to shape the amplified target signal to generate a digital square wave signal that can be demodulated.

2. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 1, characterized in that, The reference channel is used to sense an initial sensed signal containing common-mode noise and convert it into a first noise signal; The signal channel is used to sense an initial sensing signal containing a common-mode noise signal and an active pen modulation signal, and convert it into a second noise signal.

3. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 2, characterized in that, The sensing channel includes: a self-capacitance, a current transmitter, and an integrating capacitor; The self-capacitance is used to sense the initial sensing signal and input the initial sensing signal into the current transmitter; The current transmitter outputs a current signal proportional to the initial induced signal into the integrating capacitor; The integrating capacitor is used to convert the current signal into a voltage signal and then input it into the transimpedance amplifier module.

4. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 3, characterized in that, The signal channel processing link also includes a common-mode feedback circuit; One end of the common-mode feedback circuit is connected to the output of the reference channel and the signal channel, and the other end is connected to the input of the transimpedance amplifier module; The common-mode feedback circuit is used to stabilize the DC operating points of the reference channel and the signal channel within a preset voltage range.

5. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 1, characterized in that, The transimpedance amplification module includes a transimpedance amplifier; The first noise signal and the second noise signal are respectively connected to the non-inverting input terminal and the inverting input terminal of the transimpedance amplifier; The transimpedance amplifier is used to cancel the common-mode noise signal in the second noise signal and amplify the denoised signal to obtain the target signal.

6. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 5, characterized in that, It also includes the first feedback network; The first feedback network is located between the output terminal and the inverting input terminal of the transimpedance amplifier, and is used to stabilize the gain linearity of the transimpedance amplifier, suppress noise higher than the active pen signal frequency, and preserve the waveform integrity of the target signal.

7. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 5 or 6, characterized in that, It also includes DC blocking capacitors; The DC blocking capacitor receives the target signal and performs AC coupling on the target signal.

8. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 7, characterized in that, It also includes capacitively coupled amplifiers; The non-inverting input of the capacitively coupled amplifier is connected to the first noise signal, and the inverting input is connected to an AC coupling signal generated based on the target signal. The capacitively coupled amplifier outputs an AC signal that matches the frequency of the active pen.

9. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 8, characterized in that, It also includes a second feedback network; The second feedback network is located between the output terminal and the inverting input terminal of the capacitively coupled amplifier, and is used to stabilize the gain linearity of the capacitively coupled amplifier, suppress out-of-band interference, and preserve the waveform integrity of the AC signal.

10. The active pen signal receiving circuit based on differential cancellation of adjacent channels as described in claim 9, characterized in that, The signal shaping module includes: a comparator; The non-inverting input of the comparator is connected to the first noise signal, and the inverting input is connected to the AC signal. The comparator outputs the digital square wave signal that can be used for demodulation.

11. A method for receiving active pen signals based on differential cancellation of adjacent channels, characterized in that, The method includes: The reference channel and the signal channel in the processing link of two adjacent signal channels respectively acquire the first noise signal and the second noise signal; After cancelling the common-mode noise signal in the second noise signal with the first noise signal, the second noise signal is amplified to obtain the target signal; The amplified target signal is shaped to generate a digital square wave signal that can be used for demodulation.

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