A sensor power supply system with bidirectional switching between adaptive charge pump and voltage regulator

Abstract

A sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator includes a noise extraction circuit, a noise quantizer, a control circuit for switching between a charge pump and a voltage regulator, a charge pump circuit, and a voltage regulator circuit. The noise extraction circuit is connected to the differential voltage signal output of the sensor, and is used to process the differential voltage signal to obtain a noise energy value, and output the noise energy value to the noise quantizer; the noise quantizer is used to compare the noise energy value with a set noise energy threshold, and output a control instruction to the control circuit; the control circuit is used to switch the charge pump circuit and the voltage regulator circuit according to the control instruction; the charge pump circuit and the voltage regulator circuit provide two power supply modes for the sensor. Providing a power supply system for the sensor compensates for the impact of the increased noise of the pressure touch system, so that the system as a whole maintains a sufficient signal-to-noise ratio and stabilizes the signal-to-noise ratio, thereby ensuring a high pressure sensing recognition rate and measurement accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic circuits and relates to a sensor power supply system, in particular to a sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage stabilizing source. Background Art

[0002] With the continuous development of electronic technology, smart terminal devices such as mobile phones, tablets and personal computers, smart watches, virtual reality, etc. are becoming necessities of people's lives. The demand for smart terminal devices continues to increase, and people's diversified demand for smart terminals is increasing. In the use of smart terminal devices, human-computer interaction is a very important link. As an emerging technology, pressure touch plays an increasingly important role in human-computer interaction. A good user experience opens a channel for human-computer tactile interaction. Through pressure touch technology, the device can sense the difference in force between light press and light tap, and call out different corresponding functions. Compared with ordinary multi-touch technology, pressure touch increases the detection of force, making human-computer interaction more direct, so it is widely used in industry, medical care, communications and other fields.

[0003] In the field of pressure touch, with the development of flexible materials based on micro-pressure strain gauge technology, the corresponding flexible thin film micro-pressure strain gauges have begun to be widely used in various smart terminals. They are simple and easy to use, have accurate recognition rates, low costs, small size, and are easy to integrate. The flexible thin film micro-pressure strain gauge uses the Wheatstone bridge measurement method, which uses the change in resistance to measure the change in physical quantity. By collecting the voltage across the variable resistor and then processing it, the corresponding change in the pressure physical quantity can be calculated. It is a very accurate measurement method.

[0004] Commonly used pressure touch systems such as Figure 1 As shown, the Wheatstone Bridge pressure sensor (Wheatstone BridgeSensor) detects the pressure signal and converts it into a differential voltage signal V INP 、V INN The high-performance pressure-sensitive touch analog front end detects, amplifies, filters, collects, and converts the voltage signal to digital-to-analog. Finally, it outputs Dout to the host control system HOST through the system bus for pressure-sensitive algorithm processing. The pressure-sensitive touch front end includes a programmable gain amplifier PGA and an analog-to-digital converter ADC. In the entire system, a voltage regulator LDO output V sensor Apply DC voltage bias to the Wheatstone bridge sensor, Vo = V INP -V INN ∝V sensor *ΔR / R. When the sensor sensitivity S is constant, the resistance change ΔR corresponding to a certain pressure is constant, corresponding to a given V sensorBias voltage, usually the sensor signal output Vo has a correspondingly large change, thereby ensuring a certain system signal-to-noise ratio and pressing accuracy.

[0005] However, in actual applications, the sensor itself will inevitably introduce noise, and the analog front-end circuit connected to the sensor will also have noise. At the same time, external noise interference will also be superimposed on the system input. Due to changes in sensor surface material deformation, structure, ambient temperature and other conditions, the sensor noise will also change accordingly. Under certain conditions, the sensor noise will increase, the analog front-end circuit equivalent input noise will increase, and considering external noise interference, the overall superimposed total noise of the system input will increase. At a certain pressure, the sensor signal output Vo = V INP -V INN If the amount of change remains unchanged, it means that the signal-to-noise ratio of the system will decrease, which will cause the overall pressure recognition rate to decrease, limiting the application environment.

[0006] Signal-to-noise ratio, also known as signal-to-noise ratio, refers to the ratio of signal to noise in an electronic device or electronic system. The signal here refers to the electronic signal from outside the device that needs to be processed by this device, and the noise refers to the irregular additional signal (or information) that does not exist in the original signal after passing through the device, and this signal does not change with the change of the original signal. The higher the signal-to-noise ratio of a device, the less noise it generates and the better the signal quality. Summary of the invention

[0007] Based on the problem of decreased signal-to-noise ratio in the prior art, the purpose of the present invention is to provide a sensor with an adaptive power supply system to compensate for the impact of increased noise in the pressure touch system, so that the system as a whole maintains a sufficient signal-to-noise ratio and a stable signal-to-noise ratio, thereby ensuring a higher press sensing recognition rate and measurement accuracy.

[0008] The technical solution of the present invention provides a sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator, comprising a noise extraction circuit, a noise quantizer, a control circuit for switching between an adaptive charge pump and a voltage regulator, a charge pump circuit and a voltage regulator circuit. The noise extraction circuit is connected to the differential voltage signal output of the sensor, and is used to process the differential voltage signal to obtain a noise energy value, and output the noise energy value to the noise quantizer; the noise quantizer is used to compare the noise energy value with a set noise energy threshold, and output a control instruction to the control circuit; the control circuit is used to switch the charge pump circuit and the voltage regulator circuit according to the control instruction; the charge pump circuit and the voltage regulator circuit provide two power supply modes for the sensor.

[0009] The noise of the pressure touch system mainly includes sensor noise, analog front-end circuit noise in signal processing, and external interference noise. After the noise extraction circuit amplifies it and filters it with -3dB / OCT, and then performs passband filtering, full-wave rectification, and low-pass filtering, the noise energy value can be obtained, that is, the root mean square effective value of the noise related to the noise energy within the specified frequency band. At the same time, the obtained noise energy value is subjected to noise quantization processing. When the obtained noise energy value is less than the specified noise energy threshold, the power supply is output by the voltage regulator V ldo is provided to the sensor as the bias voltage V sensor , and at this time V sensor =V ldo <VDD, the change in the sensor output Vo is proportional to V sensor *ΔR / R. Since the system noise is small, the stable bias provided by the constant voltage regulator output V ldo can ensure a sufficient signal-to-noise ratio.

[0010] When the obtained noise energy value is greater than the specified noise energy threshold, the power supply is directly switched from the voltage regulator to the charge pump. The charge pump output generates a voltage V chargepump greater than the power supply VDD and provides it to the sensor as the bias voltage V sensor , and at this time V senso r = V chargepump >VDD. Although the system noise increases, the sensor bias also increases accordingly. Therefore, the change in the sensing signal Vo increases accordingly, thereby compensating for the impact of the increased system noise and enabling the overall system to maintain a sufficient signal-to-noise ratio, thus ensuring a high pressing sensing recognition rate and measurement accuracy.

[0011] The technical solution of the present invention dynamically detects the input noise of the system. The noise after being amplified by the PGA is filtered by -3dB / OCT, so that the processed noise has the same or similar energy within a certain range, and then the root mean square effective value of the noise is extracted. The extracted noise effective value is subjected to noise quantization, and the generated control signal further controls the bidirectional switching of the charge pump and the voltage regulator. When it is found that the system noise is less than the specified threshold, the voltage regulator circuit is adaptively switched to supply power to the sensor; when it is found that the system noise is too large, the charge pump circuit is adaptively switched to supply power to the sensor. By increasing the sensor bias voltage, the change in the output Vo of the sensor pressing increases accordingly. The effective increase in the pressing signal compensates for the impact of the increased noise on the signal-to-noise ratio. Therefore, the entire measurement system can still maintain a sufficient signal-to-noise ratio, thus ensuring the accuracy of the pressing measurement and expanding the application environment. Description of the Drawings

[0012] Figure 1 is the circuit diagram of the pressure touch system of the prior art.

[0013] Figure 2 It is a block diagram of the overall structural principle of the power supply system of the present invention.

[0014] Figure 3 It is a general architecture block diagram of the power supply system in an embodiment of the present invention.

[0015] Figure 4 3 is a -3dB / OCT filter transfer function diagram of the power supply system in the embodiment of the present invention.

[0016] Figure 5 yes Figure 2 Timing diagram of the power supply system in .

[0017] Figure 6 yes Figure 2 Diagram of the bidirectional switching process of the voltage regulator and charge pump in the power supply system. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] like Figure 2 , Figure 3 As shown, the output terminals V of the Wheatstone Bridge Sensor in this embodiment are INP 、V INN It is connected to a programmable gain amplifier PGA for signal amplification. The output of the programmable gain amplifier PGA is connected to the digital-to-analog converter ADC to measure the output. The switch S0 is connected to the output terminals of the pressure sensor V INP 、V INN .

[0020] The noise extraction circuit includes a dual to single converter, a -3dB / OCT filter, a bandpass filter of a specified frequency band, a full-wave rectifier circuit, and a low-pass filter, which are connected in sequence. The noise extraction circuit is connected to the output end of the programmable gain amplifier PGA for noise extraction. The dual to single converter circuit is used to convert the dual-end input signal of the differential voltage signal into a single-end output signal. After the single-end output signal is processed by the -3dB / OCT filter, the bandpass filter of the specified frequency band, the full-wave rectifier circuit, and the low-pass filter, the noise energy value is obtained. The noise energy value below is explained by taking the noise root mean square effective value as an example.

[0021] When performing noise extraction analysis, switch S0 is closed and no differential signal is input to the programmable gain amplifier PGA. At this time, the output of the programmable gain amplifier PGA only contains the amplified system noise and offset deviation. After the offset deviation is corrected by the digital-to-analog converter DAC, it only contains system noise. The low-frequency noise of the system noise has been filtered out by the programmable gain amplifier PGA with chopping, and the filtered noise is mainly random white noise.

[0022] Programmable Gain Amplifier PGA differential output V pga+ 、V pga The differential noise of - is processed by the dual-end to single-end circuit Dual to Single Converter to obtain a single-ended random white noise signal V n , white noise signal V n The output is connected to a -3dB / OCT filter. The -3dB / OCT filter is a filter with a transfer function of 1 / f. Its frequency drops by 3dB for each doubling. The corresponding transfer function is as follows: Figure 4 As shown. From the perspective of power (energy), the system random white noise signal V n After being processed by the -3dB / OCT filter, its energy decays continuously from low frequency to high frequency, and the curve is 1 / f, with a decrease of 3dB per frequency doubling. Therefore, the processed noise has the same or similar energy within a certain range.

[0023] The -3dB / OCT filter output signal V-3dB / OCT is connected to a bandpass filter BandPass, and the bandpass filter frequency and Q value are selected. The noise in the specified frequency band will pass through the bandpass filter. Because the noise processed by the -3dB / OCT filter has the same or similar energy within a certain range, as long as the bandpass filter Q value remains unchanged, the noise energy passing through different bandpass filter frequencies is equal.

[0024] The output of the bandpass filter V bandpass Through the full-wave rectifier circuit, the absolute value of the noise amplitude V is obtained. abs The output of the full-wave rectifier circuit is connected to a low-pass filter LowPass to filter out the average value. Through the processing of the bandpass filter, the full-wave rectifier circuit, and the low-pass filter, the noise root mean square effective value V directly related to the noise energy in the specified frequency band can be obtained. lowpass .

[0025] Noise RMS value V lowpass Connected to the noise level quantizer, when the noise RMS value V lowpass is less than the set noise energy threshold, the noise quantizer output V quantizer=0; when the noise RMS value V lowpass If the noise energy is greater than the set noise energy threshold, the noise quantizer output V quantizer =1.

[0026] The charge pump circuit includes capacitor C0, capacitor C1, charge and discharge switch S1, charge and discharge switch S2, charge and discharge switch S3, charge and discharge switch S4 and a switch clock control unit. The switch clock control unit is used to control the on and off of each charge and discharge switch. The N1 end of the capacitor C1 is connected to the power supply VDD after passing through the charge and discharge switch S1, and is also connected to the output end V after passing through the charge and discharge switch S4. chargepump , and the output terminal V chargepump The N2 end is connected to the ground after passing through the capacitor C0, and is connected to the power supply VDD through the charge and discharge switch S3, and is also connected to the ground after passing through the charge and discharge switch S2.

[0027] The charge pump circuit also includes a comparison detection circuit, which includes a transconductance amplifier OTA1, a drive buffer Buffer, a resistor R5 and a resistor R6. The current input terminal I1 of the transconductance amplifier OTA1 is connected to the control circuit, and the positive terminal thereof is connected to the reference level V ref , output terminal V chargepump The comparison voltage V is generated by the voltage division of resistors R5 and R6 cp Connected to the negative terminal of OTA1, and the negative terminal is grounded after passing through resistor R6. The output terminal V ota Connected to the drive buffer Buffer, the output terminal V of the drive buffer Buffer buf The switch clock control unit is connected to the control circuit and controlled by the control circuit.

[0028] The voltage regulator circuit includes a transconductance amplifier OTA2, a driving buffer Buffer and a capacitor C0. The current input terminal I2 of the transconductance amplifier OTA2 is connected to the control circuit, and its positive terminal is connected to the reference level V ref , its output terminal V ota Connected to the drive buffer Buffer, the output terminal V of the drive buffer Buffer buf After passing through the control circuit, it is connected to the negative terminal of the transconductance amplifier OTA2, and the negative terminal serves as a voltage regulator source V ldo The negative end of the capacitor C0 is connected to the ground after passing through the capacitor C0. Therefore, the capacitor C0 can be used as the main storage capacitor of the charge pump circuit and as the voltage regulator V ldo Compensation stabilization capacitor of the circuit.

[0029] The control circuit includes a switch MP3, a switch MP4, a switch MP1, a switch MP2, a switch MN1 and an inverter Inverter, wherein the switch MP4 is connected between the output current source I0 of the power supply VDD and the current input terminal I1 of the transconductance amplifier OTA1, the switch MP3 is connected between the output current source I0 of the power supply VDD and the current input terminal I2 of the transconductance amplifier OTA2, and the switch MP2 is connected to the output terminal V buf The switch MP1 is connected to the output terminal V of the driving buffer Buffer between the negative terminal of the transconductance amplifier OTA2 and the negative terminal of the transconductance amplifier OTA2. buf The output terminal V of the switching clock control unit control Between, the output terminal V control Connected to ground through switch MN1.

[0030] The output control signal of the noise quantizer is V quantizer Connected to the control terminals of switch MP2 and switch MP3, and the control signal V quantizer After passing through the inverter, it is connected to the control end of switch MP1, switch MP4 and switch MN1.

[0031] When V quantizer =0, switch MP3 is turned on, switch MP4 is turned off, current source I0 flows to transconductance amplifier OTA2 through switch MP3, bias current I2 is started, transconductance amplifier OTA2 works, transconductance amplifier OTA1 is turned off, and the output V ota Connected to the drive buffer Buffer. Switch MP2 is turned on, switch MP1 is turned off, switch MN1 is turned on, and the output V of the drive buffer Buffer buf Connected to the negative terminal of transconductance amplifier OTA2 through switch MP2, reference level V ref Connected to the positive terminal of the transconductance amplifier OTA2, so the transconductance amplifier OTA2 and the driving buffer Buffer form a voltage regulator source LDO, capacitor C0 is the compensation stabilization capacitor of the voltage regulator source LDO, and the negative terminal of the transconductance amplifier OTA2 outputs V ldo Follow V ref As the switch MN1 is turned on, the input V control = 0, the clock control circuit of the charge pump does not work, the charge pump does not work, and the sensor power supply V sensor The output V of the voltage regulator LDO ldo Decision, V sensor =V ldo .

[0032] When V quantizer =1, V through the inverter quantizerb=0, switch MP4 is turned on, switch MP3 is turned off, current source I0 flows to transconductance amplifier OTA1 through switch MP4, bias current I1 is started, transconductance amplifier OTA1 works, transconductance amplifier OTA2 is turned off, and the output V ota Connect the drive buffer Buffer. Switch MP1 is turned on, switch MP2 is turned off, switch MN1 is turned off, and the output V of the drive buffer Buffer buf V is generated by switch MP1 control , connected to the switch clock control unit Clock Control of the charge pump, the charge pump starts working, the voltage regulator source LDO loop is disconnected, and the voltage regulator does not work.

[0033] The transconductance amplifier OTA1 and the driving buffer Buffer form a comparison detection circuit. The output V chargepump The voltage is divided by resistors R5 and R6 to generate V cp Connect to the negative terminal of transconductance amplifier OTA1, reference level V ref Connected to the positive terminal of the transconductance amplifier OTA1, the comparison detection circuit compares V ref and V cp When V cp Voltage below V ref When the transconductance amplifier OTA1 outputs V ota High, driving the buffer Buffer output V buf is high, V control Also high, V control The switch clock control unit is connected to the charge pump, the switch clock control unit starts to start, and the charge pump works normally.

[0034] The working principle of the charge pump is as follows: when CK1 is high and CK2 is low, switches S1 and S2 are turned on, switches S3 and S4 are turned off, N2 is connected to ground, N1 is charged to the power supply voltage VDD, and the charge stored at both ends of capacitor C1 is C1*VDD; when CK2 is high and CK1 is low, switches S3 and S4 are turned on, switches S1 and S2 are turned off, the voltage at N2 is the power supply voltage VDD, and the charge C1*VDD is stored at both ends of capacitor C1. The voltage at N1 jumps to 2VDD, and then the load capacitor C0 and other loads are charged through switch S4. The corresponding charge C1*VDD will be transferred to the output storage capacitor C0, V chargepump Each clock cycle increases gradually. When V cp Voltage higher than V ref When V control The output is low, the switch clock control unit does not work, the charge pump stops working, and V chargepump The load is gradually discharged through the Wheatstone bridge. When V cp Less than Vref , V control is high, and the charge pump starts working again.

[0035] Through feedback regulation, the output of the charge pump will be stabilized at V cp =V chargepump *R6 / (R5+R6)=V ref , that is, V chargepump =V ref *(R5+R6) / R6. Through the regulation of the charge pump, the charge pump output is used to power the sensor, and the sensor voltage bias V sensor =V chargepump >VDD. Because Vo=V INP -V INN ∝V sensor *ΔR / R, as V sensor The bias voltage is increased, and the corresponding Wheatstone bridge pressure sensor pressure signal output Vo = V INP -V INN The signal-to-noise ratio of the system is effectively improved.

[0036] like Figure 5 As shown in the figure, it is the timing diagram of the power supply system of this embodiment. At the time of 0-50ms, the noise is small, and the extracted noise root mean square effective value V lowpass Less than the specified threshold V noise_threshold , V generated by noise quantization processing quantizer =0, the voltage regulator LDO works, the charge pump V chargepump When the noise increases at 50ms, the extracted noise RMS value V lowpass Exceeds the specified threshold V noise_threshold , V generated by noise quantization quantizer =1, the voltage regulator is turned off and switched to the charge pump. The corresponding voltage regulator-charge pump switching process is as follows: Figure 6 shown.

[0037] This embodiment dynamically detects the system input noise, and the noise after PGA amplification is processed by -3dB / OCT filtering, so that the processed noise has the same or similar energy within a certain range, and then the root mean square effective value of the noise is extracted. The extracted noise effective value is subjected to noise quantization, and the generated control signal further controls the bidirectional switching of the charge pump and the voltage regulator.

[0038] When it is found that the system noise is less than the specified threshold, the voltage regulator circuit is adaptively switched to power the sensor; when it is found that the system noise is too large, the charge pump circuit is adaptively switched to power the sensor. By increasing the sensor bias voltage, the change in the output V0 of the sensor press is increased accordingly. The effective increase in the press signal compensates for the impact of the increase in noise on the signal-to-noise ratio. Therefore, the entire measurement system can still maintain a sufficient signal-to-noise ratio, thereby ensuring the accuracy of press measurement and expanding the application environment.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator, characterized in that: The invention comprises a noise extraction circuit, a noise quantizer, a control circuit for switching a charge pump and a voltage regulator, a charge pump circuit and a voltage regulator circuit. The noise extraction circuit is connected to the differential voltage signal output of the sensor, and is used to process the differential voltage signal to obtain a noise energy value, and output the noise energy value to the noise quantizer; the noise quantizer is used to compare the noise energy value with a set noise energy threshold, and output a control instruction to the control circuit; the control circuit is used to switch the charge pump circuit and the voltage regulator circuit according to the control instruction; the charge pump circuit and the voltage regulator circuit provide two power supply modes for the sensor; When the noise RMS value is less than the set noise energy threshold, the noise quantizer output is 0, and the voltage regulator circuit is turned on; when the noise RMS value is greater than the set noise energy threshold, the noise quantizer outputs 1, and the charge pump circuit is turned on; The noise energy value refers to the noise root mean square effective value related to the noise energy in a specified frequency band.

2. The sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator according to claim 1, characterized in that: The noise extraction circuit includes a conversion circuit, a -3dB / OCT filter, a bandpass filter of a specified frequency band, a full-wave rectifier circuit and a low-pass filter connected in sequence; the conversion circuit is used to convert a double-ended input signal of a differential voltage signal into a single-ended output signal, and the single-ended output signal is processed by the -3dB / OCT filter, the bandpass filter of the specified frequency band, the full-wave rectifier circuit and the low-pass filter to obtain a noise energy value.

3. The sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator according to claim 1, characterized in that: The comparison of the noise quantizer means that when the noise energy value is greater than the noise energy threshold, the control circuit switches to the charge pump circuit for power supply, otherwise it switches to the voltage regulator circuit for power supply.

4. The sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator according to claim 1, characterized in that: The charge pump circuit includes capacitor C0, capacitor C1, charge and discharge switch S1, charge and discharge switch S2, charge and discharge switch S3, charge and discharge switch S4 and a switch clock control unit; the switch clock control unit is used to control the on and off of each charge and discharge switch, and the N1 end of the capacitor C1 is connected to the power supply VDD after passing through the charge and discharge switch S1, and is also used as the output end V after passing through the charge and discharge switch S4. chargepump , and the output terminal V chargepump The N2 end is connected to the ground after passing through the capacitor C0, and is connected to the power supply VDD through the charge and discharge switch S3, and is also connected to the ground after passing through the charge and discharge switch S2.

5. The sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator according to claim 4, characterized in that: The charge pump circuit also includes a comparison detection circuit, which includes a transconductance amplifier OTA1, a drive buffer Buffer, a resistor R5 and a resistor R6. The current input terminal I1 of the transconductance amplifier OTA1 is connected to the control circuit, and the positive terminal thereof is connected to the reference level V ref , output terminal V chargepump The comparison voltage V cp is generated by the resistor R5 and the resistor R6 and connected to the negative terminal of OTA1. The negative terminal is grounded after passing through the resistor R6. The output terminal V ota Connected to the drive buffer Buffer, the output terminal V of the drive buffer Buffer buf The switch clock control unit is connected to the control circuit and controlled by the control circuit.

6. The sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator according to claim 1, characterized in that: The voltage stabilizing source circuit includes a transconductance amplifier OTA2, a driving buffer Buffer and a capacitor C0. The current input terminal I2 of the transconductance amplifier OTA2 is connected to the control circuit, and the positive terminal is connected to the reference level V ref , its output terminal V ota Connected to the drive buffer Buffer, the output terminal V of the drive buffer Buffer buf After passing through the control circuit, it is connected to the negative end of the transconductance amplifier OTA2, the negative end is used to power the sensor, and the negative end is also grounded after passing through capacitor C0. Capacitor C0 serves as a compensation stabilizing capacitor for the voltage source.

7. The sensor power supply system with bidirectional switching between an adaptive charge pump and a voltage regulator according to claim 1, characterized in that: The control circuit includes a switch MP3, a switch MP4, a switch MP1, a switch MP2, a switch MN1 and an inverter Inverter, wherein the switch MP4 is connected between an output current source I0 of a power supply VDD and a current input terminal I1 of a transconductance amplifier OTA1, the switch MP3 is connected between an output current source I0 of a power supply VDD and a current input terminal I2 of a transconductance amplifier OTA2, and the switch MP2 is connected to an output terminal V buf The switch MP1 is connected to the output terminal V of the driving buffer Buffer between the negative terminal of the transconductance amplifier OTA2 and the negative terminal of the transconductance amplifier OTA2. buf The output terminal V of the switching clock control unit control Between the output terminals of the switch clock control unit V control Connect to ground through switch MN1; The output control signal V of the noise quantizer quantizer Connected to the control terminals of switch MP2 and switch MP3, and the control signal V quantizer After passing through the inverter, it is connected to the control ends of the switch MP1, the switch MP4 and the switch MN1.

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