A low pass filter and power supply circuit
By using an adjustable control voltage output module in a low-pass filter to stabilize the resistance value, the problem of MOS resistance being affected by temperature and process is solved, and the stability and noise reduction effect of filter performance are achieved.
Patent Information
- Application Number
- CN202111632106.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-12-29
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2041-12-29
AI Technical Summary
In traditional low-pass filters, the MOS resistance is greatly affected by temperature and process, resulting in large changes in the passband cutoff of the filter and affecting performance.
A low-pass filter is designed, including a resistor module, a capacitor array module and a voltage output module. The resistance value of the resistor module is controlled within a preset range by adjustable control voltage output module, which can adapt to different temperatures and process conditions.
It effectively avoids the problem of excessive or too small resistance value caused by temperature and process changes, ensures the stability of the filter performance, reduces noise, and improves the response speed of the filter.
Smart Images
Figure CN114285265B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of filters, and in particular to a low-pass filter and a power supply circuit. Background Art
[0002] To prevent the noise in the bandgap reference source from entering the subsequent circuit through the LDO drive circuit, the low-pass filter plays a vital role as an intermediate bridge connecting the bandgap reference source and the LDO drive. To reduce the noise at low frequencies, the cutoff frequency needs to be small enough.
[0003] Traditional low-pass filters that use MOS resistors are greatly affected by temperature and process, causing the MOS resistors to be too small or too large, causing the filter's passband cutoff frequency to vary greatly, thereby affecting the filter's performance.
[0004] Therefore the prior art still needs to be improved and enhanced. Summary of the invention
[0005] The object of the present invention is to provide a low-pass filter and a power supply circuit, which can effectively solve the problem that the resistance of the MOS tube in the filter is too large or too small, thereby affecting the performance of the filter.
[0006] In order to achieve the above object, the present invention adopts the following technical solutions:
[0007] The present application provides a low-pass filter, comprising:
[0008] Resistor module, connected to reference voltage;
[0009] A capacitor array module is connected to the resistor module and is used for charging according to a reference voltage output by the resistor module;
[0010] The voltage output module is connected to the resistance module and is connected to the power supply voltage, and is used to output an adjustable control voltage to the resistance module to control the resistance value of the resistance module to be within a preset range.
[0011] In some embodiments of the low-pass filter, a control module is further included, which is connected to the resistance module and receives a power control signal, and is used to control the capacitor array module to complete charging according to the reference voltage within a preset time according to the power control signal.
[0012] In the low pass filter of some embodiments, the voltage output module includes an adjustable resistor.
[0013] In the low-pass filter of some embodiments, the power output module includes a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a fifth MOS tube, a sixth MOS tube, a seventh MOS tube, an eighth MOS tube, a ninth MOS tube, a tenth MOS tube, an eleventh MOS tube, a first triode, a second triode, a first resistor, a second resistor, a third resistor, a fourth resistor and an operational amplifier, wherein the second resistor and the third resistor are adjustable resistors;
[0014] The source of the first MOS tube, the source of the second MOS tube, the source of the seventh MOS tube, the source of the eighth MOS tube and the source of the fifth MOS tube are all connected to electricity, the drain of the first MOS tube is connected to the source of the third MOS tube, the drain of the second MOS tube is connected to the source of the fourth MOS tube, the gate of the first MOS tube, the gate of the second MOS tube, the gate of the eighth MOS tube and the gate of the fifth MOS tube are all connected to the output end of the operational amplifier, the drain of the fifth MOS tube is connected to the source of the sixth MOS tube, the gate of the third MOS tube, the gate of the fourth MOS tube, the gate of the seventh MOS tube and the gate of the eighth MOS tube are all connected to the drain of the ninth MOS tube, the drain of the seventh MOS tube is connected to the drain of the ninth MOS tube, the gate of the ninth MOS tube is connected to the drain of the ninth MOS tube, the source of the ninth MOS tube is connected to the output end of the operational amplifier, The drain of the tenth MOS tube is connected to the drain of the eighth MOS tube, the drain of the eighth MOS tube is connected to the drain of the eleventh MOS tube, the gates of the tenth MOS tube and the eleventh MOS tube are both connected to the drain of the eleventh MOS tube, the source of the tenth MOS tube and the source of the eleventh MOS tube are both grounded, the drain of the fourth MOS tube and the first input end of the operational amplifier are connected to one end of the first resistor and one end of the third resistor, the other end of the first resistor is connected to the emitter of the second triode, the base and collector of the second triode and the other end of the third resistor are all grounded, the drain of the third MOS tube and the second input end of the operational amplifier are connected to one end of the second resistor and the emitter of the first triode, the other end of the second resistor, the base and collector of the first triode are all grounded, the drain of the sixth MOS tube and one end of the fourth resistor are both connected to the resistor module, and the other end of the fourth resistor is grounded.
[0015] In the low-pass filter of some embodiments, the resistance module includes a twelfth MOS tube, the gate of the twelfth MOS tube is connected to the drain of the sixth MOS tube and one end of the fourth resistor, the source of the twelfth MOS tube is connected to the reference voltage, and the drain of the twelfth MOS tube is connected to the capacitor array module and the control module.
[0016] In the low-pass filter of some embodiments, the capacitor array module includes a thirteenth MOS tube and a capacitor; one end of the capacitor and the gate of the thirteenth MOS tube are connected to the drain of the twelfth MOS tube, and the other end of the capacitor and the source and drain of the thirteenth MOS tube are grounded.
[0017] In the low-pass filter of some embodiments, the control module includes a fourteenth MOS tube, a fifteenth MOS tube, a sixteenth MOS tube, a seventeenth MOS tube, an eighteenth MOS tube, a nineteenth MOS tube, and a twentieth MOS tube;
[0018] The drain of the twentieth MOS tube is connected to the reference voltage, the source of the twentieth MOS tube is connected to the drain of the twelfth MOS tube, the gate of the twentieth MOS tube is connected to the drain of the eighteenth MOS tube and the drain of the nineteenth MOS tube, the source of the eighteenth MOS tube, the source of the sixteenth MOS tube and the source of the fourteenth MOS tube are all connected to electricity, the gate of the fourteenth MOS tube and the gate of the fifteenth MOS tube are all connected to the power control signal, the source of the fifteenth MOS tube, the source of the seventeenth MOS tube and the source of the nineteenth MOS tube are all grounded, the gate of the sixteenth MOS tube and the gate of the seventeenth MOS tube are all connected to the drain of the fourteenth MOS tube and the drain of the fifteenth MOS tube, and the gate of the eighteenth MOS tube and the gate of the nineteenth MOS tube are all connected to the drain of the sixteenth MOS tube and the drain of the seventeenth MOS tube.
[0019] In the low-pass filter of some embodiments, the twelfth MOS transistor is a P-channel MOS transistor.
[0020] In the low-pass filter of some embodiments, the twentieth MOS transistor is a P-channel MOS transistor.
[0021] A power supply circuit, comprising:
[0022] As the low-pass filter mentioned above;
[0023] A bandgap reference source is connected to the resistance module and is connected to a power control signal to provide a reference voltage for the resistance module;
[0024] The voltage regulator, together with the capacitor array module and the resistor module, is used to output a driving voltage according to a reference voltage output by the resistor module.
[0025] Compared with the prior art, the present invention provides a low-pass filter and a power supply circuit. The voltage output module arranged in the low-pass filter can output an adjustable control voltage, that is, it can output different voltage values to adapt to different temperatures and different process angles, thereby ensuring that the resistance value of the resistance module is within a preset range, so that the performance of the low-pass filter is not affected. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 This is a structural block diagram of the first embodiment of the low-pass filter provided by the present invention.
[0027] Figure 2 This is a structural block diagram of the second embodiment of the low-pass filter provided by the present invention.
[0028] Figure 3 This is a circuit schematic diagram of the low-pass filter provided by the present invention.
[0029] Figure 4 This is a schematic diagram of how the resistance value of the resistor module in the low-pass filter provided by the present invention changes with temperature.
[0030] Figure 5 A schematic diagram of the change of the adjustable control voltage with temperature at different process angles in the low-pass filter provided by the present invention.
[0031] Figure 6 A circuit schematic diagram of the power supply circuit provided by the present invention.
[0032] Figure 7 A schematic diagram showing a comparison of the noise output by a voltage regulator when different filters are used in the power supply circuit provided by the present invention. DETAILED DESCRIPTION
[0033] The object of the present invention is to provide a low-pass filter and a power supply circuit, which can effectively solve the problem that the resistance of the MOS tube in the filter is too large or too small, thereby affecting the performance of the filter.
[0034] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0035] See also Figure 1 The low-pass filter provided in the first embodiment of the present invention includes a resistor module 100, which is connected to a reference voltage Vref; a capacitor array module 200, which is connected to the resistor module 100 and is used to charge according to the reference voltage Vref output by the resistor module 100 to ensure the stability of the voltage input to the regulator; a voltage output module 300, which is connected to the resistor module 100 and is connected to a power supply voltage, and is used to output an adjustable control voltage Vg to the resistor module 100 to control the resistance value of the resistor module 100 within a preset range.
[0036] Specifically, the resistor module 100 of this embodiment is connected to a reference voltage Vref, which can be provided by a bandgap reference source. The resistor module 100 outputs the reference voltage Vref to the capacitor array module 200, and the capacitor array module 200 is charged according to the reference voltage Vref, so as to establish a correct reference voltage Vref input to the voltage regulator, that is, the low-pass filter in this embodiment is used to provide a stable reference voltage Vref for the voltage regulator to ensure that the voltage regulator can output correctly. Then, in order to further ensure the performance of the low-pass filter, the present invention outputs an adjustable control voltage Vg through the voltage output module 300, that is, to provide the resistor module 100 with an adjustable control voltage Vg, which can effectively control the resistance value of the resistor module 100 to be maintained within a preset range, thereby effectively avoiding the resistance value of the resistor module 100 being too large or too small due to changes in temperature or process angle, which affects the performance of the low-pass filter.
[0037] For further information, see Figure 2 In the second embodiment of the present invention, the low-pass filter also includes a control module 400, which is connected to the resistor module 100 and connected to the power control signal PD, and is used to control the capacitor array module 200 to complete charging according to the reference voltage Vref within a preset time according to the power control signal PD. After the low-pass filter is connected to the power control signal PD, the reference voltage Vref input to the voltage regulator needs to be established to the correct value before the voltage regulator can output correctly. The process of establishing the reference voltage Vref requires a certain amount of time, including the establishment time of the reference voltage Vref. The establishment time of the reference voltage Vref is usually affected by the time constant of the low-pass filter, which is equal to the product of the resistance value (the resistance value of the resistor module) and the capacitance value. Therefore, the larger the resistance value and the capacitance value, the longer the establishment time of the reference voltage Vref, and the longer the time for the voltage regulator to output the correct result. Therefore, by setting the control module 400 to be connected to the power control signal PD, the capacitor array is controlled to be charged within a preset time, and the preset time is shorter than the normal charging time when the capacitor array is not connected to the control module 400. That is, the setting of the control module 400 can ensure that the charging time of the capacitor array is reduced, so that the reference voltage Vref input to the regulator can be quickly stabilized at the correct value in a short time.
[0038] For further information, see Figure 3, the voltage output module 300 includes an adjustable resistor. Specifically, the power output module includes a first MOS tube M1, a second MOS tube M2, a third MOS tube M3, a fourth MOS tube M4, a fifth MOS tube M5, a sixth MOS tube M6, a seventh MOS tube M7, an eighth MOS tube M8, a ninth MOS tube M9, a tenth MOS tube M10, an eleventh MOS tube M11, a first triode Q1, a second triode Q2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and an operational amplifier, wherein, in this embodiment, the second resistor R2 and the third resistor R3 are adjustable resistors. The source of the first MOS tube M1, the source of the second MOS tube M2, the source of the seventh MOS tube M7, the source of the eighth MOS tube M8 and the source of the fifth MOS tube M5 are all connected to electricity, the drain of the first MOS tube M1 is connected to the source of the third MOS tube M3, the drain of the second MOS tube M2 is connected to the source of the fourth MOS tube M4, the gate of the first MOS tube M1, the gate of the second MOS tube M2, the gate of the eighth MOS tube M8 and the gate of the fifth MOS tube M5 are all connected to the output end of the operational amplifier, the drain of the fifth MOS tube M5 is connected to the source of the sixth MOS tube M6, the gate of the third MOS tube M3, the gate of the fourth MOS tube M4, the gate of the seventh MOS tube M7 and the gate of the eighth MOS tube M8 are all connected to the drain of the ninth MOS tube M9, the drain of the seventh MOS tube M7 is connected to the drain of the ninth MOS tube M9, the gate of the ninth MOS tube M9 is connected to the drain of the ninth MOS tube M9, the source of the ninth MOS tube M9 is connected to the output end of the operational amplifier, and the drain of the fifth MOS tube M5 is connected to the source of the sixth MOS tube M6. The drain of the eighth MOS tube M8 is connected to the drain of the eleventh MOS tube M11, the gates of the tenth MOS tube M10 and the eleventh MOS tube M11 are both connected to the drain of the eleventh MOS tube M11, the source of the tenth MOS tube M10 and the source of the eleventh MOS tube M11 are both grounded, the drain of the fourth MOS tube M4 and the first input end of the operational amplifier are connected to one end of the first resistor R1 and one end of the third resistor R3, the other end of the first resistor R1 is connected to the emitter of the second triode Q2, the base and collector of the second triode Q2 and the other end of the third resistor R3 are all grounded, the drain of the third MOS tube M3 and the second input end of the operational amplifier are both connected to one end of the second resistor R2 and the emitter of the first triode Q1, the other end of the second resistor R2, the base and collector of the first triode Q1 are all grounded, the drain of the sixth MOS tube M6 and one end of the fourth resistor R4 are both connected to the resistor module 100, and the other end of the fourth resistor R4 is grounded.
[0039] In this embodiment, the positive temperature coefficient can be adjusted by the resistance value of the first resistor R1, and the negative temperature coefficient can be adjusted by the ratio of the third resistor R3 to the fourth resistor R4, so as to ensure that the resistance value of the resistor module 100 can be maintained within a preset range within the full temperature range. Figure 4As shown, the resistance value of the resistor module 100 in this embodiment can be maintained between 1G and 2G ohms in the full temperature range. Figure 5 As shown, the variable resistor, i.e., the second resistor R2 and the third resistor R3, is used to fine-tune the temperature coefficient, so that the adjustable control voltage Vg output by the voltage output module 300 meets the required voltage range under each process angle, that is, by setting an adjustable resistor in the power output module, the voltage output module 300 outputs different voltages according to different process angles, which is equivalent to being able to adapt to different process angles, ensuring that the resistance value of the resistor module 100 will not be too large or too small to affect the performance of the low-pass filter. Specifically, Vg=(R4×Vbe) / R3+R4×kT×lnN / (R1×q), where R1, R3 and R4 are the resistance values of the first resistor R1, the third resistor R3 and the fourth resistor R4, Vbe is the voltage between the base and the emitter of the second transistor Q2, k is the Boltzmann constant, T is the thermodynamic temperature, which is 300k at room temperature (27°C), q is the electron charge, and N is the ratio of the size between the first transistor Q1 and the second transistor Q2.
[0040] Further, the resistor module 100 includes a twelfth MOS transistor M12, the gate of the twelfth MOS transistor M12 is connected to the drain of the sixth MOS transistor M6 and one end of the fourth resistor R4, the source of the twelfth MOS transistor M12 is connected to the reference voltage Vref, and the drain of the twelfth MOS transistor M12 is connected to the capacitor array module 200 and the control module 400. In this embodiment, the twelfth MOS transistor M12 is a P-channel MOS transistor, and the PMOS transistor working in the threshold region can be regarded as a large resistor. The adjustable control voltage Vg output by the voltage output module 300 is the gate control voltage of the PMOS transistor. By setting the adjustable resistor, the voltage output module 300 can output different voltage values to adapt to different temperatures and different process angles, ensuring that the resistance value of the resistor module 100 is within a preset range, so that the performance of the low-pass filter is not affected.
[0041] Furthermore, the capacitor array module 200 includes a thirteenth MOS tube M13 and a capacitor; one end of the capacitor and the gate of the thirteenth MOS tube M13 are connected to the drain of the twelfth MOS tube M12, and the other end of the capacitor, the source and the drain of the thirteenth MOS tube M13 are grounded. Compared with the traditional filter using passive devices that consume a lot of area, the present embodiment uses a combination of MIM capacitors and MOS tubes to form the capacitor part of the low-pass filter, which can make full use of the chip area and save the use area.
[0042] Further, the control module 400 includes a fourteenth MOS tube M14, a fifteenth MOS tube M15, a sixteenth MOS tube M16, a seventeenth MOS tube M17, an eighteenth MOS tube M18, a nineteenth MOS tube M19, and a twentieth MOS tube M20; the drain of the twentieth MOS tube M20 is connected to the reference voltage Vref, the source of the twentieth MOS tube M20 is connected to the drain of the twelfth MOS tube M12, the gate of the twentieth MOS tube M20 is connected to the drain of the eighteenth MOS tube M18 and the drain of the nineteenth MOS tube M19, the source of the eighteenth MOS tube M18, the source of the sixteenth MOS tube M16, and the source of the fourteenth MOS tube M14 are connected to the reference voltage Vref. The gates of the fourteenth MOS tube M14 and the fifteenth MOS tube M15 are connected to the power control signal PD, the source of the fifteenth MOS tube M15, the source of the seventeenth MOS tube M17 and the source of the nineteenth MOS tube M19 are grounded, the gates of the sixteenth MOS tube M16 and the seventeenth MOS tube M17 are connected to the drain of the fourteenth MOS tube M14 and the drain of the fifteenth MOS tube M15, the gates of the eighteenth MOS tube M18 and the nineteenth MOS tube M19 are connected to the drain of the sixteenth MOS tube M16 and the drain of the seventeenth MOS tube M17; in this embodiment, the twentieth MOS tube M20 is a P-channel MOS tube.
[0043] In this embodiment, the fourteenth MOS tube M14 and the fifteenth MOS tube M15 form a group of inverters, the sixteenth MOS tube M16 and the seventeenth MOS tube M17 form a group of inverters, and the eighteenth MOS tube M18 and the nineteenth MOS tube M19 form a group of inverters. The input power control signal PD can be delayed by three groups of inverters to output a delay signal PD_delay to the twentieth MOS tube M20. Specifically, when the power control signal PD is connected, the power control signal PD is turned on, and gradually increases from 0 potential to the power supply voltage VDD. After passing through the three groups of inverters, the delay signal PD_delay output is a signal that gradually decreases from the power supply voltage Vdd to 0 potential, that is, the three groups of inverters have a certain delay effect on the power control signal PD. Then the twentieth MOS tube M20 is turned on and off according to the delay signal, that is, it is disconnected after controlling the source and drain voltages of the twelfth MOS tube M12 to be quickly consistent, that is, the process of fast charging of the capacitor array module 200 is realized, and the charging time of the capacitor array module 200 is reduced. By setting the delay signal, it is ensured that the twelfth MOS tube M12 has been connected to the reference voltage Vref when the twentieth MOS tube M20 is turned on, that is, the reference voltage Vref has been established. Then, after the twentieth MOS tube M20 is turned on, the source and drain voltages of the twelfth MOS tube M12 will be quickly consistent, so that the reference voltage Vref is quickly stabilized at a correct value, which is equivalent to improving the response speed of the low-pass filter and improving the performance of the low-pass filter.
[0044] For further information, see Figure 6 The present invention also provides a power supply circuit, including the above-mentioned low-pass filter, bandgap reference source 10 and voltage regulator 20; the bandgap reference source 10 is connected to the resistor module 100 and connected to the power control signal PD, and is used to provide a reference voltage Vref for the resistor module 100; the voltage regulator 20, together with the capacitor array module 200 and the resistor module 100, is used to output a driving voltage according to the reference voltage Vref output by the resistor module 100, wherein the voltage regulator 20 is also connected to a delay signal to ensure that the input reference voltage Vref has been established at a correct value when the voltage regulator 20 is turned on, thereby ensuring the normal output of the voltage regulator 20. Since the low-pass filter is described in detail above, it will not be repeated here.
[0045] See also Figure 7 The low-pass filter provided in the power supply circuit provided by the present invention can effectively reduce the noise of the driving voltage output by the voltage stabilizer 20 by outputting the adjustable control voltage Vg through the voltage output module 300. Figure 7 From the comparison shown, it can be found that the noise of the low-pass filter in the present application is between that of the filter using 1G ohm passive resistor and that of the filter using 2G ohm passive resistor in the full temperature range, and is far superior to the filter using a fixed control voltage, i.e., Vg=200mV. That is, the noise reduction effect of the low-pass filter in the present application is far superior to the noise reduction effect of the filter using a fixed control voltage. Therefore, the low-pass filter in the present application can effectively optimize the performance of the filter by outputting an adjustable control voltage Vg, thereby achieving a better noise reduction effect.
[0046] In summary, in a low-pass filter and power supply circuit provided by the present invention, the low-pass filter includes a resistor module, which is connected to a reference voltage; a capacitor array module, which is connected to the resistor module and is used to charge according to the reference voltage output by the resistor module; a voltage output module, which is connected to the resistor module and is connected to a power supply voltage, and is used to output an adjustable control voltage to the resistor module to control the resistance value of the resistor module within a preset range. The voltage output module provided in the present invention can output an adjustable control voltage, that is, it can output different voltage values to adapt to different temperatures and different process angles, to ensure that the resistance value of the resistor module is within a preset range, so that the performance of the low-pass filter is not affected.
[0047] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.
Claims
1. A low-pass filter, characterized in that: include: Resistor module, connected to reference voltage; A capacitor array module, connected to the resistor module, and configured to charge according to the reference voltage output by the resistor module; A voltage output module is connected to the resistance module and connected to the power supply voltage, and is used to output an adjustable control voltage to the resistance module to control the resistance value of the resistance module to be within a preset range; The resistance module includes a MOS tube, a source of the MOS tube receives the reference voltage, a drain is coupled to the capacitor array module, a gate is coupled to the voltage output module and receives the adjustable control voltage, and the MOS tube adjusts the resistance of the MOS tube under the control of the adjustable control voltage so that the resistance is within a preset range.
2. The low-pass filter according to claim 1, characterized in that It also includes a control module, which is connected to the resistance module and receives a power control signal, and is used to control the capacitor array module to complete charging according to the reference voltage within a preset time according to the power control signal.
3. The low-pass filter according to claim 2, characterized in that The voltage output module includes an adjustable resistor.
4. The low-pass filter according to claim 3, characterized in that The voltage output module includes a first MOS tube, a second MOS tube, a third MOS tube, a fourth MOS tube, a fifth MOS tube, a sixth MOS tube, a seventh MOS tube, an eighth MOS tube, a ninth MOS tube, a tenth MOS tube, an eleventh MOS tube, a first triode, a second triode, a first resistor, a second resistor, a third resistor, a fourth resistor and an operational amplifier, wherein the second resistor and the third resistor are adjustable resistors; The source of the first MOS tube, the source of the second MOS tube, the source of the seventh MOS tube, the source of the eighth MOS tube and the source of the fifth MOS tube are all connected to electricity, the drain of the first MOS tube is connected to the source of the third MOS tube, the drain of the second MOS tube is connected to the source of the fourth MOS tube, the gate of the first MOS tube, the gate of the second MOS tube, the gate of the eighth MOS tube and the gate of the fifth MOS tube are all connected to the output end of the operational amplifier, the drain of the fifth MOS tube is connected to the source of the sixth MOS tube, the gate of the third MOS tube, the gate of the fourth MOS tube, the gate of the seventh MOS tube and the gate of the eighth MOS tube are all connected to the drain of the ninth MOS tube, the drain of the seventh MOS tube is connected to the drain of the ninth MOS tube, the gate of the ninth MOS tube is connected to the drain of the ninth MOS tube, the source of the ninth MOS tube is connected to the output end of the operational amplifier, The drain of the eighth MOS tube is connected to the drain of the eleventh MOS tube, the drain of the tenth MOS tube and the eleventh MOS tube are both connected to the drain of the eleventh MOS tube, the source of the tenth MOS tube and the source of the eleventh MOS tube are both grounded, the drain of the fourth MOS tube and the first input end of the operational amplifier are connected to one end of the first resistor and one end of the third resistor, the other end of the first resistor is connected to the emitter of the second triode, the base and collector of the second triode and the other end of the third resistor are all grounded, the drain of the third MOS tube and the second input end of the operational amplifier are both connected to one end of the second resistor and the emitter of the first triode, the other end of the second resistor, the base and collector of the first triode are all grounded, the drain of the sixth MOS tube and one end of the fourth resistor are both connected to the resistor module, and the other end of the fourth resistor is grounded.
5. The low-pass filter according to claim 4, characterized in that The resistance module includes a twelfth MOS tube, the gate of the twelfth MOS tube is connected to the drain of the sixth MOS tube and one end of the fourth resistor, the source of the twelfth MOS tube is connected to the reference voltage, and the drain of the twelfth MOS tube is connected to the capacitor array module and the control module.
6. The low-pass filter according to claim 5, characterized in that The capacitor array module includes a thirteenth MOS tube and a capacitor; one end of the capacitor and the gate of the thirteenth MOS tube are connected to the drain of the twelfth MOS tube, and the other end of the capacitor, the source and the drain of the thirteenth MOS tube are grounded.
7. The low-pass filter according to claim 6, characterized in that The control module includes a fourteenth MOS tube, a fifteenth MOS tube, a sixteenth MOS tube, a seventeenth MOS tube, an eighteenth MOS tube, a nineteenth MOS tube and a twentieth MOS tube; The drain of the 20th MOS tube is connected to the reference voltage, the source of the 20th MOS tube is connected to the drain of the 12th MOS tube, the gate of the 20th MOS tube is connected to the drain of the 18th MOS tube and the drain of the 19th MOS tube, the source of the 18th MOS tube, the source of the 16th MOS tube and the source of the 14th MOS tube are all powered, the gate of the 14th MOS tube and the gate of the 15th MOS tube are all connected to the power control signal, the source of the 15th MOS tube, the source of the 17th MOS tube and the source of the 19th MOS tube are all grounded, the gate of the 16th MOS tube and the gate of the 17th MOS tube are all connected to the drain of the 14th MOS tube and the drain of the 15th MOS tube, and the gate of the 18th MOS tube and the gate of the 19th MOS tube are all connected to the drain of the 16th MOS tube and the drain of the 17th MOS tube.
8. The low-pass filter according to any one of claims 5 to 7, characterized in that: The twelfth MOS tube is a P-channel MOS tube.
9. The low-pass filter according to claim 7, characterized in that: The twentieth MOS tube is a P-channel MOS tube.
10. A power supply circuit, characterized in that: include: A low-pass filter as claimed in any one of claims 1 to 9; A bandgap reference source, connected to the resistance module and connected to a power supply control signal, for providing the reference voltage for the resistance module; A voltage regulator, together with the capacitor array module and the resistor module, is used to output a driving voltage according to the reference voltage output by the resistor module.