CN210572490U - Alternating current amplifying circuit with direct current component elimination and frequency characteristic analyzer - Google Patents
Alternating current amplifying circuit with direct current component elimination and frequency characteristic analyzer Download PDFInfo
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- CN210572490U CN210572490U CN201921124101.4U CN201921124101U CN210572490U CN 210572490 U CN210572490 U CN 210572490U CN 201921124101 U CN201921124101 U CN 201921124101U CN 210572490 U CN210572490 U CN 210572490U
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Abstract
An alternating current amplifying circuit with a direct current component elimination function and a frequency characteristic analyzer comprise a voltage follower, a low-pass filter and a differential amplifier, wherein an output end and an input end of the differential amplifier are used as an output end and an input end of the alternating current amplifying circuit, and the voltage follower and the low-pass filter are sequentially connected between the input end of the alternating current amplifying circuit and the other input end of the differential amplifier in series. The electric signal to be amplified is divided into two paths of same electric signals, one path of the electric signals is filtered to remove alternating current, then the electric signals and the other path of the electric signals are subjected to differential amplification and then are output as output signals of the alternating current amplification circuit, so that direct current components in the signals can be eliminated without adopting capacitive coupling, and further, a circuit for amplifying small alternating current electric signals superposed on large direct current voltage is realized. Because the capacitive coupling is not adopted, the phase jump of the low frequency band caused by the capacitive coupling can not be introduced, the frequency range of the phase jump is greatly reduced, and the very low frequency signal can be amplified without introducing large phase error.
Description
Technical Field
The application relates to the technical field of signal processing, in particular to an alternating current amplifying circuit with a direct current component elimination function and a frequency characteristic analyzer.
Background
In production and life, a weak electrical signal is often required to control a large power load, or in order to detect the weak electrical signal, the weak signal needs to be amplified first. The alternating current amplifying circuit is used for converting weak alternating current signals into stronger alternating current signals. In some practical application scenarios, it is necessary to amplify a small ac signal in the presence of a large dc voltage, for example, when measuring the loop gain characteristic of a switching power supply.
The traditional scheme for suppressing direct current is to use a capacitive coupling circuit, although the capacitive coupling circuit can block direct current, when an electric signal to be amplified is in a low frequency band, a large phase jump is introduced, the phase change is not stable, the frequency range covered by the phase jump is large, and a phase error is easily introduced. Therefore, it is necessary to design a circuit structure capable of amplifying an ac signal and suppressing a dc signal while achieving dc coupling.
Disclosure of Invention
The present application aims to disclose a dc component cancellation circuit that suppresses a dc signal while ensuring amplification of an ac signal, and that does not introduce a large phase error even when measuring a very low frequency signal.
According to a first aspect, an embodiment provides an ac amplifying circuit with dc component cancellation, including a voltage follower, a low-pass filter, and a differential amplifier;
the output end of the differential amplifier is used as the output end of the alternating current amplifying circuit;
one input end of the differential amplifier is used as the input end of the alternating current amplifying circuit, the voltage follower and the low-pass filter are connected in series and then connected between the two input ends of the differential amplifier, and the differential amplifier is used for dividing an electric signal to be amplified into two paths of same electric signals, wherein one path of electric signal is subjected to alternating current filtering processing through the voltage follower and the low-pass filter, and then is subjected to differential amplification with the other path of electric signal and then is output;
the voltage follower is used for improving the input impedance of the alternating current amplifying circuit;
the low-pass filter is used for filtering alternating current of one path of electric signals.
Further, the differential amplifier comprises a first amplifier U1, a second amplifier U2, a third amplifier U3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6 and a resistor R7;
the positive input of the first amplifier U1 is used as one input end of the differential amplifier;
the resistor R2 is connected in series between the negative input end and the output end of the first amplifier U1;
the resistor R4 is connected in series between the negative input terminal of the first amplifier U1 and the negative input terminal of the third amplifier U3;
the positive input end of a third amplifier U3 is used as the other input end of the differential amplifier;
the resistor R5 is connected in series between the negative input end and the output end of the third amplifier U3;
the resistor R3 is connected in series between the output end of the first amplifier U1 and the positive input end of the second amplifier U2;
the resistor R6 is connected in series between the output terminal of the third amplifier U3 and the negative input terminal of the second amplifier U2;
the output end of the second amplifier U2 is used as the output end of the differential amplifier;
the resistor R1 is connected in series between the positive input end of the second amplifier U2 and the ground;
a resistor R7 is connected in series between the negative input and the output of the second amplifier U2.
Further, the differential amplifier further comprises a capacitor C1, a capacitor C1, a capacitor C1 and/or a capacitor C4;
the capacitor C1 is connected with the resistor R1 in parallel; the capacitor C2 is connected with the resistor R1 in parallel; the capacitor C3 is connected with the resistor R5 in parallel; the capacitor C4 is connected in parallel with the resistor R7.
Further, the voltage follower includes a fourth amplifier U4, a positive input terminal of which is used as the input terminal of the voltage follower, and a negative input terminal of which is connected with the output terminal to be used as the output terminal of the voltage follower.
Further, the low-pass filter is a first order low-pass filter, a second order low-pass filter, or a higher order low-pass filter.
Further, the low pass filter comprises a fifth amplifier U5, a resistor R8, a resistor R9, a capacitor C5 and a capacitor C6;
one end of the resistor R8 is used as the input end of the low-pass filter;
the resistor R9 is connected in series between the other end of the resistor R8 and the positive input end of the fifth amplifier U5;
the capacitor C6 is connected in series between the other end of the resistor R8 and the negative input end of the fifth amplifier U5;
the capacitor C5 is connected in series between the positive input terminal of the fifth amplifier U5 and ground;
the output of the fifth amplifier U5 serves as the output of the low pass filter.
And the switching circuit is connected between the input end and the output end of the voltage follower and used for bypassing the voltage follower when the voltage amplitude of the electric signal to be amplified is smaller than a preset value.
According to a second aspect, an embodiment provides a frequency characteristic analyzer, which includes an upper computer, a signal transmitting circuit and two signal receiving circuits with the same structure;
the signal transmitting circuit is connected with the upper computer and used for generating a reference signal and inputting the reference signal into the circuit to be tested when receiving the control electric signal transmitted by the upper computer;
each signal receiving circuit is respectively connected with the upper computer and used for respectively acquiring and processing the analog signals output by the circuit to be tested, converting the analog signals into digital information and sending the digital information to the upper computer;
the upper computer is used for sending control electric signals to the signal transmitting circuit and acquiring the frequency characteristics of the circuit to be tested according to the received digital signals sent by the two signal receiving circuits;
the signal receiving circuit includes the ac amplifying circuit according to the first aspect.
According to the alternating current amplifying circuit with the direct current component elimination of the embodiment, the alternating current amplifying circuit comprises the voltage follower, the low-pass filter and the differential amplifier, wherein the output end of the differential amplifier serves as the output end of the alternating current amplifying circuit, one input end of the differential amplifier serves as the input end of the alternating current amplifying circuit, and the voltage follower and the low-pass filter are sequentially connected between the input end of the alternating current amplifying circuit and the other input end of the differential amplifier in series. The electric signal to be amplified is divided into two paths of same electric signals, one path of the electric signals is filtered to remove alternating current, then the electric signals and the other path of the electric signals are subjected to differential amplification and then are output as output signals of the alternating current amplification circuit, so that direct current components in the signals can be eliminated without adopting capacitive coupling, and further, a circuit for amplifying small alternating current electric signals superposed on large direct current voltage is realized.
Drawings
Fig. 1 is a schematic view of a frequency characteristic analyzer;
FIG. 2 is a schematic diagram of an AC amplifier circuit according to an embodiment;
FIG. 3 is a schematic diagram of an embodiment of an AC amplifying circuit;
fig. 4 is a circuit diagram of an ac amplifying circuit according to an embodiment.
Detailed Description
The present application will be described in further detail below with reference to the accompanying drawings by way of specific embodiments. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
The frequency characteristic analyzer mainly transmits a sweep frequency signal to be input to a tested circuit, the transmitted signal generates phase or amplitude change after passing through the tested circuit, the frequency characteristic analyzer processes and analyzes the changed signal, and the frequency characteristic of the circuit can be reflected and output by extracting phase and amplitude information. Referring to fig. 1, a schematic structural diagram of a frequency characteristic analyzer includes an upper computer 1, a signal transmitting circuit 3, and two signal receiving circuits 4 and 5 with the same structure. The signal transmitting circuit 3 is connected with the upper computer 1 and used for generating a reference signal and inputting the reference signal into the circuit to be detected 2 when receiving the control electric signal sent by the upper computer 1. The signal receiving circuit 4 and the signal receiving circuit 5 are respectively connected with the upper computer 1, and are used for respectively acquiring and processing the analog signals output by the detected circuit 2, converting the analog signals into digital information and sending the digital information to the upper computer 1. The upper computer 1 is used for sending a control electric signal to the signal transmitting circuit 3 and acquiring the frequency characteristic of the circuit 2 to be tested according to the received digital signals sent by the signal receiving circuit 4 and the signal receiving circuit 5. Since the frequency characteristic analyzer only processes and analyzes the ac signal, the signal receiving circuit 4 and the signal receiving circuit 5 need to perform dc cancellation processing and simultaneously amplify the analog signal output by the circuit under test 2 in order to improve the measurement accuracy. In one embodiment, the signal receiving circuit 5 includes a front-end protection circuit 51, a front-end noise reduction circuit 52, a first-order amplification circuit 53, and a second-order amplification circuit 54. The front-end protection circuit 51 is used to limit the frequency range and intensity of the analog signal output by the circuit under test 2 to protect the front-end noise reduction circuit 52. The front-end noise reduction circuit 52 is configured to perform noise reduction processing on the analog signal output by the circuit 2 to be tested, and output the analog signal to the first-order amplification circuit 53. The first-order amplification circuit 53 is connected to the second-order amplification circuit 54, and performs dc filtering, low-pass filtering, and/or program-controlled amplification processing on the analog signal output from the front-end noise reduction circuit 52. The second-order amplification circuit 54 is connected to the upper computer 1, and is configured to perform program-controlled amplification on the analog signal output by the first-order amplification circuit 53 according to the frequency of the analog signal or perform program-controlled amplification after mixing with a preset signal, and then perform analog-to-digital conversion and output the analog signal to the upper computer 1. The front-end noise reduction circuit 52, the first-order amplification circuit 53, and the second-order amplification circuit 54 all need to eliminate the dc component of the signal to be processed and amplify the ac component thereof.
The embodiment of the application discloses an alternating current amplifying circuit with a direct current component elimination function, and the alternating current amplifying circuit divides an electric signal to be amplified into two paths of same electric signals, filters alternating current of one path of electric signal, performs differential amplification on the other path of electric signal, and outputs the electric signal as an output signal of the alternating current amplifying circuit, so that the direct current component in the signal can be eliminated without adopting capacitive coupling, and a circuit for amplifying a small alternating current electric signal superposed on a large direct current voltage is further realized.
Example one
Referring to fig. 2, a schematic diagram of an ac amplifying circuit in an embodiment includes a voltage follower 30, a low pass filter 20, and a differential amplifier 10. The output end of the differential amplifier 10 is used as the output end of the alternating current amplifying circuit, one input end of the differential amplifier 10 is used as the input end of the alternating current amplifying circuit, the voltage follower 30 and the low-pass filter 20 are connected in series and then connected between the two input ends of the differential amplifier 10, the voltage follower and the low-pass filter are used for dividing the electric signal to be amplified into two paths of same electric signals, and one path of electric signal is output after being filtered and alternating-current processed by the voltage follower and the low-pass filter and then being differentially amplified with the other path of electric. The voltage follower 30 is used to increase the input impedance of the ac amplifying circuit, and the low-pass filter 20 is used to filter ac from one path of electrical signal.
Referring to fig. 3, a schematic structural diagram of an ac amplifying circuit in an embodiment is shown, in an embodiment, the ac amplifying circuit includes a voltage follower 30, a low pass filter 20, a differential amplifier 10, and a switch circuit 40 connected between an input end and an output end of the voltage follower 30, for bypassing the voltage follower when a voltage amplitude of an electrical signal to be amplified is smaller than a preset value. That is, if the ac amplifier circuit does not have a high impedance requirement, the voltage follower 30 can be bypassed. In one embodiment, when the switching circuit 40 is turned on, the voltage follower 30 is short-circuited by the switching circuit 40, i.e. the electrical signal to be amplified bypasses the voltage follower 30 and is input into the low pass filter 20.
Referring to fig. 4, a circuit diagram of an ac amplifying circuit in an embodiment includes a differential amplifier, a voltage follower and a low pass filter. The differential amplifier comprises a first amplifier U1, a second amplifier U2, a third amplifier U3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6 and a resistor R7. The positive input of the first amplifier U1 serves as one input of a differential amplifier. A resistor R2 is connected in series between the negative input terminal and the output terminal of the first amplifier U1. A resistor R4 is connected in series between the negative input of the first amplifier U1 and the negative input of the third amplifier U3. The positive input of the third amplifier U3 serves as the other input of the differential amplifier. A resistor R5 is connected in series between the negative input terminal and the output terminal of the third amplifier U3. The resistor R3 is connected in series between the output terminal of the first amplifier U1 and the positive input terminal of the second amplifier U2. A resistor R6 is connected in series between the output of the third amplifier U3 and the negative input of the second amplifier U2. The output of the second amplifier U2 serves as the output of the differential amplifier. The resistor R1 is connected in series between the positive input of the second amplifier U2 and ground. A resistor R7 is connected in series between the negative input and the output of the second amplifier U2. In one embodiment, the differential amplifier further comprises a capacitor C1, a capacitor C1, a capacitor C1, and/or a capacitor C4. The capacitor C1 is connected in parallel with the resistor R1, the capacitor C2 is connected in parallel with the resistor R1, the capacitor C3 is connected in parallel with the resistor R5, and the capacitor C4 is connected in parallel with the resistor R7. The voltage follower includes a fourth amplifier U4 having a positive input terminal as an input terminal of the voltage follower and a negative input terminal connected to the output terminal as an output terminal of the voltage follower. The low pass filter may be a first order low pass filter, a second order low pass filter, or a higher order low pass filter. In one embodiment, the low pass filter includes a fifth amplifier U5, a resistor R8, a resistor R9, a capacitor C5, and a capacitor C6. One end of the resistor R8 serves as an input terminal of the low-pass filter. A resistor R9 is connected in series between the other end of the resistor R8 and the positive input of the fifth amplifier U5. The capacitor C6 is connected in series between the other end of the resistor R8 and the negative input terminal of the fifth amplifier U5. The capacitor C5 is connected in series between the positive input of the fifth amplifier U5 and ground. The output of the fifth amplifier U5 acts as the output of the low pass filter. The differential amplifier subtracts and amplifies the two paths of signals, and the capacitor C1, the capacitor C2, the capacitor C3 and the capacitor C4 are phase compensation capacitors and are used for keeping the stability of the amplifying circuit.
The principle of the ac amplifying circuit in this embodiment is that the input electrical signal to be amplified includes useless dc signals and useful ac signals, the electrical signal to be amplified is divided into two paths after entering the ac amplifying circuit, and one path directly enters one of the input ends of the differential amplifier; and the other path firstly passes through a voltage follower and then a low-pass filter to filter the input alternating current signal, and only the direct current signal is reserved. When two paths of electric signals to be amplified enter a differential amplifier, one path of the electric signals comprises direct current and alternating current signals, the other path of the electric signals only comprises direct current signals, the amplitudes of the two paths of direct current signals are equal, the differential amplifier subtracts and amplifies the two paths of signals, finally, the output direct current signals are eliminated, and the alternating current signals are amplified. The voltage follower can improve input impedance and ensure isolation between an input and the low-pass filter. The cut-off frequency of the low-pass filter can be set to be an extremely low frequency value and can be designed to be a high-order low-pass filter, and the specific cut-off frequency and the filter order are determined according to the response time of a required circuit and the frequency of an alternating current signal required to be amplified. The circuit disclosed in this embodiment employs a second order low pass filter.
The utility model discloses an alternating current amplifier circuit of taking direct current component to eliminate does not adopt capacitive coupling, and directly adopts direct current coupling, can not introduce the phase place sudden change of the low-frequency channel that brings because capacitive coupling, reduces the frequency range of phase place sudden change greatly, when can guaranteeing that direct current and alternating current signal appear simultaneously, only enlargies alternating current signal, and direct current signal is suppressed, and its measurable quantity is signal of very low frequency, and does not introduce big phase error.
Example two
The application also discloses a frequency characteristic analyzer, which comprises an upper computer, a signal transmitting circuit and two signal receiving circuits with the same structure. The signal transmitting circuit is connected with the upper computer and used for generating a reference signal and inputting the reference signal into the circuit to be tested when receiving the control electric signal sent by the upper computer. Each signal receiving circuit is respectively connected with an upper computer and used for respectively acquiring and processing the analog signals output by the circuit to be detected, converting the analog signals into digital information and sending the digital information to the upper computer. The upper computer is used for sending control electric signals to the signal transmitting circuit and is also used for acquiring the frequency characteristics of the circuit to be detected according to the received digital signals sent by the two signal receiving circuits. Wherein each signal receiving circuit comprises an ac amplifying circuit as described in the first embodiment. Each signal receiving circuit adopts direct current coupling, because the frequency characteristic analyzer does not analyze direct current, and the circuit input may have large direct current components, the alternating current amplifying circuit with the direct current component elimination can effectively eliminate the direct current components on the premise of direct current coupling. A frequency characteristic analyzer employing an ac amplification circuit with dc component cancellation can measure very low frequency signals without introducing large phase errors.
The present application has been described with reference to specific examples, which are provided only to aid understanding of the present application and are not intended to limit the present application. Numerous simple deductions, modifications or substitutions may also be made by those skilled in the art to which the present application pertains, according to the spirit of the present application.
Claims (8)
1. An alternating current amplifying circuit with a direct current component elimination function is characterized by comprising a voltage follower, a low-pass filter and a differential amplifier;
the output end of the differential amplifier is used as the output end of the alternating current amplifying circuit;
one input end of the differential amplifier is used as the input end of the alternating current amplifying circuit, the voltage follower and the low-pass filter are connected in series and then connected between the two input ends of the differential amplifier, and the differential amplifier is used for dividing an electric signal to be amplified into two paths of same electric signals, wherein one path of electric signal is subjected to alternating current filtering processing through the voltage follower and the low-pass filter, and then is subjected to differential amplification with the other path of electric signal and then is output;
the voltage follower is used for improving the input impedance of the alternating current amplifying circuit;
the low-pass filter is used for filtering alternating current of one path of electric signals.
2. The alternating current amplification circuit of claim 1, wherein the differential amplifier includes a first amplifier U1, a second amplifier U2, a third amplifier U3, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, and a resistor R7;
the positive input of the first amplifier U1 is used as one input end of the differential amplifier;
the resistor R2 is connected in series between the negative input end and the output end of the first amplifier U1;
the resistor R4 is connected in series between the negative input terminal of the first amplifier U1 and the negative input terminal of the third amplifier U3;
the positive input end of a third amplifier U3 is used as the other input end of the differential amplifier;
the resistor R5 is connected in series between the negative input end and the output end of the third amplifier U3;
the resistor R3 is connected in series between the output end of the first amplifier U1 and the positive input end of the second amplifier U2;
the resistor R6 is connected in series between the output terminal of the third amplifier U3 and the negative input terminal of the second amplifier U2;
the output end of the second amplifier U2 is used as the output end of the differential amplifier;
the resistor R1 is connected in series between the positive input end of the second amplifier U2 and the ground;
a resistor R7 is connected in series between the negative input and the output of the second amplifier U2.
3. The alternating current amplification circuit according to claim 2, wherein the differential amplifier further comprises a capacitor C1, a capacitor C1, a capacitor C1, and/or a capacitor C4;
the capacitor C1 is connected with the resistor R1 in parallel; the capacitor C2 is connected with the resistor R1 in parallel; the capacitor C3 is connected with the resistor R5 in parallel; the capacitor C4 is connected in parallel with the resistor R7.
4. The ac amplifying circuit according to claim 1, wherein said voltage follower comprises a fourth amplifier U4 having a positive input terminal as an input terminal of said voltage follower and a negative input terminal connected to an output terminal as an output terminal of said voltage follower.
5. The ac amplifying circuit according to claim 1, wherein the low-pass filter is a first-order low-pass filter, a second-order low-pass filter, or a higher-order low-pass filter.
6. The alternating current amplification circuit of claim 5, wherein the low-pass filter includes a fifth amplifier U5, a resistor R8, a resistor R9, a capacitor C5 and a capacitor C6;
one end of the resistor R8 is used as the input end of the low-pass filter;
the resistor R9 is connected in series between the other end of the resistor R8 and the positive input end of the fifth amplifier U5;
the capacitor C6 is connected in series between the other end of the resistor R8 and the negative input end of the fifth amplifier U5;
the capacitor C5 is connected in series between the positive input terminal of the fifth amplifier U5 and ground;
the output of the fifth amplifier U5 serves as the output of the low pass filter.
7. The ac amplifying circuit according to claim 1, further comprising a switching circuit connected between the input terminal and the output terminal of the voltage follower for bypassing the voltage follower when the voltage amplitude of the electrical signal to be amplified is smaller than a predetermined value.
8. A frequency characteristic analyzer is characterized by comprising an upper computer, a signal transmitting circuit and two signal receiving circuits with the same structure;
the signal transmitting circuit is connected with the upper computer and used for generating a reference signal and inputting the reference signal into the circuit to be tested when receiving the control electric signal transmitted by the upper computer;
each signal receiving circuit is respectively connected with the upper computer and used for respectively acquiring and processing the analog signals output by the circuit to be tested, converting the analog signals into digital information and sending the digital information to the upper computer;
the upper computer is used for sending control electric signals to the signal transmitting circuit and acquiring the frequency characteristics of the circuit to be tested according to the received digital signals sent by the two signal receiving circuits;
the signal receiving circuit includes an ac amplifying circuit as claimed in any one of claims 1 to 7.
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| CN201921124101.4U CN210572490U (en) | 2019-07-17 | 2019-07-17 | Alternating current amplifying circuit with direct current component elimination and frequency characteristic analyzer |
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| CN201921124101.4U CN210572490U (en) | 2019-07-17 | 2019-07-17 | Alternating current amplifying circuit with direct current component elimination and frequency characteristic analyzer |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111665460A (en) * | 2020-05-29 | 2020-09-15 | 南方电网数字电网研究院有限公司 | Sensor direct-current component compensation method and device and sensor device |
| CN113193839A (en) * | 2021-04-08 | 2021-07-30 | 成都蕊感微电子有限公司 | Signal receiving and amplifying circuit and sensor |
| WO2022067682A1 (en) * | 2020-09-30 | 2022-04-07 | 焦旭 | Multi-signal parallel collection circuit, electronic device, and body feature signal collector |
-
2019
- 2019-07-17 CN CN201921124101.4U patent/CN210572490U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111665460A (en) * | 2020-05-29 | 2020-09-15 | 南方电网数字电网研究院有限公司 | Sensor direct-current component compensation method and device and sensor device |
| CN111665460B (en) * | 2020-05-29 | 2021-07-06 | 南方电网数字电网研究院有限公司 | Sensor direct-current component compensation method and device and sensor device |
| WO2022067682A1 (en) * | 2020-09-30 | 2022-04-07 | 焦旭 | Multi-signal parallel collection circuit, electronic device, and body feature signal collector |
| CN113193839A (en) * | 2021-04-08 | 2021-07-30 | 成都蕊感微电子有限公司 | Signal receiving and amplifying circuit and sensor |
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