A bidirectional voltage detection circuit based on high input impedance absolute value circuit

Abstract

The application discloses a bidirectional voltage detection circuit based on a high input impedance absolute value circuit, which comprises a high resistance sampling module, a differential amplification module and a high resistance input absolute value module; wherein the high resistance sampling module is used for sampling the output voltage of an actual system and reducing the influence on the system output by using the characteristic of high input resistance; the differential amplification module is used for amplifying or reducing the sampled voltage signal to different selectable degrees so as to adapt to different voltage ranges required by the feedback loop of the actual system; and the high resistance input absolute value module is used for transmitting the feedback voltage after polarity correction to the feedback loop, and then adjusting the actual output voltage value of the actual system through negative feedback. The application can reduce the influence on the working state of the actual system under the condition of ensuring the reliable working of the circuit, can adapt to different system voltage ranges, and improves the universality of the detection system.

Description

Technical Field

[0001] This invention relates to the field of detection circuit technology, and in particular to a bidirectional voltage detection circuit based on a high input impedance absolute value circuit. Background Technology

[0002] In programmable power supplies, to output a stable voltage or current value, it is usually necessary to detect the voltage or current at the output terminal in real time and transmit the detection result back to the input terminal for feedback control. However, when the system supports bidirectional voltage output, traditional voltage detection circuits cannot accurately distinguish the positive and negative polarities of the output voltage. This causes the feedback loop to fail to correctly identify the direction of the output voltage and may generate erroneous feedback. Therefore, designing a high-precision bidirectional voltage detection circuit is crucial for ensuring the stability of the system output. There are several approaches to implementing bidirectional voltage detection circuits, such as Chinese Patent No. CN 112649659 A, published on April 13, 2021, which specifically discloses a bidirectional DC current detection circuit and its detection method, including a sampling unit, an amplification unit, a comparison unit, and a main control chip. The sampling unit collects and amplifies the bidirectional DC signal to form an initial signal; the amplification unit further amplifies the initial signal to obtain an amplified signal; the comparison unit compares the amplified signal with a reference voltage to obtain a comparison result; and the main control chip outputs the corresponding current value based on the comparison result. For example, Chinese Patent No. CN 105977922 A, published on September 28, 2016, discloses a bidirectional overvoltage detection and protection module. It uses four high-voltage fast recovery diodes to form a rectifier bridge to merge the polarity of the measured voltage signal. The merged voltage signal passes sequentially through a current-limiting resistor, a device under test, a sampling resistor, and a Zener diode to obtain an overvoltage signal. The current-limiting resistor, the device under test, and the sampling resistor are connected in series, and the sampling resistor is connected in parallel with the Zener diode. The obtained overvoltage signal is broadened into a wide pulse signal by a single resonant oscillator.

[0003] The shortcomings of existing bidirectional voltage detection circuits are that comparing with a reference voltage makes the design less versatile and imposes significant limitations and requirements on the actual output voltage range; while using full-wave rectification to merge polarities draws or injects current from the system output, which may affect the actual load's operating state and thus reduce the reliability and accuracy of the detection, especially in the field of weak signal detection, where even milliampere or microampere currents can have a significant impact on the system's measurement. Summary of the Invention

[0004] To address the issues of existing bidirectional voltage or current detection circuits lacking versatility and easily affecting the operating state of the device under test, this invention provides a bidirectional voltage detection circuit based on a high input impedance absolute value circuit.

[0005] One aspect of this invention provides a bidirectional voltage detection circuit based on a high input impedance absolute value circuit, comprising: a high-impedance sampling module, a differential amplifier module, and a high-impedance input absolute value module;

[0006] The input terminal of the high-impedance sampling module is connected to the output voltage of the actual system to be tested, and the output terminal is connected to the input terminal of the differential amplifier module, which is used to sample the output voltage of the actual system.

[0007] The output of the differential amplifier module is connected to the input of the high-impedance input absolute value module, and is used to amplify or reduce the sampled voltage signal to different degrees to obtain a feedback voltage, so as to adapt to the different voltage ranges of the feedback loop of the actual system.

[0008] The output terminal of the high-impedance input absolute value module is connected to the feedback loop, and is used to transmit the feedback voltage to the feedback loop after polarity correction, and to adjust the output voltage value of the actual system through negative feedback.

[0009] Optionally, the high-impedance sampling module includes a first operational amplifier and a second operational amplifier;

[0010] The input terminal of the first operational amplifier is connected to the high end of the output voltage of the actual system, and is used to transmit the high end voltage of the actual system to the differential amplifier module.

[0011] The input terminal of the second operational amplifier is connected to the low end of the output voltage of the actual system, and is used to transmit the low-end voltage output by the actual system to the differential amplifier module.

[0012] Optionally, the differential amplifier module includes a first multiplexer, a second multiplexer, a third operational amplifier, and a first proportional coefficient resistor for determining the amplification or reduction ratio;

[0013] The first multiplexer and the second multiplexer are used to amplify or reduce the signal generated by the high-impedance sampling module through the first proportional coefficient resistor and then transmit it to the third operational amplifier.

[0014] Optionally, the first proportional coefficient resistor includes multiple inverting proportional resistors and multiple non-inverting proportional resistors; the first multiplexer and the second multiplexer are inverting multiplexers; and the third operational amplifier is a differential-to-single-ended operational amplifier.

[0015] Optionally, the inverting input proportional resistor includes a plurality of first inverting input proportional resistors and a plurality of second inverting input proportional resistors, and the non-inverting input proportional resistor includes a plurality of first non-inverting input proportional resistors and a plurality of second non-inverting input proportional resistors; the first multiplexer corresponds to the first inverting input multiplexer, and the second multiplexer corresponds to the second inverting input multiplexer.

[0016] One end of the first inverting input proportional resistor is connected to the high-side voltage signal generated by the high-impedance sampling module, and the other end is connected to one end of the second inverting input proportional resistor and the data input terminal of the first inverting input multiplexer, respectively, for inputting the high-side voltage signal generated by the high-impedance sampling module to the inverting input of the differential amplifier module in different proportions;

[0017] The other end of the second inverting proportional resistor is connected to the output of the differential-to-single-ended operational amplifier;

[0018] The data output terminal of the first inverting multiplexer is connected to the inverting input terminal of the differential-to-single-ended operational amplifier;

[0019] One end of the first non-inverting input proportional resistor is connected to the low-end voltage signal generated by the high-impedance sampling module, and the other end is connected to one end of the second non-inverting input proportional resistor and the data input terminal of the second inverting input multiplexer, respectively, for inputting the low-end voltage signal generated by the high-impedance sampling module into the non-inverting input of the differential amplifier module at different ratios;

[0020] The other end of the proportional resistor at the second non-inverting input is grounded;

[0021] The data output terminal of the second inverting multiplexer is connected to the non-inverting input terminal of the differential-to-single-ended operational amplifier;

[0022] The data selection terminals of the first inverting input multiplexer and the second inverting input multiplexer share a set of control signals, which are used to select the same proportion of the first proportional coefficient resistors to connect the output voltage of the actual system to the input terminal of the differential to single-ended operational amplifier in proportion. The control signals include a first control signal and a second control signal.

[0023] The output of the differential-to-single-ended operational amplifier serves as the output voltage of the converted actual system, which is then transmitted to the high-impedance input absolute value module.

[0024] Optionally, the proportional coefficient of the inverting input proportional resistor is equal to the proportional coefficient of the non-inverting input proportional resistor, so that the differential-to-single-ended operational amplifier transmits the output voltage of the actual system proportionally to the high-impedance input absolute value module.

[0025] Optionally, the high-impedance input absolute value module includes a fourth operational amplifier, a first diode, a second diode, a fifth operational amplifier, and a second proportional coefficient resistor.

[0026] Optionally, the second proportional coefficient resistor includes a first resistor, a second resistor, a third resistor, and a fourth resistor;

[0027] One end of the first resistor is grounded, and the other end is connected to the inverting input terminal of the fourth operational amplifier, the cathode of the first diode, and one end of the second resistor, respectively.

[0028] The anode of the first diode is connected to the output terminal of the fourth operational amplifier and the cathode of the second diode, respectively;

[0029] The other end of the second resistor is connected to the anode of the second diode and one end of the third resistor, respectively;

[0030] The other end of the third resistor is connected to one end of the fourth resistor and the inverting input of the fifth operational amplifier, respectively.

[0031] The other end of the fourth resistor is connected to the output terminal of the fifth operational amplifier;

[0032] The non-inverting input terminal of the fourth operational amplifier is connected to the non-inverting input terminal of the fifth operational amplifier and the output voltage of the actual system generated and converted by the differential amplifier module, respectively.

[0033] The output of the fifth operational amplifier serves as a polarity-corrected feedback voltage, which is transmitted to the feedback loop and adjusts the output voltage value of the actual system through negative feedback.

[0034] Optionally, the resistance ratio of the first resistor, the second resistor, the third resistor, and the fourth resistor is 1:1:1:2.

[0035] Optionally, the first operational amplifier, the second operational amplifier, the third operational amplifier, the fourth operational amplifier, and the fifth operational amplifier are all JFET-type operational amplifiers.

[0036] The beneficial effects of this invention are as follows:

[0037] Compared with existing technologies, the present invention provides a bidirectional voltage detection circuit based on a high input impedance absolute value circuit. It can use a high-impedance sampling module and a high-impedance input absolute value module to sample and correct the polarity of the operating voltage of the actual system to be detected, thereby minimizing the impact on the actual system's operating state. In addition, the present invention can amplify or reduce the sampled voltage signal to different degrees through a differential amplifier module, thus improving its versatility and adapting to different system voltage ranges. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A schematic diagram of a bidirectional voltage detection circuit based on a high input impedance absolute value circuit is provided for an embodiment of the present invention.

[0040] Figure 2 An example circuit diagram of a high-impedance sampling module provided in an embodiment of the present invention;

[0041] Figure 3 An example circuit diagram of a differential amplifier module provided in an embodiment of the present invention;

[0042] Figure 4 This is an example circuit diagram of a high-impedance input absolute value module provided in an embodiment of the present invention. Detailed Implementation

[0043] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figure 1 As shown, this embodiment of the invention provides a bidirectional voltage detection circuit based on a high input impedance absolute value circuit, including a high-impedance sampling module, a differential amplifier module, and a high-impedance input absolute value module.

[0045] like Figure 2As shown, the high-impedance sampling module includes a first operational amplifier U1 and a second operational amplifier U2. The input terminal of the first operational amplifier U1 is connected to the high end Vin_H of the actual system's output voltage, while the input terminal of the second operational amplifier U2 is connected to the low end Vin_L of the actual system's output voltage. Overall, the high-impedance sampling module is used to sample the output voltage of the actual system, while utilizing the high-impedance characteristic to reduce the impact on the system output.

[0046] like Figure 3 As shown, the differential amplifier module includes a first multiplexer U3, a second multiplexer U4, a third operational amplifier U5, and resistors R1 to R16 for determining the amplification or reduction ratio, i.e., first proportional coefficient resistors. The first proportional coefficient resistors include multiple inverting input proportional resistors and multiple non-inverting input proportional resistors. Further, the inverting input proportional resistors include multiple first inverting input proportional resistors and multiple second inverting input proportional resistors, and the non-inverting input proportional resistors include multiple first non-inverting input proportional resistors and multiple second non-inverting input proportional resistors. Specifically, the first inverting input proportional resistors correspond to R1 to R4, the second inverting input proportional resistors correspond to R9 to R12, the first non-inverting input proportional resistors correspond to R5 to R8, and the second non-inverting input proportional resistors correspond to R13 to R16.

[0047] Specifically, the data input terminal of the first multiplexer U3 is connected to the middle of the inverting input proportional resistors R1 to R4 and R9 to R12, while the other end of the inverting input proportional resistors R1 to R4 is connected to the high-side voltage signal Vin_H_buffer generated by the high-impedance sampling module. The other end of R9 to R12 is connected to the output terminal of the third operational amplifier U5, and the data output terminal of the first multiplexer U3 is connected to the inverting input terminal of the third operational amplifier U5. The connection method of the second multiplexer U4 is similar and will not be described again. The other end of the non-inverting input proportional resistors R5 to R8 is connected to the low-side voltage signal Vin_L_buffer generated by the high-impedance sampling module, and the other end of R13 to R16 is grounded. In addition, the data selection terminals of the first multiplexer U3 and the second multiplexer U4 share a set of selection signals S0 and S1. Overall, the differential amplifier module is used to amplify or reduce the sampled voltage signal to different degrees to adapt to different voltage ranges of the system feedback loop.

[0048] like Figure 4 As shown, the high-impedance input absolute value module includes a fourth operational amplifier U6, a first diode D1, a second diode D2, a fifth operational amplifier U7, and proportional resistors R17 to R20 to ensure the normal operation of the absolute value module, i.e., the second proportional coefficient resistors. The second proportional coefficient resistors may include a first resistor, a second resistor, a third resistor, and a fourth resistor, corresponding to R17 to R20 respectively.

[0049] Specifically, one end of resistor R17 is grounded, and the other end is connected to the inverting input of the fourth operational amplifier U6, the cathode of the first diode D1, and one end of resistor R18. The output of the fourth operational amplifier U6 is connected to the anode of the first diode D1 and the cathode of the second diode D2. The other end of resistor R18 is connected to the anode of the second diode D2 and one end of resistor R19. The inverting input of the fifth operational amplifier U7 is connected between resistors R19 and R20, and resistor R20 is connected to the output of the fifth operational amplifier U7. At the same time, the non-inverting inputs of the fourth operational amplifier U6 and the fifth operational amplifier U7 are connected to the converted system output voltage VFB generated by the differential amplifier module. Overall, the high-impedance input absolute value module is used to transmit the feedback voltage to the feedback loop after polarity correction, thereby adjusting the actual output voltage value of the system through negative feedback.

[0050] Specifically, such as Figure 2 As shown, the high-impedance sampling module uses JFET-type operational amplifiers U1 and U2 to form two voltage follower buffers, which buffer the high-end Vin_H and low-end Vin_L of the actual system output voltage into Vin_H_buffer and Vin_L_buffer respectively, and then pass them to the subsequent differential amplifier module.

[0051] like Figure 3 As shown, the differential amplifier module, through different combinations of proportional resistors, combined with multiplexers U3 and U4 and operational amplifier U5, constitutes a differential amplifier capable of achieving various different gains. After the high-side buffer Vin_H_buffer and low-side buffer Vin_L_buffer signals generated by the high-impedance sampling module are differentially converted into single-ended signals, a voltage difference signal VFB is generated and transmitted to the subsequent high-impedance input absolute value module.

[0052] like Figure 3 As shown, in this embodiment, the differential amplifier module forms a differential amplifier with four different gains through two four-way multiplexers. Taking resistors R1, R9, R5, and R13 as an example, if the ratio of R9 to R1 is β and the ratio of R13 to R5 is α, according to the principle of the differential amplifier structure, the voltage difference signal VFB in this case can be obtained as:

[0053]

[0054] From the above formula, if the ratio of resistors R1 to R4 to R9 to R12 is equal to the ratio of resistors R5 to R8 to R13 to R16, then in the above example, α = β. Therefore, the voltage difference signal VFB can be simplified as:

[0055] VFB=(V in_L_buffer-V in_H_buffer )×α

[0056] Therefore, the gain of the differential amplifier module is only related to the ratio between the different proportional resistors. Thus, the gain of the differential amplifier module can be controlled by controlling the ratio between the proportional resistors, thereby supporting a more flexible voltage input range.

[0057] like Figure 4 As shown, the high-impedance input absolute value module uses JFET-type operational amplifiers U6 and U7, combined with two nonlinear devices, diodes D1 and D2, to form an absolute value circuit structure with high-impedance input characteristics. This transforms the voltage difference signal VFB generated by the differential amplifier module into a polarity-corrected absolute value voltage signal VFB_abs, which is then transmitted to the system's feedback loop to stabilize the system's output voltage.

[0058] like Figure 4 As shown, in this embodiment, the resistance ratio of resistors R17, R18, R19, and R20 should be 1:1:1:2 to ensure normal circuit operation. Meanwhile, diodes D1 and D2 divide the circuit into two different structures according to the polarity of the input signal. Taking the input signal VFB as a negative voltage signal as an example, diode D1 is turned off and D2 is turned on. At this time, operational amplifier U6 forms a non-inverting amplifier structure with a gain of 2, and is cascaded with operational amplifier U7 to form an overall inverting circuit.

[0059] Specifically, when the input signal VFB is a negative voltage signal -V, since the gain of the non-inverting proportional amplifier structure of operational amplifier U6 is 2, the voltage at the midpoint between resistors R18 and R19 is -2V. Due to the open-loop gain characteristic of operational amplifier U7, the voltage at the midpoint between resistors R19 and R20 is -V. Finally, using the series relationship between resistors R19 and R20, and the ratio that R20 is twice the resistance of R19, the final output voltage of operational amplifier U7 is +V, thus achieving the inversion of the input signal VFB.

[0060] When the input signal VFB is a positive voltage signal, it can be proven through a similar derivation process that the output voltage is equal to the input voltage.

[0061] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

[0062] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A bidirectional voltage detection circuit based on a high input impedance absolute value circuit, characterized in that, The application relates to a high-impedance sampling module, a differential amplification module and a high-impedance input absolute value module. The input end of the high-impedance sampling module is connected with the output voltage of an actual system to be detected, and the output end is connected with the input end of the differential amplification module, so as to sample the output voltage of the actual system. The output end of the differential amplification module is connected with the input end of the high-impedance input absolute value module, so as to amplify or reduce the sampled voltage signal to different degrees and obtain a feedback voltage, so as to adapt to different voltage ranges of a feedback loop of the actual system. The output end of the high-impedance input absolute value module is connected with the feedback loop, so as to transmit the feedback voltage to the feedback loop after polarity correction and adjust the output voltage value of the actual system through negative feedback. The high-impedance sampling module comprises a first operational amplifier and a second operational amplifier. The input end of the first operational amplifier is connected with the high end of the output voltage of the actual system, so as to transmit the high end voltage output by the actual system to the differential amplification module. The input end of the second operational amplifier is connected with the low end of the output voltage of the actual system, so as to transmit the low end voltage output by the actual system to the differential amplification module. The first operational amplifier and the second operational amplifier are both JFET input type operational amplifiers. Vin_H_buffer and Vin_L_buffer are high end buffer signals and low end buffer signals generated by the high-impedance sampling module. The differential amplification module forms a differential amplifier with four different gains through two four-way multiplexers, and the differential amplification module comprises resistors R1, R9, R5 and R13, wherein the ratio of R9 to R1 is , the ratio of R13 to R5 is , and according to the principle of the differential amplification structure, the voltage difference signal VFB in this case is obtained as follows: ； The differential amplification module comprises a first multiplexer, a second multiplexer, a third operational amplifier and a first proportional coefficient resistor for determining amplification or reduction ratio; the third operational amplifier is a JFET input type operational amplifier.

2. The bidirectional voltage detection circuit based on the high input impedance absolute value circuit according to claim 1, characterized in that, The first multiplexer and the second multiplexer are used for transmitting the signal generated by the high-impedance sampling module to the third operational amplifier after amplification or reduction through the first proportional coefficient resistor. The first proportional coefficient resistor comprises a plurality of inverse terminal proportional resistors and a plurality of same terminal proportional resistors; the first multiplexer and the second multiplexer are inverse terminal multiplexers.

3. The bidirectional voltage detection circuit based on high input impedance absolute value circuit according to claim 2, characterized in that, The third operational amplifier is a differential to single end operational amplifier. The inverse terminal proportional resistors comprise a plurality of first inverse terminal proportional resistors and a plurality of second inverse terminal proportional resistors; the same terminal proportional resistors comprise a plurality of first same terminal proportional resistors and a plurality of second same terminal proportional resistors; the first multiplexer corresponds to a first inverse terminal multiplexer, and the second multiplexer corresponds to a second inverse terminal multiplexer.

4. The bidirectional voltage detection circuit based on the high input impedance absolute value circuit according to claim 3, characterized in that, One end of the first inverse terminal proportional resistor is connected with the high end voltage signal generated by the high-impedance sampling module, and the other end is connected with one end of the second inverse terminal proportional resistor and a data input end of the first inverse terminal multiplexer respectively, so as to connect the high end voltage signal generated by the high-impedance sampling module to the inverse terminal of the differential amplification module in different proportions. The other end of the second inverse terminal proportional resistor is connected with the output end of the differential to single end operational amplifier. ​ The data output end of the first opposite-phase end multiplexer is connected with the opposite-phase input end of the differential-to-single-end operational amplifier; One end of the first same-phase end proportional resistor is connected with the low-end voltage signal generated by the high-impedance sampling module, and the other end is connected with one end of the second same-phase end proportional resistor and the data input end of the second opposite-phase end multiplexer respectively, for connecting the low-end voltage signal generated by the high-impedance sampling module into the same-phase end of the differential amplification module in different proportions; The other end of the second same-phase end proportional resistor is grounded; The data output end of the second opposite-phase end multiplexer is connected with the same-phase input end of the differential-to-single-end operational amplifier; The data selection ends of the first opposite-phase end multiplexer and the second opposite-phase end multiplexer share a group of control signals, for selecting the same proportion of the first proportional coefficient resistor to connect the output voltage of the actual system into the input end of the differential-to-single-end operational amplifier proportionally, and the control signals include a first control signal and a second control signal; The output end of the differential-to-single-end operational amplifier is used as the converted output voltage of the actual system, for being transmitted to the high-impedance input absolute value module.

5. The bidirectional voltage detection circuit based on high input impedance absolute value circuit according to claim 3, characterized in that, The proportional coefficient of the opposite-phase end proportional resistor is equal to the proportional coefficient of the same-phase end proportional resistor, so that the differential-to-single-end operational amplifier transmits the output voltage of the actual system to the high-impedance input absolute value module proportionally.

6. The bidirectional voltage detection circuit based on high input impedance absolute value circuit according to claim 1, characterized in that, The high-impedance input absolute value module includes a fourth operational amplifier, a first diode, a second diode, a fifth operational amplifier and a second proportional coefficient resistor; the fourth operational amplifier and the fifth operational amplifier are both JFET input type operational amplifiers.

7. The bidirectional voltage detection circuit based on high input impedance absolute value circuit according to claim 6, characterized in that, The second proportional coefficient resistor includes a first resistor, a second resistor, a third resistor and a fourth resistor; One end of the first resistor is grounded, and the other end is connected with the opposite-phase input end of the fourth operational amplifier, the cathode of the first diode and one end of the second resistor respectively; The anode of the first diode is connected with the output end of the fourth operational amplifier and the cathode of the second diode respectively; The other end of the second resistor is connected with the anode of the second diode and one end of the third resistor respectively; The other end of the third resistor is connected with one end of the fourth resistor and the opposite-phase input end of the fifth operational amplifier respectively; The other end of the fourth resistor is connected with the output end of the fifth operational amplifier; The same-phase input end of the fourth operational amplifier is connected with the same-phase input end of the fifth operational amplifier and the converted output voltage of the actual system generated by the differential amplification module respectively; The output end of the fifth operational amplifier is used as the feedback voltage after polarity correction, for being transmitted to the feedback loop and adjusting the output voltage value of the actual system through negative feedback.

8. The bidirectional voltage detection circuit based on the high input impedance absolute value circuit according to claim 7, characterized in that, The resistance values of the first resistor, the second resistor, the third resistor and the fourth resistor are in the proportion of 1:1:1:2.

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