An ac-dc separation circuit and an ac-dc separation device

Abstract

The utility model discloses a kind of AC-DC separation circuit and AC-DC separation device, for current processing technical field.Wherein, the positive pole of current signal source is connected with voltage power supply, the negative pole of current signal source is connected with the opposite phase input end of transimpedance amplifier and the input end of transistor;The input end of voltage division module is connected with voltage power supply, the output end of voltage division module is connected with the same phase input end of transimpedance amplifier and the same phase input end of operational amplifier integration module;The positive power supply end of transimpedance amplifier is connected with voltage power supply, the negative power supply end of transimpedance amplifier is grounded, the output end of transimpedance amplifier is connected with the opposite phase input end of operational amplifier integration module;The positive power supply end of operational amplifier integration module is connected with voltage power supply, the negative power supply end of operational amplifier integration module is grounded, the output end of operational amplifier integration module is connected with the conduction control end of transistor, the output end of transistor is grounded;It can divide into two channels that do not interfere with each other by the AC-DC signal input of current signal source.

Description

Technical Field

[0001] This utility model relates to the field of current processing technology, and in particular to an AC / DC separation circuit and an AC / DC separation device. Background Technology

[0002] In electronic systems, current signals are often a superposition of direct current (DC) and alternating current (AC) components. A DC signal refers to a current signal whose direction and magnitude do not change with time, with a frequency of 0 Hz, and its waveform is a horizontal straight line. An AC signal refers to a current signal whose direction and magnitude change periodically with time, with a frequency greater than 0 Hz, and its waveform is typically a sine wave, square wave, or triangle wave. Since the current signal output by a sensor may contain a stable DC bias signal and an AC signal that varies with the physical quantity, AC / DC splitting circuits are often used to separate the coexisting DC and AC signals in the current signal to meet different application requirements.

[0003] Existing AC / DC separation circuits often utilize the characteristic of capacitors to pass AC while blocking DC to separate DC signals from current signals. However, in such AC / DC separation circuits, the separated DC signal is blocked at one end of the capacitor, lacking an effective DC path for processing the DC signal, which can easily lead to interference between AC and DC signals. Utility Model Content

[0004] This invention provides an AC / DC separation circuit and an AC / DC separation device, which can split AC / DC signals into two non-interfering channels.

[0005] This utility model provides an AC / DC separation circuit, including: a current signal source, a voltage power supply, a voltage divider module, a transimpedance amplifier, an operational amplifier integration module, and a transistor;

[0006] The positive terminal of the current signal source is connected to the voltage power supply, and the negative terminal of the current signal source is connected to the inverting input terminal of the transimpedance amplifier and the input terminal of the transistor; the current signal of the current signal source includes: DC signal and AC signal;

[0007] The input terminal of the voltage divider module is connected to the voltage power supply, and the output terminal of the voltage divider module is connected to the non-inverting input terminal of the transimpedance amplifier and the non-inverting input terminal of the operational amplifier integration module; wherein, the voltage output by the voltage divider module is less than the voltage corresponding to the DC signal input to the inverting input terminal of the transimpedance amplifier;

[0008] The positive power supply terminal of the transimpedance amplifier is connected to the voltage power supply, the negative power supply terminal of the transimpedance amplifier is grounded, and the output terminal of the transimpedance amplifier is connected to the inverting input terminal of the operational amplifier integration module.

[0009] The positive power supply terminal of the operational amplifier integrator module is connected to the voltage power supply, the negative power supply terminal of the operational amplifier integrator module is grounded, the output terminal of the operational amplifier integrator module is connected to the conduction control terminal of the transistor, and the output terminal of the transistor is grounded; the transistor is a switching transistor with high-level conduction characteristics.

[0010] Furthermore, the voltage divider module includes: a first voltage divider resistor and a second voltage divider resistor;

[0011] One end of the first voltage divider resistor is connected to the voltage power supply, and the other end of the first voltage divider resistor is connected to one end of the second voltage divider resistor, the non-inverting input terminal of the transimpedance amplifier, and the non-inverting input terminal of the operational amplifier integration module; the other end of the second voltage divider resistor is grounded.

[0012] Furthermore, the voltage divider module also includes a filter capacitor; one end of the filter capacitor is connected to one end of the second voltage divider resistor, and the other end of the filter capacitor is grounded.

[0013] Furthermore, the transimpedance amplifier includes: a first operational amplifier and a first feedback resistor;

[0014] The inverting input terminal of the first operational amplifier is connected to the negative terminal of the current signal source and one end of the first feedback resistor; the resistance value of the first feedback resistor is greater than a preset resistance threshold.

[0015] The non-inverting input of the first operational amplifier is connected to the output of the voltage divider module, the positive power supply of the first operational amplifier is connected to the voltage power supply, the negative power supply of the first operational amplifier is grounded, and the output of the first operational amplifier is connected to the other end of the first feedback resistor and the inverting input of the operational amplifier integration module.

[0016] Furthermore, the operational amplifier integration module includes: a second operational amplifier, an input resistor, and an integration feedback unit;

[0017] One end of the input resistor is connected to the output terminal of the transimpedance amplifier, and the other end of the input resistor is connected to the inverting input terminal of the second operational amplifier and one end of the integral feedback unit.

[0018] The non-inverting input of the second operational amplifier is connected to the output of the voltage divider module, the positive power supply of the second operational amplifier is connected to the voltage power supply, the negative power supply of the second operational amplifier is grounded, and the output of the second operational amplifier is connected to the other end of the integral feedback unit and the conduction control terminal of the transistor.

[0019] Furthermore, the integral feedback unit includes: a second feedback resistor and an integral capacitor;

[0020] One end of the second feedback resistor and one end of the integrating capacitor are connected to the inverting input terminal of the second operational amplifier;

[0021] The other end of the second feedback resistor and the other end of the integrating capacitor are connected to the output terminal of the second operational amplifier.

[0022] Furthermore, the transistor includes: an NPN transistor;

[0023] The base of the NPN transistor is connected to the output terminal of the operational amplifier integration module, the collector of the NPN transistor is connected to the negative terminal of the current signal source, and the emitter of the NPN transistor is grounded through a resistor.

[0024] Furthermore, the transistor includes: an NMOS transistor;

[0025] The gate of the NMOS transistor is connected to the output terminal of the operational amplifier integration module, the drain of the NMOS transistor is connected to the negative terminal of the current signal source, and the source of the NMOS transistor is grounded through a resistor.

[0026] Furthermore, this also includes: current-limiting resistors;

[0027] One end of the current-limiting resistor is connected to the output terminal of the operational amplifier integration module, and the other end of the current-limiting resistor is connected to the conduction control terminal of the transistor.

[0028] This application also provides an AC / DC separation device, which includes the AC / DC separation circuit described above.

[0029] As can be seen from the above technical solutions, this utility model has the following advantages:

[0030] In this invention, the AC / DC separation circuit includes: a current signal source, a voltage power supply, a voltage divider module, a transimpedance amplifier, an operational amplifier integrator module, and a transistor. The positive terminal of the current signal source is connected to the voltage power supply, and the negative terminal of the current signal source is connected to the inverting input terminal of the transimpedance amplifier and the input terminal of the transistor. The current signal of the current signal source includes both DC and AC signals. The input terminal of the voltage divider module is connected to the voltage power supply, and the output terminal of the voltage divider module is connected to the non-inverting input terminal of the transimpedance amplifier and the non-inverting input terminal of the operational amplifier integrator module. The voltage output by the voltage divider module is less than the voltage corresponding to the DC signal input to the inverting input terminal of the transimpedance amplifier. The positive power supply terminal of the transimpedance amplifier is connected to the voltage power supply, the negative power supply terminal of the transimpedance amplifier is grounded, and the output terminal of the transimpedance amplifier is connected to the inverting input terminal of the operational amplifier integrator module. The positive power supply terminal of the operational amplifier integrator module is connected to the voltage power supply, the negative power supply terminal of the operational amplifier integrator module is grounded, the output terminal of the operational amplifier integrator module is connected to the conduction control terminal of the transistor, and the output terminal of the transistor is grounded. The transistor is a high-level conduction switching transistor.

[0031] As can be seen, in this invention, when a DC signal is input from a current signal source, the voltage output from the voltage divider module is less than the voltage corresponding to the DC signal input from the inverting input of the transimpedance amplifier. The transimpedance amplifier is in reverse saturation, and its output voltage is limited to the zero potential corresponding to ground. The operational amplifier integrator module is in forward saturation, and its output voltage is limited to the high potential corresponding to the voltage power supply. The operational amplifier integrator module provides fast feedback response to control the transistor to turn on, and the DC signal reaches ground through the transistor. However, because the capacitive reactance of the operational amplifier integrator module to high-frequency AC signals is small, its feedback speed cannot keep up with the rapid fluctuations of the AC signal. When an AC signal is input, the transistor's on / off state cannot keep up with the rapid fluctuations of the AC signal, and the AC signal cannot reach ground through the transistor. The AC signal can only be amplified and output through the transimpedance amplifier. In other words, in the AC / DC separation circuit, the DC signal input from the current signal source reaches ground through the transistor, and the AC signal input from the current signal source is amplified and output through the transimpedance amplifier, thus separating the AC and DC signals into two non-interfering channels. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0033] Figure 1 This is a circuit block diagram of an AC / DC separation circuit disclosed in this utility model;

[0034] Figure 2This is a circuit diagram of an AC / DC separation circuit disclosed in this utility model;

[0035] Figure 3 This is a circuit diagram of another AC / DC separation circuit disclosed in this utility model. Detailed Implementation

[0036] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0037] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0038] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0039] In electronic systems, current signals are often a superposition of direct current (DC) and alternating current (AC) components. A DC signal refers to a current signal whose direction and magnitude do not change with time, with a frequency of 0 Hz, and its waveform is a horizontal straight line. An AC signal refers to a current signal whose direction and magnitude change periodically with time, with a frequency greater than 0 Hz, and its waveform is typically a sine wave, square wave, or triangle wave. Since the current signal output by a sensor may contain a stable DC bias signal and an AC signal that varies with the physical quantity, AC / DC splitting circuits are often used to separate the coexisting DC and AC signals in the current signal to meet different application requirements.

[0040] Existing AC / DC splitter circuits often utilize the characteristic of capacitors to separate DC and AC signals in a current signal, allowing AC signals to pass while blocking DC signals. However, in these circuits, the separated DC signal is blocked at one end of the capacitor, lacking an effective DC path for processing, which easily leads to AC / DC signal interference. Therefore, this invention provides an AC / DC splitter circuit capable of separating AC and DC signals into two non-interfering channels, such as... Figure 1 As shown, the details are as follows:

[0041] In this invention, the AC / DC separation circuit includes: a current signal source I100, a voltage power supply VCC, a voltage divider module 100, a transimpedance amplifier 200, an operational amplifier integrator module 300, and a transistor. The positive terminal of the current signal source I100 is connected to the voltage power supply VCC, and the negative terminal of the current signal source I100 is connected to the inverting input terminal of the transimpedance amplifier 200 and the input terminal of the transistor. The current signal output by the current signal source I100 can flow to the inverting input terminal of the transimpedance amplifier 200 and the input terminal of the transistor. The current signal of the current signal source I100 includes both DC and AC signals. The current source I100 is a constant current source and requires voltage drive. By connecting the positive terminal of the current source I100 to the voltage power supply VCC, the current source I100 can generate a constant current signal. This current signal is typically a weak current signal, such as microamperes (µA) or nanoamperes (nA). The DC signal (dc) in the current source I100 can be 1µA, and the AC signal (ac) can be 1nA. The DC signal in the current source I100 is much larger than the AC signal. The voltage power supply VCC can be a VCC3V3 power supply, i.e., a 3.3V voltage source.

[0042] The input terminal of the voltage divider module 100 is connected to the voltage power supply VCC, and the output terminal of the voltage divider module 100 is connected to the non-inverting input terminal of the transimpedance amplifier 200 and the non-inverting input terminal of the operational amplifier integrator module 300. It can be understood that the voltage divider module 100 is used to divide the voltage power supply VCC, and the output voltage after voltage division is less than the voltage of the voltage power supply. That is, the non-inverting input terminal of the transimpedance amplifier 200 receives the voltage after voltage division from the voltage power supply VCC, and the non-inverting input terminal of the operational amplifier integrator module 300 receives the same voltage after voltage division. The transimpedance amplifier 200 can be called a transimpedance operational amplifier. As the first-stage operational amplifier circuit, the transimpedance amplifier 200 is mainly used to convert the current signal from the current signal source I100 into a voltage signal. The operational amplifier integrator module 300, as the second-stage operational amplifier circuit, is mainly used to perform integration operations on the input signal, that is, the output signal is proportional to the integral of the input signal. In this case, the voltage output by the voltage divider module 100 is less than the voltage corresponding to the DC signal input to the inverting input of the transimpedance amplifier 200. At this time, the voltage divided by the voltage divider module 100 is input to the non-inverting input of the transimpedance amplifier 200, and the voltage corresponding to the DC signal from the current signal source I100 is input to the inverting input of the transimpedance amplifier 200. The transimpedance amplifier 200 is in reverse saturation state.

[0043] The positive power supply terminal V+ of the transimpedance amplifier 200 is connected to the voltage power supply VCC, and the negative power supply terminal V- is grounded. The output terminal OUT of the transimpedance amplifier 200 is connected to the inverting input terminal of the operational amplifier integrator module 300. It can be understood that, since the transimpedance amplifier 200 is in reverse saturation, the output voltage of the transimpedance amplifier 200 is limited to the zero potential of the negative power supply terminal V- grounded, that is, the output voltage of the transimpedance amplifier 200 is close to 0V. At this time, the voltage input to the inverting input terminal of the operational amplifier integrator module 300 is also close to 0V.

[0044] The positive power supply terminal V+ of the operational amplifier integrator module 300 is connected to the voltage power supply VCC, and the negative power supply terminal v- is grounded. The output terminal of the operational amplifier integrator module 300 is connected to the turn-on control terminal of the transistor, and the output terminal of the transistor is grounded. The transistor is a high-level turn-on switching transistor. This transistor can be an NPN transistor or an NMOS transistor, which is not limited here. It can be understood that when the AC / DC separation circuit starts running, the transistor is in the off state, and the DC signal from the current signal source I100 is converted into a voltage output by the transimpedance amplifier 200. At this time, the non-inverting input terminal of the operational amplifier integrator module 300 receives the voltage after voltage division, and the inverting input terminal receives 0V. The operational amplifier integrator module 300 is in a positive saturation state, and the output of the operational amplifier integrator module 300 is limited to the high-level voltage corresponding to the voltage power supply VCC, such as close to 3.3V. At this time, a high-level voltage is input to the transistor's conduction control terminal, and the transistor conducts; that is, the operational amplifier integration module 300 quickly feeds back to control the transistor to conduct, and the DC signal of the current signal source I100 is grounded through the transistor; while the AC signal of the current signal source I100 cannot be fed back quickly in the operational amplifier integration module 300, so the AC signal of the current signal source I100 is converted into an AC voltage amplified signal by the transimpedance amplifier 200.

[0045] It is understandable that the current signal source I100 is a constant current source, and the first-stage operational amplifier circuit corresponding to the transimpedance amplifier 200 and the second-stage operational amplifier circuit corresponding to the operational amplifier integration module 300 can jointly form an adaptive constant current source driving circuit, thereby sending the DC signal of the current signal source I100 to ground through the transistor.

[0046] As can be seen, the AC / DC separation circuit of this utility model includes: a current signal source, a voltage power supply, a voltage divider module, a transimpedance amplifier, an operational amplifier integrator module, and a transistor; the positive terminal of the current signal source is connected to the voltage power supply, and the negative terminal of the current signal source is connected to the inverting input terminal of the transimpedance amplifier and the input terminal of the transistor; the current signal of the current signal source includes: a DC signal and an AC signal; the input terminal of the voltage divider module is connected to the voltage power supply, and the output terminal of the voltage divider module is connected to the non-inverting input terminal of the transimpedance amplifier and the non-inverting input terminal of the operational amplifier integrator module; wherein, the voltage output by the voltage divider module is less than the voltage corresponding to the DC signal input to the inverting input terminal of the transimpedance amplifier; the positive power supply terminal of the transimpedance amplifier is connected to the voltage power supply, the negative power supply terminal of the transimpedance amplifier is grounded, and the output terminal of the transimpedance amplifier is connected to the inverting input terminal of the operational amplifier integrator module; the positive power supply terminal of the operational amplifier integrator module is connected to the voltage power supply, the negative power supply terminal of the operational amplifier integrator module is grounded, the output terminal of the operational amplifier integrator module is connected to the conduction control terminal of the transistor, and the output terminal of the transistor is grounded; the transistor is a high-level conduction switching transistor.

[0047] In this invention, for a DC signal input from a current signal source, the voltage output from the voltage divider module is less than the voltage corresponding to the DC signal input from the inverting input of the transimpedance amplifier. The transimpedance amplifier is in reverse saturation, and its output voltage is limited to the zero potential corresponding to ground. The operational amplifier integrator module is in forward saturation, and its output voltage is limited to the high potential corresponding to the voltage supply. The operational amplifier integrator module provides fast feedback response to control the transistor to turn on, allowing the DC signal to reach ground through the transistor. However, because the capacitive reactance of the operational amplifier integrator module to high-frequency AC signals is small, its feedback speed cannot keep up with the rapid fluctuations of the AC signal. That is, the AC signal cannot be fed back quickly by the operational amplifier integrator module, and the transistor's on / off state cannot keep up with the rapid fluctuations of the AC signal. Therefore, the AC signal cannot reach ground through the transistor and can only be amplified and output by the transimpedance amplifier. In other words, in the AC / DC separation circuit, the DC signal input from the current signal source reaches ground through the transistor, and the AC signal input from the current signal source is amplified and output by the transimpedance amplifier, thus splitting the AC and DC signals into two non-interfering channels. This completes the separation of AC and DC signals from the current signal source. Both the AC and DC signals of the current signal source have independent channels for transmission. Furthermore, the AC signal of the current signal source can be amplified to avoid attenuation of the AC signal after AC / DC separation.

[0048] Furthermore, the following will combine Figure 2 The AC / DC separation circuit in this utility model is described in detail, such as... Figure 2 As shown:

[0049] In the AC / DC separation circuit of this utility model, the voltage divider module 100 includes: a first voltage divider resistor R100 and a second voltage divider resistor R101; one end of the first voltage divider resistor R100 is connected to the voltage power supply VCC, and the other end of the first voltage divider resistor R100 is connected to one end of the second voltage divider resistor R101, the non-inverting input terminal of the transimpedance amplifier 200, and the non-inverting input terminal of the operational amplifier integrator module 300; the other end of the second voltage divider resistor R101 is grounded. That is, the non-inverting input terminal of the transimpedance amplifier 200 and the non-inverting input terminal of the operational amplifier integrator module 300 are connected to the voltage division point of the first voltage divider resistor R100 and the second voltage divider resistor R101, and the voltage Vref (reference voltage) after voltage division is input. The first voltage divider resistor R100 and the second voltage divider resistor R101 can be 100KΩ. When the voltage power supply VCC is 3.3V, the voltage Vref after voltage division is 1.65V.

[0050] Furthermore, the voltage divider module 100 also includes a filter capacitor C100; one end of the filter capacitor C100 is connected to one end of the second voltage divider resistor R101, and the other end of the filter capacitor C100 is grounded. It can be understood that the filter capacitor C100 and the second voltage divider resistor R101 form an RC low-pass filter, which can filter out high-frequency ripple or noise in the voltage power supply VCC, ensuring a stable divided voltage Vref input to the non-inverting input of the transimpedance amplifier 200 and the non-inverting input of the operational amplifier integrator module 300. The filter capacitor C100 can be 10uF.

[0051] Furthermore, in this invention, the transimpedance amplifier 200 can be a differential input transimpedance amplifier or an active feedback transimpedance amplifier, and the specific type is not limited here. Preferably, the transimpedance amplifier 200 includes: a first operational amplifier U101 (LMV321) and a first feedback resistor R104; the inverting input terminal of the first operational amplifier U101 is connected to the negative terminal of the current signal source I100 and one end of the first feedback resistor R104; the resistance value of the first feedback resistor R104 is greater than a preset resistance threshold. This preset resistance threshold is greater than Vref / dc, that is, the preset resistance threshold is greater than the quotient of the voltage Vref after voltage division by the voltage divider module 100 divided by the DC signal dc of the current signal source I100, so that the voltage output by the voltage divider module 100 is less than the voltage corresponding to the DC signal input to the inverting input terminal of the transimpedance amplifier 200. It is understood that the resistance value of the first feedback resistor R104 is less than a first resistance threshold, which is less than Vref / ac. That is, the first resistance threshold is less than the quotient of the voltage Vref after voltage division by the voltage divider module 100 divided by the AC signal ac of the current signal source. This ensures that the voltage output from the output terminal of the voltage divider module 100 is greater than the voltage corresponding to the AC signal input to the inverting input terminal of the transimpedance amplifier 200, causing the transimpedance amplifier 200 to saturate in the forward direction and amplify the input AC signal. When the voltage supply is 3.3V, the DC signal of the current signal source is 1uA, and the AC signal of the current signal source is 1nA, the resistance value of the first resistor R104 can be 20MΩ or 25MΩ; the specific value is not limited here.

[0052] The non-inverting input of the first operational amplifier U101 is connected to the output of the voltage divider module 100. The positive power supply terminal V+ of the first operational amplifier U101 is connected to the voltage power supply VCC, and the negative power supply terminal V- is grounded. The output of the first operational amplifier U101 is connected to the other end of the first feedback resistor R104 and the inverting input of the operational amplifier integration module 300. It can be understood that the output signal of the first operational amplifier U101... Where I is the DC signal of the current signal source I100. It can be understood that the non-inverting input, inverting input, positive power supply, negative power supply, and output of the first operational amplifier U101 are the same as the non-inverting input, inverting input, positive power supply, negative power supply, and output of the transimpedance amplifier 200.

[0053] Furthermore, in this invention, the operational amplifier integration module 300 can be an active integration circuit or a dual-power supply integration circuit, and the specific design is not limited here. Preferably, the operational amplifier integration module 300 includes: a second operational amplifier U102, an input resistor R102, and an integration feedback unit 301; the input resistor R102 can be 1MΩ, one end of the input resistor R102 is connected to the output terminal of the transimpedance amplifier 200, and the other end of the input resistor R102 is connected to the inverting input terminal of the second operational amplifier U102 and one end of the integration feedback unit 301.

[0054] The non-inverting input of the second operational amplifier U102 is connected to the output of the voltage divider module 100. The positive power supply terminal V+ of the second operational amplifier U102 is connected to the voltage power supply VCC, and the negative power supply terminal V- is grounded. The output of the second operational amplifier U102 is connected to the other end of the integrating feedback unit 301 and the conduction control terminal of the transistor Q100. It can be understood that the non-inverting input, inverting input, positive power supply terminal, negative power supply terminal, and output of the second operational amplifier U102 are the same as the non-inverting input, inverting input, positive power supply terminal, negative power supply terminal, and output of the operational amplifier integrating module 300.

[0055] Furthermore, the integral feedback unit 301 includes a second feedback resistor R103 and an integrating capacitor C101; the second feedback resistor R103 can be 10MΩ, and the integrating capacitor C101 can be 10μF; one end of the second feedback resistor R103 and one end of the integrating capacitor C101 are connected to the inverting input terminal of the second operational amplifier U102; the other end of the second feedback resistor R103 and the other end of the integrating capacitor C101 are connected to the output terminal of the second operational amplifier U102. That is, the second feedback resistor R103 and the integrating capacitor C101 are connected in parallel to form the integral feedback unit 301 in the operational amplifier integration module 300, forming a corresponding feedback network.

[0056] Furthermore, in this invention, transistor Q100 includes: an NPN transistor; the base of the NPN transistor is connected to the output terminal of the operational amplifier integration module 300, the collector of the NPN transistor is connected to the negative terminal of the current signal source I100, and the emitter of the NPN transistor is grounded through resistor R106.

[0057] Combination Figure 2When the voltage supply VCC is 3.3V, the working principle of the AC / DC separation circuit is as follows: When the AC / DC separation circuit starts running, the NPN transistor Q100 is in the off state, and the DC signal from the current signal source I100 is completely converted into a voltage output through the transimpedance amplifier 200. At this time, the first operational amplifier U101 in the transimpedance amplifier 200 is in reverse saturation, and the output voltage VOUT of the first operational amplifier U101 in the transimpedance amplifier 200 is close to 0V. The input voltage of the inverting input terminal of the second operational amplifier U102 in the operational amplifier integration module 300 is close to 0V, and the second operational amplifier U102 in the operational amplifier integration module 300 is in forward saturation. The output voltage of the second operational amplifier U102 in the operational amplifier integration module 300 is close to 3.3V, the NPN transistor Q100 is turned on, and the DC signal from the current signal source I100 is directly conducted to ground through the NPN transistor Q100. At this point, the input voltage at the inverting input terminal of the first operational amplifier U101 in the transimpedance amplifier 200 is close to 0V, causing the first operational amplifier U101 to saturate in the forward direction, and its output voltage is close to 3.3V. The input voltage at the inverting input terminal of the second operational amplifier U102 in the operational amplifier integrator module 300 is greater than the input voltage at the non-inverting input terminal, causing the second operational amplifier U102 to saturate in the reverse direction, and its output voltage is close to 0V. At this time, the NPN transistor Q100 is cut off. The operational amplifier integrator module 300 in the AC / DC separation circuit forms a feedback circuit that oscillates rapidly and then tends towards equilibrium. The DC signal of the current signal source I100 is grounded through the NPN transistor Q100. Since the AC signal of the current signal source I100 cannot be fed back quickly in the operational amplifier integration module 300, the AC signal of the current signal source I100 is amplified by the transimpedance amplifier 200 and then output, thus splitting the AC and DC signals of the current signal source I100 into two non-interfering channels.

[0058] Furthermore, such as Figure 3 As shown, the transistor Q100 can also be an NMOS transistor; the gate of the NMOS transistor is connected to the output terminal of the operational amplifier integrator module 300, the drain of the NMOS transistor is connected to the negative terminal of the current signal source I100, and the source of the NMOS transistor is grounded through resistor R106. The NMOS transistor conducts when its gate receives a high-level voltage corresponding to the voltage supply VCC output by the operational amplifier integrator module 300, and is cut off when its gate receives a 0V voltage corresponding to ground output by the operational amplifier integrator module 300.

[0059] Furthermore, in this invention, the AC / DC separation circuit also includes a current-limiting resistor R105; one end of the current-limiting resistor R105 is connected to the output terminal of the operational amplifier integrator module 300, and the other end of the current-limiting resistor R105 is connected to the conduction control terminal of the transistor. When the operational amplifier integrator module 300 outputs a high-level voltage, the current-limiting resistor R105 provides current-limiting protection for the conduction control terminal of the transistor, preventing excessive current from damaging the transistor.

[0060] This utility model also provides an AC / DC separation device, which includes the AC / DC separation circuit described above. In this AC / DC separation device, the AC / DC signal in the current signal source is separated into two non-interfering channels by the AC / DC separation circuit, effectively avoiding interference between AC and DC signals.

[0061] In this invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0062] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model.

Claims

1. An AC / DC separation circuit, characterized in that, include: Current signal source, voltage power supply, voltage divider module, transimpedance amplifier, operational amplifier integrator module, and transistor; The positive terminal of the current signal source is connected to the voltage power supply, and the negative terminal of the current signal source is connected to the inverting input terminal of the transimpedance amplifier and the input terminal of the transistor. The current signal from the current signal source includes: DC signal and AC signal; The input terminal of the voltage divider module is connected to the voltage power supply, and the output terminal of the voltage divider module is connected to the non-inverting input terminal of the transimpedance amplifier and the non-inverting input terminal of the operational amplifier integration module; wherein, the voltage output by the voltage divider module is less than the voltage corresponding to the DC signal input to the inverting input terminal of the transimpedance amplifier; The positive power supply terminal of the transimpedance amplifier is connected to the voltage power supply, the negative power supply terminal of the transimpedance amplifier is grounded, and the output terminal of the transimpedance amplifier is connected to the inverting input terminal of the operational amplifier integration module. The positive power supply terminal of the operational amplifier integrator module is connected to the voltage power supply, the negative power supply terminal of the operational amplifier integrator module is grounded, the output terminal of the operational amplifier integrator module is connected to the conduction control terminal of the transistor, and the output terminal of the transistor is grounded; the transistor is a switching transistor with high-level conduction characteristics.

2. The AC / DC separation circuit according to claim 1, characterized in that, The voltage divider module includes: a first voltage divider resistor and a second voltage divider resistor; One end of the first voltage divider resistor is connected to the voltage power supply, and the other end of the first voltage divider resistor is connected to one end of the second voltage divider resistor, the non-inverting input terminal of the transimpedance amplifier, and the non-inverting input terminal of the operational amplifier integration module; the other end of the second voltage divider resistor is grounded.

3. The AC / DC separation circuit according to claim 2, characterized in that, The voltage divider module further includes a filter capacitor; one end of the filter capacitor is connected to one end of the second voltage divider resistor, and the other end of the filter capacitor is grounded.

4. The AC / DC separation circuit according to claim 1, characterized in that, The transimpedance amplifier includes: a first operational amplifier and a first feedback resistor; The inverting input terminal of the first operational amplifier is connected to the negative terminal of the current signal source and one end of the first feedback resistor; the resistance value of the first feedback resistor is greater than a preset resistance threshold. The non-inverting input of the first operational amplifier is connected to the output of the voltage divider module, the positive power supply of the first operational amplifier is connected to the voltage power supply, the negative power supply of the first operational amplifier is grounded, and the output of the first operational amplifier is connected to the other end of the first feedback resistor and the inverting input of the operational amplifier integration module.

5. The AC / DC separation circuit according to claim 1, characterized in that, The operational amplifier integration module includes: a second operational amplifier, an input resistor, and an integration feedback unit; One end of the input resistor is connected to the output terminal of the transimpedance amplifier, and the other end of the input resistor is connected to the inverting input terminal of the second operational amplifier and one end of the integral feedback unit. The non-inverting input of the second operational amplifier is connected to the output of the voltage divider module, the positive power supply of the second operational amplifier is connected to the voltage power supply, the negative power supply of the second operational amplifier is grounded, and the output of the second operational amplifier is connected to the other end of the integral feedback unit and the conduction control terminal of the transistor.

6. The AC / DC separation circuit according to claim 5, characterized in that, The integral feedback unit includes: a second feedback resistor and an integral capacitor; One end of the second feedback resistor and one end of the integrating capacitor are connected to the inverting input terminal of the second operational amplifier; The other end of the second feedback resistor and the other end of the integrating capacitor are connected to the output terminal of the second operational amplifier.

7. The AC / DC separation circuit according to claim 1, characterized in that, The transistor includes: an NPN transistor; The base of the NPN transistor is connected to the output terminal of the operational amplifier integration module, the collector of the NPN transistor is connected to the negative terminal of the current signal source, and the emitter of the NPN transistor is grounded through a resistor.

8. The AC / DC separation circuit according to claim 1, characterized in that, The transistor includes: an NMOS transistor; The gate of the NMOS transistor is connected to the output terminal of the operational amplifier integration module, the drain of the NMOS transistor is connected to the negative terminal of the current signal source, and the source of the NMOS transistor is grounded through a resistor.

9. The AC / DC separation circuit according to claim 1, characterized in that, Also includes: Current-limiting resistor; One end of the current-limiting resistor is connected to the output terminal of the operational amplifier integration module, and the other end of the current-limiting resistor is connected to the conduction control terminal of the transistor.

10. An AC / DC separation device, characterized in that, The AC / DC separation device includes the AC / DC separation circuit described in any one of claims 1 to 9.

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