Capacitor reverse connection negative feedback amplifier circuit

Abstract

The present invention provides a capacitor reverse connection type negative feedback amplifier circuit, which includes an operational amplifier, a feedback resistor and a feedback voltage divider branch, wherein the feedback resistor is connected between the output end and the inverting input end of the operational amplifier, and the feedback voltage divider branch includes a voltage divider resistor and a DC-isolating coupling capacitor, wherein the DC-isolating coupling capacitor is set to be a tantalum capacitor or a niobium capacitor and has polarity. By reversely connecting the DC-isolating coupling capacitor, the common sense requirement and inertial cognition of technicians in this field that reverse connection of polar capacitors is strictly prohibited to avoid increasing leakage current and irreversible structural damage are broken, and a change trend characteristic that the internal resistance of the feedback voltage divider branch decreases with the increase of the amplitude of the signal is formed, and based on the characteristic that the amplification factor of the input signal of the capacitor reverse connection type negative feedback amplifier circuit is associated with the resistance ratio of the feedback resistor and the feedback voltage divider branch, the amplification effect on low-amplitude signals is suppressed to improve the signal-to-noise ratio.

Description

Technical Field

[0001] The invention relates to the field of signal amplification, and in particular to a capacitor reverse connection type negative feedback amplifier circuit. Background Art

[0002] An operational amplifier is an integrated circuit that is widely used and easy to use. In circuit applications that use the operational amplifier for signal amplification, the negative feedback amplifier circuit formed by adding a negative feedback network to the operational amplifier is widely used because it can form a closed-loop gain that tends to be constant, has a relatively flat amplitude-frequency characteristic, and has a wide bandwidth.

[0003] Specifically, refer to the accompanying drawings of the specification. Figure 1A and Figure 1B As shown, the structural principle of the negative feedback amplifier circuit in the same-phase input state and the inverting input state is respectively illustrated, wherein the negative feedback amplifier circuit includes the operational amplifier and the negative feedback network, wherein the operational amplifier has a same-phase input terminal (+), an inverting input terminal (-) and an output terminal, wherein the negative feedback network includes at least one feedback resistor R2 and a feedback voltage divider branch having at least one voltage divider resistor R1, wherein one end of the feedback resistor R2 is electrically connected to the inverting input terminal (-) of the operational amplifier, and the other end of the feedback resistor R2 is electrically connected to the The output terminal, that is, the output terminal is connected to the inverting input terminal (-) through the feedback resistor R2, so as to feed back a part of the output signal to the inverting input terminal (-) to form a negative feedback to the operational amplifier, wherein the feedback voltage-dividing branch is electrically connected to the inverting input terminal (-) in a state where one end of the voltage-dividing resistor R1 is electrically connected to the inverting input terminal (-), so that based on the virtual short characteristic of the operational amplifier, that is, when no power supply voltage is applied to the output terminal, the non-inverting input terminal (+) and the inverting input terminal (-) are equivalent to a short circuit and are considered to have the same voltage (corresponding to the voltage V at point A in the figure). A )'s electrical properties, Figure 1A The negative feedback amplifier circuit shown in the figure is in an inverting input state, corresponding to the other end of the voltage divider resistor R1 connected to the input signal V in , and the input signal V is connected to the non-inverting input terminal (+) in The voltage across the voltage divider resistor R1 is (V in -V A ), according to Ohm's law, the current I1 passing through the voltage divider resistor R1 = (V in -V A) / R1, where since the input impedance of the operational amplifier is extremely high, there is basically no current in the inverting input terminal (-), so when I1 flows to the feedback resistor R2 via point A, the current flowing through the feedback resistor R2 is substantially equal to I1, and the output voltage signal V out =V A -I1·R2, so the gain of the negative feedback amplifier circuit in the inverting input state corresponds to (V A -V out ) / (V in -V A )=R2 / R1 and is directly related to the resistance ratio of the feedback resistor R2 and the voltage dividing resistor R1; and Figure 1B The non-inverting input state of the negative feedback amplifier circuit shown in the figure corresponds to the input signal V connected to the non-inverting input terminal (+). in , and the other end of the voltage divider resistor R1 is connected to the input signal V in The reference ground state, the voltage across the voltage divider resistor R1 is V A Based on the virtual short characteristics of the operational amplifier and the V in Equal, according to Ohm's law, the current I1 passing through the voltage divider resistor R1 = V in / R1, and since the current flowing through the feedback resistor R2 is substantially equal to I1, the output voltage signal V out =I1·(R1+R2), so the gain of the negative feedback amplifier circuit in the in-phase input state corresponds to V out / V in =1+R2 / R1 and is also related to the resistance ratio of the feedback resistor R2 to the voltage divider resistor R1. That is to say, in the inverting input state and the non-inverting input state of the negative feedback amplifier circuit, the amplification factor of the input signal of the negative feedback amplifier circuit is related to the resistance ratio of the feedback resistor R2 to the feedback voltage divider branch.

[0004] Further, corresponding to Figure 2A and Figure 2BWhen the negative feedback amplifier circuit is applied to amplify a low-frequency signal with a DC component, such as a Doppler intermediate frequency signal generated based on the microwave Doppler effect principle, it is often necessary to further connect a DC-isolating coupling capacitor C in series with the feedback voltage-dividing branch, wherein the DC-isolating coupling capacitor C is connected in series with the voltage-dividing resistor R1 in the feedback voltage-dividing branch, and the feedback voltage-dividing branch corresponds to a state in which the two ends of the DC-isolating coupling capacitor C are respectively electrically connected to the inverting input terminal (-) and the voltage-dividing resistor R1, or the two ends of the voltage-dividing resistor R1 are respectively electrically connected to the inverting input terminal (-) and the DC-isolating coupling capacitor. The state of C is electrically connected to the inverting input terminal (-), wherein based on the electrical characteristics of the capacitor being equivalent to an ideal capacitor C0 in series with an equivalent series resistor ESR and an equivalent series inductor ESL in an actual circuit, the amplification factor of the input signal in the negative feedback amplifier circuit is associated with the state of the resistance ratio of the feedback resistor R2 and the feedback voltage divider branch. In order to ensure the stability, response speed and signal-to-noise ratio of the negative feedback amplifier circuit when it is used to amplify a low-frequency signal with a DC component, the DC-isolating coupling capacitor C is usually required to have electrical performances of high capacitance, low internal resistance, high response speed and low leakage current in a low-frequency state. Therefore, when the negative feedback amplifier circuit is applied to amplify a low-frequency signal with a DC component, the DC-isolating coupling capacitor C is usually set to a tantalum capacitor with polarity to simultaneously meet the electrical performance requirements of the DC-isolating coupling capacitor C in a low-frequency state, such as high capacitance, low internal resistance, high response speed and low leakage current. Based on the common sense and inertial cognition of technicians in this field that capacitors with polarity are strictly prohibited from being reversely connected to avoid increasing leakage current and irreversible structural damage or even explosion, when the DC-isolating coupling capacitor C is set to a tantalum capacitor, in the in-phase input state of the negative feedback amplifier circuit, the feedback voltage divider branch is electrically connected to the inverting input terminal (-) in a state where the positive electrode of the tantalum capacitor is electrically connected to the inverting input terminal (-), and one end of the corresponding voltage divider resistor R1 is connected to The positive electrode of the tantalum capacitor and the other end of the voltage-dividing resistor R1 are connected to the inverting input terminal (-), or the positive electrode of the tantalum capacitor is electrically connected to the inverting input terminal (-), and the negative electrode of the tantalum capacitor is electrically connected to the voltage-dividing resistor R1; and in the inverting input state of the negative feedback amplifier circuit, the feedback voltage-dividing branch is electrically connected to the inverting input terminal (-) in a state in which the negative electrode of the tantalum capacitor is electrically connected to the inverting input terminal (-), correspondingly forming a state in which one end of the voltage-dividing resistor R1 is connected to the negative electrode of the tantalum capacitor and the other end of the voltage-dividing resistor R1 is connected to the inverting input terminal (-), or the negative electrode of the tantalum capacitor is electrically connected to the inverting input terminal (-), and the positive electrode of the tantalum capacitor is electrically connected to the voltage-dividing resistor R1. Summary of the invention

[0005] One object of the present invention is to provide a capacitor reverse-connected negative feedback amplifier circuit, wherein the capacitor reverse-connected negative feedback amplifier circuit can reduce the influence of environmental noise during the amplification process and the original background noise in the amplified signal on the amplified output signal in the application of signal amplification, thereby facilitating the improvement of the signal-to-noise ratio of the amplified output signal and having good anti-interference characteristics.

[0006] Another object of the present invention is to provide a capacitor reverse connection type negative feedback amplifier circuit, wherein the capacitor reverse connection type negative feedback amplifier circuit comprises an operational amplifier and a negative feedback network, wherein the negative feedback network comprises a feedback resistor and a feedback voltage divider branch, wherein one end of the feedback resistor is electrically connected to the inverting input terminal of the operational amplifier, and the other end of the feedback resistor is electrically connected to the output terminal of the operational amplifier, wherein one end of the feedback voltage divider branch is electrically connected to the inverting input terminal of the operational amplifier, so that the capacitor reverse connection type negative feedback amplifier circuit has an amplification factor of the input signal associated with the feedback resistor. The characteristic of the ratio of the internal resistance and the resistance value of the feedback voltage divider branch is formed by changing the response of the internal resistance of the feedback voltage divider branch to signals of different amplitudes, so that the internal resistance of the feedback voltage divider branch decreases as the amplitude of the signal increases, and correspondingly, the trend characteristic of the amplification factor of the input signal of the capacitor reverse connection negative feedback amplifier circuit increases as the amplitude of the input signal increases, so that the amplification effect of the low-amplitude signal can be suppressed in the application of signal amplification, which is beneficial to suppress the amplification effect of the environmental noise and the original background noise in the amplified signal in the application of signal amplification, thereby improving the signal-to-noise ratio of the signal after the amplification output.

[0007] Another object of the present invention is to provide a capacitor reverse connection type negative feedback amplifier circuit, wherein the feedback voltage dividing branch includes a voltage dividing resistor and a DC-isolating coupling capacitor connected in series with the voltage dividing resistor, wherein the DC-isolating coupling capacitor is a tantalum capacitor or a niobium capacitor and has a polar state, breaking through the common sense requirement and inertial cognition of technicians in this field that capacitors with polarity are strictly prohibited from being reversed to avoid increasing leakage current and irreversible structural damage or even explosion. By reversely connecting the DC-isolating coupling capacitor set as a tantalum capacitor or a niobium capacitor, based on the electrical characteristics of the DC-isolating coupling capacitor set as a tantalum capacitor or a niobium capacitor under reverse voltage, it is found that the response of the internal resistance of the feedback voltage dividing branch to signals of different amplitudes is changed, and specifically the change trend characteristic that the internal resistance of the feedback voltage dividing branch decreases with the increase of the amplitude of the signal is formed. In this way, based on the characteristic that the capacitor reverse connection type negative feedback amplifier circuit has the amplification factor of the input signal associated with the resistance ratio of the feedback resistor and the feedback voltage dividing branch, the amplification effect on low-amplitude signals is suppressed in signal amplification applications, thereby improving the signal-to-noise ratio of the amplified output signal.

[0008] Another object of the present invention is to provide a capacitor reverse-connected negative feedback amplifier circuit, wherein based on the exploration that the DC-isolating coupling capacitor set as a tantalum capacitor or a niobium capacitor still has a low leakage current in the corresponding reverse voltage interval associated with the corresponding working environment parameters and the intrinsic electrical parameters and can work stably for a long time, it is found that in the state where the amplitude interval of the input signal is adapted to the corresponding reverse voltage interval, the reverse voltage of the DC-isolating coupling capacitor set as a tantalum capacitor or a niobium capacitor can be adapted to the corresponding reverse voltage interval or adjusted to be adapted to the corresponding reverse voltage interval, so as to ensure the stability and working life of the DC-isolating coupling capacitor in the reverse-connected state, that is, the capacitor reverse-connected negative feedback amplifier circuit is suitable for amplifying the corresponding input signal, especially the input signal in the form of a weak signal, such as a Doppler intermediate frequency signal generated based on the principle of the microwave Doppler effect, thereby breaking through the common sense or even explosive requirements and inertial cognition of technicians in this field that capacitors with polarity are strictly prohibited from being reversed to avoid increasing leakage current and irreversible structural damage.

[0009] Another object of the present invention is to provide a capacitor reverse-connected negative feedback amplifier circuit, wherein in the same-phase input state of the capacitor reverse-connected negative feedback amplifier circuit, corresponding to the state in which the corresponding input signal is connected to the same-phase input terminal of the operational amplifier, and the reference ground of the input signal is connected to the other end of the feedback voltage divider branch, the DC-isolating coupling capacitor is arranged in series with the feedback voltage divider branch in a state in which its negative electrode is electrically connected to the inverting input terminal of the operational amplifier, such as the DC-isolating coupling capacitor is arranged in series with the feedback voltage divider branch in a state in which its negative electrode is directly electrically connected to the inverting input terminal of the operational amplifier, or is arranged in series with the feedback voltage divider branch in a state in which its negative electrode is electrically connected to the inverting input terminal of the operational amplifier via the voltage divider resistor, so that in the same-phase input state of the capacitor reverse-connected negative feedback amplifier circuit, the DC-isolating coupling capacitor is arranged in series with the feedback voltage divider branch in reverse polarity.

[0010] Another object of the present invention is to provide a capacitor reverse-connected negative feedback amplifier circuit, wherein in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit, corresponding to the state in which the input signal is connected to the other end of the feedback voltage divider branch, and the reference ground of the input signal is connected to the non-inverting input end of the operational amplifier, the DC-isolating coupling capacitor is arranged in series with the feedback voltage divider branch in a state in which its positive electrode is electrically connected to the inverting input end of the operational amplifier, such as the DC-isolating coupling capacitor is arranged in series with the feedback voltage divider branch in a state in which its positive electrode is directly electrically connected to the inverting input end of the operational amplifier, or is arranged in series with the feedback voltage divider branch in a state in which its positive electrode is electrically connected to the inverting input end of the operational amplifier via the voltage divider resistor, so that in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit, the DC-isolating coupling capacitor is arranged in series with the feedback voltage divider branch in reverse polarity.

[0011] Another object of the present invention is to provide a capacitor reverse-connected negative feedback amplifier circuit, wherein in a state where the amplitude range of the input signal is adapted to the corresponding reverse voltage range, based on the requirement for adjusting the reverse voltage of the DC-isolating coupling capacitor set as a tantalum capacitor or a niobium capacitor, by adjusting the voltage division size of the feedback voltage-dividing branch, the reference voltage of the input signal can be adjusted to adjust the reverse voltage of the DC-isolating coupling capacitor to be adapted to the corresponding reverse voltage range, so as to break through the common sense requirement and inertial cognition of technicians in this field that capacitors with polarity are strictly prohibited from reverse connection to avoid increased leakage current and irreversible structural damage or even explosion, and ensure the stability and service life of the DC-isolating coupling capacitor in the reverse connection state, while reducing the restriction of the reverse connection of the DC-isolating coupling capacitor on the voltage amplitude of the input signal amplified by the capacitor reverse-connected negative feedback amplifier circuit, thereby helping to improve the applicability of the capacitor reverse-connected negative feedback amplifier circuit.

[0012] Another object of the present invention is to provide a capacitor reverse connection type negative feedback amplifier circuit, wherein the capacitor reverse connection type negative feedback amplifier circuit further includes a reference voltage adjustment branch, wherein the reference voltage adjustment branch has a voltage dividing node and two branch resistors with preset resistance values ​​separated by the voltage dividing node, wherein the reference voltage adjustment branch is electrically connected to the non-inverting input terminal of the operational amplifier at its voltage dividing node, so as to adjust the voltage magnitudes of the non-inverting input terminal and the inverting input terminal of the operational amplifier based on the voltage difference setting at both ends of the reference voltage adjustment branch and the preset resistance value setting of the two branch resistors, and adjust the reference voltage of the input signal in the non-inverting input state or the inverting input state of the capacitor reverse connection type negative feedback amplifier circuit, thereby forming a voltage division adjustment for the feedback voltage division branch and adjusting the reverse voltage of the DC-isolating coupling capacitor set as a tantalum capacitor or a niobium capacitor, so as to ensure the stability and service life of the DC-isolating coupling capacitor in the reverse connection state when the DC-isolating coupling capacitor set as a tantalum capacitor or a niobium capacitor is connected in series with the feedback voltage division branch in reverse polarity.

[0013] To achieve at least one of the above purposes, the present invention provides a capacitor reverse-connected negative feedback amplifier circuit, wherein the capacitor reverse-connected negative feedback amplifier circuit includes at least one capacitor reverse-connected negative feedback amplifier circuit unit, wherein the capacitor reverse-connected negative feedback amplifier circuit unit includes:

[0014] an operational amplifier, wherein the operational amplifier has a non-inverting input terminal, an inverting input terminal and an output terminal; and

[0015] A negative feedback network, wherein the negative feedback network includes a feedback resistor and a feedback voltage divider branch, wherein one end of the feedback resistor is electrically connected to the inverting input terminal of the operational amplifier, and the other end of the feedback resistor is electrically connected to the output terminal of the operational amplifier, wherein the feedback voltage divider branch includes a voltage divider resistor and a DC-isolating coupling capacitor connected in series with the voltage divider resistor, wherein the DC-isolating coupling capacitor is set as a tantalum capacitor or a niobium capacitor and has polarity, wherein one end of the feedback voltage divider branch is electrically connected to the inverting input terminal of the operational amplifier in a state where the DC-isolating coupling capacitor is connected in series with the feedback voltage divider branch in reverse polarity, corresponding to the in-phase input terminal of the capacitor inverse negative feedback amplifier circuit unit. In the input state, that is, the corresponding input signal is connected to the non-inverting input terminal of the operational amplifier, and the reference ground of the input signal is connected to the other end of the feedback voltage divider branch, the DC-isolating coupling capacitor is electrically connected to the inverting input terminal of the operational amplifier with its negative electrode in series with the feedback voltage divider branch, and in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit, that is, the input signal is connected to the other end of the feedback voltage divider branch, and the reference ground of the input signal is connected to the non-inverting input terminal of the operational amplifier, the DC-isolating coupling capacitor is electrically connected to the inverting input terminal of the operational amplifier with its positive electrode in series with the feedback voltage divider branch.

[0016] In one embodiment, the DC-isolating coupling capacitor is directly electrically connected to the inverting input terminal of the operational amplifier in a state where it is connected in series with the feedback voltage-dividing branch with reverse polarity. Corresponding to the non-inverting input state of the capacitor inverting negative feedback amplifier circuit unit, the negative electrode of the DC-isolating coupling capacitor is directly electrically connected to the inverting input terminal of the operational amplifier, and the positive electrode of the DC-isolating coupling capacitor is directly electrically connected to one end of the voltage-dividing resistor. In the inverting input state of the capacitor inverting negative feedback amplifier circuit unit, the positive electrode of the DC-isolating coupling capacitor is directly electrically connected to the inverting input terminal of the operational amplifier, and the negative electrode of the DC-isolating coupling capacitor is directly electrically connected to one end of the voltage-dividing resistor, so as to form a connection relationship in which one end of the feedback voltage-dividing branch is electrically connected to the inverting input terminal of the operational amplifier in a state where the DC-isolating coupling capacitor is connected in series with the feedback voltage-dividing branch with reverse polarity.

[0017] In one embodiment, the DC-isolating coupling capacitor is electrically connected to the inverting input terminal of the operational amplifier via the voltage-dividing resistor in a state where it is reversely connected in series with the feedback voltage-dividing branch. Corresponding to the non-inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit, one end of the voltage-dividing resistor is electrically connected to the inverting input terminal of the operational amplifier, and the other end of the voltage-dividing resistor is electrically connected to the negative electrode of the DC-isolating coupling capacitor. In the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit, one end of the voltage-dividing resistor is electrically connected to the inverting input terminal of the operational amplifier, and the other end of the voltage-dividing resistor is electrically connected to the positive electrode of the DC-isolating coupling capacitor, so as to form a connection relationship in which one end of the feedback voltage-dividing branch is electrically connected to the inverting input terminal of the operational amplifier in a state where the DC-isolating coupling capacitor is reversely connected in series with the feedback voltage-dividing branch.

[0018] In one embodiment, the capacitor reverse-connected negative feedback amplifier circuit unit also includes a reference voltage adjustment branch, wherein the reference voltage adjustment branch has a voltage dividing node and two branch resistors with preset resistance values ​​separated by the voltage dividing node, wherein the reference voltage adjustment branch is electrically connected to the non-inverting input terminal of the operational amplifier at the voltage dividing node.

[0019] In one embodiment, the input signal is a Doppler intermediate frequency signal generated based on the principle of microwave Doppler effect.

[0020] In one embodiment, the capacitor reverse-connected negative feedback amplifier circuit further includes a voltage follower, wherein the positive electrode of the DC-isolating coupling capacitor is electrically connected to the inverting input terminal of the operational amplifier, and the negative electrode of the DC-isolating coupling capacitor is electrically connected to the output terminal of the voltage follower to form an inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit and a state in which the DC-isolating coupling capacitor is connected in series with the feedback voltage divider branch with reverse polarity in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit.

[0021] In one embodiment, the capacitor reverse-connected negative feedback amplifier circuit includes at least two capacitor reverse-connected negative feedback amplifier circuit units, wherein the capacitor reverse-connected negative feedback amplifier circuit uses one of the capacitor reverse-connected negative feedback amplifier circuit units as a front-stage circuit and the other capacitor reverse-connected negative feedback amplifier circuit unit as a rear-stage circuit, corresponding to a two-stage amplifier circuit in which the in-phase input terminal of the rear-stage circuit is electrically connected to the output terminal of the front-stage circuit in the in-phase input state of the rear-stage circuit, and a two-stage amplifier circuit in which the feedback voltage divider branch of the rear-stage circuit is electrically connected between the output terminal of the front-stage circuit and the inverting input terminal of the rear-stage circuit in the inverting input state of the rear-stage circuit.

[0022] In one embodiment, the capacitor reverse negative feedback amplifier circuit includes a capacitor reverse negative feedback amplifier circuit unit in a common-phase input state and a capacitor reverse negative feedback amplifier circuit unit in an inverting input state, wherein the capacitor reverse negative feedback amplifier circuit uses the capacitor reverse negative feedback amplifier circuit unit in a common-phase input state as a front-stage circuit, and uses the capacitor reverse negative feedback amplifier circuit unit in an inverting input state as a rear-stage circuit, and the feedback voltage divider branch corresponding to the rear-stage circuit is electrically connected to the two-stage amplifier circuit between the output end of the front-stage circuit and the inverting input end of the rear-stage circuit.

[0023] In one embodiment, the capacitor reverse negative feedback amplifier circuit includes two capacitor reverse negative feedback amplifier circuit units in the same phase input state, wherein the capacitor reverse negative feedback amplifier circuit uses one of the capacitor reverse negative feedback amplifier circuit units as a front-stage circuit and the other capacitor reverse negative feedback amplifier circuit unit as a rear-stage circuit, corresponding to a two-stage amplifier circuit in which the output end of the front-stage circuit is electrically connected to the same phase input end of the rear-stage circuit.

[0024] In one embodiment, the capacitor reverse negative feedback amplifier circuit includes two capacitor reverse negative feedback amplifier circuit units in an inverting input state, wherein the capacitor reverse negative feedback amplifier circuit uses one of the capacitor reverse negative feedback amplifier circuit units as a front-stage circuit and the other capacitor reverse negative feedback amplifier circuit unit as a rear-stage circuit, and the feedback voltage divider branch corresponding to the rear-stage circuit is electrically connected to the two-stage amplifier circuit between the output end of the front-stage circuit and the inverting input end of the rear-stage circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1A The schematic diagram is a structural principle diagram of an existing negative feedback amplifier circuit in an inverting input state.

[0026] Figure 1B The present invention is a schematic diagram showing the structural principle of an existing negative feedback amplifier circuit in a common-phase input state.

[0027] Figure 2A The present invention is a schematic diagram of the structural principle of an existing negative feedback amplifier circuit in an inverting input state when a DC-isolating coupling capacitor is provided.

[0028] Figure 2B The present invention is a schematic diagram of the structural principle of an existing negative feedback amplifier circuit in a common-phase input state when a DC-isolating coupling capacitor is provided.

[0029] Figure 3A FIG. 4 is a schematic structural diagram of a capacitor reverse connection type negative feedback amplifier circuit according to an embodiment of the present invention.

[0030] Figure 3B FIG. 4 is a schematic structural diagram of a capacitor reverse connection type negative feedback amplifier circuit according to another embodiment of the present invention.

[0031] Figure 4A FIG. 4 is a schematic structural diagram of a capacitor reverse connection type negative feedback amplifier circuit according to another embodiment of the present invention.

[0032] Figure 4B FIG. 4 is a schematic structural diagram of a capacitor reverse connection type negative feedback amplifier circuit according to another embodiment of the present invention.

[0033] Figure 5A It is a schematic diagram of signal comparison after amplifying and outputting the Doppler intermediate frequency signal corresponding to the unmanned state output by the capacitor reverse-connected negative feedback amplifier circuit according to the above embodiment of the present invention before and after the DC-isolating coupling capacitor is reversely connected.

[0034] Figure 5B It is a schematic diagram of signal comparison after amplifying and outputting the Doppler intermediate frequency signal corresponding to the human state output by the same microwave detection module before and after the DC-isolating coupling capacitor of the capacitor reverse-connected negative feedback amplifier circuit according to the above embodiment of the present invention is reversely connected.

[0035] Fig. 6A FIG. 4 is a schematic structural diagram of a capacitor reverse connection type negative feedback amplifier circuit according to another embodiment of the present invention.

[0036] Figure 6B FIG. 4 is a schematic structural diagram of a capacitor reverse connection type negative feedback amplifier circuit according to another embodiment of the present invention.

[0037] Figure 6C FIG. 4 is a schematic structural diagram of a capacitor reverse connection type negative feedback amplifier circuit according to another embodiment of the present invention.

[0038] Fig.6D FIG. 4 is a schematic structural diagram of a capacitor reverse connection type negative feedback amplifier circuit according to another embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0040] Those skilled in the art should understand that, in the disclosure of the present invention, the orientation or position relationship indicated by the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0041] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0042] The present invention provides a capacitor reverse-connected negative feedback amplifier circuit, wherein the capacitor reverse-connected negative feedback amplifier circuit can reduce the influence of environmental noise in the amplification process and the original background noise in the amplified signal on the amplified output signal in the application of signal amplification, thereby facilitating the improvement of the signal-to-noise ratio of the amplified output signal and having good anti-interference characteristics.

[0043] Referring to the accompanying drawings of the present invention Figure 3A and Figure 3B Based on the in-phase input and inverting input of the capacitor reverse-connected negative feedback amplifier circuit, the circuit structures of the capacitor reverse-connected negative feedback amplifier circuit according to two embodiments of the present invention are respectively illustrated, wherein the capacitor reverse-connected negative feedback amplifier circuit includes an operational amplifier 10 and a negative feedback network 20, wherein the operational amplifier 10 has an inverting input terminal 11, a in-phase input terminal 12 and an output terminal 13, wherein the negative feedback network 20 includes a feedback resistor 21 and a feedback voltage divider branch 22, wherein one end of the feedback resistor 21 is electrically connected to the inverting input terminal 11 of the operational amplifier 10, and the other end of the feedback resistor 21 is electrically connected to the output terminal 13 of the operational amplifier 10, that is, the output terminal 13 of the operational amplifier 10 is connected to the inverting input terminal 11 via the feedback resistor 21, so as to feed back a part of the output signal to the inverting input terminal 11 to form negative feedback to the operational amplifier 10.

[0044] It is worth mentioning that, in fact, the operational amplifier 10 also has a positive power pin, a negative power pin, an offset input pin, etc., and without further limiting the power pin and the offset input pin of the operational amplifier 10 and their circuit connection relationship, in the diagram of the present invention, the power pin and the offset input pin of the operational amplifier 10 are not marked, which does not constitute a limitation on the structure of the operational amplifier 10 and the circuit connection relationship related to the power pin and the offset input pin of the operational amplifier 10 in the description of the present invention.

[0045] Furthermore, one end of the feedback voltage divider branch 22 is electrically connected to the inverting input terminal 11 of the operational amplifier 10, so that the capacitor reverse connection negative feedback amplifier circuit has a characteristic that the amplification factor of the input signal is associated with the resistance ratio of the feedback resistor 21 and the feedback voltage divider branch 22, wherein by changing the response of the internal resistance of the feedback voltage divider branch 22 to signals of different amplitudes, a changing trend characteristic is formed in which the internal resistance of the feedback voltage divider branch 22 decreases as the amplitude of the signal increases, correspondingly forming a trend characteristic in which the amplification factor of the input signal of the capacitor reverse connection negative feedback amplifier circuit increases as the amplitude of the input signal increases, thereby being able to suppress the amplification effect on low-amplitude signals in signal amplification applications, thereby facilitating the suppression of the amplification effect on environmental noise and the original background noise in the amplified signal in signal amplification applications, thereby improving the signal-to-noise ratio of the signal after amplification output.

[0046] Specifically, the feedback voltage-dividing branch 22 includes a voltage-dividing resistor 221 and a DC-isolating coupling capacitor 222 connected in series with the voltage-dividing resistor 221, wherein the DC-isolating coupling capacitor 222 is a tantalum capacitor or a niobium capacitor with polarity, breaking through the common sense and inertial cognition of those skilled in the art that capacitors with polarity are strictly prohibited from being reversely connected to avoid increasing leakage current and irreversible structural damage or even explosion, and by reversely connecting the DC-isolating coupling capacitor 222 set as a tantalum capacitor or a niobium capacitor, based on the isolation capacitor set as a tantalum capacitor or a niobium capacitor The electrical characteristics of the direct-coupled capacitor 222 under reverse voltage were explored and found that by changing the response of the internal resistance of the feedback voltage-divider branch 22 to signals of different amplitudes, the internal resistance of the feedback voltage-divider branch 22 decreases with the increase of the amplitude of the signal. In this way, based on the characteristic that the amplification factor of the input signal of the capacitor reverse-connected negative feedback amplifier circuit is related to the resistance ratio of the feedback resistor 21 and the feedback voltage-divider branch 22, the amplification effect of low-amplitude signals is suppressed in signal amplification applications, thereby improving the signal-to-noise ratio of the amplified output signal.

[0047] It is worth mentioning that the DC-isolating coupling capacitor 222, which is set as a tantalum capacitor (such as a manganese dioxide tantalum capacitor, a conductive polymer tantalum capacitor) or a niobium capacitor (such as a manganese dioxide niobium capacitor, a conductive polymer niobium capacitor), still has a low leakage current and can work stably for a long time in the corresponding reverse voltage range associated with the corresponding working environment parameters and intrinsic electrical parameters. For example, when the manganese dioxide tantalum capacitor is in an operating environment of 25°C, the reverse voltage range is a range where the voltage value is less than 10% of the rated voltage or 1V, and the minimum value of the two is taken; in an operating environment of 85°C, the reverse voltage range is a range where the voltage value is less than 5% of the rated voltage or 0.5V, and the minimum value of the two is taken; in an operating environment of 125°C, the reverse voltage range is a range where the voltage value is less than 1% of the rated voltage or 0.1V, and the minimum value of the two is taken. For another example, for a conductive polymer tantalum capacitor, under a working environment of 25°C, the reverse voltage interval is an interval in which the voltage value is less than 15% of the rated voltage; under a working environment of 55°C, the reverse voltage interval is an interval in which the voltage value is less than 10% of the rated voltage; under a working environment of 85°C, the reverse voltage interval is an interval in which the voltage value is less than 5% of the rated voltage; and under a working environment of 105°C, the reverse voltage interval is an interval in which the voltage value is less than 1% of the rated voltage. In a state in which the amplitude interval of the input signal is adapted to the corresponding reverse voltage interval, the reverse voltage of the DC-isolating coupling capacitor 222, which is set as a tantalum capacitor or a niobium capacitor, can be adapted to the corresponding reverse voltage interval or adjusted to be adapted to the corresponding reverse voltage interval to ensure the stability and service life of the DC-isolating coupling capacitor 222 in a reverse-connected state, that is, the capacitor reverse-connected negative feedback amplifier circuit is suitable for amplifying the corresponding input signal, especially the input signal in a weak signal form with a signal amplitude interval corresponding to the reverse voltage interval, such as a Doppler intermediate frequency signal generated based on the principle of the microwave Doppler effect, and in a state in which the input signal is reverse-connected, the reverse voltage of the DC-isolating coupling capacitor 222 can be adjusted to be adapted to the corresponding reverse voltage interval, so as to ensure the stability and service life of the DC-isolating coupling capacitor 222 in a reverse-connected state, that is, the capacitor reverse-connected negative feedback amplifier circuit is suitable for amplifying the corresponding input signal, especially the input signal in a weak signal form with a signal amplitude interval corresponding to the reverse voltage interval, such as a Doppler intermediate frequency signal generated based on the principle of the microwave Doppler effect, and in a state in which the input signal is reverse-connected, the reverse voltage interval of the DC-isolating coupling capacitor 222 is adjusted to be adapted to the reverse voltage interval of the DC When applied to microwave detection to amplify the Doppler intermediate frequency signal generated based on the principle of microwave Doppler effect, since the signal-to-noise ratio of the amplified output signal can be improved, when the Doppler intermediate frequency signal is based on long-distance (high installation) detection conditions, or is extremely weak corresponding to human breathing movements / heartbeat movements / limb micro-movements, the amplification factor of the effective signal in the weak Doppler intermediate frequency signal can be increased, thereby improving the sensitivity and accuracy of the corresponding microwave detection device, thus breaking through the common sense requirement and inertial cognition of technical personnel in this field that capacitors with polarity are strictly prohibited from being reversely connected to avoid increased leakage current and irreversible structural damage or even explosion.

[0048] Furthermore, based on the correlation between the reverse voltage range of the DC-isolating coupling capacitor 222 set as a tantalum capacitor or a niobium capacitor and the material and process of the DC-isolating coupling capacitor 222, the DC-isolating coupling capacitor is preferably set as an AVX brand tantalum capacitor, so as to determine the reverse voltage range according to the specifications of the corresponding model of AVX brand tantalum capacitor.

[0049] Specifically, referring to the accompanying drawings of the present invention, Figure 3A As shown, based on the description in the above description that "one end of the feedback voltage-dividing branch 22 is electrically connected to the inverting input terminal 11 of the operational amplifier 10", in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit, corresponding to the state in which the other end of the feedback voltage-dividing branch 22 is connected to the input signal, and the state in which the reference ground of the input signal is connected to the in-phase input terminal 12 of the operational amplifier 10, the DC-isolating coupling capacitor 222 is arranged in series with the feedback voltage-dividing branch 22 in a state in which its positive electrode is electrically connected to the inverting input terminal 11 of the operational amplifier 10. 22, including the state that the DC-isolating coupling capacitor 222 is directly and electrically connected with the inverting input terminal 11 of the operational amplifier 10 with its positive electrode and is arranged in series in the feedback voltage-dividing branch 22, and the state that the DC-isolating coupling capacitor 222 is electrically connected with the inverting input terminal 11 of the operational amplifier 10 with its positive electrode and is arranged in series in the feedback voltage-dividing branch 22 via the voltage-dividing resistor 221, so that in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit, the DC-isolating coupling capacitor 222 is in reverse polarity and is connected in series in the feedback voltage-dividing branch 22.

[0050] Referring to the accompanying drawings of the present invention Figure 3BAs shown, based on the description in the above description that "one end of the feedback voltage-dividing branch 22 is electrically connected to the inverting input terminal 11 of the operational amplifier 10", in the in-phase input state of the capacitor reverse-connected negative feedback amplifier circuit, corresponding to the state in which the in-phase input terminal 12 of the operational amplifier 10 is connected to the corresponding input signal, and the other end of the feedback voltage-dividing branch 22 is connected to the reference ground of the input signal, the DC-isolating coupling capacitor 222 is arranged in series with the feedback voltage-dividing branch 22 in a state in which its negative electrode is electrically connected to the inverting input terminal 11 of the operational amplifier 10. 22, including the state that the DC-isolating coupling capacitor 222 is directly and electrically connected with the inverting input terminal 11 of the operational amplifier 10 with its negative electrode and is arranged in series in the feedback voltage-dividing branch 22, and the state that the DC-isolating coupling capacitor 222 is electrically connected with the inverting input terminal 11 of the operational amplifier 10 with its negative electrode and is arranged in series in the feedback voltage-dividing branch 22 via the voltage-dividing resistor 221, so that in the same-phase input state of the capacitor reverse-connected negative feedback amplifier circuit, the DC-isolating coupling capacitor 222 is in a state of reverse polarity being connected in series in the feedback voltage-dividing branch 22.

[0051] It is worth mentioning that those skilled in the art should understand that the series connection and / or parallel connection of at least two resistors can be equivalent to one resistor, and the series connection and / or parallel connection of at least two capacitors can also be equivalent to one capacitor. Therefore, in the description of the present invention, the understanding of the description of the feedback resistor 21 does not constitute a limitation on the number and connection relationship of the actual resistors connected between the inverting input terminal 11 and the output terminal 13 of the operational amplifier 10, and it should be understood as the equivalent resistance of the line connected between the inverting input terminal 11 and the output terminal 13 of the operational amplifier 10. Similarly, the understanding of the description of the DC-isolating coupling capacitor 222 and the voltage-dividing resistor 221 in the feedback voltage-dividing branch 22 does not constitute a limitation on the number and connection relationship (including the connection order) of the actual resistors and capacitors in the feedback voltage-dividing branch 22, and it should be understood as the equivalent capacitors and resistors connected in series with each other in the feedback voltage-dividing branch 22.

[0052] That is to say, in the actual circuit structure of the capacitor reverse negative feedback amplifier circuit, the feedback resistor 21 is a resistor connected between the inverting input terminal 11 and the output terminal 13 of the operational amplifier 10, or a resistor formed by multiple resistors connected between the inverting input terminal 11 and the output terminal 13 of the operational amplifier 10 based on series and / or parallel equivalent connection. The DC-isolating coupling capacitor 222 is a tantalum capacitor or a niobium capacitor arranged in series in the feedback voltage-dividing branch 22, or a capacitor formed by multiple tantalum capacitors and / or niobium capacitors in the feedback voltage-dividing branch 22 based on series and / or parallel equivalent connection. The voltage-dividing resistor 221 is a resistor arranged in series in the feedback voltage-dividing branch 22, or a resistor connected in series in the feedback voltage-dividing branch 22 formed by multiple resistors in the feedback voltage-dividing branch based on series and / or parallel equivalent connection, and the present invention does not limit this.

[0053] It is worth mentioning that, in the state where the amplitude range of the input signal is adapted to the corresponding reverse voltage range, based on the requirement for adjusting the reverse voltage of the DC-isolating coupling capacitor 222 set as a tantalum capacitor or a niobium capacitor, by adjusting the voltage division size of the feedback voltage-dividing branch 22, the reference voltage of the input signal can be adjusted to adjust the reverse voltage of the DC-isolating coupling capacitor 222 to adapt to the corresponding reverse voltage range, so as to break through the common sense requirement and inertial cognition of technicians in this field that capacitors with polarity are strictly prohibited from reverse connection to avoid increased leakage current and irreversible structural damage or even explosion, and to ensure the stability and service life of the DC-isolating coupling capacitor 222 in the reverse connection state, while reducing the restriction of the reverse connection of the DC-isolating coupling capacitor 222 on the voltage amplitude of the input signal amplified by the capacitor reverse connection negative feedback amplifier circuit, thereby helping to improve the applicability of the capacitor reverse connection negative feedback amplifier circuit.

[0054] Correspondingly, refer to the accompanying drawings of the specification of the present invention. Figure 4A and Figure 4BAs shown, based on the requirement for adjusting the reverse voltage of the DC-isolating coupling capacitor 222 set as a tantalum capacitor or a niobium capacitor, the capacitor reverse-connected negative feedback amplifier circuit further includes a reference voltage adjustment branch 30, wherein the reference voltage adjustment branch has a voltage dividing node 32 and two branch resistors 31 with a preset resistance value bounded by the voltage dividing node 32, wherein the reference voltage adjustment branch 30 is electrically connected to the in-phase input terminal 12 of the operational amplifier 10 at its voltage dividing node 32, so as to set the voltage difference between the two ends of the reference voltage adjustment branch 30 and the preset resistance value of the two branch resistors 31. The setting adjusts the voltage magnitudes of the non-inverting input terminal 12 and the inverting input terminal 11 of the operational amplifier 10, and adjusts the reference voltage of the input signal in the non-inverting input state or the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit, thereby forming a voltage division adjustment for the feedback voltage division branch 22 and adjusting the reverse voltage of the DC-isolating coupling capacitor 222 which is set as a tantalum capacitor or a niobium capacitor, so as to ensure the stability and service life of the DC-isolating coupling capacitor 222 in the reverse connection state when the DC-isolating coupling capacitor 222 which is set as a tantalum capacitor or a niobium capacitor is connected in series with the feedback voltage division branch 22 with reverse polarity.

[0055] It can also be understood that in the actual circuit structure of the capacitor reverse negative feedback amplifier circuit, the branch resistor 31 is a resistor in the reference voltage adjustment branch 30 with the voltage dividing node 32 as the boundary, or is a resistor formed by multiple resistors in the reference voltage adjustment branch 30 with the voltage dividing node 32 as the boundary based on series and / or parallel equivalence, and the present invention is not limited to this.

[0056] Further, referring to the accompanying drawings of the present invention, Figure 5A and Figure 5B As shown, in order to fully demonstrate the beneficial effect of the capacitor reverse connection negative feedback amplifier circuit of the present invention on improving the signal-to-noise ratio of the amplified output signal, corresponding to Figure 4B The capacitor reverse connection negative feedback amplifier circuit of the present invention amplifies and outputs the Doppler intermediate frequency signal of the unmanned state and the Doppler intermediate frequency signal of the manned state output by the same microwave detection module before and after the DC isolation coupling capacitor 222, which is set as a tantalum capacitor or a niobium capacitor, is reversely connected, and the signals after the amplification are compared and shown, wherein the corresponding Figure 5A , the amplitude of the signal after the capacitor reverse-connection negative feedback amplifier circuit amplifies and outputs the Doppler intermediate frequency signal (i.e., the environmental noise signal) in the unmanned state output by the same microwave detection module before and after the DC-isolating coupling capacitor 222 is reversed is similar, that is, the amplification factor of the capacitor reverse-connection negative feedback amplifier circuit for the low-amplitude signal before and after the DC-isolating coupling capacitor 222 is reversed tends to be the same, and the corresponding Figure 5B, the amplitude difference of the signal after the capacitor reverse connection type negative feedback amplifier circuit amplifies and outputs the Doppler intermediate frequency signal corresponding to the human state output by the same microwave detection module before and after the DC isolation coupling capacitor 222 is reversed is obvious, which is specifically reflected in that the capacitor reverse connection type negative feedback amplifier circuit has a greater amplification factor for the Doppler intermediate frequency signal corresponding to the human state output by the same microwave detection module when the DC isolation coupling capacitor 222 is reversed. That is to say, since the capacitor reverse connection type negative feedback amplifier circuit has the characteristic that the amplification factor of the input signal is associated with the resistance ratio of the feedback resistor 21 and the feedback voltage divider branch 22, based on the above comparison, in the state where the DC isolation coupling capacitor 222 is reversed, the feedback voltage divider branch 22 has a change trend characteristic that its internal resistance decreases as the amplitude of the signal increases, correspondingly showing the change trend that the amplification factor of the input signal of the capacitor reverse connection type negative feedback amplifier circuit increases as the amplitude of the signal increases, so as to suppress the amplification effect of the low-amplitude signal in the signal amplification application and improve the signal-to-noise ratio of the amplified output signal.

[0057] It is worth mentioning that in order to clearly and briefly explain and understand the basic circuit form and principle of the capacitor reverse negative feedback amplifier circuit of the present invention, in the drawings corresponding to these embodiments of the present invention, the capacitor reverse negative feedback amplifier circuit is illustrated as a basic circuit form of a first-stage amplification in a non-inverting input state or a reverse input state, but this does not limit the capacitor reverse negative feedback amplifier circuit of the present invention to a first-stage amplifier circuit. The capacitor reverse negative feedback amplifier circuit can be either a first-stage amplifier circuit or a second-stage amplifier circuit. FIG. 3A to FIG. 4B The basic circuit form of the first-stage amplification shown in any of the drawings in the specification of the present invention may also be a basic circuit form of the first-stage amplification shown in any of the drawings in the specification of the present invention. FIG. 3A to FIG. 4B A one-stage or multi-stage amplifier circuit of the basic circuit form of a one-stage amplifier as shown in any of the drawings, such as the one-stage amplifier circuit of the present invention, FIG. 3A to FIG. 4B A one-stage or multi-stage amplifier circuit formed by combining the basic circuit form of the first-stage amplifier shown in any of the drawings and the existing voltage follower and / or the existing negative feedback amplifier circuit, or a one-stage or multi-stage amplifier circuit based on the drawings of the specification of the present invention FIG. 3A to FIG. 4B The multi-stage amplifier circuit is formed by combining the basic circuit forms of the first-stage amplifier shown in the same or different figures, and the present invention is not limited to this.

[0058] That is to say, the drawings of the specification of the present invention are named FIG. 3A to FIG. 4BThe basic circuit form of the first-stage amplification of the capacitor reverse-connected negative feedback amplifier circuit in the same-phase input state or the inverting input state as shown in any of the accompanying drawings is a capacitor reverse-connected negative feedback amplifier circuit unit. The capacitor reverse-connected negative feedback amplifier circuit of the present invention includes at least one capacitor reverse-connected negative feedback amplifier circuit unit, wherein the capacitor reverse-connected negative feedback amplifier circuit unit includes the operational amplifier 10 and the negative feedback network 20, or further includes the reference voltage adjustment branch 30, wherein the operational amplifier 10 has the inverting input terminal 11, the same-phase input terminal 12 and the output terminal 13; The negative feedback network 20 includes the feedback resistor 21 and the feedback voltage-dividing branch 22, wherein one end of the feedback resistor 21 is electrically connected to the inverting input terminal 11 of the operational amplifier 10, and the other end of the feedback resistor 21 is electrically connected to the output terminal 13 of the operational amplifier 10, that is, the output terminal 13 of the operational amplifier 10 is connected to the inverting input terminal 11 via the feedback resistor 21, wherein the feedback voltage-dividing branch 22 includes the voltage-dividing resistor 221 and the DC-isolating coupling capacitor 222 connected in series with the voltage-dividing resistor 221, wherein the DC-isolating coupling capacitor 22 2 is set as a tantalum capacitor or a niobium capacitor and has polarity, wherein one end of the feedback voltage-dividing branch 22 is electrically connected to the inverting input terminal 11 of the operational amplifier 10 in a state where the DC-isolating coupling capacitor 222 is connected in series with the feedback voltage-dividing branch 22 in reverse polarity, corresponding to when the capacitor reverse-connected negative feedback amplifier circuit unit is input in phase, that is, when the corresponding input signal is connected to the in-phase input terminal 12 of the operational amplifier 10, and when the other end of the feedback voltage-dividing branch 22 is connected to the reference ground of the input signal, the DC-isolating coupling capacitor 222 is connected with the inverting input terminal 11 of the operational amplifier 10 by its negative electrode. The DC-isolating coupling capacitor 222 is arranged in series with the feedback voltage-dividing branch 22 in a state where the DC-isolating coupling capacitor 222 is electrically connected to the inverting input terminal 11 of the operational amplifier 10, and when the capacitor reverse-connected negative feedback amplifier circuit unit is input in an inverted phase, that is, the input signal is connected to the other end of the feedback voltage-dividing branch 22, and the non-inverting input terminal 12 of the operational amplifier 10 is connected to the reference ground of the input signal, the DC-isolating coupling capacitor 222 is arranged in series with the feedback voltage-dividing branch 22 in a state where the positive electrode thereof is electrically connected to the inverting input terminal 11 of the operational amplifier 10, so as to form a state where the DC-isolating coupling capacitor 222 is connected in series with the feedback voltage-dividing branch 22 in reverse polarity;The reference voltage adjustment branch has the voltage dividing node 32 and two branch resistors 31 with preset resistance values ​​separated by the voltage dividing node 32, wherein the reference voltage adjustment branch 30 is electrically connected to the non-inverting input terminal 12 of the operational amplifier 10 at its voltage dividing node 32, so as to adjust the voltage magnitudes of the non-inverting input terminal 12 and the inverting input terminal 11 of the operational amplifier 10 based on the voltage difference setting at both ends of the reference voltage adjustment branch 30 and the preset resistance value setting of the two branch resistors 31, and adjust the reference voltage of the input signal in the non-inverting input state or the inverting input state of the capacitor reverse connection negative feedback amplifier circuit, thereby forming a voltage division adjustment for the feedback voltage dividing branch 22 and adjusting the reverse voltage of the DC-isolating coupling capacitor 222 set as a tantalum capacitor or a niobium capacitor, so as to ensure the stability and working life of the DC-isolating coupling capacitor 222 in the reverse connection state when the DC-isolating coupling capacitor 222 set as a tantalum capacitor or a niobium capacitor is connected in series with the feedback voltage dividing branch 22 in reverse polarity. ;

[0059] For example, referring to the accompanying drawings of the present invention, FIG. 6A to FIG. 6D As shown, based on the combination between the capacitor reverse negative feedback amplifier circuit unit and the existing voltage follower, and the two-stage combination with the same or different capacitor reverse negative feedback amplifier circuits, the capacitor reverse negative feedback amplifier circuits of different embodiments are respectively illustrated.

[0060] Corresponds to Fig. 6A Based on the combination between the capacitor reverse negative feedback amplifier circuit unit in the inverting input state and the existing voltage follower, the capacitor reverse negative feedback amplifier circuit according to an embodiment of the present invention is illustrated, wherein the capacitor reverse negative feedback amplifier circuit includes the capacitor reverse negative feedback amplifier circuit unit in the inverting input state and the voltage follower, wherein the feedback voltage divider branch 22 of the capacitor reverse negative feedback amplifier circuit unit in the inverting input state is electrically connected between the inverting input end of the capacitor reverse negative feedback amplifier circuit unit and the output end of the voltage follower, so as to improve the amplification factor of the capacitor reverse negative feedback amplifier circuit unit in the inverting input state to the input signal based on the effect of the voltage follower on reducing the internal resistance of the signal source.

[0061] Corresponds to Figure 6B, based on the combination of the capacitor reverse negative feedback amplifier circuit unit in the same phase input state and the capacitor reverse negative feedback amplifier circuit unit in the inverting input state, the capacitor reverse negative feedback amplifier circuit according to another embodiment of the present invention is illustrated, wherein the capacitor reverse negative feedback amplifier circuit uses the capacitor reverse negative feedback amplifier circuit unit in the same phase input state as the front-stage circuit, and the capacitor reverse negative feedback amplifier circuit unit in the inverting input state as the rear-stage circuit, and the feedback voltage divider branch 22 corresponding to the rear-stage circuit is electrically connected to the two-stage amplifier circuit between the output terminal 13 of the front-stage circuit and the inverting input terminal 11 of the rear-stage circuit.

[0062] Corresponds to Figure 6C , based on the combination of the two capacitor reverse-connected negative feedback amplifier circuit units in the same-phase input state, the capacitor reverse-connected negative feedback amplifier circuit according to another embodiment of the present invention is illustrated, wherein the capacitor reverse-connected negative feedback amplifier circuit uses one of the capacitor reverse-connected negative feedback amplifier circuit units in the same-phase input state as a front-stage circuit, and the other capacitor reverse-connected negative feedback amplifier circuit unit as a rear-stage circuit, corresponding to the two-stage amplifier circuit formed by the output terminal 13 of the front-stage circuit being electrically connected to the same-phase input terminal 12 of the rear-stage circuit.

[0063] Corresponds to Fig.6D , based on the combination of the two capacitor reverse-connected negative feedback amplifier circuit units in the inverting input state, the capacitor reverse-connected negative feedback amplifier circuit according to another embodiment of the present invention is illustrated, wherein the capacitor reverse-connected negative feedback amplifier circuit uses one of the capacitor reverse-connected negative feedback amplifier circuit units in the inverting input state as a front-stage circuit, and the other capacitor reverse-connected negative feedback amplifier circuit unit as a rear-stage circuit, and the feedback voltage divider branch 22 corresponding to the rear-stage circuit is electrically connected to the two-stage amplifier circuit between the output terminal 13 of the front-stage circuit and the inverting input terminal 11 of the rear-stage circuit.

[0064] It should be understood by those skilled in the art that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments, and the embodiments of the present invention may be deformed or modified in any way without departing from the principles.

Claims

1. Capacitor reverse connection negative feedback amplifier circuit, characterized in that: The capacitor reverse-connection negative feedback amplifier circuit comprises at least one capacitor reverse-connection negative feedback amplifier circuit unit, wherein the capacitor reverse-connection negative feedback amplifier circuit unit comprises: an operational amplifier, wherein the operational amplifier has a non-inverting input terminal, an inverting input terminal and an output terminal; and A negative feedback network, wherein the negative feedback network includes a feedback resistor and a feedback voltage divider branch, wherein one end of the feedback resistor is electrically connected to the inverting input terminal of the operational amplifier, and the other end of the feedback resistor is electrically connected to the output terminal of the operational amplifier, wherein the feedback voltage divider branch includes a voltage divider resistor and a DC-isolating coupling capacitor connected in series with the voltage divider resistor, wherein the DC-isolating coupling capacitor is set as a tantalum capacitor or a niobium capacitor and has polarity, wherein one end of the feedback voltage divider branch is electrically connected to the inverting input terminal of the operational amplifier in a state where the DC-isolating coupling capacitor is connected in series with the feedback voltage divider branch in reverse polarity, corresponding to the in-phase input terminal of the capacitor inverse negative feedback amplifier circuit unit. In the input state, that is, the corresponding input signal is connected to the non-inverting input terminal of the operational amplifier, and the reference ground of the input signal is connected to the other end of the feedback voltage divider branch, the DC-isolating coupling capacitor is electrically connected to the inverting input terminal of the operational amplifier with its negative electrode in series with the feedback voltage divider branch, and in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit, that is, the input signal is connected to the other end of the feedback voltage divider branch, and the reference ground of the input signal is connected to the non-inverting input terminal of the operational amplifier, the DC-isolating coupling capacitor is electrically connected to the inverting input terminal of the operational amplifier with its positive electrode in series with the feedback voltage divider branch.

2. The capacitor reverse-connected negative feedback amplifier circuit according to claim 1, wherein the DC-isolating coupling capacitor is directly electrically connected to the inverting input terminal of the operational amplifier in a state where it is connected in series with the feedback voltage divider branch with reverse polarity, and correspondingly in a non-inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit, the negative electrode of the DC-isolating coupling capacitor is directly electrically connected to the inverting input terminal of the operational amplifier, and the positive electrode of the DC-isolating coupling capacitor is directly electrically connected to one end of the voltage divider resistor, and in an inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit, the positive electrode of the DC-isolating coupling capacitor is directly electrically connected to the inverting input terminal of the operational amplifier, and the negative electrode of the DC-isolating coupling capacitor is directly electrically connected to one end of the voltage divider resistor, so as to form a connection relationship in which one end of the feedback voltage divider branch is electrically connected to the inverting input terminal of the operational amplifier in a state where the DC-isolating coupling capacitor is connected in series with the feedback voltage divider branch with reverse polarity.

3. The capacitor reverse-connected negative feedback amplifier circuit according to claim 1, wherein the DC-isolating coupling capacitor is electrically connected to the inverting input terminal of the operational amplifier via the voltage-dividing resistor in a state where it is reversely connected in series with the feedback voltage-dividing branch, corresponding to the non-inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit, one end of the voltage-dividing resistor is electrically connected to the inverting input terminal of the operational amplifier, and the other end of the voltage-dividing resistor is electrically connected to the negative electrode of the DC-isolating coupling capacitor, and in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit, one end of the voltage-dividing resistor is electrically connected to the inverting input terminal of the operational amplifier, and the other end of the voltage-dividing resistor is electrically connected to the positive electrode of the DC-isolating coupling capacitor, so as to form a connection relationship in which one end of the feedback voltage-dividing branch is electrically connected to the inverting input terminal of the operational amplifier in a state where the DC-isolating coupling capacitor is reversely connected in series with the feedback voltage-dividing branch.

4. The capacitor reverse-connected negative feedback amplifier circuit according to claim 1, wherein the capacitor reverse-connected negative feedback amplifier circuit unit also includes a reference voltage adjustment branch, wherein the reference voltage adjustment branch has a voltage dividing node and two branch resistors with preset resistance values ​​separated by the voltage dividing node, wherein the reference voltage adjustment branch is electrically connected to the in-phase input terminal of the operational amplifier at the voltage dividing node. 5 . The capacitor reverse-connection negative feedback amplifier circuit according to claim 1 , wherein the input signal is a Doppler intermediate frequency signal generated based on the principle of microwave Doppler effect.

6. A capacitor reverse-connected negative feedback amplifier circuit according to any one of claims 1 to 4, wherein the capacitor reverse-connected negative feedback amplifier circuit further includes a voltage follower, wherein the positive electrode of the DC-isolating coupling capacitor is electrically connected to the inverting input terminal of the operational amplifier, and the negative electrode of the DC-isolating coupling capacitor is electrically connected to the output terminal of the voltage follower to form an inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit and a state in which the DC-isolating coupling capacitor is connected in series with the feedback voltage divider branch in reverse polarity in the inverting input state of the capacitor reverse-connected negative feedback amplifier circuit unit.

7. A capacitor reverse-connected negative feedback amplifier circuit according to any one of claims 1 to 4, wherein the capacitor reverse-connected negative feedback amplifier circuit comprises at least two capacitor reverse-connected negative feedback amplifier circuit units, wherein the capacitor reverse-connected negative feedback amplifier circuit uses one of the capacitor reverse-connected negative feedback amplifier circuit units as a front-stage circuit, and uses the other capacitor reverse-connected negative feedback amplifier circuit unit as a rear-stage circuit, corresponding to a two-stage amplifier circuit in which the in-phase input terminal of the rear-stage circuit is electrically connected to the output terminal of the front-stage circuit in the in-phase input state of the rear-stage circuit, and a two-stage amplifier circuit in which the feedback voltage divider branch of the rear-stage circuit is electrically connected between the output terminal of the front-stage circuit and the inverting input terminal of the rear-stage circuit in the inverting input state of the rear-stage circuit.

8. The capacitor reverse-connected negative feedback amplifier circuit according to claim 7, wherein the capacitor reverse-connected negative feedback amplifier circuit comprises a capacitor reverse-connected negative feedback amplifier circuit unit in a common-phase input state and a capacitor reverse-connected negative feedback amplifier circuit unit in an inverting input state, wherein the capacitor reverse-connected negative feedback amplifier circuit has the capacitor reverse-connected negative feedback amplifier circuit unit in a common-phase input state as a front-stage circuit, and the capacitor reverse-connected negative feedback amplifier circuit unit in an inverting input state as a rear-stage circuit, and the feedback voltage divider branch corresponding to the rear-stage circuit is electrically connected to the two-stage amplifier circuit between the output end of the front-stage circuit and the inverting input end of the rear-stage circuit.

9. The capacitor reverse-connected negative feedback amplifier circuit according to claim 7, wherein the capacitor reverse-connected negative feedback amplifier circuit comprises two capacitor reverse-connected negative feedback amplifier circuit units in the same-phase input state, wherein the capacitor reverse-connected negative feedback amplifier circuit uses one of the capacitor reverse-connected negative feedback amplifier circuit units as a front-stage circuit, and uses the other capacitor reverse-connected negative feedback amplifier circuit unit as a rear-stage circuit, corresponding to forming a two-stage amplifier circuit in which the output end of the front-stage circuit is electrically connected to the same-phase input end of the rear-stage circuit.

10. The capacitor reverse-connected negative feedback amplifier circuit according to claim 7, wherein the capacitor reverse-connected negative feedback amplifier circuit comprises two capacitor reverse-connected negative feedback amplifier circuit units in an inverting input state, wherein the capacitor reverse-connected negative feedback amplifier circuit uses one of the capacitor reverse-connected negative feedback amplifier circuit units as a front-stage circuit, and the other capacitor reverse-connected negative feedback amplifier circuit unit as a rear-stage circuit, and the feedback voltage divider branch corresponding to the rear-stage circuit is electrically connected to the two-stage amplifier circuit between the output end of the front-stage circuit and the inverting input end of the rear-stage circuit.

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