A transconductance amplifier

Abstract

The invention discloses a transconductance amplifier, comprising a buffer isolation circuit for isolating an input signal and an output signal; a signal distribution circuit for matching a transconductance coefficient to evenly distribute a voltage signal output by the buffer isolation circuit; and a transconductance conversion circuit for proportionally amplifying the voltage signal output by the signal distribution circuit into a current signal; wherein the buffer isolation circuit is connected to the signal distribution circuit, and the signal distribution circuit is connected to the transconductance conversion circuit, and the beneficial effect is that a large current of hundreds of amperes can be output to a load, and when the frequency is from direct current to 40 kHz, the accuracy is within 0.3%, and when the frequency is from 40 kHz to 200 kHz, the accuracy is within 3%.

Description

Technical Field

[0001] The present invention belongs to the technical field of amplifiers, and more specifically, relates to a transconductance amplifier. Background Art

[0002] In common electronic circuits, transconductance amplifiers can usually only output tens of milliamperes. However, in practical applications and theoretical research, especially in circuit simulation, power system simulation and transient analysis, testing of various passive components, calibration testing of current sensors, electromagnetic analysis, radio frequency and plasma, low-frequency communications and other occasions, a verification tool that can output tens or hundreds of amperes and a frequency of more than 100K is needed, namely a transconductance amplifier.

[0003] The commonly used power system simulation amplifiers currently have the following defects: First, those that meet the requirements of broadband output cannot output currents of hundreds of amperes; second, those that meet the requirements of large current output cannot meet the requirements of broadband outputs of more than 100K. Currently, there are no transconductance amplifiers on the market that can simultaneously output large currents and broadband. The nominal bandwidth of the Clarke-Hess8100 transconductance amplifier in the United States is 0-100K, and the output current can reach 100A, but the maximum output voltage is 7V effective value. When the output is 100A, it can only carry loads with an impedance of less than 0.07 ohms, which is not practical. Summary of the invention

[0004] The object of the present invention is to provide a transconductance amplifier to solve the technical problem in the prior art that the transconductance amplifier cannot output a wide frequency band and a large current at the same time.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A transconductance amplifier, comprising:

[0007] A buffer isolation circuit, used for isolating an input signal from an output signal, wherein both the input signal and the output signal are voltage signals;

[0008] A signal distribution circuit, used for matching the transconductance coefficient to evenly distribute the voltage signal output by the buffer isolation circuit;

[0009] A transconductance conversion circuit, used for proportionally amplifying the voltage signal output by the signal distribution circuit into a current signal;

[0010] The buffer isolation circuit is connected to the signal distribution circuit, and the signal distribution circuit is connected to the transconductance conversion circuit.

[0011] Preferably, the buffer isolation circuit comprises a first operational amplifier, the first operational amplifier comprises a non-inverting input terminal, a reverse input terminal and an output terminal, the non-inverting input terminal is used to input the voltage signal, and the output terminal is connected to the reverse input terminal.

[0012] Preferably, the signal distribution circuit comprises a plurality of groups of resistors.

[0013] Preferably, the number of the transconductance conversion circuits is multiple groups, and the transconductance conversion circuits are in a parallel structure.

[0014] Preferably, the transconductance conversion circuit includes a second operational amplifier and a third operational amplifier, the second operational amplifier is connected to the signal distribution circuit, and the third operational amplifier is connected to the second operational amplifier.

[0015] Preferably, the transconductance conversion circuit further includes a high-frequency channel unit and a current driving circuit, and the high-frequency channel unit and the current driving circuit are connected.

[0016] Preferably, the high-frequency channel unit includes a first diode, a second diode and a resistor, and the resistor is connected to the first diode and the second diode respectively.

[0017] Preferably, the current driving circuit comprises an NPN transistor and a PNP transistor, the number of the NPN transistor is multiple, and the number of the PNP transistor is multiple.

[0018] Preferably, the current driving circuit adopts discrete components.

[0019] Preferably, the transconductance conversion circuit further includes a positive power supply, a negative power supply and a first capacitor.

[0020] The beneficial effects provided by the present invention are:

[0021] 1. The present invention isolates input signals and output signals through an isolation buffer circuit, so that interference and intermodulation distortion are not easily generated between the input signals and the output signals, and the load capacity of the signal distribution circuit is improved, thereby avoiding the situation where the voltage of the input signal is pulled down when the signal distribution circuit and the transconductance conversion circuit require a higher input power, resulting in an output signal voltage that is disproportionate.

[0022] 2. The present invention distributes the voltage signal output by the buffer isolation circuit to the transconductance conversion circuit in proportion through a signal distribution circuit, which is used to match the transconductance coefficient so that the ratio of the input voltage signal value to the output current value is within a designed range.

[0023] 3. The present invention uses a transconductance conversion circuit to proportionally amplify the voltage signal output by the signal distribution circuit into a current signal. The number of transconductance conversion circuits is multiple groups, and the transconductance conversion circuits are in a parallel structure. After the multiple groups of transconductance conversion circuits are connected in parallel, the output current signal is doubled, and a large current of hundreds of amperes can be output to the load. When the frequency is from DC to 40 kHz, the accuracy is within 0.3%, and when the frequency is from 40 kHz to 200 kHz, the accuracy is within 3%.

[0024] 4. The present invention includes a high-frequency channel unit and a current driving circuit. The high-frequency channel unit is used to improve high-frequency linearity, and the current driving circuit is used to reduce the power of a single transistor. Multiple transistors are connected in parallel, and a complementary symmetrical method is used to increase the current output by connecting multiple transistors in parallel.

[0025] 5. The current driving circuit of the present invention adopts discrete components. The use of discrete components is more conducive to heat dissipation and uniform heat dissipation on the one hand, and can obtain a wider frequency band on the other hand. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 It is a flow chart of the transconductance amplifier;

[0028] Figure 2 It is a schematic diagram of the structure of the buffer isolation circuit;

[0029] Figure 3 is a schematic diagram of the structure of a signal distribution unit;

[0030] Figure 4 It is a structural diagram of a transconductance conversion circuit. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] This embodiment includes a transconductance amplifier such as Figure 1 As shown, it includes a buffer isolation circuit for isolating input signals and output signals, both of which are voltage signals; a signal distribution circuit for matching the transconductance coefficient to evenly distribute the voltage signal output by the buffer isolation circuit; and a transconductance conversion circuit for proportionally amplifying the voltage signal output by the signal distribution circuit into a current signal; wherein the buffer isolation circuit is connected to the signal distribution circuit, and the signal distribution circuit is connected to the transconductance conversion circuit.

[0034] like Figure 2 As shown, the buffer isolation circuit includes a first operational amplifier AR1, which includes a non-inverting input terminal, a reverse input terminal and an output terminal. The non-inverting input terminal is used to input a voltage signal, and the output terminal is connected to the reverse input terminal.

[0035] The isolation buffer circuit is a voltage follower composed of a first operational amplifier AR1. Since the operational amplifier has an extremely high open-loop gain, the voltage follower composed of the operational amplifier does not require any peripheral components and is close to an ideal performance. Specifically, the voltage follower composed of the first operational amplifier AR1 has an extremely high input impedance and almost does not draw current from the input signal, i.e., the voltage signal. It also has an extremely low output impedance and almost does not cause a voltage drop internally when outputting current.

[0036] Therefore, it can be used to isolate input signals and output signals, making it less likely for interference and intermodulation distortion to occur between the input signals and the output signals, and improving the load capacity of the signal distribution circuit, thereby avoiding the situation where the voltage of the input signal is pulled down when the signal distribution circuit and the transconductance conversion circuit require a higher input power, resulting in an output signal voltage that is disproportionate.

[0037] The signal distribution circuit includes multiple groups of resistors, which are used to distribute the voltage signal output by the buffer isolation circuit to the transconductance conversion circuit in proportion. Figure 3 As shown, in this embodiment, the signal distribution unit includes four groups of resistors, and the four groups of resistors are in a parallel structure. Each group of resistors includes two resistors connected in series. The two resistors connected in series constitute a series voltage divider circuit for matching the transconductance coefficient so that the ratio of the input voltage signal value to the output current value is within a designed range. The transconductance coefficient refers to the ratio between the change value of the output current and the change value of the input voltage.

[0038] Specifically, taking two groups of resistors as an example, the twenty-first resistor R21 and the twenty-second resistor R22 are connected in series to form a first group of resistors, and the twenty-third resistor R23 and the twenty-fourth resistor R24 ​​are connected in series to form a second group of resistors. The first group of resistors and the second group of resistors are in parallel. Taking the input voltage of 5V as an example, after the signal distribution circuit, the output voltage of each group is 0.5 times the input voltage, that is, 2.5V. The signal distribution circuit completely uses resistors for voltage division, so that the output signal of the isolation buffer circuit is proportionally output to the transconductance conversion circuit after passing through the signal distribution circuit.

[0039] like Figure 4 As shown, the transconductance conversion circuit includes a second operational amplifier AR2 and a third operational amplifier AR3, the second operational amplifier AR2 is connected to the signal distribution circuit, and the third operational amplifier AR3 is connected to the second operational amplifier AR2. The voltage follower formed by the second operational amplifier AR2 is used to isolate the input signal and the output signal, and improve the current output accuracy under different load conditions. Since the second operational amplifier AR2 is basically similar to the first operational amplifier AR1, the description is relatively simple, and the relevant parts can be referred to the partial description of the first operational amplifier AR1.

[0040] The transconductance conversion circuit also includes a high-frequency channel unit and a current driving circuit, and the high-frequency channel unit is connected to the current driving circuit. Since the third operational amplifier AR3 cannot output a large current of hundreds of amperes, the current driving circuit is connected, and the third operational amplifier AR3 is connected to the current driving circuit.

[0041] The current push circuit includes NPN transistors and PNP transistors. In order to reduce the power of a single transistor, multiple transistors are connected in parallel. At the same time, a complementary symmetric method is adopted to increase the current output by connecting multiple transistors in parallel. Therefore, the number of NPN transistors is multiple and the number of PNP transistors is multiple. The current push circuit uses discrete components. On the one hand, the use of discrete components is more conducive to heat dissipation and uniform heat dissipation, and on the other hand, a wider frequency band can be obtained. The high-frequency channel unit includes a first diode D1, a second diode D2 and a resistor. The resistor is connected to the first diode D1 and the second diode D2 respectively. The high-frequency channel unit is used to improve high-frequency linearity.

[0042] In this embodiment, the transconductance conversion circuit also includes a positive power supply VCC2, a negative power supply VEE2, a first capacitor C1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor 17, an eighteenth resistor 18, a nineteenth resistor 19 and a twentieth resistor R20.

[0043] As a preferred embodiment, the number of NPN transistors is 5, and the number of PNP transistors is 5. Specifically, the NPN transistor includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4 and a fifth transistor Q5, and the PNP transistor includes a sixth transistor Q6, a seventh transistor Q7, an eighth transistor Q8, a ninth transistor Q9 and a tenth transistor Q10.

[0044] The base of the fourth triode Q4 is connected to the fourth resistor R4, the collector of the fourth triode Q4 is connected to the third resistor R3, the emitter of the fourth triode Q4 is connected to the base of the fifth triode Q5, the collector of the fifth triode Q5 is connected to the first resistor R1, the emitter of the fifth triode Q5 is respectively connected to the base of the first triode Q1, the base of the second triode Q2 and the base of the third triode Q3, the collector of the first triode Q1, the collector of the second triode Q2 and the collector of the third triode Q3 are all connected to the positive power supply VCC2, and the emitter of the first triode Q1, the emitter of the second triode Q2 and the emitter of the third triode Q3 are all connected to the seventh resistor R7.

[0045] The base of the seventh triode Q7 is connected to the seventeenth resistor R17, the collector of the seventh triode Q7 is connected to the eighteenth resistor R18, the emitter of the seventh triode Q7 is connected to the base of the sixth triode Q6, the collector of the sixth triode Q6 is connected to the nineteenth resistor R19, the emitter of the sixth triode Q6 is connected to the base of the eighth triode Q8, the base of the ninth triode Q9 and the base of the tenth triode Q10, respectively, the collector of the eighth triode Q8, the collector of the ninth triode Q9 and the base of the tenth triode Q10 are connected to the base of the eighth triode Q8, the collector of the ninth triode Q9 and the base of the tenth triode Q10. The collector of the transistor Q10 is connected to the negative power supply VEE2, the emitter of the eighth transistor Q8, the emitter of the ninth transistor Q9 and the emitter of the tenth transistor Q10 are connected to the fourteenth resistor R14, the anode of the first diode D1 is connected to the positive power supply VCC2, the cathode of the first diode D1 is connected to the twelfth resistor R12, the anode of the second diode D2 is connected to the fifteenth resistor R15, the cathode of the second diode D2 is connected to the negative power supply VEE2, and the first capacitor C1 and the sixth resistor R6 are connected in parallel.

[0046] By changing the value of the eighth resistor R8, different voltage-to-current conversion coefficients, i.e., transconductance coefficients, can be obtained. Figure 1As shown, there are multiple groups of transconductance conversion circuits, which are in parallel structure. The transconductance conversion circuit is used to proportionally amplify the voltage signal output by the signal distribution circuit into a current signal. After multiple groups of transconductance conversion circuits are connected in parallel, the output current signal is doubled, and a large current of hundreds of amperes can be output to the load. When the frequency is from DC to 40 kHz, the accuracy is within 0.3%, and when the frequency is from 40 kHz to 200 kHz, the accuracy is within 3%.

[0047] It should be noted that:

[0048] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0049] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0050] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different. Any equivalent or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. The technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A transconductance amplifier, characterized in that: include: A buffer isolation circuit, used for isolating an input signal from an output signal, wherein both the input signal and the output signal are voltage signals; A signal distribution circuit, used for matching the transconductance coefficient to evenly distribute the voltage signal output by the buffer isolation circuit; A transconductance conversion circuit, used for proportionally amplifying the voltage signal output by the signal distribution circuit into a current signal; Wherein, the buffer isolation circuit is connected to the signal distribution circuit, and the signal distribution circuit is connected to the transconductance conversion circuit; The transconductance conversion circuit comprises: an input terminal INI, an output terminal OUT, a positive power supply VCC and a negative power supply VEE, The input terminal INI is respectively connected to the in-phase input terminal of the operational amplifier AR2 and the first terminal of the resistor R11 and is grounded; The inverting input terminal of the operational amplifier AR2 is connected to the output terminal of the operational amplifier AR2, and the output terminal of the operational amplifier AR2 is connected to the first terminal of the resistor R8; The second end of the resistor R8 is connected to the inverting input end of the operational amplifier AR3, the first end of the resistor R6 and the first end of the capacitor C1 respectively; the second ends of the resistor R6 and the capacitor C1 are both connected to the first end of the resistor R9, and the second end of the resistor R9 is connected to the output end OUT; The second end of the resistor R11 is connected to the in-phase input end of the operational amplifier AR3 and the first end of the resistor R20, the second end of the resistor R20 is connected to the output end OUT, the output end of the operational amplifier AR3 is respectively connected to the first ends of the resistor R10, the resistor R5 and the resistor R13, and the second end of the resistor R10 is connected to the first end of the resistor R9; The positive power supply VCC is connected to the positive power supply terminal of the operational amplifier AR2 and the first end of the resistor R2 respectively, and the second end of the resistor R2 is connected to the positive power supply terminal of the operational amplifier AR3; the negative power supply terminal of the operational amplifier AR2 is connected to the negative power supply VEE, and the negative power supply terminal of the operational amplifier AR3 is connected to the negative power supply VEE through the resistor R16; The positive power supply VCC is also connected to the collectors of transistors Q1, Q2 and Q3, and the first ends of resistors R1 and R3 respectively; the second end of resistor R1 is connected to the first end of resistor R4 and the collector of transistor Q5 respectively, and the second end of resistor R3 is connected to the collector of transistor Q4; the second ends of resistors R4 and R5 are both connected to the base of transistor Q4, the emitter of transistor Q4 is connected to the base of transistor Q5, the emitter of transistor Q5 is respectively connected to the bases of transistors Q1, Q2 and Q3, and the first end of resistor R15, the second end of resistor R15 is connected to the positive electrode of diode D2, and the negative electrode of diode D2 is connected to the negative power supply VEE; the emitters of transistors Q1, Q2 and Q3 are all connected to the first end of resistor R7, and the second end of resistor R7 is connected to the first ends of resistors R14 and R9; The positive power supply VCC is also connected to the positive electrode of the diode D1, the negative electrode of the diode D1 is connected to the first end of the resistor R12, the second end of the resistor R12 is respectively connected to the base of the transistor Q8, the transistor Q9 and the transistor Q10 and the collector of the transistor Q6, the base of the transistor Q6 is connected to the collector of the transistor Q7, and the emitter of the transistor Q6 is connected to the first end of the resistor R19; the second end of the resistor R13 is respectively connected to the base of the transistor Q7 and the first end of the resistor R17, and the emitter of the transistor Q7 is connected to the negative power supply VEE through the resistor R18; the second end of the resistor R17 is connected to the first end of the resistor R19, and the second end of the resistor R19 is connected to the negative power supply VEE; The second end of the resistor R14 is connected to the collectors of the transistors Q8 , Q9 and Q10 , respectively. The emitters of the transistors Q8 , Q9 and Q10 are all connected to the negative power supply VEE.

2. A transconductance amplifier as claimed in claim 1, characterized in that: The buffer isolation circuit includes a first operational amplifier, which includes a non-inverting input terminal, a reverse input terminal and an output terminal. The non-inverting input terminal is used to input the voltage signal, and the output terminal is connected to the reverse input terminal.

3. A transconductance amplifier as claimed in claim 1, characterized in that: The signal distribution circuit includes a plurality of resistor groups.

4. A transconductance amplifier as claimed in claim 1, characterized in that: The number of the transconductance conversion circuits is multiple groups, and the transconductance conversion circuits are in a parallel structure.

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