Linear voltage amplifier

Abstract

The utility model discloses a linear voltage amplifier which comprises a non-inverting amplifier and an inverting amplifier, differential output is formed between the non-inverting amplifier and the inverting amplifier, the non-inverting amplifier comprises an operational amplifier A1, an operational amplifier A2 and an operational amplifier A3, and the operational amplifier A1, the operational amplifier A2 and the operational amplifier A3 form a voltage series negative feedback circuit. Wherein the operational amplifier A1 and the operational amplifier A3 form a voltage follower to serve as a power supply of the operational amplifier A2, the inverting amplifier comprises an operational amplifier A4, an operational amplifier A5 and an operational amplifier A6, and the operational amplifier A4, the operational amplifier A5 and the operational amplifier A6 form a voltage parallel negative feedback circuit.

Description

Technical Field

[0001] This utility model relates to the field of voltage amplifier technology, and in particular to a linear voltage amplifier. Background Technology

[0002] High-voltage measurements, such as dielectric measurements and other high-voltage applications, require sophisticated high-voltage instruments. Currently, high-voltage measurements demand linear, high-voltage, high-frequency bandwidth power supplies, necessitating precise monitoring and control. Existing high-voltage amplifiers generally employ multiplexers, whose main drawbacks are insufficient output voltage and gain. Utility Model Content

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a linear voltage amplifier with high output voltage and high gain.

[0004] The linear voltage amplifier according to an embodiment of the present invention includes: a non-inverting amplifier and an inverting amplifier, wherein the non-inverting amplifier and the inverting amplifier form a differential output; the non-inverting amplifier includes operational amplifiers A1, A2, and A3, and operational amplifiers A1, A2, and A3 form a voltage series negative feedback circuit, wherein operational amplifiers A1 and A3 constitute a voltage follower to serve as the power supply for operational amplifier A2; the inverting amplifier includes operational amplifiers A4, A5, and A6, and operational amplifiers A4, A5, and A6 form a voltage parallel negative feedback circuit.

[0005] According to some embodiments of this utility model, the input terminal of the non-inverting amplifier circuit and the input terminal of the inverting amplifier circuit are respectively electrically connected to the output terminal of the external high-voltage unit to form a cascaded unit, and multiple cascaded units are connected in series to form a cascaded circuit to output high voltage.

[0006] According to some embodiments of this utility model, the non-inverting amplifier further includes: resistors R11, R12, R13, and R14. The positive input terminal of operational amplifier A2 is electrically connected to the positive output terminal of an external high-voltage unit. One end of resistor R11 is grounded, and the other end is electrically connected to the inverting input terminal of operational amplifier A2 and one end of resistor R12, respectively. The other end of resistor R12 is electrically connected to the output terminal of operational amplifier A2. One end of resistor R13 is electrically connected to the output terminal of operational amplifier A1 and one power supply terminal of operational amplifier A2, respectively. The other end of resistor R13 is electrically connected to the inverting input terminal of operational amplifier A1. The positive input terminal of operational amplifier A1 is electrically connected to the output terminal of operational amplifier A2 via a series resistor. One end of resistor R14 is electrically connected to the other power supply terminal of operational amplifier A2. The other end of resistor R14 is electrically connected to the inverting input terminal of operational amplifier A3. The positive input terminal of operational amplifier A3 is electrically connected to the output terminal of operational amplifier A2 via a series resistor.

[0007] According to some embodiments of this utility model, the inverting amplifier further includes: resistors R21, R22, R23, and R24. The positive input terminal of operational amplifier A5 is grounded. One end of resistor R21 is electrically connected to the negative output terminal of the external high-voltage unit, and the other end is electrically connected to the inverting input terminal of operational amplifier A5 and one end of resistor R22. The other end of resistor R22 is electrically connected to the output terminal of operational amplifier A5. One end of resistor R23 is electrically connected to the output terminal of operational amplifier A4 and one power supply terminal of operational amplifier A5. The other end of resistor R23 is electrically connected to the inverting input terminal of operational amplifier A4. The positive input terminal of operational amplifier A4 is electrically connected to the output terminal of operational amplifier A5 via a series resistor. One end of resistor R24 ​​is electrically connected to the other power supply terminal of operational amplifier A5. The other end of resistor R24 ​​is electrically connected to the inverting input terminal of operational amplifier A6. The positive input terminal of operational amplifier A6 is electrically connected to the output terminal of operational amplifier A5 via a series resistor.

[0008] The linear voltage amplifier according to the embodiments of this utility model has at least the following beneficial effects: It employs one non-inverting amplifier and one inverting amplifier, resulting in a differential output between the two amplifiers, such that the total gain of the circuit is the sum of the gains of the non-inverting amplifier and the inverting amplifier. Furthermore, the output voltage range can be increased by cascading external high-voltage units; multiple cascaded units connected in series can provide even higher gains.

[0009] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0010] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings;

[0011] Figure 1 This is the schematic diagram of a linear voltage amplifier;

[0012] Figure 2 It shows the waveforms of the output voltage and the load voltage;

[0013] Figure 3 This is the schematic diagram of a cascaded circuit;

[0014] Figure 4 This is a simplified circuit diagram of a voltage parallel negative feedback circuit;

[0015] Figure 5 It is a frequency response curve;

[0016] Figure 6 It is a graph showing how Vo / Vs changes over time. Detailed Implementation

[0017] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0018] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first" or "second" is used in the description, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0020] Reference Figures 1 to 6 This utility model discloses a linear voltage amplifier, comprising: multiple cascaded units 10, each cascaded unit 10 including an external high-voltage unit 12, a voltage source, and a voltage amplifier circuit 11. The voltage amplifier circuit 11 includes a non-inverting amplifier 111 and an inverting amplifier 112. The output of the voltage amplifier circuit 11 is the differential output between the non-inverting amplifier 111 and the inverting amplifier 112. The voltage source supplies power to the voltage amplifier circuit 11. The positive output terminal of the external high-voltage unit 12 is electrically connected to the input terminal of the non-inverting amplifier circuit, and the negative output terminal of the external high-voltage unit 12 is electrically connected to the input terminal of the inverting amplifier circuit. Multiple cascaded units 10 are connected in series to output a high voltage. Figure 1As shown, the non-inverting amplifier 111 is composed of op-amps A1, A2 and A3 forming a voltage series negative feedback circuit. In practice, its voltage gain is adjusted to 20 times. The maximum withstand voltage of op-amps A1, A2 and A3 is 100V. Among them, op-amps A1 and A3 form a voltage follower to serve as the power supply for op-amp A2. The non-inverting amplifier 111 specifically includes resistors R11, R12, R13, and R14. The positive input terminal of operational amplifier A2 is electrically connected to the positive output terminal of the external high-voltage unit 12. One end of resistor R11 is grounded, and the other end is electrically connected to the inverting input terminal of operational amplifier A2 and one end of resistor R12, respectively. The other end of resistor R12 is electrically connected to the output terminal of operational amplifier A2. One end of resistor R13 is electrically connected to the output terminal of operational amplifier A1 and one power supply terminal of operational amplifier A2, respectively. The other end of resistor R13 is electrically connected to the inverting input terminal of operational amplifier A1. The positive input terminal of operational amplifier A1 is electrically connected to the output terminal of operational amplifier A2 via a series resistor. One end of resistor R14 is electrically connected to the other power supply terminal of operational amplifier A2. The other end of resistor R14 is electrically connected to the inverting input terminal of operational amplifier A3. The positive input terminal of operational amplifier A3 is electrically connected to the output terminal of operational amplifier A2 via a series resistor.

[0021] like Figure 2 As shown, with the change of input voltage, the positive voltage V01 and negative voltage V02 of op-amp A2 also fluctuate. The positive voltage V01 and negative voltage V02 are in phase. Nevertheless, the absolute value of the power supply voltage will always remain at 100V. The output voltage can reach up to 400VPP. Similarly, the inverting amplifier 112 includes op-amps A4, A5, and A6, and op-amps A4, A5, and A6 form a voltage parallel negative feedback circuit. The inverting amplifier 112 also includes resistors R21, R22, R23, and R24. The positive input terminal of op-amp A5 is grounded. One end of resistor R21 is electrically connected to the negative output terminal of the external high-voltage unit 12, and the other end is electrically connected to the inverting input terminal of op-amp A5 and one end of resistor R22, respectively. The other end of resistor R22... The output of op-amp A5 is electrically connected. One end of resistor R23 is electrically connected to the output of op-amp A4 and one power supply terminal of op-amp A5, respectively. The other end of resistor R23 is electrically connected to the inverting input terminal of op-amp A4. The non-inverting input terminal of op-amp A4 is electrically connected to the output terminal of op-amp A5 via a series resistor. One end of resistor R24 ​​is electrically connected to the other power supply terminal of op-amp A5, and the other end of resistor R24 ​​is electrically connected to the inverting input terminal of op-amp A6. The non-inverting input terminal of op-amp A6 is electrically connected to the output terminal of op-amp A5 via a series resistor. In practice, its voltage gain can be adjusted to 20 times, and the total gain of voltage amplifier circuit 11 will eventually reach 40 times. In actual operation, considering the maximum power supply voltage limit of 100 V, the maximum swing of the input voltage should be limited to a small value to ensure that the amplifier operates within its linear range.

[0022] like Figure 3 The output voltage range can be increased by cascading external high-voltage units 12. By connecting n cascaded units 10 in series to form a cascaded circuit, the entire cascaded circuit can achieve a gain of 40n times. The signal source VS0 is an arbitrary waveform generator that provides input signals in the frequency range from mHz to kHz through software programming. The voltage source from Vs1 to Vsn can use an AMPX power supply.

[0023] The voltage amplifier circuit 11 employs a non-inverting amplifier 111 and an inverting amplifier 112. The final output is the differential output between the non-inverting amplifier 111 and the inverting amplifier 112, making the total gain of the voltage amplifier circuit 11 the sum of the gains of the non-inverting amplifier 111 and the inverting amplifier 112. Furthermore, the output voltage range is increased by cascading external high-voltage units 12, and multiple cascaded units 10 connected in series can provide even higher gains.

[0024] Multiplexers and cascaded amplifiers differ significantly in their characteristics. A multiplexer is composed of multiple amplifiers connected in series. In the amplitude-frequency response of a multiplexer, the relationship between the total gain and unity gain is given by the following equation: For phase-frequency characteristics, the total phase shift is... The lower frequency limit is The upper frequency limit is The slew rate of the multiplexer is SR = 13 (V / μs). The amplitude-frequency response of the cascaded amplifier is the same as that of the multiplexer. Due to the cascading connection of the circuit units, the phase-frequency response is... The lower frequency limit is The upper frequency limit is The slew rate is SR = 13 × 2n (V / μs). Transmission gain and phase error mainly depend on the difference between cascaded components. Compared to multiplexers, cascaded circuits offer better flexibility and wider bandwidth. By increasing the number of cascaded units 10, the total gain increases significantly, but the total bandwidth remains unchanged. Furthermore, a single cascaded unit 10 or the entire cascaded circuit can provide the same current. Compared to multiplexers, cascaded units 10 offer better flexibility and wider bandwidth, mainly in the following aspects: 1. Flexibility in gain design: With multiple cascaded units 10 connected in series, the total gain is the product of the gains of each cascaded unit 10. Designers can precisely control the total gain by adjusting the gain of individual voltage amplifier circuits 11. This step-by-step adjustment method is particularly flexible when achieving high gain requirements. 2. Flexibility in frequency response: The frequency characteristics of each stage of voltage amplifier circuit 11 can be adjusted independently, thus avoiding frequency distortion or bandwidth limitations. For example, designers can improve the frequency response of the entire system by adding a high-pass or low-pass filter to a certain stage. 3. By allocating bandwidth to different amplification stages, wideband designs can be more easily achieved. 4. Modular design facilitates fault isolation and maintenance. If a stage fails, only that stage's circuitry needs to be tested and repaired. In contrast, fault diagnosis in multi-channel amplifiers can be more complex due to the tight coupling between the channels. Furthermore, each voltage amplification stage operates independently, making it easy to upgrade or replace individual modules.

[0025] Assuming the network is a purely resistive R-type load, the equivalent circuit diagram of the voltage parallel negative feedback (inverting amplifier 112) is as follows: Figure 4 As shown. Assume the circuit unit has a gain of [value missing] at the intermediate frequency. The upper limit frequency is The lower limit frequency is Therefore, the gain in the high-frequency band for After introducing negative feedback, the expression for the high-frequency band gain Ahf can be rewritten as follows: Where F is the feedback coefficient. Rearranged, we get... .in This represents the gain of the negative feedback amplifier circuit in the mid-frequency range. For the reason Defined upper limit frequency. Figure 4 In this context, v represents the signal source voltage, and Rs represents the internal resistance of v. Through voltage, It is the input resistance of a basic amplifier circuit. This is the input current of the amplifier. This is the output resistance of the amplifier. The output of a basic amplifier circuit can be considered equivalent to a voltage source. = With equivalent output resistance Series, It is the feedback resistor. After introducing negative feedback, the effect of the input resistance is usually expressed as the feedback depth (1 + AF). Considering the internal resistance of the signal source and load cannot fully convey the relationship between the components of the output circuit and the input resistance. Figure 1 The general form of the voltage parallel negative feedback amplifier circuit of the intermediate operational amplifier A5 can be as follows: Figure 1 As shown. According to Thevenin's theorem, when the load resistor RL is connected to the output terminal, the decrease in output voltage Vof will cause a change in input and output current. Therefore, we obtain the output voltage as... According to Kirchhoff's current law, in Figure 4 We get The output voltage is .because Figure 1 The operational amplifier A2 introduces series voltage negative feedback, which increases the input resistance by a factor of (1+AF). It is worth noting that... Figure 1 The input resistors of operational amplifiers A2 and A5 are different. When selecting appropriate input and feedback resistors in operational amplifiers, the impact of the input resistors on amplifier accuracy can be ignored. For example... Figure 2 As shown. An amplifier always has an internal output resistance, which causes it to be considered an oscillator. When connected to a capacitive load, the transfer function of the amplifier circuit adds an additional pole. The Bode plot of the additional pole is steeper than that of the main pole, resulting in a phase shift. 90 When both open-loop gain and feedback attenuation are greater than 1, the amplifier circuit is in an unstable state. If the operating frequency is lower than the closed-loop bandwidth, the loop phase shift will exceed 180°. Therefore, an operational amplifier will act as an oscillator, such as... Figure 5 As shown, Figure 5 The frequency response relationship was obtained using Texas Instruments' Tina analysis software.

[0026] The phase margin of an operational amplifier circuit is defined as the phase difference between the phase at the gain crossover frequency and the phase of the operational amplifier circuit. 180 The phase difference between the phases at the points. To extend the additional phase margin, the additional pole from the capacitive load should be greater than 10 times the closed-loop bandwidth of the circuit. The frequency of the additional pole is determined by... = 1 / 2π Given. When analyzing the step response of an amplifier circuit, a small-signal equivalent circuit can be used. Step voltages can be divided into rising curves and saturation curves; their exponential characteristics can simplify the circuit. In the corresponding high-frequency range, some step voltages rise faster than the steady-state voltage. Therefore, a low-pass filter circuit can be used to describe this phenomenon. For example... Figure 6 As shown, the output voltage is In the formula This is the final stable value of the step response voltage. Due to the output voltage... It grows exponentially until it reaches the final voltage. It takes time, which will lead to leading-edge distortion. Rise time. (The duration from 10% to 90% of the final voltage) is used to represent leading-edge distortion, by Provided. Figure 6 The upper limit of the medium frequency is Therefore, the rise time is estimated to be From the above formula, we can see that the rise time... With upper limit frequency They are inversely proportional. The higher the upper limit frequency, the shorter the rise time and the smaller the edge distortion. The upper limit frequency depends on the depth of the negative feedback, but linear amplifiers typically require higher gain. To ensure lower edge distortion and higher gain, the negative feedback depth is 1 + AOLβ, where AOL is the open-loop gain and β is the feedback factor.

[0027] It will be readily understood by those skilled in the art that the above preferred methods can be freely combined and superimposed without conflict.

[0028] The above are merely preferred embodiments of this utility model and do not limit the patent scope of this utility model. Any equivalent structural transformations made based on the inventive concept of this utility model and the contents of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are included within the patent protection scope of this utility model.

Claims

1. A linear voltage amplifier, characterized in that, include: A non-inverting amplifier (111) and an inverting amplifier (112) form a differential output between the non-inverting amplifier (111) and the inverting amplifier (112). The non-inverting amplifier (111) includes operational amplifiers A1, A2, and A3, and operational amplifiers A1, A2, and A3 form a voltage series negative feedback circuit. Operational amplifiers A1 and A3 form a voltage follower to serve as the power supply for operational amplifier A2. The inverting amplifier (112) includes operational amplifiers A4, A5, and A6, and operational amplifiers A4, A5, and A6 form a voltage parallel negative feedback circuit.

2. The linear voltage amplifier according to claim 1, characterized in that: The input terminals of the non-inverting amplifier and the inverting amplifier are electrically connected to the output terminal of the external high-voltage unit (12) to form a cascaded unit. Multiple cascaded units (10) are connected in series to form a cascaded circuit to output high voltage.

3. The linear voltage amplifier according to claim 2, characterized in that, The non-inverting amplifier (111) further includes: resistors R11, R12, R13, and R14. The positive input terminal of operational amplifier A2 is electrically connected to the positive output terminal of the external high-voltage unit (12). One end of resistor R11 is grounded, and the other end is electrically connected to the inverting input terminal of operational amplifier A2 and one end of resistor R12, respectively. The other end of resistor R12 is electrically connected to the output terminal of operational amplifier A2. One end of resistor R13 is electrically connected to the output terminal of operational amplifier A1 and one power supply terminal of operational amplifier A2, respectively. The other end of resistor R13 is electrically connected to the inverting input terminal of operational amplifier A1. The positive input terminal of operational amplifier A1 is electrically connected to the output terminal of operational amplifier A2 via a series resistor. One end of resistor R14 is electrically connected to the other power supply terminal of operational amplifier A2. The other end of resistor R14 is electrically connected to the inverting input terminal of operational amplifier A3. The positive input terminal of operational amplifier A3 is electrically connected to the output terminal of operational amplifier A2 via a series resistor.

4. The linear voltage amplifier according to claim 2, characterized in that: The inverting amplifier (112) further includes: resistors R21, R22, R23, and R24. The positive input terminal of operational amplifier A5 is grounded. One end of resistor R21 is electrically connected to the negative output terminal of the external high-voltage unit (12), and the other end is electrically connected to the inverting input terminal of operational amplifier A5 and one end of resistor R22. The other end of resistor R22 is electrically connected to the output terminal of operational amplifier A5. One end of resistor R23 is electrically connected to the output terminal of operational amplifier A4 and one power supply terminal of operational amplifier A5. The other end of resistor R23 is electrically connected to the inverting input terminal of operational amplifier A4. The positive input terminal of operational amplifier A4 is electrically connected to the output terminal of operational amplifier A5 via a series resistor. One end of resistor R24 ​​is electrically connected to the other power supply terminal of operational amplifier A5. The other end of resistor R24 ​​is electrically connected to the inverting input terminal of operational amplifier A6. The positive input terminal of operational amplifier A6 is electrically connected to the output terminal of operational amplifier A5 via a series resistor.

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