Low-distortion field effect transistor analog amplifier

Abstract

The utility model provides a low-distortion field effect transistor analog amplifier, which relates to the field of electronic circuits and comprises an FET differential pair consisting of Q1 and Q2, Q3 and Q8 serving as main voltage amplification stages, Q4 and Q5 serving as complementary output stages, and a mirror image constant current source circuit consisting of Q6, Q7, R2 and R4, after an input signal passes through a differential pair of Q1 and Q2, a drain electrode signal of Q1 is transmitted to a base electrode of Q3 through R1; drain signals of the Q2 are output to a base electrode of the Q8 by the R5 through a mirror image constant current source consisting of the Q6, the Q7, the R2 and the R4; the Q3 and the Q8 are paired PNP and NPN triodes and are respectively responsible for amplifying positive and negative half-cycle signals, the amplified signals are transmitted to the complementary current amplification stages of the Q4 and the Q5 through the R3 to be output, and the R6 and the R7 are used for determining the working current of the voltage amplification stages Q3 and Q8. According to the circuit, through a unique circuit design, a voltage amplification stage is changed from a single tube to double tubes, and half-cycle amplification of signals is realized by using a mirror image constant current source, so that the problem of high distortion degree of a traditional circuit is effectively solved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, in particular to a low-distortion field effect tube analog amplifier. Background Art

[0002] In analog amplifier technology, traditional discrete field effect tube analog amplifiers (such as Figure 1 (as shown) has certain limitations. In this circuit, Q1 and Q2 form a differential pair for the input signal, Q3 serves as the main voltage amplifier stage, and Q4 and Q5 form the complementary output stage. After being processed by the differential pair Q1 and Q2, the input signal is transferred to Q3 via R1 for voltage amplification. The amplified signal is then sent to Q4 and Q5 for complementary current amplification. The voltage difference across R3 ensures that Q4 and Q5 operate during the positive and negative half-cycles of the signal, respectively. However, this circuit structure has a major problem: the voltage amplifier stage Q3 is overloaded. Because both the positive and negative half-cycle signals pass through Q3, the transistor responsible for the full swing of the amplified signal in both the positive and negative half-cycles is Q3. This makes it difficult to achieve ideal distortion for the entire circuit, affecting the amplifier's performance. To address this issue, we propose a low-distortion field-effect transistor analog amplifier. Utility Model Content

[0003] The purpose of the present invention is to provide a low-distortion field effect tube analog amplifier to solve the problem raised in the above background technology: using a push-pull transistor to replace a single transistor for amplification.

[0004] To achieve the above objectives, the present invention adopts the following technical solutions: providing a low-distortion field-effect transistor analog amplifier, including a FET differential pair consisting of Q1 and Q2, Q3 and Q8 as a main voltage amplifier stage, Q4 and Q5 as a complementary output stage, and a mirror constant current source circuit consisting of Q6, Q7, R2, R4, and R5; after the input signal passes through the Q1 and Q2 differential pair, the Q1 drain signal is transmitted to the Q3 base via R1, and the Q2 drain signal is output to the Q8 base via R5 via the mirror constant current source consisting of Q6, Q7, R2, and R4; the main function of the constant current conversion circuit is to convert the original signal on R2 relative to the positive power supply into a signal on R5 relative to the negative power supply; Q3 and Q8 are paired PNP and NPN transistors, respectively responsible for push-pull voltage amplification of the positive and negative half-cycles of the signal, and the amplified signal is transmitted to the complementary current amplifier output stage Q4 and Q5 via R3; R6 and R7 are used to determine the operating current of the voltage amplifier stages Q3 and Q8 to reduce the distortion of the amplifier.

[0005] As a preferred embodiment, Q1 and Q2 are high transconductance and low noise field effect transistors, Q3, Q6, Q7, and Q8 are high amplification and low noise transistors, and Q4 and Q5 are paired transistors of appropriate power according to the discharger current requirements.

[0006] As a preferred implementation, the resistance values ​​of resistors R1, R2, R4, R5, R6, and R7 are selected based on the circuit's amplification requirements, operating current requirements, and signal processing characteristics.

[0007] As a preferred implementation, the mirror image constant current source circuit is applied to other circuit scenarios requiring analog signal phase conversion.

[0008] As a preferred embodiment, during operation, the circuit performance is optimized by selecting the pairing of Q3 and Q8 and adjusting the resistance values ​​of R6 and R7.

[0009] Compared with the existing technology, the advantages and positive effects of this utility model are: the utility model, through a unique circuit design, changes the voltage amplifier stage from a single tube to a double tube, and uses a mirror constant current source to achieve half-cycle amplification of the signal, effectively solving the problem of high distortion of the traditional circuit. Figure 1 Compared with the analog circuit, the distortion is reduced by about -10dB (or 68% distortion reduction), which greatly improves the signal quality of the analog amplifier.

[0010] The newly added in-frame circuit (Q6, Q7, R2, R4, R5, Q8) cleverly utilizes a mirrored constant current source to shift the phase of an analog signal for output. This design not only plays a key role in reducing distortion in the analog amplifier circuit of this utility model, but also has broad application potential in many scenarios requiring analog signal phase shift, and has high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of a common discrete component field effect tube analog amplifier circuit in this utility model;

[0012] Figure 2 This is the circuit principle diagram of the improved low-distortion field-effect tube analog amplifier of the utility model. DETAILED DESCRIPTION

[0013] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0014] See also Figure 1-Figure 2The utility model provides a technical solution: a low-distortion field-effect tube analog amplifier, including a FET differential pair consisting of Q1 and Q2, Q3 and Q8 as a main voltage amplifier stage, Q4 and Q5 as a complementary push-pull output stage, and a mirror image constant current source circuit consisting of Q6, Q7, R2, R4, and R5; after the input signal passes through the differential pair of Q1 and Q2, the drain signal of Q1 is output to the base of Q3 through R1; the drain signal of Q2 is output to Q8 through R5 through the mirror image constant current source composed of Q6, Q7, R2, and R4; Q3 and Q8 are paired transistors, which respectively amplify the positive and negative half-cycle signals of the signal. The amplified signal is transmitted to the push-pull output of the complementary current amplifier stage Q4 and Q5 through R3. R6 and R7 are used to determine the operating current of the voltage amplifier stage Q3 and Q8. Selecting the appropriate operating current can effectively reduce the distortion of the amplifier. Q1 and Q2 are field-effect transistors with high transconductance and low noise characteristics. Q3, Q8, Q6, and Q7 are low-noise, high-beta, low-power transistors. The power parameters of Q4 and Q5 are selected according to the output current requirements of the circuit; the resistance values ​​of R1, R2, R4, R5, R6, and R7 are selected according to the circuit's amplification requirements, operating current requirements, and signal processing characteristics. The mirror constant current source circuit is used in other circuit scenarios that require analog signal phase conversion. During operation, the circuit performance is optimized by pairing Q3 and Q8 and adjusting the resistance values ​​of R6 and R7.

[0015] according to Figure 2 The circuit structure shown is wired and connected. First, select field-effect transistors Q1, Q2 and transistors Q3-Q8 with appropriate parameters. These transistors should meet the circuit's performance requirements, such as on-resistance, amplification factor, etc. At the same time, select resistors R1, R2, R4, R5, R6, R7, etc. with appropriate resistance values. When connecting the circuit, ensure that Q1 and Q2 accurately form a FET differential pair, Q3 and Q8 are correctly connected as the main voltage amplifier stage, Q4 and Q5 form a complementary output stage, and connect the newly added in-frame circuit (Q6, Q7, R2, R4, R5, Q8) in strict accordance with the design requirements to ensure the normal operation of the mirror constant current source. During the circuit debugging process, the output signal of the circuit is monitored by inputting a standard test signal and using professional electronic measuring instruments (such as an oscilloscope, distortion analyzer, etc.). Observe whether the waveform of the output signal meets expectations, measure the distortion of the circuit, and optimize the circuit performance by adjusting component parameters (such as the pairing selection of Q3 and Q8, the resistance adjustment of R6 and R7, etc.) to ensure that the design goal of low distortion is achieved. Figure 1 The conventional circuit shown is subjected to comparative testing under the same test conditions to verify the distortion reduction effect of the circuit of the present invention.

[0016] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any other form. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes for application in other fields. However, any simple modification, equivalent change and modification of the above embodiment made according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A low-distortion field-effect tube analog amplifier, characterized in that: It includes a FET differential pair consisting of Q1 and Q2, Q3 and Q8 as the main voltage amplifier stage, Q4 and Q5 as the complementary output stage, and a mirror constant current source phase-inverting circuit composed of Q6, Q7, R2, R4, and R5; after the input signal passes through the Q1 and Q2 differential pair, the drain signal of Q1 is input to the base of Q3 through R1; the drain signal of Q2 is output to Q8 by R5 through the mirror constant current source composed of Q6, Q7, R2, and R4. This circuit converts the original signal of Q2 drain relative to the positive power supply into a signal relative to the negative power supply to drive Q8. In this way, Q3 and Q8 form a push-pull voltage amplifier stage, which amplifies the positive and negative half-cycle signals respectively. The amplified signal is transmitted to the complementary current amplifier stage output of Q4 and Q5 through R3. R6 and R7 are used to determine the operating current of the voltage amplifier stage Q3 and Q8 to reduce the distortion of the amplifier.

2. The low-distortion field-effect transistor analog amplifier according to claim 1, characterized in that: Q1 and Q2 field-effect transistors are field-effect transistors with high transconductance and low noise characteristics; Q3, Q8, Q6, and Q7 are low-noise, high-β, low-power transistors; the power parameters of Q4 and Q5 are selected according to the circuit current output requirements.

3. The low-distortion field-effect transistor analog amplifier according to claim 1, characterized in that: The resistance values ​​of resistors R1, R2, R4, R5, R6, and R7 are selected according to the circuit's amplification requirements, operating current requirements, and signal processing characteristics.

4. The low-distortion field-effect transistor analog amplifier according to claim 1, characterized in that: The mirror image constant current source circuit is used in other circuit scenarios that require analog signal phase conversion.

5. The low-distortion field-effect transistor analog amplifier according to claim 1, characterized in that: During the operation of the circuit, the circuit performance is optimized by selecting the pairing of Q3 and Q8 and adjusting the resistance values ​​of R6 and R7.

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