Low-distortion field effect transistor post-stage circuit
By designing a low-distortion MOSFET power supply circuit, the problems of poor consistency and limited high-frequency performance of high-power MOSFETs were solved, achieving the effects of reducing production costs and improving the quality of audio signal reproduction.
Patent Information
- Application Number
- CN202423152264.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2026-01-16
- Estimated Expiration
- 2034-12-20
AI Technical Summary
High-power MOSFETs have poor consistency and large gate junction capacitance, resulting in high production costs, high manufacturing difficulty, and limited high-frequency performance, which affects the quality of audio signal reproduction.
The circuit employs a low-distortion MOSFET, including a voltage amplification stage and a current amplification stage. A mirror constant current source and a voltage regulation network are used to provide the gate-source voltage for the complementary MOSFET. The high-frequency bandwidth is compensated by a pre-compensation capacitor. In cascaded mode, a power transistor is added and its gate-source voltage is adjusted.
It reduces power transistor matching requirements, expands bandwidth, reduces distortion, improves production efficiency and circuit stability, and enhances the high-frequency reproduction capability and sound quality of audio signals.
Smart Images
Figure CN223809751U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to audio power amplifier circuit technical field, concretely is a kind of low distortion field effect transistor post stage's circuit. BACKGROUND
[0002] Field effect transistor is favored in the field of sound because of natural loose sound perception, with the "guts" of similar electronic tube sound.However, its large-scale application in power amplifier or ear amplifier is limited, the main reasons are as follows:
[0003] The consistency of high-power field effect transistor is poor, and pairing operation is usually required, which increases production cost and production difficulty;
[0004] The gate junction capacitance of high-power field effect transistor is large, which has a great impact on the bandwidth of power amplifier, resulting in limited high-frequency performance, and further affecting the restoration quality of audio signal.
[0005] Therefore, it is urgent to improve this defect, and the utility model provides a low distortion field effect transistor post stage's circuit for the research and improvement of the existing structure and defects. INVENTION CONTENTS
[0006] The utility model aims at providing a low distortion field effect transistor post stage's circuit to solve the problems in the background art.
[0007] To achieve the above object, the utility model provides the following technical scheme: a low distortion field effect transistor post stage's circuit, including voltage amplification stage and current amplification stage, the voltage amplification stage is composed of Q1, Q2 push-pull voltage amplification, R1, R2 are used for adjusting voltage amplification stage current;Mirror image constant current source I1, I2, R3, VR1, VR2 constitute a voltage regulating network, provide gate-source stage voltage for complementary field effect transistor Q3, Q4, wherein I1, I2 current flows through two R3 to produce voltage drop, VR1, VR2 respectively adjust the voltage drop at both ends of R3, so that Q3, Q4 enter amplification state;Signal is amplified after Q1, Q2 and is transmitted to Q3, Q4 from VR1, VR2 for current amplification;Further including the key capacitor Cg for compensating the high-frequency bandwidth of Q3, Q4, its value is between 47-470pF according to the different field effect power tube behind.
[0008] Further, in cascade mode, a pair of power tubes Q5, Q6 are added, and the VGS adjustment is realized by independent potentiometers VR3 and VR4, and each power tube is provided with a front compensation capacitor Cg for high-frequency compensation.
[0009] Further, in the voltage amplification stage, the resistance value of R1 and R2 ranges from several hundred ohms to several thousand ohms.
[0010] Further, in the voltage regulating network, the resistance value of VR1, VR2, VR3 and VR4 ranges from several kilo-ohms to several tens of kilo-ohms.
[0011] Further, the field effect tubes Q3, Q4, Q5 and Q6 can be selected from IRFP240 / 9240.
[0012] Further, when the field effect power tube with a large input capacitance is selected, the Cg capacitor tends to have a large value, such as 470pF.
[0013] The utility model provides a kind of low distortion field effect tube rear stage's circuit, with the following beneficial effects:
[0014] 1, the utility model reduces power tube pairing requirement: by independent adjustment each power tube VGS, different model or parameter difference larger power tube can be used, reduce the pairing workload in production process, improve production efficiency.
[0015] 2, the utility model expands bandwidth and reduces distortion: the pre-compensation effect of Cg capacitor effectively offsets the junction capacitance of field effect power tube, significantly extends the bandwidth of power amplifier, reduces high-frequency distortion, improves the high-frequency restoration capability of audio signal, so that sound quality is more clear and natural.
[0016] 3, the utility model expands bandwidth and reduces distortion: improve circuit performance stability: each power tube can independently work in the best state, reduce the inconsistency caused by tube parameter difference, improve the stability and reliability of entire circuit, reduce distortion or overload phenomenon caused by tube pairing problem. DRAWINGS
[0017] Figure 1 It is a typical field effect tube push-pull type rear stage current amplification circuit schematic diagram of the utility model low distortion field effect tube rear stage's circuit.
[0018] Figure 2 It is a circuit schematic diagram of the utility model low distortion field effect tube rear stage's circuit.
[0019] Figure 3 It is a two-stage cascade circuit schematic diagram of the utility model low distortion field effect tube rear stage's circuit.
[0020] Figure 4 It is a cascade mode circuit schematic diagram of the utility model low distortion field effect tube rear stage's circuit. DETAILED DESCRIPTION
[0021] The embodiment of the utility model is further described in detail in combination with the drawings and examples. The following examples are used to illustrate the utility model, but cannot be used to limit the scope of the utility model.
[0022] As Figure 1 and Figure 4 shown, a low-distortion field effect tube post-stage circuit, including a voltage amplification stage and a current amplification stage, the voltage amplification stage consists of Q1, Q2 push-pull voltage amplification, R1, R2 for adjusting the voltage amplification stage current; mirror constant current source I1, I2, R3, VR1, VR2 (R3 >> VR1, VR2) constitute a voltage regulating network, for complementary field effect tube Q3, Q4 provide gate-source stage voltage (VGS), wherein I1, I2 current through two R3 produces a voltage drop, VR1, VR2 respectively on R3 voltage drop for adjusting, so that Q3, Q4 into amplification state; signal after Q1, Q2 amplification from VR1, VR2 to Q3, Q4 for current amplification; also includes a key capacitor Cg for compensation Q3, Q4 high frequency bandwidth, its value according to the different field effect power tube behind between 47-470 pF.
[0023] In cascade mode, a pair of power tubes Q5, Q6, its VGS adjustment with independent potentiometer VR3, VR4, each power tube is provided with a pre-compensation capacitor Cg for high frequency compensation, in the voltage amplification stage, R1, R2 resistance range is several hundred ohms to several thousand ohms, in the voltage regulating network, VR1, VR2, VR3, VR4 resistance range is several tens of ohms to several hundred ohms, field effect tube Q3, Q4, Q5, Q6 can be selected IRFP240 / 9240 type, when using input capacitance greater field effect power tube, Cg capacitor value tends to be larger, such as 470 pF,
[0024] Q1, Q2 can be selected from the commonly used pair of bipolar transistors, such as 2N3904, 2N3906, etc., its parameters should meet the current and power requirements of the voltage amplification stage, field effect tube Q3, Q4, Q5, Q6 can be selected according to the actual power requirements of the appropriate model, such as IRFP240 / 9240, etc., due to the lower requirements for power tube pairing, different models or parameters can be selected within a certain range, the resistance R1, R2, R3 value is determined according to the current of the voltage amplification stage, voltage regulating network requirements and power tube working conditions, for example, R1, R2 can be valued between several hundred ohms to several thousand ohms, VR1, VR2 resistance should be much larger than R3, the specific can be determined according to the actual circuit debugging, potentiometer VR1, VR2, VR3, VR4 for accurate adjustment of the VGS of the power tube, its resistance range can be selected according to the actual adjustment requirements, generally between several tens of ohms to several hundred ohms, capacitor Cg according to the input capacitance of the selected field effect power tube for selection, the range is between 47-470 pF, for input capacitance greater power tube, such as IRFP240 / 9240 (input capacitance up to 1000 pF), can be appropriately selected larger Cg, such as 470 pF, to better achieve high frequency compensation;
[0025] First, adjust R1, R2 to make the voltage amplification stage current in the appropriate range, to ensure that Q1, Q2 normal work.
[0026] Then, by adjusting VR1, VR2, using an oscilloscope to observe the output waveform of Q3, Q4, make it work in the amplification interval and waveform undistorted, in the process, can be adjusted R1, R2 to optimize the overall circuit performance.
[0027] For the cascade mode ( Figure 4 ), adjust VR3, VR4 respectively, make Q5, Q6 also work in the best state, while paying attention to the observation of the coordinated work between the power tubes, to ensure the stability of the whole circuit output, low distortion.
[0028] In the debugging Cg capacitor, can use spectrum analyzer to observe the bandwidth of power amplifier, according to the actual situation in 47-470pF range to select the most appropriate Cg value, to achieve the best high frequency compensation effect, reduce high frequency distortion.
[0029] The embodiments of the present application are given for the purpose of example and description, and are not exhaustive or limit the present application to the disclosed form. Many modifications and variations will be apparent to those skilled in the art. The embodiments are selected and described in order to better illustrate the principles and practical application of the present application, and to enable those skilled in the art to understand the present application so as to design various embodiments with various modifications suitable for specific purposes.
Claims
1. A circuit for a low-distortion field-effect transistor (FET) stage, characterized in that, It includes voltage amplification stage and current amplification stage, the voltage amplification stage is composed of Q1, Q2 push-pull voltage amplification, R1, R2 are used for adjusting voltage amplification stage current;Mirror constant current source I1, I2, R3, VR1, VR2 constitute a voltage regulating network, provide gate-source level voltage for complementary field effect tube Q3, Q4, wherein I1, I2 current flows through two R3 and generates voltage drop, VR1, VR2 respectively adjust the voltage drop on both ends of R3, make Q3, Q4 enter amplification state;Signal is amplified through Q1, Q2 and is transmitted from VR1, VR2 to Q3, Q4 for current amplification;It also includes key capacitor Cg for compensating Q3, Q4 high frequency bandwidth, its value is between 47-470pF according to different field effect power tube.
2. A low-distortion field-effect transistor post-stage circuit according to claim 1, characterized in that In cascade mode, a pair of power tubes Q5, Q6 are added, and the VGS adjustment is realized by independent potentiometers VR3, VR4. Each power tube is provided with a pre-compensation capacitor Cg for high-frequency compensation.
3. A low-distortion field-effect transistor post-stage circuit according to claim 1, wherein Field effect tubes Q3, Q4, Q5, Q6 are selected from IRFP240 / 9240 models.