Static Analysis of FET Amplifier Circuits: A Step-by-Step Guide
Date：2025-04-24 Categories：Product knowledge Hits：428 From：Guangdong Youfeng Microelectronics Co., Ltd
Identify Circuit Configuration
FET amplifiers typically use common-source (CS), common-gate (CG), or common-drain (CD) configurations. For example, the CS setup is widely adopted for voltage amplification due to its high gain and input impedance .
Construct DC Equivalent Circuit
Replace capacitors with open circuits and AC sources with ground. This isolates the DC biasing network, simplifying calculations for gate-source voltage (VGS), drain current (ID), and drain-source voltage (VDS).
Apply Kirchhoff’s Laws
Gate Loop: For self-bias circuits (e.g., JFETs), VGS = -ID * RS .
Drain Loop: VDS = VDD - ID * (RD + RS), where VDD is the supply voltage.
Transfer Characteristic: For JFETs, use ID = IDSS*(1 - VGS/VP)² . For MOSFETs, ID = (k/2)(VGS - VTH)² (enhancement mode) or ID = IDSS(1 - VGS/VP)² (depletion mode) .
Solve for Q-Point
Iterate or use graphical methods (e.g., DC load line) to find IDQ and VDSQ. Ensure the Q-point lies within the linear region for distortion-free operation.
Key Considerations:
Bias Stability: 分压式偏置电路 (voltage divider biasing) enhances thermal stability by fixing VGS .
YFW Diode Advantage: Our FETs (e.g., N-channel MOSFETs) feature low noise, high temperature stability, and precise IDSS/VP parameters, minimizing Q-point drift .
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Classification, Structure, and Principle of MOSFET
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Understanding the Difference Between Field-Effect Transistors (FETs) and Bipolar Junction Transistors (BJTs)
