To See the Input Resistance of Amplifier Circuit from Network Characteristic and Physical Meaning

Amplifier circuit has several performances such as input resistance, output resistance, gain, frequency response and nonlinear distortion, which are the scale standard whether the amplifier circuit is good or not. Input resistance decides how much peak value amplifier can extract from signal source. Aiming at input terminal network characteristic of amplifier circuit, the paper not only uses the method of test voltage source to calculate input resistance in teaching practice, but also solves input resistance through conversion concept from physical meaning. Anyway the latter method is simply and effective.