Equivalent circuits of Signal source *Thevnin circuit(戴维宁等效电路) Rs Amplifier R 电压源等效电路(Voltage source circuit) *Norton circuits(诺顿等效电路) Amplifier Vo 电流源等效电路(current source circuit)*Thevnin circuit(戴维宁等效电路) Equivalent circuits of Signal source *Norton circuits(诺顿等效电路) S S S R V I  Rs Amplifier Ii Io + – VO + – Vs + – Vi RL 电压源等效电路(Voltage source circuit) Rs Amplifier Io Ii + – VO + – Is + – Vi RL 电流源等效电路(current source circuit)