Amplifier Amplifier Equivalent of Input Port vo Voltage controlled voltage source Current controlled voltage current Equivalent of Output PortRs Amplifier Ii Io + – VO + – Vs + – Vi RL Rs Amplifier Io Ii + – VO + – Is + – Vi RL Vi Ri + Equivalent of Input Port Io Ro A I IS i A V V + VO o + i Ro Equivalent of Output Port Voltage controlled voltage source Current controlled voltage current