Linear amplifiers have an output which is an input scaled up by gain, typically depicted with the equation $v_{o} = A v_{i}$ . However, linearity can be limited by amplifier saturation. Meanwhile, nonlinear amplifiers experience distortion and are approximated with Taylor series.

Amplifier Types

Amplifiers are two port networks which can share a common ground.

Amplifier Type
Voltage Amplifier
Current Amplifier
Transresistance Amplifier
Transconductance Amplifier
Open Circuit Voltage Gain
$A_{v o} \equiv \frac{v _{o}}{v _{i}}$

Short Circuit Current Gain
$A_{i s} \equiv \frac{i _{o}}{i _{i}}$

Short Circuit Transconductance
$R_{m} \equiv \frac{i _{o}}{v _{i}}$

Open Circuit Transresistance
$G_{m} \equiv \frac{v _{o}}{i _{i}}$

Relationships
$A_{v o} = A_{i s} (\frac{R _{o}}{R _{i}}) = G_{m} R_{o} = \frac{R _{m}}{R _{i}}$

Input Resistance
$R_{i} = \frac{v _{i}}{i _{i}}$

Output Resistance
Eliminate input source, then apply test voltage $v_{x}$ at output
$R_{o} = \frac{v _{x}}{i _{x}}$

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Amplifier

Amplifier Types