# Fundamental Physics/Electronics/Electronics Amplifier

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## Electronics Amplifier

Electronics amplifier is an electronics device that provides voltage amplification . Electronics amplifier has a transfer function

$H={\frac {v_{o}}{v_{i}}}=\pm A$ With

A - Amplification factor
the positive sign - means positive amplification . The circuit that provides positive amplification is called Non-inverting amplifier
the negative sign - means negative amplification . The circuit that provides negative amplification is called Inverting amplifier

## DC Amplifier

### Non-inverting amplifier

Using Op amp to provide positive amplification

${\frac {v_{o}}{v_{i}}}=1+{\frac {R_{2}}{R_{1}}}$ With $R_{2}=AR_{1}$ . $v_{o}=Av_{i}$ Using Transistor to provide positive amplification

${\frac {v_{o}}{v_{i}}}=({\frac {R_{2}}{R_{2}+R_{1}}})({\frac {R_{4}}{R_{3}}})$ With $R_{1}=0.R_{4}=AR_{3}$ . $v_{o}=Av_{i}$ Using Transformer to provide positive amplification

${\frac {v_{o}}{v_{i}}}={\frac {N_{2}}{N_{1}}}$ With $N_{2}=AN_{1}$ . $v_{o}=Av_{i}$ ### Inverting amplifier

Using Op amp to provide positive amplification

${\frac {v_{o}}{v_{i}}}=-{\frac {R_{2}}{R_{1}}}$ With $R_{2}=AR_{1}$ . $v_{o}=-Av_{i}$ Using Transistor to provide positive amplification

${\frac {v_{o}}{v_{i}}}={\frac {R_{2}}{R_{2}+R_{1}}}{\frac {R_{4}}{R_{3}}}$ With $R_{1}=0.R_{4}=(A+1)R_{3}$ . $v_{o}=-Av_{i}$ Using Transformer to provide positive amplification

${\frac {v_{o}}{v_{i}}}=-{\frac {N_{2}}{N_{1}}}$ With $N_{2}=AN_{1}$ . $v_{o}=-Av_{i}$ 