Electronics Handbook/Devices/Amplifier/DC Volatge Amplifier

Transformer Amplifier

${\frac {V_{s}}{V_{p}}}={\frac {N_{s}}{N_{p}}}$

Transformer acts as Amplifier if N₂ > N₂

Transistor Amplifier

When Transistor conducts current

I_b ≠ 0 , I_e = α I_b , I_c = β I_b

Inverting Amplifier

${\frac {V_{o}}{V_{i}}}=1-{\frac {R_{2}}{R_{2}+R_{1}}}{\frac {R_{3}}{R_{4}}}$

When R₁

${\frac {V_{o}}{V_{i}}}=1-{\frac {R_{3}}{R_{4}}}$

${\frac {V_{o}}{V_{i}}}=-n$ provided that R₃ = (n+1)R₄

Non Inverting Amplifier

${\frac {V_{o}}{V_{i}}}={\frac {R_{2}}{R_{2}+R_{1}}}{\frac {R_{3}}{R_{4}}}$

When R₁

${\frac {V_{o}}{V_{i}}}={\frac {R_{3}}{R_{4}}}$

${\frac {V_{o}}{V_{i}}}=n$ provided that R₃ = nR₄

Op Amp Amplifier

Inverting amplifier

$V_{\mathrm {out} }=-V_{\mathrm {in} }\left({R_{f} \over R_{1}}\right)$

Non-inverting amplifier

$V_{\mathrm {out} }=V_{\mathrm {in} }\left(1+{R_{2} \over R_{1}}\right)$