Operational Amplifier#
Abstract:
An operational amplifier (short op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and a single-ended output.
All amplifier circuits have the feedback to the negative input!
An
Op-Amp does not draw current from the input!
Voltage Follower/Buffer#
\(\(V_{\mathrm{out}} = V_{\mathrm{in}}\)\) Provides current at the output
without loading the input.
Non-Inverting Amplifier#
\[V_{\mathrm{out}} = \left(1 + \frac{R_2}{R_1} \right) V_{\mathrm{in}}\]
with resistances \(R_1, R_2 \in \R\) and the voltages \(V_{\mathrm{in}}, V_{\mathrm{out}} \in \R\).
Inverting Amplifier#
\[V_{\mathrm{out}} = -\frac{R_2}{R_1} V_{\mathrm{in}}\]
with resistances \(R_1, R_2 \in \R\) and the voltages \(V_{\mathrm{in}}, V_{\mathrm{out}} \in \R\).
Differential Amplifier#
\[V_{\mathrm{out}} = \frac{R_2}{R_1}\left(- V_1 + V_2 \frac{R_4}{R_4 + R_3}\right) + \frac{R_4}{R_4 + R_3} V_2\]
with resistances \(R_1, R_2, R_3, R_4 \in \R\) and the voltages \(V_{\mathrm{in}}, V_{\mathrm{out}} \in \R\).
Schmitt-Trigger#
Offset: \(V_{\mathrm{ref}} \frac{R_2}{R_1 + R_2}\)
\(V^{+} = (V_{in} - V_{out}) \frac{R_4}{R_3 + R_4}\)
Bias: \(\Delta V\)