OP AMP MODELS
Ideal op amp
- Vo = A(V+ - V-) where A is infinite.
- No current flows into either input (Rin = infinity).
Almost ideal op amp
- Vo = A(V+ - V-) where the gain,
A is very large ~ 105
- Vo saturates at the power supply voltages.
- Often good model for commercial op amps.
Additions for higher frequencies
- The gain, A decreases at 20 dB per decade starting at a low frequency
(about 10-100 Hz)
and reaching 1 at ft (about 1-10 MHz).
- the output can not change faster than the slew rate.
© Copyright 1998 New Mexico Institute of Mining and Technology