Operational Amplifier Fundamentals Unit 4 – The Voltage Follower
The voltage at the op amp inverting terminal equals the output voltage (VO).
VO follows the circuit input voltage (VI).
VD, the op amp differential input voltage, is 0V.
The GBW product of an op amp is specified at unity gain.
A voltage follower circuit operates with unity gain. Therefore, the circuit bandwidth essentially
equals the specified op amp GBW product (1 MHz for the LF441 op amp).
The ability of an op amp voltage follower to accurately duplicate an input voltage is related to
levels of operation called small-signaland large-signal.
Typically, small-signal refers to voltages with amplitudes equal to or less than 1 Vpk-pk.
Typically, large-signal refers to voltages with amplitudes between 10 Vpk-pk and 20 Vpk-pk.
Small-signal operation is primarily related to the GBW product of an op amp.
Large-signal operation is primarily related to op amp slew rate and full-power bandwidth.