Operational Amplifier Fundamentals Unit 2 – The Inverting Amplifier
UNIT 2 – THE INVERTING AMPLIFIER
UNIT OBJECTIVE
At the completion of this unit, you will be able to demonstrate the dc and ac characteristics of an
inverting operational amplifier by measuring circuit performance.
UNIT FUNDAMENTALS
An inverting amplifier is a closed-loop op amp circuit in which feedback is applied to the
inverting input through the feedback resistor (RF).
The circuit input is applied to the inverting terminal of the op amp through the input resistor
(RIN).
The circuit output, developed across RL, is amplified and inverted with respect to the circuit
input.
Circuit gain (Av) is function of the ratio between RF and RIN.
Av = RF /RINOutput voltage is calculated by multiplying the input voltage by the circuit gain value. The (-)
sign indicates inversion, not that the output voltage must be negative.
VO = - (VI x Av)