Explain the operation of an inverting amplifier. What is meant by the gain of the operational amplifier? What is the relationship between inverting amplifier gain and Rf and Rr
2007-09-02 20:17:40 · 1 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Assuming a 'perfect' op-amp, the current flowing through the input resistor (Ri) and the feedback resistor (Rf) will be equal in magnitude but opposite in polarity. That means that the 'summing junction' at the point where Rf, Ri, and the inverting input of the amplifier connect will have a potential of 0 volts. Since the non-inverting input of the op-amp is at ground potential, any deviation of the summing junction from 0 volts will cause the output of the amplifier to move in the 'opposite' direction and drive the summing junction back to 0 volts. (The summing junction is also called a 'virtual ground' for this reason.)
The 'gain' of the amplifier is simply the ratio of the output voltage change to the input voltage change (just like any other amplifier).
The gain of a simple inverting op-amp circuit is given by
G = -Rf/Ri
HTH
Doug
2007-09-02 20:31:15 · answer #1 · answered by doug_donaghue 7 · 1⤊ 0⤋