Inverting operational amplifier:
The output is an 180° out of phase amplified version of the input.
The input signal is applied through a series input resistor Ri to the inverting (-) input and the output is fed back through a feedback resistor Rf to the same input. The non-inverting (+) input is grounded.
The amplification Acl (closed loop voltage gain) is calculated by [Av = - Rf/Rin].
The negative sign indicates that there is a 180° phase phase shift between the output and input signals.
