
72 Analog Electronics
Figure 3.16b shows the response of a typical
opamp in the inverting mode with the feedback
resistor Rf open-circuit (Figure 3.16a). If R, is
short-circuited (or the input impedance of the
opamp is very high) then the voltage e at the
inverting input is simply v,. Taking this to be unity,
then at very low frequencies the output will be
numerically equal to/lvoi, which is typically 200 000
in the case of the opamp whose characteristics are
illustrated in Figure 3.15e. Figure 3.16b presents
the same information as the Bode plot of Figure
3.15e, but represented as an output vector whose
magnitude and phase relative to the