Sign Switcher

In this circuit the switch configures the operational amplifier circuit as a voltage follower or a unity gain inverting amplifier. When the control voltage is high the input signal is feed to the noninverting terminal through resistor Rp, Rn is connected in parallel with the feedback resistor Rf. When the control voltage is low the input signal is feed to the inverting terminal through resistor Rn, Rp connects the noninverting terminal to ground.