20.1

AC-Coupled Single-Supply Inverting Amplifier. Gain is set by the ratio of the feedback resistance to the series combination of the input resistor and the capacitive reactance of the input coupling capacitor. The resistive voltage divider sets the voltage at the input terminals of the operational amplifier at half the supply voltage. The input capacitor prevents the op amp from amplifying the DC voltage at its input terminal so the DC voltage is simply buffered through the feedback resistor. The output DC level is then at half the supply voltage. This DC level is then filtered out by the output coupling capacitor so only the amplified AC signal appears at the load.