A buffer amplifier with unity voltage gain, high input impedance, high speed, high current gain, high output power and low offset includes three stages and a DC servo circuit. The first stage of the buffer amplifier contains complementary N-channel and P-channel MOSFET source followers that provide high input impedance to buffer the input signal source. A feedback DC servo signal is provided to correct the subsequent stages so as to maintain the output at virtual DC ground level. The second stage is a driver stage that also contains complementary N-channel and P-channel MOSFET source followers to provide sufficient current to drive the output stage. The last stage is an output stage that contains at least one pair of complementary power MOSFETs or BJTs to deliver high currents to a load.
