A compact output stage for low-power low-distortion amplifier with diode negative feedback

This paper describes a compact output stage for low-power rail to rail operational amplifier. A negative feedback diode could be used to decrease even harmonic distortion and simplify frequencies compensation. The amplifier is designed to be loaded 20pF capacitive load, and the unity-gain bandwidth is 200 KHz at 65° phase margin. The quiescent current is limit to 45uA when voltage supply is 5V. The THD down to -95dB when signal frequency at 1 KHz. Finally, this circuit has been thoroughly simulated in a standard 0.8um bipolar process.