1.2-V CMOS op-amp with a dynamically biased output stage

A very low-voltage operational amplifier in a standard CMOS process with a 0.75-V threshold voltage is presented. It uses a novel dynamically biased output stage based on the switched-capacitor approach. Thanks to this, drive performance is greatly improved and accurate current control is also achieved. The amplifier is capable of working with a power supply as low as 1.2 V while providing a -74-dB total harmonic distortion with a 700-mV peak-to-peak output voltage into a 500-Omega and 20-pF output load. The open-loop gain and the gain-bandwidth product are higher than 90 dB and 2.2 MHz, respectively.