A 1.5-V high drive capability CMOS op-amp

A novel CMOS operational amplifier with a 1.5-V power supply is presented. It is based on a folded-mirror transconductance amplifier and a high-efficiency output stage. The amplifier achieves an open-loop gain and a gain-bandwidth product higher than 65 dB and 1 MHz, respectively. In addition, a 1-V peak-to-peak output voltage into a 500-Ohm and 50-pF output load is provided with a total harmonic distortion of -77 dB, This performance was achieved using maximum aspect ratios of 120/1.2 and 360/1.2 for the NMOS and PMOS transistors, respectively, and a quiescent current as low as 60 mu A for the driver transistors. The amplifier was implemented in a standard 1.2-mu m CMOS process,vith threshold voltages around 0.8 V. It dissipates less than 300 mu W.