The Design of an Operational Amplifier with 300mA Output Current Based on 0.18 μm CMOS Process

This work presents an operational amplifier (op amp) which output current is 300mA through 0.18 μm CMOS standard process. This circuit is composed of four parts: fully differential folding cascode as input stage, class-AB output stage and three-branch reference current source. Through simulation under the conditions of 5V power supply voltage, 100kΩ resistance and 10pF capacitive load, the gain, phase margin, bandwidth and the peak-to-peak output current value of the operational amplifier are 105dB, 72°, 3.6MHz and 370mA, respectively. This paper implements a high current output op amp with die area of 1.0013 mm2, the actual measurement results show that the circuit can achieve more than 300mA current output. Meanwhile rail-to-rail output voltage swing could be got under the condition of 5V power supply voltage. It can work normally over the temperature range from -40°C~85°C.