A Low Power Operational Amplifier Circuit with Strong Anti-Interference Ability and High Gain

The operational amplifier circuit is a fundamental unit module in integrated circuit design. With the development of deep sub-micron standard CMOS technology, system power consumption and power supply voltage have gradually decreased. Traditional amplifiers can no longer meet the requirements of wide output swing at low voltage. The use of a track-to-track structure in this design can effectively solve this problem. However, traditional rail-to-rail amplifiers have the disadvantage of lower stability than conventional amplifiers. This design uses a self-biased common source common gate current source circuit as the bias circuit for the rail-to-rail amplifier circuit, ensuring circuit stability. The amplifier designed in this article has the advantages of strong anti-interference ability, low power consumption, and high gain, and maintains good stability in noisy environments. Based on the Smic18mmrf CMOS process, the open-loop gain reaches 99 dB, the phase margin is 44°, the common mode rejection ratio and power supply rejection ratio are 100 dB and 99 dB, respectively, and the static power consumption is 104 uW. The layout area is approximately 94 μ m * 89 μ m.