Design and Performance analysis of Constantgm Low-Power Rail-to-Rail Operational Amplifier

A low power CMOS op-amp rail to rail op-amp. We realizes in SCNO 180nm technology. Under 1.8 power supply voltage. A constant transcondutance is ensured for the whole common-mode input range. The class AB output stage also has a full voltage swing. The circuit provides a gain bandwidth of 17.3-MHz and a DC gain of 83.67 dB. The input transistors operate in weak inversion, which have big gm/Id value, so the power consumption is reduced.