A 0.8 V quasi-floating-gate fully differential CMOS op-amp with positive feedback

This paper presents a 0.8 V fully differential CMOS op-amp. The input stage of the circuit is designed using quasi-floating-gate (QFG) transistors with positive feedback, while QFG transistors in the output stage are connected in the class AB configuration. QFG transistors are employed, enabling the circuit to operate under low supply voltage. The proposed amplifier is designed using 0.18 μm CMOS technology, and simulation results show rail-to-rail input and output swings. The open-loop gain is 80.4 dB with the gain-bandwidth product of 8.66 MHz. Phase margin is 45° (C
_L
= 20 pF). The CMRR is 107 dB (at 1 kHz) and the power consumption is 54.9 μW.