An efficient approach to enhance bulk-driven amplifiers

In this paper, a single-stage class AB bulk-driven amplifier operating in weak inversion region is proposed. The presented amplifier benefits from an improved high input swing structure using quasi-floating-gate technique. The composite transistors and recycling configuration used at the input stage enable the input differential pair to operate under low supply voltages with larger transconductance as compared to the conventional models at no expense of power budget. The circuit is designed in 0.18 µm CMOS technology and simulation results show 61.5 dB low frequency gain with the gain bandwidth of 30.15 kHz and 55.3 V/ms average slew rate. The total current of 275 nA and 0.6 V supply voltage make the proposed amplifier a suitable choice for ultra-low-power applications.