Ultra low-power bulk and gate-driven, class AB, sub-threshold transconductor

Operational Transconductance Amplifier (OTA), is a main building block of analog signal systems. This paper presents a novel low-voltage and low-power rail-to-rail wide linear range OTA, operating in weak inversion region. The bulk and source-degenerated input stage provides, rail-to-rail input and output signal swings, whereas the class AB flipped voltage follower generates the bias current for the input stage. To enhance the current drive capability, a positive feedback has been employed at gates of input transistors. The OTA uses a single 0.5 V supply and dissipates 32 nW power to provide 38 dB gain and 50 kHz gain bandwidth product. The Cadence VIRTUOSO environment using UMC 0.18 μm CMOS process technology has been used to simulate the proposed circuit. Simulation results showed that the circuit exhibits less than -52 dB total harmonic distortions, for 100 mV_(p-p) signal at 200 Hz frequency in its unity gain configuration.