A modified bias scheme for high-gain low-noise folded cascode OTAs

Achieving large low-frequency gain together with low noise and a high unity-gain bandwidth (UGB) imposes conflicting requirement on bias currents in single stage operational transconductance amplifiers (OTA). In this work, we propose a modified biasing scheme for folded cascode OTAs to de-couple the gain versus noise/UGB trade-off. The effectiveness of proposed biasing scheme is illustrated with the aid of an ultra-low noise OTA design achieving 350 pV / √Hz along with 70 dB DC gain in 130nm CMOS process while consuming roughly half the bias current as compared to conventional biasing scheme.