A High Gain, 808 MHz GBW Four-Stage OTA in 65 nm CMOS

A four-stage operational transconductance amplifier (OTA) with a novel compensation structure combining multipath G(m)-C compensation and no capacitor feed-forward compensation is proposed in this paper. Based on the small-signal model, stability analysis and design consideration are carried out to demonstrate the stability of the compensation technique. To verify the effectiveness of the compensation scheme, the proposed OTA which drives a 2 pF capacitance, is simulated in TSMC 65 nm 1.2 V CMOS process, achieving 808 MHz gain-bandwidth, 119 dB DC gain, 585 V/mu s slew rate (SR) and 6 ns 1% settling time. The circuit is operated at the single supply voltage of 1.2 V with power consumption of 2.17 mW and the layout area is 0.011 mm(2).