A Rail-to-Rail Ultra-Low Power OTA Based on a Hybrid Nauta-DIGOTA Topology

A novel ultra-low power amplifier is presented, composed of a Nauta amplifier (1
^st
stage) and a digital OTA (2
^nd
stage). This configuration significantly improves the performance in terms of signal distortion, by allowing the DIGOTA to work in a better operating window. The proposed amplifier has been a validated through simulations in TSMC
$0.18\ \mu \mathrm{m}$
and compared to the DIGOTA: when used as a voltage-follower it features a much lower output distortion, especially for low amplitude signals.