Single-Stage OTA Biased by Voltage-Combiners With Enhanced Performance Using Current Starving

This brief presents an improved single-stage amplifier biased by voltage-combiners, through the proper usage of current starving. The topology designed and fabricated shows an enhancement of the low-frequency gain, an improvement in the establishing time due to enhanced gain-bandwidth product, and a high improvement of the energy efficiency. The circuit was optimized using AIDA-C, a state-of-the-art multi-objective multi-constraint analog IC sizing and optimization tool, and simulation results demonstrate that a gain above 60 dB and a figure-of-merit over 900 MHzxpF/mA are acquirable with this circuit, using the UMC 130-nm technology design kit. The circuit was fabricated and experimentally measured, presenting a gain of 58 dB with a figure-of-merit of 1102 MHzxpF/mA, for a 3.3 V supply source.