Ultra-high current efficiency single-stage class-AB OTA with completely symmetric slew rate

An ultra-high current efficiency single-stage class-AB OTA with completely symmetric slew rate is presented. Based on adaptive biasing and nonlinear current mirror techniques employed in a proposed symmetric current recycling structure, the proposed OTA not only achieves the maximum output current proportional to Vin8, but also has the symmetric positive and negative slew rates. Also, the proposed self-biasing output stage makes the slew rate unconstrained. Simulation results demonstrate that the slew rate of the proposed OTA is enhanced by 1500% over that of the conventional folded cascode counterpart with a little increased power, which is suitable for large capacitive load applications.