Maximizing Temperature and Process Corner Performance of Operational Amplifiers with a Novel Self-Adjusting Biasing Technique

A novel self-adjusting biasing technique for current sources in CMOS operational amplifiers is presented. The method is deduced from the fundamental characteristics of a mosfet and a simple line of reasoning. Opamps using this technique can produce a more constant gain over process corners and temperature. This is especially important under large-signal conditions, when the output is near one of the supply rails or a large current needs to be driven. Therefore it reduces worst case distortion in a given Opamp circuit that uses feedback over temperature and process corners. It is also capable of driving low-V_t-devices that typically exhibit less noise, increasing the achievable noise performance of the Opamp almost without additional current consumption. The method was implemented and simulated in tsmc 180 nm CMOS. Simulation results are presented that clearly show the increased performance compared to the state of the art.