Improvements in Biasing and Compensation of CMOS Opamps In this paper, we present modifications to the constantgm bias circuit and Millerlead compensation of operational amplifiers which eliminate or minimize some of their shortcomings. First, we demonstrate how parasitic pad capacitance can cause instability in the constantgm bias circuit, and show that the transconductance is constant only for specific bias conditions. Next, we suggest a new circuit topology that requires 75% less compensation capacitance to achieve stability. We also discuss problems with Millerlead compensation that arise from temperature, process, and load variations. Finally, we present a new biasing technique to correct these problems, and, through simulation, demonstrate a 40? improvement in phase margin over load current variations.

CMOS LowVoltage Indirect Current Feedback Instrumentation Amplifiers With Improved Performance Indirect current feedback (ICF) is a very common operation principle used in the design of CMOS instrumentation amplifiers (IA). The input and output transconductors required in an ICF IA usually consist on resistivedegenerated simple differential pairs. In this contribution conventional sourcefollower (SF) structures used in IA transconductors are replaced by flippedvoltagefollower (FVF) and supersourcefollower (SSF) cells, respectively. As a result, the overall performance and efficiency of the IA is enhanced with a minimum cost. The principle of operation governing CMRR is also analyzed and its behavior is confirmed by means of extensive simulations. A singlestage IA with a fixed voltage gain equal to 10 VV has been designed in  0.35boldsymbolmu mathbfm  standard CMOS technology to operate with 1.8 V supply. Simulation results show improved metrics in terms of voltage gain accuracy, while the overall performance of the IA is comparable to other contributions in the literature.