CMRR frequency response of CMOS operational transconductance amplifiers

Abstract

In this paper an accurate and complete analysis of the CMRR for the most commonly used CMOS OTA's has been carried out. The analysis provides equations which can profitably be used in the design of high-accuracy integrated amplifiers to be employed in instrumentation circuits. The analysis shows that the CMRR of these circuits is highly affected by two poles which are caused by the zeros of the common-mode gain. By using the Spice simulator and the models of a 1.2-/spl mu/m CMOS process, we have found that the calculated frequency response of CMRR well fits the simulated curves for input frequencies as high as 100 MHz.