Analysis of random common-mode rejection ratio in op-amps

摘要

One of the important nonideal factors causing op-amp errors is the common-mode rejection ratio (CMRR). The CMRR of CMOS op-amps and its statistical characteristics are thoroughly analyzed. The random and deterministic CMRR of a two-stage CMOS op-amp are derived. The statistical characteristics of the total CMRR are discussed. A definition of the CMRR for processes is given. A sample amplifier has been designed for high-speed and high-precision applications. The simulated performances of the op-amp are shown.