An efficient and high-performances CMOS op amp with rail-to-rail mode and high CMRR

In this paper, we present a new structure of a CMOS Op Amp offering high performances differential frequency response with high CMRR, high slew rate and input/output rail-to-rail mode. These performances are due both to a new efficient gain stage with a compact layout and to a simple way to obtain a high CMRR. Simulation experiments have been performed with three different (0.8 μm, 1.2 μm, 2.4 μm) CMOS technologies. In particular for the 0.8 μm one, the main performances-under single 5 V power supply are a unity gain bandwidth of 40 MHz, a phase margin of 63 degrees, a slew rate of 60 V/μs, all performed on heavy load such as 2.5 kΩ||20 pF. Simulated results have been experimentally confirmed for the 2.4 μm CMOS technology for which we have measured a low frequency CMRR of 100 dB