A 180nm CMOS three stage feedforward compensation op-amp with linearity improvement technique for active RC LPF

The nonlinearity analysis of the full differential operational amplifier (op-amp) and Cascade System are introduced. A multistage op-amp with feedforward compensation (FFC) and linearity improvement technique circuit is designed. The proposed op-amp utilizes a current-reusing, split path technology. A 10MHz bandwidth 4th-order, Chebyshev-I, ladder active-RC LPF employing the op-amp in this paper is simulated and optimized with the guideline of the nonlinearity analysis. The optimized in-band IIP3 of the LPF can achieve 50.2dBm in a test two-tone input signal at 4.5MHz and 4.6MHz while consuming 14.76mW from a 1.8V supply in 180nm CMOS technology.