Linearised bidirectional distributed amplifier with 20 dB IM3 distortion reduction

Abstract

Proposed is the design of a linearised CMOS bidirectional distributed amplifier (DA) that greatly suppresses the third-order intermodulation (IM3) distortion. The drain and gate transmission lines are staggered to purposely mismatch their time-delay and filter out the IM3 distortion. A modified CMOS cross-coupled cascomp circuit is proposed to enhance the linearity of the gain cell with a varactor-based active post nonlinear drain capacitance compensator for wider linearisation bandwidth. The proposed linearised CMOS bidirectional DA achieves a measured IM3 reduction of 20 dB in both RF directions, with ultra-wideband 0.1 to 9.5 GHz frequency of operation.