Digital Adaptive IIP2 Calibration Scheme for CMOS Downconversion Mixers

Abstract

This paper presents a cancellation scheme of second order intermodulation distortion based on adaptive digital calibration of the RF downconversion mixer. The system utilizes a low-complexity LMS-based equalizer, which correlates differential mode distortion with common mode distortion to estimate optimum settings of the analog IP2 calibration circuit. A tunable IQ mixer prototype, fabricated in a 0.13 mum RF CMOS technology and operating under low voltage supply of 1.5 V, is presented. Experimental results confirm the feasibility of the proposed IP2 calibration method.