A 2-GHz CMOS image-reject receiver with LMS calibration

This paper describes a sign-sign least-mean squares (LMS) technique to calibrate gain and phase errors in the signal path of a Weaver image-reject receiver. The calibration occurs at startup and the results are stored digitally, allowing continuous signal reception thereafter. Fabricated in a standard digital 0.25-mum CMOS technology, the receiver achieves an image-rejection ratio of 57 dB after calibration, a noise figure of 5.2 dB, and a third-order input intercept point of -17 dBm. The circuit consumes 55 mW in calibration mode and 50 mW in normal receiver mode from a 2.5-V power supply. The prototype occupies an area of 1.23 x 1.84 mm(2). Index Terms-Digital-to-analog conversion, image rejection, least mean square (LMS) calibration,low-noise amplifier, mixer, radio frequency (RF) CMOS, variable-delay circuit.