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

The trade-off between image rejection and channel selection in heterodyne receivers often restricts the frequency planning and requires external image-reject filters. Hartley and Weaver image reject architectures partially resolve this issue at the cost of requiring precise phase and gain matching in both the signal path and the local oscillator (LO) path. The use of polyphase filters to improve the matching typically leads to a high power dissipation whereas analog calibration mandates periodic refreshing, a difficult issue in CDMA systems that must receive continuously. In this Weaver receiver, gain and phase mismatches are calibrated simultaneously by a least-mean-square (LMS) algorithm. The receiver targets a sensitivity and blocking performance commensurate with wideband CDMA (WCDMA) systems.