Adaptive dual-loop algorithm for cancellation of time-varying offsets in direct conversion mixers

Graduation date: 2001The thesis presents a new algorithm and structure that is to be used in conjunction\ud with a specially modified CMOS Gilbert cell mixer to remove time-varying DC offsets\ud in direct conversion receivers. In our approach, the DC offset is detected at the output\ud of the mixer using a dedicated coarse ADC and tracked using a low gate count digital\ud structure. The estimated offset is then used to dynamically adjusting the bias of a\ud specially modified Gilbert cell mixer to cancel the offset in the mixer. This prevents\ud saturation and desensitization of the analog downstream stages. The presented approach\ud is suitable for TDMA as well as continuous reception techniques such as W-CDMA and\ud FH-SS while being fully integrable on-chip