Digitally Assisted Equalization of Third-Order Intermodulation Products in Wideband Direct Conversion Receivers

E. A. Keehr and A. Hajimiri

An effective linearization technique capable of equalizing IM3 products resulting from an arbitrary out-of-band blocking scenario in a wideband direct conversion receiver is presented. IM3 products are regenerated in the RF analog domain of a low-power mixed-signal feedforward path and are used to cancel analogous signal terms in the original receiver at digital baseband via adaptive equalization. The composite SAW-less receiver achieves an improvement in effective IIP3 from 27.1 to รพ5.3 dBm under worst-case UMTS Region 1 blocking when the feedforward path is active.