Equalization of IM3 Products in Wideband Direct- Conversion Receivers

E. Keehr and A. Hajimiri

The wideband direct-conversion receiver architecture is proposed in this paper. In order to provide a quantitative design objective, the UMTS standard is targeted. The single-ended-to-differential conversion previously handled by an inter-stage SAW filter is now performed by a balun. The balun is followed by high-P2 MP mixers driven by Cherry-Hooper LO buffers. The MP BB filter is an active-RC 3 rd-order Chebyshev architecture that drives an 8b pipelined ADC with fs=50 MHz. The AP is a scaled-down version of the MP, with the primary difference being the inclusion of an IM3 generator. As scaling reduces the breakdown voltage of CMOS devices and as system integration trends demand the further elimination of off- chip components, there arises a great need to improve the linearity of RF receivers.