Nortel Networks Corporation

Henric Van Vliet

Peter John Mole

Chettan Babla

To reduce the impact of image frequencies generated by mixing an incident carrier signal down to a relatively low intermediate frequency signal used in subsequent signal processing, a mixing frequency is selected such that the generated intermediate frequency signal has a frequency offset relative to DC that is substantially that of a single channel spacing between frequency adjacent incident carrier signals, as shown in FIG.,Image rejection is further improved through the integration of a current-driven polyphase filter (,) directly between an input stage (Q,to Q,) and a mixer stage (Q,to Q,) of an image reject mixer (FIG.,) such as to mitigate quadrature divergence between separate in-phase and quadrature paths within the image reject mixer.

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Dormansland, United Kingdom

Henric Van Vliet