Matching transformer for dual-band radio receiver

Claim 1

A dual-band radio receiver comprising: a first RF signal section outputting a first RF signal in a first broadcast band; a first mixer coupled to said first RF signal section outputting a first IF signal having a first intermediate frequency; a second RF signal section outputting a second RF signal in a second broadcast band; a second mixer coupled to said second RF signal section outputting a second IF signal having a second intermediate frequency substantially equal to said first intermediate frequency; means for activating only one of said first or second mixers at a time; a resonant circuit including a single impedance matching transformer receiving both of said first and second IF signals, said transformer including a primary winding coupled to said first and second mixers in parallel and including a transformer secondary circuit inductively coupled to said primary winding; a first IF filter coupled to said secondary circuit and adapted to filter said first IF signal when said receiver is receiving in said first broadcast band; a second IF filter coupled to said secondary circuit and adapted to filter said second IF signal when said receiver is receiving in said second broadcast band; and an isolation circuit coupled between said first IF filter and said second IF filter; whereby said single impedance matching transformer provides impedance matching between said first mixer and said first IF filter and between said second mixer and said second IF filter.