Patent ID: 7692513

Claim:
A high frequency radio device, comprising: a high frequency reception processing device having receiver input ports presenting a balanced input having a receiver input impedance including a receiver input real impedance; a surface acoustic wave filter module, comprising: a substrate having a pair of output port terminals; a surface acoustic wave filter provided on the substrate and having a filter characteristic for distinguishing received high frequency signals, and including a pair of balanced output ports presenting a balanced filter output having a filter output port impedance including a filter output port real impedance; a pair of signal paths disposed on said substrate and connected respectively to the pair of balanced output ports of the surface acoustic wave filter and the pair of output port terminals of the substrate; and an impedance matching circuit provided on the substrate configured to effect impedance matching between the balanced output of the surface acoustic wave filter with the receiver input port of the high frequency reception processing device; the pair of output port terminals connected to each of the pair of signal paths and also connected to the receiver input ports; said surface acoustic wave filter being structured so that the filter output port real impedance is substantially matched with the receiver input real impedance of said high frequency reception processing device, wherein said surface acoustic wave filter includes an interdigital transducer and a reflector, and adjustment of the filter output port real impedance of is performed by adjusting at least one of the interdigital transducer or the reflector by setting at least one of a number of electrodes of the interdigital transducer, an overlap width, a film thickness of the electrodes, or a pitch and shape of the electrodes; and said impedance matching circuit being provided only between the signal paths of the pair of signal paths on the substrate, the impedance matching circuit having at least one matching element connected to and between the signal paths of the pair of signal paths on the substrate and selected such that the filter output port impedance of said surface acoustic wave filter module and the receiver input impedance of the high frequency reception processing device are in a complex conjugation relationship.