Patent ID: 7236519

Claim:
A transceiving filter comprising: a first port; a second port; a first transmission path having an amplifier circuit for amplifying a reception signal; a second transmission path for allowing a transmission signal to pass; a first directional circuit at a first junction of the first transmission path and the second transmission path, the first directional circuit transmitting the reception signal from the first port toward the second port via the first transmission path; and a second directional circuit at a second junction of the first transmission path and the second transmission path, the second directional circuit transmitting the transmission signal from the second port toward the first port via the second transmission path, wherein the first directional circuit includes a first double stage 90° hybrid circuit for transmitting the reception signal input from the first port to the amplifier circuit and transmitting the transmission signal from the second transmission path to the first port, the first double stage 90° hybrid circuit including two reception filters having similar respective characteristics that allow a signal in a receive frequency band to pass, and wherein the second directional circuit includes a second double stage 90° hybrid circuit for transmitting the reception signal amplified by the amplifier circuit to the second port and transmitting the transmission signal input from the second port to the second transmission path, the second double stage 90° hybrid circuit including two reception filters having similar respective characteristics that allow the signal in the receive frequency band to pass.