Patent ID: 7167687

Claim:
A switch circuit for selectively switching the connection of a receiving circuit or a transmitting circuit for two communication systems, in which a receiving frequency bandwidth in a first communication system partially overlaps a transmitting frequency bandwidth in a second communication system, and an antenna circuit, said switch circuit comprising switching elements, inductors, and capacitors, including a first switch and a second switch, said first switch comprising a first port connected to said antenna circuit, a second port connected to said transmitting circuit of said first and second communication systems, and a third port connected to said second switch, and said second switch comprising a fourth port connected to said first switch via a capacitor, a sixth port connected to said receiving circuit of said first communication system, and a fifth port connected to said receiving circuit of said second communication system; a first inductor being disposed between said fourth port and said fifth port; a first switching element being disposed between said fifth port and a ground; a second switching element being disposed between said fourth port and said sixth port; and said first and second switching elements being controlled in an ON state while said the transmitting circuit of said first and second communication systems is connected to said antenna circuit.