TRANSMISSION-RECEPTION CIRCUIT, SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE AND COMMUNICATION RADIO EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To provide a transmission-reception circuit, a semiconductor integrated circuit device and communication radio equipment having this transmission/ reception circuit, which maintain high isolation and do not deteriorate S/N ratio of a reception amplifier. SOLUTION: This transmission-reception circuit has an antenna part 2, a transmission circuit part 4 having a transmission amplifier which amplifies a transmission signal, a reception circuit part 5 which has a reception amplifier for amplifying a reception signal and has a mixer connected to its rear stage and an antenna changeover switch part 3 which switches the first connection state for having the transmission circuit part 4 output the transmission signal, and the second connection state for having the antenna part 2 output the reception signal. In this case, a switch element 12 which is turned off in the first connection state is provided between the reception amplifier 10 of the reception circuit part 5 and the mixer 11.