MOBILE COMMUNICATION APPARATUS

摘要

A frequency synthesizer part capable of providing a simultaneous transmission and reception operation can be realized by use of a simple structure. A mobile communication apparatus has a first frequency-switchable VCO (11) for generating local oscillation signals for transmission and for reception, and a second VCO (12) for generating a local oscillation signal for transmission during a simultaneous transmission and reception operation. There is also provided a switch (16) that connects, during a transmission or reception operation, the first VCO (11) to a transmission mixer (31) and to a reception mixer (21), and that connects, during a simultaneous transmission and reception operation, the second VCO (12) and the first VCO (11) to the transmission mixer (31) and the reception mixer (21), respectively. The oscillation frequency of the second VCO (12) is set to twice that of the first VCO (11) during the transmission operation. There are also provided a switch (17) and a one-half frequency divider (18) that frequency divides an output of the second VCO (12) by two during the operation of the second VCO (12).