RADIO TERMINAL DEVICE

摘要

A wireless terminal device includes an antenna (10), a transmitting circuit (11), a direct conversion receiving circuit (12), a circulator (13) and a band rejection filter (14). The direct conversion receiving circuit (12) can have smaller sizes than a receiving circuit of a heterodyne type, and is required to remove fewer spurious jamming waves. Owing to them, the whole size of the wireless terminal device can be small. Further, the direct conversion receiving circuit (12) includes even harmonic mixers (20 and 21), and a frequency (flo) of a local oscillation wave (LO) is equal to half a frequency (frx) of the received wave so that leakage of the local oscillation wave (LO) toward the antenna (10) and therefore deterioration in sensitivity do not occur. <IMAGE>