To obtain a transmission characteristic and a reception characteristic with excellent quality by eliminating occurrence of distortion other than a required frequency component of a reference signal so as to decrease phase jitter of a high frequency output signal of a frequency synthesizer.

A waveform shaping circuit 10 using a filter or a tuning circuit to pass only a reference signal and to attenuate an undesired frequency component is provided to an output terminal of a reference signal oscillator TCXO 5 and an output of the TCXO 5 is given to a frequency divider 7. Thus, the purity of a waveform in the vicinity of a threshold level of the frequency divider 7 is improved and a phase jitter of a local oscillation signal outputted from a voltage controlled oscillator VCO 3 is suppressed.