| 摘要 |
PURPOSE:To change only an output phase in response to an external signal by providing a voltage controlled oscillator, a reference oscillator, a phase comparator circuit, an offset control circuit and a loop filter so as to attain excellent noise performance. CONSTITUTION:The phase of an output signal of the voltage controlled oscillator (VCO) 2 phase-locked to the reference oscillator 3 is varied by controlling the DC offset of the output of the phase comparator circuit 4 in the phase-locked circuit. Thus, a modulation signal is inputted from an offset control signal input terminal 16 via an offset control circuit 13 as the DC offset control signal of the circuit 4 so as to act an output phase variable phase locked oscillator 15 like a phase modulator. Further, is using a signal source with an excellent phase noise characteristic for the oscillator 3, the phase noise characteristic up to the off-carrier frequency corresponding to the in-band of the loop filter to the VCO output signal is improved. Thus, only the output phase is changed in response to the external signal. |
