Patent ID: 6236843
Filing Date: 2001-05-22
Classification: H03J,H03K,H03L

Abstract:
A radio terminal device including:a radio signal receiving circuit for receiving a signal at a receiving frequency;an oscillator producing an oscillation signal at an oscillation frequency and supplied to said radio signal receiving circuit;a digital phase locked loop (DPLL) receiving an output signal from said radio signal receiving circuit for detecting phase difference between the receiving frequency of the signal received by said radio signal receiving circuit and the oscillation frequency of said oscillator, and producing a correction signal in resnse to the phase difference detected;a capacitor selectably connectable within said oscillator for changing the oscillation frequency;a first switch for connecting and disconnecting said capacitor within said oscillator;a second switch connected between said capacitor and an intermediate potential; andcontrol means for alternatingly closing and opening said first and second switches in response to the correction signal produced by said DPLL.