APPARATUS AND METHOD FOR FREQUENCY CALIBRATION IN FREQUENCY SYNTHESIZER

摘要

PURPOSE: A frequency calibration apparatus of a frequency synthesizer and a method thereof are provided to suppress the use of a loop switch for selecting an open loop and closed loop, thereby reducing phase noise. CONSTITUTION: A reference frequency divider(1) controls the frequency of an inputted signal. A phase detector(2) compares a frequency signal of the reference frequency divider and the phase of a feedback frequency signal. A charge pump(3) generates up/down voltage based on phase differences of the phase detector. A loop filter(5) eliminates noise of the up/down voltage. A voltage controlled oscillator(VCO,6) controls an oscillation frequency by the output voltage of the loop filter. A VCO bank(7) establishes the oscillation frequency of the voltage controlled oscillator. A pre-scaler(8) lowers the frequency signal oscillated in the VCO by demultiply to integer-fold. A program divider(9) demultiplies the oscillation frequency to a reference frequency through the pre-scaler.