Patent ID: 7804367
Filing Date: 2010-09-28
Classification: H03L

Abstract:
1. A frequency synthesizer comprising: a reference divider which divides a frequency of a reference signal with a division ratio of 1/(R a phase detector which outputs a pulse corresponding to a phase difference between a fine mode signal and a signal output from the reference divider; a main divider which outputs a coarse mode signal and the fine mode signal by using the output signal of the reference divider; a charge pump which generates a pumping voltage corresponding to a width and sign of the pulse output from the phase detector; a loop filter which removes noises generated during operation of frequency calibration loop and determines a voltage level of the pumping voltage; a first switch which transfers the pumping voltage applied to the one terminal thereof to a VCO (voltage control oscillator) connected to the other terminal thereof in response to a first switch control signal; a second switch which transfers a reference voltage applied to the one terminal thereof to the VCO connected to the other terminal in response to a second switch control signal; the VCO which outputs the output signal corresponding to a frequency control signal and a control voltage applied through the first and second switches; and a automatic frequency calibration block which generates the frequency control signal, the first switch control signal the first switch control signal, and the second switch control signal in response to the pumping voltage, the reference signal, and the coarse mode signal.