Patent ID: 8279014

Claim:
A frequency synthesizer of a transceiver for generating a calibrated crystal oscillation frequency and a calibrated carry frequency, in accordance with a wireless signal received, comprising: a phase frequency detector having a first input terminal to receive a crystal oscillation frequency F IN ; a charge pump connected to an output terminal of said phase frequency detector; a loop filter connected to an output terminal of said charge pump; a VCO (voltage-controlled oscillator) connected to an output terminal of said loop filter and having a first output terminal to output a frequency-locked signal F OUT1′ ; a first multi-modulus divider connected to said VCO and outputting a signal to a second input terminal of said phase frequency detector; a first Σ-Δ modulator having a second input terminal, a third input terminal, and an output terminal, wherein said second input terminal is to receive a channel information of said wireless signal, thereby a predetermined first divisor D is determined, and said third input terminal is to receive a frequency offset value represented by a “k” in a unit of ppm (parts per million) k, and said output terminal of said first Σ-Δ modulator is to output a first calibrated divisor D′ to an input terminal of said first multi-modulus divider, according to an equation D′=D(1+k ppm); a second multi-modulus divider connected to said VCO and having a second output terminal of said frequency synthesizer to generate said calibrated crystal oscillation frequency while said frequency synthesizer runs into a phase locked mode; and a second Σ-Δ modulator having an input terminal to receive said channel information of said wireless signal, and an output terminal connected to said second multi-modulus divider to provide said predetermined first divisor D according to said channel information.