The present invention relates to a C-band frequency synthesizer, comprising a temperature controlled crystal oscillator for generating reference frequency signal; a low pass filter for converting the reference frequency signal from current to voltage; a voltage controlled oscillator for generating an output frequency signal based on the output frequency signal of the low pass filter; and characterized by a phase frequency detector for measuring phase difference; and a N-divider module for dividing the output frequency signal of the voltage controlled oscillator down to an operational frequency of the phase frequency detector.