Frequency converter for outputting a stable frequency by feedback via a phase locked loop

A frequency converter, comprising:

• a local oscillator for generating a local oscillation frequency signal;
• a first amplifier for providing a local frequency signal by amplifying said local oscillation frequency signal to a first predetermined level;
• a second amplifier for outputting an amplified frequency signal by amplifying said local oscillation frequency signal;
• a divider for dividing said amplified frequency signal output from said second amplifier;
• a phase locked loop circuit for generating a first direct-current (DC) voltage by comparing an output of said divider to an input reference clock frequency signal and filtering a resultant thereof, said first DC voltage being applied as a first control voltage for controlling said local oscillator;
• a mixer for mixing said local frequency signal and a feedback frequency signal to generate a mixed frequency signal;
• a first filter for outputting a first filtered frequency signal by filtering said mixed frequency signal;
• a phase comparator for generating a voltage signal corresponding to a phase difference between an input frequency to said frequency convertor and said first filtered frequency signal output from said first filter;
• a second filter for converting said voltage signal output by said phase comparator to a second DC voltage having any noise component eliminated by said second filter;
• and
• a voltage controlled oscillator receiving said second DC voltage as a second control voltage for generating a stable output frequency signal, said stable output frequency signal being provided as said feedback frequency signal to said mixer.