Patent ID: 8659472

Claim:
An apparatus comprising: a stable local oscillator comprising a first control loop, the first control loop comprising (i) a first voltage-controlled oscillator configured to generate a first output signal and (ii) a first phase-locked loop module; a frequency up-converter configured to increase a frequency of the first output signal; a second control loop configured to receive the up-converted first output signal, the second control loop comprising (i) a second voltage-controlled oscillator configured to generate a second output signal, (ii) a second phase-locked loop module, and (iii) a mixer having a first input coupled to the frequency up-converter, a second input coupled to the second voltage-controlled oscillator, and an output coupled to the second phase-locked loop module; a buffer coupled between the stable local oscillator and the frequency up-converter; and a filter coupled between the frequency up-converter and the mixer.