Patent ID: 7508898
Filing Date: 2009-03-24
Classification: H01L,H03F,H04B

Abstract:
1. A frequency synthesizer implemented as a phase-locked loop without mixers, the phase-locked loop comprising: a first voltage-controlled oscillator; a second voltage-controlled oscillator; a first resonance circuit coupled to the first voltage-controlled oscillator and adapted to produce a first tuning signal to tune a frequency range of a first frequency signal produced by the first voltage controlled oscillator; a second resonance circuit coupled to the second voltage-controlled oscillator and adapted to produce a second tuning signal to tune a frequency range of a second frequency signal produced by the second voltage controlled oscillator; a switch; two cascaded divide-by-N circuits coupled to the first and second voltage-controlled oscillators via the switch, wherein the switch is operable to couple at least one of the first frequency signal and the second frequency signal to the cascaded divide-by-N circuits; and a divide-by-M circuit coupled to the cascaded divide-by-N circuits in a feedback loop with the first and second voltage-controlled oscillators.