In a frequency synthesizer, a first, constant frequency divider is connected to a reference frequency oscillator, and a second, variable frequency divider is connected to a voltage-controlled oscillator. A phase difference is detected by a phase detector between the frequency dividers and a first output...http://www.google.com/patents/US6173025?utm_source=gb-gplus-sharePatent US6173025 - PLL frequency synthesizer using frequency dividers reset by initial phase difference
