A high-frequency phase-compensation fractional-N frequency synthesizer

In this paper, a new type of high-frequency fractional-N frequency divider with a phase compensation technique is developed, which can operate for the frequency ranging from 1 GHz to 2.5 GHz, and achieve the divide ratio of (256 similar to 271) + (f / 16). The on-chip phase compensation by a delay-locked loop (DLL) is adopted to reduce the fractional spurs in the fractional-N frequency synthesizer. The fractional-N synthesizer is simulated with using a 0.35- mu m standard CMOS technology and the power dissipation is about 70 mW under the supply voltage of 3.3 V.