Design of low phase noise and wideband frequency synthesizer from 31.25MHz to 8GHz

PLL is widely used in a variety of frequency synthesis systems. This paper presents a wideband frequency synthesizer method using a passive frequency double and programmable frequency dividers. The wideband frequency synthesizer contains basic PLL, programmable power processing circuitry, frequency multiplying circuit and frequency dividing circuit. The paper finally provide a wideband frequency from 31.25MHz to 8GHz, typical phase noise is -110dBc/Hz@100Hz, -114.dBc/Hz@1kHz, -115dBc/Hz@10kHz, -112dBc/Hz@100kHz, -131.3dBc/Hz@1MHz with all frequency normalized to 1GHz.