A frequency agile synthesizer using DDS and PLL techniques for FMCW radar

A frequency synthesizer using phase-locked loop (PLL) and direct digital synthesis (DDS) techniques for frequency modulated continuous-wave (FMCW) radar which has low phase noise is presented. Fast switching time and narrow channel spacing can be achieved by DDS. The modulation width of 850MHz, from 12.6GHz to 13.45GHz, is achieved. The phase noise of 13.4GHz frequency synthesizer at 1 MHz offset is -118.34dBc/Hz, the reference spur is better than -69dBc and the output power is over -3dBm.