Design and Improvement of a Frequency Synthesizer Based on PLL+DDS+PLL

摘要

A L-band high performance frequency synthesizer is presented for space TT&C channel. PLL+DDS+PLL structure is used to realize small step-size, high spectrum purity and low phase noise. Experimental result shows that its phase noise is better than -100dBc/Hz@10KHz and its spurious suppression is better than -75dBc. But the additive spurious results co-frequency interference. Find out the case of co-frequency interference and propose corresponding countermeasures by analysis.