Method to suppress DDFS spurious signals in a frequency-hopping synthesizer with DDFS-driven PLL architecture
Kun‐Sup Kwon, Won‐Sang Yoon · IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control · 2010
In this paper we propose a method of removing from synthesizer output spurious signals due to quasi-amplitude modulation and superposition effect in a frequency-hopping synthesizer with direct digital frequency synthesizer (DDFS)-driven phase-locked loop (PLL) architecture, which has the advantages of high frequency resolution, fast transition time, and small size. There are spurious signals that depend on normalized frequency of DDFS. They can be dominant if they occur within the PLL loop bandwidth. We suggest that such signals can be eliminated by purposefully creating frequency errors in the developed synthesizer.