Frequency synthesizers come in many forms, including those based on analog and digital technologies. In spite of the many design approaches, the goal has always been to provide output signals that are unerringly stable. And that stability can often be hard to come by with changes in temperature and under vibration. Although direct-digital synthesizers (DDS) have had shortcomings in the past, the engineers at Synergy Microwave Corp. have refined DDS technology to the point where it is reliable and stable. This is exhibited by broadband 2-to-8-GHz sources with phase noise of only -97 dBc/Hz offset 10 kHz from the carrier and more than respectable spurious performance of -50 dBc. For more on these frequency synthesizers, click here.