Welcome to Part 4 of this 5-part series on ultra-low-noise synthesizer design. Part 1 introduced advanced loop design and included both passive and active filters. Part 2 covered noise sources in the loop outside of the synthesizer integrated circuit (IC). Part 3 added synthesizer IC noises and how they are modeled, as well as how all of the noise sources are combined and shaped by the loop.
This article covers the key parts required by design engineers seeking the lowest-noise designs, or lowest noise for a particular cost. Since the designer is naturally concerned with the cost tradeoffs of these key parts, that information is presented in some detail here. Additional information is available in the long version posted on the Longwing Technology website. Part 5 will bring it all together in the form of low-noise examples, comparing and contrasting the performance attained by the various methods and the available parts.