This article is the fifth and concluding installment in this series on ultra-low-noise synthesizers. Part 1 introduced higher-order phase-locked-loop (PLL) design, while Part 2 reviewed noise sources. Part 3 analyzed noise shaping in the loop followed by Part 4, which presented commercially available parts for the low-noise PLL designer.
Longer and more detailed versions of these articles are available for download at www.longwingtech.com. This final article is intended to focus on the noise-performance results and tradeoffs in design examples using the low-noise techniques and parts presented earlier. Here, we compare the best performance available with fully integrated synthesizers to that which is possible with discrete voltage-controlled oscillators (VCOs) and external active filters.