There are many misconceptions around Fractional N PLLs. One of them is that they require different design equations and simulation techniques that are used for integer N PLLs. In fact, they use the same concepts and equations. The difference, though, is the performance. By having smaller N value, Fractional N PLLs theoretically have better phase noise performance. Although Fractional N PLLs contain compensation circuitry for the fractional spurs, typically it is still a net improvement.

This webinar will address some of the misunderstanding of fractional N PLLs, introduce the advantages and disadvantages of fractional N PLLs over integer N PLLs, fractional N PLL design consideration as well as design tricks.

Length: 26 minutes

Published Date: December 2008

Topics covered in this online seminar include:

• Basic PLL Overview and Benefit of Fractional N PLL
• The Mis-Use of Fractional N
• Fractional N PLL Details
• Spurs and Their Reduction Methodology
• Summary

Presenter: Don Foong, Staff Field Application Engineer

Don has over 20 years of experience in the electronics industry holding various positions such as components procurement and field application. He joined National from Westech Electronics where served as a Senior Field application engineer for five years. Don graduated from Nanyang Technological University with a degree in Electrical and Electronics Engineering.