Interactive Digital Phase Locked Loop Design


This is an interactive design package for designing digital (i.e. software) phase locked loops (PLLs). Fill in the form and press the ``Submit'' button, and a PLL will be designed for you.

I've been advised to say that, although I believe the package to be bug-free, you use the results at your own peril, and you're advised to check them for correctness before using them. Don't blame me if your aircraft falls out of the sky!

The Java code generated by this package is the way it is for pedagogic reasons, and could easily be ``tightened up''.

The graphs are produced with the help of the excellent gd GIF manipulation library, originally from Quest Protein Database Center.

Here are some references to textbooks which will tell you about analogue and digital PLLs, and here is a short glossary of technical terms.

A companion page generates digital filters.

An email message, saying what you like and don't like about this package, will be appreciated.

Fixed fields:

One day, you might be able to alter these values.

Parameter Value
Order of loop 2
Input Complex z
Output Real phase phi
Phase detector dphi = Im { z e-j phi }
Loop filter Proportional-Integral

Fill in all of the following:

Parameter Symbol Units Value
Sample rate fs sample/sec
Centre frequency f0 Hz

Select two of the following:

You must select one A button and one B button. The following combinations are legal:

  A B
Combination 1: zeta any other parameter
Combination 2: tau1 tau2

A B Parameter Symbol Units Values