Page 337 - Analog and Digital Filter Design

334 Analog and Digital Filter Design

Finally, for the active filter:

WL . R2
wc =-
R1

It is interesting that neither the lead-lag network nor the active filter capture
range is determined by the filter’s capacitor value; it is just the lock range
multiplied by a ratio of R1 and R2.

This chapter has covered the basics and shown that using a lead-lag network
filter with a damping factor of 0.7071 enables component values to be easily
calculated. Readers who have demanding applications are recommended to read
some of the books devoted to phase-locked loop design. One of the most revered
books is Gardner’s Phaselock Techniques, which is now out of print but should
be available from libraries.

Reference

1. Gardner, E M. Phaselock Techniques. New York: John Wiley & Sons,
1979.