Chapter 8

Designing Lowpass Filters

Sallen & Key

Designing Real Filters

In Chapter 7 we saw how just about any filter you can dream up can be implemented by cascading 1st- and 2nd-order filter blocks. In this chapter we look at the best ways to turn those theoretical blocks into reality. There are many ways to do this, but for the moderate Q values normally required, one of the simplest and the best methods is the well-known Sallen & Key configuration. This chapter and Chapter 9 on highpass filters focus entirely on various versions of the Sallen & Key filter. Other configurations, such as the multiple-feedback filter (MFB), are described in Chapter 10. To accurately implement high Q’s, more complicated multi-amplifier configurations such as ...

Get The Design of Active Crossovers, 2nd Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.