I’ve blogged how I trying to assemble a group of filter fanatics. I that post I mentioned that I had a great article coming from Chris Paul, an engineer at Motorola. Well it took a while, but we ...

In the last edition of Don’t Fear the Filter, we built up two examples of the simplest and most-used active filter of all time: the two-pole Sallen-Key lowpass. This time, we’re going to put two of ...

There comes a time in every electronic designer’s life when, whether they know it or not, they need an analog filter in their design. If you’re coming from a digital background, where everything is ...

When you design an analog, lowpass, antialiasing filter, you would expect its gain amplitude to continuously decrease beyond the filter's cutoff frequency. For the most part, this assumption is a safe ...

Recently, people in various publications have been pointing out that using an ordinary op amp in a Sallen-Key filter can cause problems. A typical op-amp circuit, as shown in Figure 1, can have a ...

I was concocting a rather silly low-pass filter design, when I remembered that Messrs Sallen and Key did it better in the 1950s, and decided to use their two-pole design to implement a Butterworth ...

Almost all efforts immediately constrain implementations by unity gain in the op amp, equal R or equal C, or both. When multi-stage filters are implemented with gain, most of the gain is placed in the ...