# Author: Kendall Castor-Perry

All posts by Kendall Castor-Perry below:

## Design a fast-settling bias voltage filter with high ripple rejection

Higher-order lowpass filters made using a “DC-free” technique can be much more effective in removing ripple from high voltage sources, yet respond rapidly to step-voltage changes and allow far lower capacitor Continue Reading...

## Filter DC Voltages Outside Your Supply Rails

Want to filter a bias, reference or even supply voltage effectively, but using only circuitry that runs off a much lower voltage rail? Might sound impossible, but it’s not. The Filter Wizard shows how it’s Continue Reading...

## Lowpass Filters That Don’t: A Tale of Leakage Current

There’s no DC return path to ground (or to either supply) for the current at the inputs of U2, U4 and U6 that connect to the resistor network that stretches along the top of the Continue Reading...

## Gee, I see! The Ins and Outs of Generalized Impedance Converters

Well, it turns out that we can perform impedance scaling on actual components; let’s look at how we deploy key properties of the humble op-amp to do Continue Reading...

## An appendix to Filter Wizard #14 (“Match Point”)

Designing a filter using a spreadsheet. No sophisticated charts, no pole zero relationships, determination of a response type, none of those overly complex equations I learned in Continue Reading...

## Bruton Charisma: Make Those Inductors Vanish Using Savvy Scaling

We set out to eliminate the inductors in our LC lowpass filter – and ended up doubling the number of them! We’ll see shortly just how these can be made to disappear in one mathematical Continue Reading...

## Dualling Master: Swap Current and Voltage for Easier Filter Design

Using optimization to design circuits (some might call it organized guesswork – for some algorithms, that’s a pretty good description) isn’t a new Continue Reading...

## Match Point: Why Maximum Power means Minimum Sensitivity

You have a sinewave signal generator with a (resistive) 50 ohm output impedance, and it can produce 1 Vrms into an open circuit. Your customer has given you a black box with an input impedance of 3.3 kohm, and for it to function correctly, it requires an input Continue Reading...

## Filter Design using the “Million Monkeys Method”

There’s a further cool thing you can do with a spreadsheet that most SPICEs can’t. That’s to use the spreadsheet ‘solver’ functionality to adjust component values in the search for a better-fitting circuit – or even to find a set of component Continue Reading...