Previously on The Filter Wizard ("Simulate Circuits in a Spreadsheet with some ‘Ladderal Thinking' "), we saw how to use a spreadsheet such as Excel to calculate the frequency response of a filter network with a ladder form. This form covers a wide range of common filter circuits, from loudspeaker crossover networks through to high performance communications filters.
Now we’ve not yet done anything you can’t do for free with a good circuit simulator such as LTSpice. But writing down the expressions to do the impedance calculations for the ladder branches is good learnin’. You should never take your tools for granted, and doing something in a slightly more ‘primitive’ way keeps the fundaments fresh in the engineering part of your brain.
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 values for a circuit you can’t otherwise design. Using familiar spreadsheet cell methods makes this a simple task.
To read this article, which originally appeared at the EE Times Europe-Analog web site, click here. ♦