Also worth noting, LTspice lets you parameterize component values directly from within LTspice. You can set up conditions that drive a calculated value prior to simulation. There's also quite a good Yahoo group dedicated to all things LTspice.
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.
Now, our customer doesn’t want to buy big, expensive, high quality capacitors to build an active filter with this response. So, having established the principle of optimizing in the analogue domain, let’s look at whether need to make any changes in order to use it to create a digital filter – which we’ll be able to implement on the Cypress PSoC 3