Spicing Things Up

One of the most useful tools for the analog circuit designer is SPICE circuit modeling software. While most hams are at least nominally familiar with antenna modeling programs like EZNEC or 4NEC2, relatively few hams are familiar with SPICE (“Simulation Program with Integrated Circuit Emphasis”). While SPICE was originally created, as the name suggests, to make IC design sim pler, it actually is an amazing program for doing any kind of “traditional” circuit modeling, whether passive or active. The “Elsie” (LC) filter design program included with the ARRL Handbook is SPICE at its core, though specifically designed for passive filters.

Though there are a number of SPICE flavors available, most of them freeware, I recommend learning on a stripped-down version like AIMSpice,) ThemostoutstandingfeatureofICAP4isthatitallows you to alter component values on the fly, during an actual simulation, something no other version of SPICE can do, to the best of my knowledge.