Software for
circuit layout
Updated June 26,
2010
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Layout software has long been
integrated into the microwave vendor design suites. The problem
with this integration is twofold: usually the interface is often
frustrating, and often, a mechanical engineer is responsible for
final layout of a design, and he sure as heck isn't gonna go for
using a microwave analysis tool when there are lots better ME packages
available that he might want to learn to build his (or her resume).
The layout software that you
use depends on what product you are developing. Let's divide layout
software into three categories:
Laying out thin-film
networks
Laying out printed
wiring boards
Free PWB
software!
Laying out
MMICs
The one thing that is wrong (in
our opinion) in the printed-circuit industry today is the use of the
Gerber interface. Dating back to the 1970s, this arcane language asks
you to define apertures and flashes, just as if you were drawing the
artwork with a miniature flashlight (in the old days you were indeed
doing that!) Today's modern photo-plotter uses a laser raster scan,
but quite often the laser must be driven from a .gbr file. Not many
software packages can read Gerber files. Want a free Gerber previewer?
Graphicode has one for you!
Laying out thin-film networks
One of our favorite layout software
tools is AutoCAD. The same software that you might use to plant
bushes on your next house plot plan. AutoCAD does it all, it isn't
hard to learn, and it fits onto your PC with room to spare. The
output of a file can be put into different formats such as .dxf,
which are "readable" in many other CAD programs.
Laying out printed wiring boards
If you want to generate a multilayer
layout from a schematic, AutoCAD is too limited. Try Protel. Or
try some freeware... see below!
Free printed
circuit board software
Here's some links to suppliers
that will etch prototype boards cheaply. They get free links on
this page, just because we like this kind of service! But please
tell them we recommended them.
Cheap FR-4 printed wiring boards
might not be the best way to manufacture a microwave circuit card,
these ultra-cheap board fab houses can be useful, especially with
free online design rule checking (DRC) that checks your gerber files
for manufacturability issues, and other freeware. FR-4 boards are
great for all the ancillary stuff that goes with microwave engineering,
such as regulators and control circuits.
Express
PCB is home of the $51 circuit board, and they'll give you
free software for doing the layout.
Advanced
Circuits is home to the $33 each and $66 each boards. They
also make barebones boards without soldermask for cheap, and have
overnight and weekend turnaround options as well as deals for
starving engineering students. The best part is that they also
have their own free layout software, as well as free
online design rule check. Thanks to Sarah!
PCBExpress offers a similar
service, with two boards etched for $60.
Check them out! Their site offers a ton of freeware, and a
PCB tutorial. Tell them that Microwaves101 sent you!
Laying out MMICs
Some of the more expensive EDA
tools can at least get your layout started. Chances are you will
have to finish the design in Cadence.
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