Mike,
I will tell all of our Engineers that you are calling them Voodoo
Witch Doctors, right? 8^>
They'll shake their little mojo bags and put a curse upon you, better watch
it!
Now seriously, your "voodoo" design is an integral part of microwave
designs. It is not at all black magic but it can seem that way at times. I
do not do any of the design but strictly implement the design as given to me
by the designer. To date, we have not used circular spiral inductors, we do
commonly use squared spiral inductors. The reasons why are beyond me, quite
possibly it is because someone a longtime ago told them not to do it because
it is too difficult to implement in the CAD tools. This would not be true at
this juncture because I would just import the Gerber. I don't know why but
maybe I will ask a couple of the Engineers today.
Our microwave designs are typically simulated and verified on
Anasoft's Symphony & ??? tools and then passed to me for implementation on
the PCB in Protel. The symphony tools will verify the operation of the
microwave elements but it is not perfect, after fabrication there is quite
often a little bit of tweaking going on based upon the actual circuit
performance. For some other design aspects we also use a couple of different
HFSS packages for full field simulation (I think this is an intensive finite
element type analysis of all fields and their interactions.).
Brad Velander,
Lead PCB Designer,
Norsat International Inc.,
#300 - 4401 Still Creek Dr.,
Burnaby, B.C., V5C 6G9.
Tel. (604) 292-9089 direct
Fax (604) 292-9010
website www.norsat.com
> -----Original Message-----
> From: Mike Reagan [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, June 13, 2001 8:55 AM
> To: Protel EDA Forum
> Subject: Re: [PEDA] AW: Spiral trace construction?
>
>
> Hello All.
> I wanted to throw in my two cents:
> While a Spiraled trace to simulate an inductor might be a desirable
> accomplishment, I try to convince engineers to stay away from
> this type of
> design. I call it Voodoo design. Unless the trace is
> designed first by a
> very powerful tool that takes into account three dimensional
> design, the
> probability of obtaining a coil with any good characteristics
> is slim and
> inconsistent. For edge to edge coupling to be effective
> coupling the traces
> would have to be closer than 7 mils apart. Then there is "Q"
> factor for
> this inductor, meaning it will be a very poor Quality inductor. I
> personally think and would suggest finding a real component
> to design in.
> Your design will be more reproducible and consistent from
> board to board,
> because of a number of problems inherent to varied
> inconsistencies of a
> fibers in any board. There are a whole lot of reasons why I
> would stay
> away from voodoo design. Sorry Bill, I don't mean to insult
> you, are the
> only TOP GUN registered on this list. But I wouldn't attempt
> it unless I
> could fully simulate it at my desired frequency, with prepreg
> thickness,
> with known prepreg material, fiber density, dielectric
> constant, gnd plane
> underneath, relative humidity, and it goes on.
>
> I will wait for Brad V's Comments on this because he had
> mentioned his
> company simulates some of this stuff, right?
>
>
> Mike Reagan
> EDSI
> Frederick Md
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* To post a message: mailto:[EMAIL PROTECTED]
*
* To leave this list visit:
* http://www.techservinc.com/protelusers/subscrib.html
* - or email -
* mailto:[EMAIL PROTECTED]?body=leave%20proteledaforum
*
* Contact the list manager:
* mailto:[EMAIL PROTECTED]
*
* Browse or Search previous postings:
* http://www.mail-archive.com/[email protected]
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
