Fri 22 Jun 2007
Today’s chip is a multi-mode CDMA low-noise amplifier/mixer (not a RS-232 tranciever as the name suggests). The source of the chip is a Motorola V60 handset. It is somewhat interesting that the chip has both round and square coils on the surface, if any IC designers are reading this and know the rationale behind it, please leave a comment.
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July 4th, 2007 at 11:09 pm
I used to design spiral inductors and the only reason I can think of that you’d use a square inductor when a round one was available is that the square one was previously completely characterized.
In the days before accurate computer simulation tools like ASITIC and Momentum and rules of thumb like Thomas Lee’s formula, people used to do whole test chips full of inductors and they’d pick one from among them to use.
July 7th, 2007 at 1:01 am
Thanks for the insight. Do you happen to know the purpose of the waffle pattern under the inductor loops? Is it to minimize eddy currents in the substrate?