[gta02-core] ecn progress

Werner Almesberger werner at openmoko.org
Tue Oct 6 02:05:54 CEST 2009

Rene Harder wrote:
> One possible option to keep the capacitor would be
> to add another inductor in parallel to C7602. This will compensate the
> effects of C7601 and the result will be a 50Ohm impedance match.

We discussed possible values on IRC. Rene suggested 3.6 pF for the
capacitor and 9.4 nH for the inductor. The closest value I found in
a 0402 package at Digi-Key has 9.5 nH, but that would be

Things look better at 9.1 nH +/- 5%, where we can choose from three
companies. Self-resonant frequencies of the possible choices are all
at 2.5 GHz or higher. We want something like 4 GHz. (Note: we should
record this non-trivial design parameter in ECN and/or schematics.)

The cheapest choice would be Taiyo Yuden's HK10059N1J-T, with a
self-resonant frequency of 3.4 GHz:

There are plenty of choices for 3.6 pF 0402 C0G/C0H capacitors. E.g.,
the Murata GJM1555C1H3R6CB01D:

More details about Murata's capacitors can be found here:

- Werner

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