[gta02-core] ecn progress

[Werner Almesberger]

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
single-source.

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:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=587-1518-1-ND

There are plenty of choices for 3.6 pF 0402 C0G/C0H capacitors. E.g.,
the Murata GJM1555C1H3R6CB01D:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=490-1271-1-ND

More details about Murata's capacitors can be found here:
http://www.murata.com/products/catalog/pdf/c02e.pdf

- Werner