[Arm-netbook] HDMI High-Frequency Layout: Recommendations--Taper
Luke Kenneth Casson Leighton
lkcl at lkcl.net
Sat Jan 6 04:28:55 GMT 2018
still doing these tiny little changes, it's just the way it goes:
every time you look at the board in close zoom, it's like... "hmmm,
yeah that could be improved" and this latest one, it's the (now pair
of) capacitors for the main DDR3 power stabilisation.
previously this was a single 0805 capacitor lined up vertically.
there was plenty of connecting VIAs down to layer 4 DDR3 1.5v power
plane.... but because there were a MASSIVE array of tracks underneath
the GND pads there were no GND vias. whoops. and when replacing with
two 0603 4.7uF capacitors, i maintained that mistake.
i decided to turn both 0603 capacitors horizontal and then to beef up
the number of GND vias. this has the unintended side-effect of
drilling quite a lot of holes into the layer 4 DDR3 1.5v power plane
however as the GND vias are at the edge of the plane i consider this
acceptable. i have however made sure that the plane is free of holes
for getting the actual 1.5v power *in* to the plane, if that makes any
anyway a few more things like this... richard if you're happy with the
beginning of the HDMI area i'll send the gerbers off straight away.
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