[Arm-netbook] HDMI High-Frequency Layout: Impedance
Luke Kenneth Casson Leighton
lkcl at lkcl.net
Fri Aug 4 08:19:05 BST 2017
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Thu, Aug 3, 2017 at 11:53 PM, Richard Wilbur
<richard.wilbur at gmail.com> wrote:
> We can still take some of the recommendations to heart:
> 1. Use minimal size vias for high-frequency traces to reduce
> parasitic capacitance.
yep. 0402 all the way round. can't go smaller as it risks the drill
hitting the edge of the ring.
> 2. Place the two vias of the differential pair in close proximity to
> increase capacitive coupling between the signals.(smaller via pitch)
yep. doing that.
> 3. Instead of using two separate anti-pads on signal vias, combine
> them into an oval shared antipad (on every layer) to reduce parasitic
oo. never heard of this practice. never heard of "anti-pads"
either! so sorry, if you put some references i missed them.
> 4. Place ground vias next to signal vias to provide low-impedance
> ground-return paths.[22, Figure 2]
yep doing that.
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