I'm moving away from project boards for the first time and was looking to get a bit of feedback before I send my PCB design into production. I'll preface this by saying that the design itself has been prototyped and is working, and that portions of the design came from the assembler games forums, though I've made some additions and tweaks.
Anyways, I'm building a Dreamcast RGBs and 480i/480p switcher for myself and a few friends who're interested in one. I'm pretty happy with its current state and I just need to ask a couple of questions before it's finalised.
My PCB is has two layers and the bottom layer of it is a solid dedicated ground plane. I'm fairly certain it's adequate, though I want to be sure. I've not dealt with using planes before.
The top layer of the PCB contains all of the traces and components. My R, G, B and Left and Right audio lines are fairly sensitive, given analogue video and analogue unbalanced audio. I've spaced the traces generously (upwards of 15 times the traces width in some spots for video signals) but the top of my PCB currently has no copper fill. Will not having the spaces between my analogue traces filled or via shielded lead to interference concerns? I've also heard of boards becoming warped if one side is filled and the other isn't. Is this true?
Off-topic, but for my decoupling capacitors I have three vias on each ground pad going to the ground plane. I was reading a Texas Instruments document that mentioned to do this. Given that inductance is reduced in parallel, is this a good design choice?
Lastly, if I did fill the top layer, the video and audio traces run along the length of the board (my spacing is to minimize cross-talk and parasitic capacitance, due to running these traces in parallel) and the video traces each have a 220µF capacitor in series. The combination of the spaces between the capacitors and the parallel traces would create ground loops and I'm unsure of a way around it. Given my spacing I'm unsure of whether or not I would see a large benefit of having a ground plane on the top layer. Any pointers are appreciated.
In case it matters, Vsync is at 60Hz, while Hsync will be at either 15.75kHz or 31kHz, depending on the SPDT switch position. I don't believe the audio lines will exceed 44.1kHz and RGB lines should peak at around 14Mhz. It's a low frequency circuit, overall. My power and ground traces are 20 mils and data lines are 10 mils. I don't expect current much over 50mA - 100mA. My +5V source is from the multi out on the Dreamcast which itself comes from the power supply 5V rail.
That was a lot. Thanks to anybody who read that and has suggestions.