I want to design a PCB with few "low dropout linear voltage regulators", which would be used to power some sensors we are building. None of the parts on the PCB is expected to do any high speed switching. The sensor is on a separate board, and the power from the PCB is routed through SMA cables to the sensor. (The power requirements are low ~mW, and SMA is used just as an additional shielding). Sensor operates at 10 MHz, and I need the supply to be clean upto few 100 MHz. The regulators will be decoupled by low ESR capacitors and will be powerd from batteries.
I wanted the PCB not to pickup any external interference and was suggested a 4 layer design, where the stack was 1-GND, 2-Signal, 3-Signal, 4-GND. But, many online forums reccomend against this, and they prefer the reference planes at the layers 2 and 3.
Can someone experienced in this field give their views on this? I dont mind if reworking the board would be impossible.
Should I add a grounded copper pour on the layers carrying the signals?
How closely should the via stiching be done? (Some of the major noise sources I get are at 2 MHz, 100 MHz-FM and 555 MHz).
Please let me know if further informaton is needed. Thanks.