Michael Schmitt,

Thanks for the time you took to comment. I've been considering the power and ground plane as a way to rip some traces and make room for the additional filtering my subcontractor suggested.

Do you consider it advantageous to run those high speed signals (baud communications to IrDA transceiver) through a portion of the power or ground plane? Not enough to split the plane.

The additional planes would help with the PLCCs' chip filter on power input. I could isolate a rectangle under the chip for it to draw from and bridge the rectangle with the chip filter.

This design is about half the volume of the original. I used double-side SMT layout with lots of grounded copper fills in strategic areas. The new design doesn't have any space left for that approach and while noise generation is not important in our primary market, we'd like to use the same design in other market applications. Power & Ground planes may be worthwhile.

As you saw from my description, this design does not push the envelop of performance. The SMT crystals are all adjacent to chip input pins for minimum trace length, surface layer only.

Your filter comments confirm my subcontractor's though the circuit choices are slightly different.

Thank you,
aka j