Dear Dialog - I'm reading your AN-B-075 DA14531 Hardware Guidelines and looking at the layouts of the dev kit, and I have a question about ground connections.
The app note says
"Separate RF ground pins of DA14531 CFGQFN24 from the rest ground pins
Connect pin 19 to GND with vias as shown in Figure 26
Short 20, 21, 23 GND pins together and use two GND vias, as shown in Figure 26"
The examples show GNDRF1 and GNDRF2 separated from each other, as well as RFIOm separated from GNDRF1. Basically, there are four independent ground connections: 2, 18, 19, 20+21+23.
Is it necessary to separate all four? Can 19 and 2 be tied directly to each other? How about 18, 19 and 2?
I'd like to attempt a simplified design with all grounds tied directly to a ground island under the chip with multiple vias; I'd give up the ability to use P0_5 and P0_6 and tie them to ground as well, so that pcb tolerances can be reduced. Would this work? If it doesn't, what would be the negative effect?
If not everything tied together, is it possible to at least tie all RF pins 18+19+2 and all non-RF pins 20+21+22+23 in two groups? (multiple vias each)