I am trying to design a grounding plan for an RF transciever system. I dont want to go into the component and part details. The basic system is as shown below
simulate this circuit – Schematic created using CircuitLab
My doubt pertains to different grounds and their importance or significance during layout. The basic components in my system are —
Battery that will give about 20V, 2 buck regulators that step down 20 to 5V and 3V3, Microcontroller, RF ICs, Converters ADC and DAC.
Now, the different grounds in my system will be, if I am right, PGND,DGND and AGND. My understanding of the different grounds are as stated — PGND or power ground — It is the ground return path from the Vcc lines and to the ground. DGND — The ground reference for digital signals. The signals being most GPIOs. Now, how can the MCUs have a PGND and DGND. The MCU has many GND pins which are PGND. Then where does the DGND come up and which pins should be considered as DGND.For eg if I have 6 GND pins in MCU how many will be DGND and how many are PGND. Then, how will the 2 be connected. Will it be a star connection. Then this will be true for all digital or linear ICs.
AGND — analogue ground in ADC and DACs. The same principles will apply there as well. Then a good PCB will end up with a multitude of star connections. And finally somewhere I must connect it to the PGND. How is that done. And god forbid I have any differential trancievers, I will have another ground line for them.
Is my understanding right please? Kindly comment.
Now, the whole system is enclosed in a box that has a chassis ground. How is this brought into the whole picture ?