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
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 ?