Hello there:
Now a pcb of our lab that has both digital signal (most from dsp TMS320F28027) and analog signal. Our PCB board has four layers. And on the top layer of the board we have copper pour separated on digital ground and analog ground(the power ground is not separated with analog ground). And connected them with a 0 ohm resistance.We do the same thing on bottom layer except connect them. The second layer is analog ground and the third layer is digital ground.
Now our problem is, to avoid the noise goes from digital circuit to the analog circuit, we tried to change the 0 ohm resistance to a inductance (now the value is 56nH) . The noise decreases a little. But the problem is that we can't erase the program in the DSP with the JTAG emluator (XDS510LC). So has anybody ever met this kind of problem and could you give me some suggestion of solving it?
Thank you.
Yini