| ??? 03/05/05 17:32 Read: times |
#89169 - Need not to be a problem Responding to: ???'s previous message |
Prahlad said:
I am using splitted ground planes for the Analog section and Digital section. If I use an analog switch its very likely that I will need to keep it in Analog section and it will need the switch control signal from digital signals. In this case the switch control signals will travel from Digital section to Analog section and will be crossing the splitted plane boundry. Can this create noise problems? At present I have no signal going from Ananlog Section do Digital section and Vice versa. This need not to be problematically, as you can low pass filter the select signals of micro before they reach the analog section: Just feed the select signals via high ohmic resistances of 10...100kOhm over the barrier to the switches. This will minimize analog ground erosion by minimizing the resulting currents flowing across the analog ground back to the micro. Also, the select signals will not toggle all the time, so the select signals will only carry a certain portion of digital ground noise most of the time, which can sufficiently filtered out by the help of high ohmic resistors in the select lines. Kai |
