At 00:57 08.03.97 +1100, you wrote:
>I wish to use a pic to determine a signal which has a resolution of 10
>microvolts in 200 millivolts. It also has a requirement for any component to

Perhaps, it would be easier, to have corrections on the analog
side of the system.
Do the two signals (10 microV  vs.  200 mV) have different frequencies? Try
to filter them with an appropriate high-pass / low-pass including
amplification.
Then an 8-bit ADC may be sufficient.

regards,

Wolfram


+-----------------------------------------------------+
| Wolfram Liebchen                                    |
| Forschungsinstitut fŸr Optik, TŸbingen, Deutschland |
| mailto:liebchen@ffo.fgan.de                         |
+-----------------------------------------------------+