V G wrote:
> I'm trying to read the output from an amplifier that can potentially
> swing from -3V to +3V with an ADC (on a PIC32). Should I use an opamp
> (LTC to "shift" the signal into the positive voltage range? Or can I
> just use two 10K resistors to scale the -3V to 3V output into the 0V
> - 3V range?

That's fine, although the accuracy of the 3V supply no effects the reading.

> I'm leaning towards the resistor divider. Seems simple and effective,
> but I wouldn't know any complicated implications it could have. Also,
> what values of resistors should I use?

To start with, make sure the output of the resistor divider doesn't exceed
the source impedence required by the PIC A/D converter.  This used to be
10KOhms on most PICs with 10 bit A/D converters.  It is substantially less
on some newer, faster, or higher resolution PICs.


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