<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Hi all,<div class=""><br class=""></div><div class="">The dsPIC 33FJ128GP802 uP (and others in the family) includes a 16-bit DAC on the chip. The outputs from the DAC are provided as a differential output to help cancel any noise generated by the uP internally. NOt a bad idea, seeing as that is probably inevitable. Despite this precaution, the DAC is reasonably noisy and not suitable for all applications.</div><div class=""><br class=""></div><div class="">The example circuit for combining the differential outputs is shown attached - a simple diff amp with 10K resistors everywhere.</div><div class=""><br class=""></div><div class="">Now, my question is this:</div><div class=""><br class=""></div><div class="">If I change the gain of the differential amp by increasing R6/R8 (to 47K, say) does this affect the noise cancellation properties of the diff amp?</div><div class=""><br class=""></div><div class="">It seems to me that it might, because the positive input now has a different proportion of signal going to it than the negative input.</div><div class=""><br class=""></div><div class="">Thanks,</div><div class="">Tom</div><div class=""><br class=""></div><div class=""><div class="">
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