So I have a unipolar differential input ADC here ad need to feed some unipolar single ended signals into it (gyros, thermopile horizon sensors, etc). THe proble is all these outputs are single-ended and feeding them directly into the ADC would cause me to lose half my dynamic range (the negative ADC codes would be unused since the output signal could never go below the reference signal, which for single ended signals is ground).
Also, seeing as how a lot of these sensors (like gyros) have bipolar physical values (ie. +/- rotation) it would be kind of nice to get rid of their single-ended DC-bias so the ADC could read 0V differential as 0 degrees/sec). It would seem I need a bunch of differential output amplifiers to solve this problem and I seem to have having some trouble finding ICs with a large amount of diff amps packed into them (ie. the THS4524 is not available at either Digikey or Mouser). THere's also the problem that these differential output amps have a very low input resistance (ie. the THS4524 has an input impedance of 100K). It's not that big a problem for other sensors, but for thermopiles with an output impedance of 60K it is.
Is there no way around this than to find higher input impedance differential output amps? Or to use a single-ended buffer between the thermopiles and the diff amp?
Also, seeing as how a lot of these sensors (like gyros) have bipolar physical values (ie. +/- rotation) it would be kind of nice to get rid of their single-ended DC-bias so the ADC could read 0V differential as 0 degrees/sec). It would seem I need a bunch of differential output amplifiers to solve this problem and I seem to have having some trouble finding ICs with a large amount of diff amps packed into them (ie. the THS4524 is not available at either Digikey or Mouser). THere's also the problem that these differential output amps have a very low input resistance (ie. the THS4524 has an input impedance of 100K). It's not that big a problem for other sensors, but for thermopiles with an output impedance of 60K it is.
Is there no way around this than to find higher input impedance differential output amps? Or to use a single-ended buffer between the thermopiles and the diff amp?
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