Tlaloc
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Posts: 81
Dallas, TX
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The base current requirement certainly would be a major drawback. I guess, though, that a small bias current and large capacitances would mitigate the problem.
Another problem is capacitor mismatch. If your capacitors mismatch, then the common mode voltage times the mismatch parameter shows up as a differential signal. This may be a small effect, but it may or may not be negligible.
Are gain-and-offset correction techniques not good enough using MOSFETS? Bipolar inputs may see an order of magnitude improvement in offset, but these other two effects seem like they would worsen the overall picture. Also, a small collector current, i.e. a small base current, would see larger input referred noise.
Adam
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