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Low Voltage Signal Conditioning Theory Question
Evan.Cornell:
So it seems AD8656 is specified only for single rail 5V operation. Since I want input impedance > 100kohm to avoid loading my sensor, that hints at non-inverting. But since AD8656 is unipolar, that means sensor has to be biased around 2.5V. So, that makes me look at ac-coupling the sensor, but that means series C to ac-couple, plus resistor fed from bias supply. Does that resistor (R3 in the snippet) become the input impedance value? So then it's either loading down my sensor or adding a bunch of resistor noise?
Is there a better way to do this? I am trying to achieve ~50V/V, if it makes a difference.
EDIT: Or am I just stuck with bi-polar operation so I can directly DC couple my sensor to non-inverting input?
Ref: https://ocw.mit.edu/courses/media-arts-and-sciences/mas-836-sensor-technologies-for-interactive-environments-spring-2011/readings/MITMAS_836S11_read02_bias.pdf
Vovk_Z:
You can feed ad8656 with +- 2.5V.
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