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Sometimes the self-capacitance of the large resistor in a resistive
divider can cause an unwanted passing of high frequencies. This is
often corrected with an added capacitor across the smaller resistor.
But, this can also be corrected numerically:
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This is the resistive divider with unwanted capacitance, C
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Using similar analysis as with the RC
filters, one derives this transfer function, H, |
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The correction, H', is just the inverse of H, |
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where,
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So, the corrected output is just the original output plus resistor
ratio times the original signal through a low pass filter. Note
that the low pass filter is easily
implemented
numerically. |
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