![bullet](../../_themes/blends/blebul1a.gif) |
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:
![bullet](../../_themes/blends/blebul2a.gif) |
This is the resistive divider with unwanted capacitance, C
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![](hpdiv1.png)
![bullet](../../_themes/blends/blebul2a.gif) |
Using similar analysis as with the RC
filters, one derives this transfer function, H, |
![](hpdiv2.png)
![bullet](../../_themes/blends/blebul2a.gif) |
The correction, H', is just the inverse of H, |
![](hpdiv3.png)
![bullet](../../_themes/blends/blebul2a.gif) |
where,
![](hpdiv4.png)
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![bullet](../../_themes/blends/blebul2a.gif) |
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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