# calculating the resistors, capacitor values for pole zero low pass filter

Discussion in 'General Electronics Chat' started by dumindu89, Jul 18, 2012.

1. ### dumindu89 Thread Starter Member

Oct 28, 2010
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I need to calculate the resistors and capacitor values for a pole zero (low pass) filter. The cut off frequency is 70 kHz.

2. ### nomurphy AAC Fanatic!

Aug 8, 2005
567
12
F = 1 / 2pi*R*C, therefore R = 1 / 2pi*F*C, or C = 1 / 2pi*R*F

In the reasonable value range, one answer out of many is 22.6K and 100pF.

3. ### crutschow Expert

Mar 14, 2008
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3,362
That, of course, is for a single-pole filter which has the low rolloff rate of 6dB/octave.

4. ### dumindu89 Thread Starter Member

Oct 28, 2010
113
0
I am asking the calculations for a pole zero filter as shown in the following figure. There are two resistors instead of one. Then what would be the case in calculating the values?

5. ### Jony130 AAC Fanatic!

Feb 17, 2009
3,990
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All you need to do is to find the transfer function

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