choose R& C for Low Pass filter

[ambition]

I want the cufoff of the LPF to be 5kHz ...
my question is how can I choose the Rs and Cs?

I have calculated the w which is 1/(2*pi* 5k) but the result is very small

can someone explain to me , how can I come up with the resistors and capacitors values ?
thanks

 

[jcpu]

Hello, information here could be helpful:

http://www.circuitsage.com/filter.html

Calculation gives R~10KOHm and C~several nF
These are reasonable for board level implementation.

 

[Davood Amerion]

check below links:
http://www.ecircuitcenter.com/Circuits/opsalkey1/opsalkey1.htm
**broken link removed**

 

[mpig09]

Dear ambition :

please use transfer function of the low pass filter to simulate with Matlab
, you can find the valid value for every R & C !!



mpig09

 

[jlee]

This is a Active Biquad Sallen-Key Low-Pass Filter.

The equations to find the poles, wp and Qp are being taught in Berkeley's EE247 ADC class. Please refer to the lecture note:

**broken link removed**

Slide #4.

 

[mircea]

fc=1/(2*3.1415*R*C)=5kHz
just choose 2 values convenient for you which verify the formula above.

rgds,
M

 

[zenisle]

equations to find the poles, wp and Qp are being taught