Cool Apps | Cypress Semiconductor
March 31, 2010
If you look below my picture, (Not the cool monochromatic on at the top but the uglier one below.) You will see a section called cool apps. There are some interactive filter works sheets.
Open up the Sallen Key Lowpass
Set the frquency to 5kHz and the damping to 1.414
Click the “C1Hint” key and it will recommend a C1 value of 2000pF
Change C1 to a standard 2200pF.
Click the R1 R2 solve button and standardized values are calculated.
Click the actual frequency/damping button at the button to calculate the actual values and the error from the desired input.
Congratulations, you have just designing a second order 5kHz Butterworth filter.
The other tools pretty much work the same.