Hi,
I would like to use an op amp configured as an integrator as a low pass filter. How to calculate the R and C to get the target corner frequency? If I want to use two successive integrators for a second order low pass filter, again, how to calculate the Rs and Cs for the two op amps. Thanks for the advice or pointer to where I can learn about this!
Regards
Andy

 

1/2piRC
have a look here...

http://www.electronics-tutorials.ws/opamp/opamp_6.html

 

The transfer function of an integrator is

1 / jωRC

Can you work out the corner frequency from that?
BTW there are better ways to make filters.

 

I would like to use an op amp configured as an integrator as a low pass filter. How to calculate the R and C to get the target corner frequency? If I want to use two successive integrators for a second order low pass filter, again, how to calculate the Rs and Cs for the two op amps.

Microchip offers a Windows app, FilterLab, with which you can synthesize 2nd- through 8th-order filters. Very handy.

http://www.microchip.com/pagehandler/en_us/devtools/filterlab-filter-design-software.html

 

Two integrators will give a 2nd order filter with a low damping factor and poor characteristics around the corner frequency.
Use some type of filter design software such as OBW0549 suggested to generate a proper Butterworth active filter or other 2nd order filter with good characteristics.

 

thank you guys, this is all helpful. I am building a Class D amplifier. I was thinking of using a couple of integrators for the loop filter. This is common in Class D amps I have studied, and an integrator also provides a convenient way to create a triangle reference needed to generate the PWM signal. But possibly integrators are used for the filter for cost reasons in integrated circuits (and these are ones I have studied). Since I will be doing a discrete design, I can probably be more flexible in the approach to the loop filter.