mixed_signal wrote on Apr 6th, 2012, 8:12pm:Hi RobG,
Thank you for your relpy!
I want to find the integrated noise at the Vref of my temperature sensor. What should be my frequency range over I should integrate? My sensor will be followed by sigma delta. The sensor should give 1 reading per minute.
I integrated from 1/60 Hz till flicker corner =10KHz and it was 6 uV.
Thanks!
ms... I think the proper way is to find the noise power density VN2() over the interval that you care about (say 1/(1 year) to 100 MHz) and then multiply by the frequency response (squared) of the sigma-delta, then integrate the product. You'll find the lower bound of integration isn't important after some point so maybe 1/(1 hour) is low enough frequency.
I'm not sure how to get the sigma-delta frequency response in the calculator. Maybe you could do something like VN2()*(sin(f)/f)^2. Alternatively, you could derive what the effective bandwidth is to the first zero, and then just integrate VN2() out to that voltage.
Let me know if you get a definitive answer!
Rob