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Design >> Mixed-Signal Design >> Op Amp gain required for Sigma-Delta ADC
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Message started by Mohammad Ashraful Alam on Sep 30^th, 2016, 2:33pm

Title: Op Amp gain required for Sigma-Delta ADC
Post by Mohammad Ashraful Alam on Sep 30^th, 2016, 2:33pm

Hi,

I need help to determine the op amp gain required to match certain ADC specifications. I need to design a delta sigma 14 bit ADC and need to find out required op-amp gain. Is there any certain formula to find out that?

Title: Re: Op Amp gain required for Sigma-Delta ADC
Post by jdp on Oct 2^nd, 2016, 7:11pm

If you search literature, you will frequently see that the opamp gain required is of the order of the OSR or more. Higher the better (like 60-75dB), but minimum is ~ OSR.

Title: Re: Op Amp gain required for Sigma-Delta ADC
Post by deba on Oct 15^th, 2016, 12:01am

The loop gain required is of the order of (OSR/pi)^n, n is the order of the loop filter. But across corners, to have margin you need to design it for a higher loop gain.