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Op Amp gain required for Sigma-Delta ADC (Read 52 times)
ashrafSazid
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Op Amp gain required for Sigma-Delta ADC
Sep 30th, 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?
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jdp
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Re: Op Amp gain required for Sigma-Delta ADC
Reply #1 - Oct 2nd, 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.
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deba
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Re: Op Amp gain required for Sigma-Delta ADC
Reply #2 - Oct 15th, 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.
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