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Measurements >> Other Measurements >> Measurement of offset of ADC
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Message started by babunp114525 on Aug 1^st, 2007, 9:04am

Title: Measurement of offset of ADC
Post by babunp114525 on Aug 1^st, 2007, 9:04am

Hi,

This is regarding measurement of offset value of ADC.

Can any body tell me whether do i need to consider the value of DNL while calculating offset value.

The standard equation for calculation is offset=Tp(1) - 1LSB where Tp(1) is the 1st transition point of a staircase digital output. Do i need to consider the DNL value of that code while measuring the offset value i.e. is the following equation correct for measurement of the offset error of an ADC?

offset = Tp(1) - 1LSB - DNL ( at code 1)

Please reply me ASAP.

Title: Re: Measurement of offset of ADC
Post by ywguo on Aug 7^th, 2007, 11:19pm

Hi,

I don't think you need substract DNL from TP(1). Normally, the offset are corrected before calculate DNL.

Yawei

Title: Re: Measurement of offset of ADC
Post by babunp114525 on Aug 9^th, 2007, 10:24am

hi ywguo,

you are right that while calculating the DNL, offset is nullified as DNL = Tp[i+1] - Tp[i]. Now, here Tp[i+1] and Tp[i] are having same amount of offset. Therefore, while measuring DNL, offset is getting nullified.

But DNL is present at each and every code. Therefore, can I write Tp[1] = 1LSB width+DNL+Offset?

if this is true, then we need to consider the DNL value while considering the offset, else not. But, I am not sure whether, the above equation is right?

Title: Re: Measurement of offset of ADC
Post by ywguo on Aug 14^th, 2007, 8:46pm

Hi,

The above equation is NOT right. We measure the TP[1] at x-axis, while offset at y-axis. Right?

Yawei