what does PGA Gain Mismatch Error mean for ADUC7061

Question

HI, 
 in ADUC7061, datasheet shows that the main channel ADC has feature of PGA Gain Mismatch Error(0.1%) 
 what does the ADC match for? 
 1. does it mean that different device match different device? for example, 1st device has same gain error with 2nd device within 0.1%. 
 2. does it mean that different gain math another gain in the same device. for example gainX1/gainX2(ratio) has same gain error with gainX1/gainX4(ratio) within 0.1%. 
 best regards.

Karl.O · Accepted Answer

Hi, 
 The PGA Gain Mismatch Error is the error between different gains. 
 A similar question in the thread below further explains the gain mismatch error. 
 ADUCM360: PGA Gain Mismatch Error - Q&A - Precision Microcontrollers - EngineerZone (analog.com) 
 Regards, 
 Karl)

boy · Answer

Hi, Karl 
 in datasheet(page 10, about gain error parameter), it says that: 
 8 System calibration at a specific gain range removes the error at this gain range. ADC factory calibration done with chop off. 
 as you know, offset is included with chop off. so, does it mean that ADI compute gain mismatch without removing offset? 
 or does ADI just only compute full-scale gain without removing offset (chop off)? 
 best ragards

Karl.O · Answer

The ADC of ADUC7061 is calibrated during factory testing to get an offset and gain calibration coefficient to compensate for these errors. 
 The gain mismatch error should have been computed with the offset error removed since the offset calibration coefficient would have compensated for offset errors.

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what does PGA Gain Mismatch Error mean for ADUC7061