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Maintaining accuracy with small magnitude signals

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Pushek.Madaan
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re: Maintaining accuracy with small magnitude signals
Pushek.Madaan   2/14/2011 7:51:22 AM
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Thanks Ross! Yes, it is a typo. Best regards, Pushek

HANKFAB68
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re: Maintaining accuracy with small magnitude signals
HANKFAB68   2/9/2011 3:36:00 AM
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To author, Is it a typo for the m calculation here by m = (Y2 Y1))(X2 X1)? Should it be mm = (Y2 Y1)/(X2 X1)? Thanks. Regards ROSS

Pushek.Madaan
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re: Maintaining accuracy with small magnitude signals
Pushek.Madaan   1/27/2011 6:52:15 PM
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Harry, Yes, current will be divided between TIA and Rs. TIA is shown that it can be used to calibrate the IDAC and once calibrated we can disconnect it. This IDAC and all other components are a part of SOC, thus it provides us real flexibility by controlling the connection and switching the specified ON or OFF to control the power or implement some functionality.

harryadi
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re: Maintaining accuracy with small magnitude signals
harryadi   1/27/2011 5:11:31 AM
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Have you built figure 4?? How can you predict how the current divides between the TIA and Rs? Part number/data sheet for the IDAC??

Sanjib.A
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re: Maintaining accuracy with small magnitude signals
Sanjib.A   1/25/2011 6:11:35 PM
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Thanks for your reply! Are you talking about limiting the drift to a fairly low value by use of calibration technique? It might depend on how frequently the calibration is performed...correct? In most of the cases I have seen calibration being done only once after power-up. In that case we might not be able to correct the drift...right?

Pushek.Madaan
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re: Maintaining accuracy with small magnitude signals
Pushek.Madaan   1/24/2011 9:39:22 PM
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@Terry: Thanks for your feedback. I'll take care of the points you have specified in the next revision of this article. @Sanjib: I don't have the NMR number readily available but a minimum CMRR of such devices is about 80dB and it has a drift of about 12uV/C. You might find this drift fairly large as compared to standard instrumentation amplifiers but please note that the techniques discussed here can be used to bring drift with temperature down to even less than a uV. Will get back to you with details about NMR.

Sanjib.A
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re: Maintaining accuracy with small magnitude signals
Sanjib.A   1/24/2011 5:03:54 PM
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Do these SOCs suggested in this article possess the specifications (such as accuracy, low drift, CMRR, NMR etc.) closer to (if not superior than) those of the standard instrumentation amplifiers available with the analog chip manufacturers? e.g. For small signal measurement, noise mode rejection (NMR) is an important specification. What is the NMR spec. of these SOC devices?

GREAT-Terry
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re: Maintaining accuracy with small magnitude signals
GREAT-Terry   1/24/2011 8:01:43 AM
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Interesting article. There are indeed more to mention about small signal measurement. Current source for bridge application is also a good topic to discuss more. I rather see more instrumentation amplifier topics to how the technology is advanced.

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