From b582c396d811018deb81161ac74838a5229fe1a6 Mon Sep 17 00:00:00 2001 From: xans Date: Thu, 3 Oct 2024 00:44:08 +0200 Subject: [PATCH] Update readme.md --- readme.md | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/readme.md b/readme.md index 307cefe..c624986 100644 --- a/readme.md +++ b/readme.md @@ -57,13 +57,15 @@ Another healthy upgrade I did was to update the firmware to the latest version,

## U180 drift evaluation -Now the big question with any 3458A project is whether the U180 ASIC at the heart of the meter is still in good condition. This requires an extensive check, powering the meter and monitoring the calibration constants from the ACAL DCV. For this, a toolkit was written. And although this is a rather short data capture, several captures were made. All with similar results in terms of the drift observed. +Now the big question with any 3458A project is whether the U180 ADC ASIC at the heart of the meter is still in good condition. This requires an extensive check, powering the meter and monitoring the calibration constants from the ACAL DCV. For this, a toolkit was written. And although this is a rather short data capture, several captures were made. All with similar results in terms of the drift observed. ![u180-drift](3458-WorkLog/u180-drift.png) +In terms of the [infamous service note 18](3458-WorkLog/Sn18A.pdf) this meter passes, though it is not a golden meter by any means. But excellent that it's not failing this and not permanently out of spec. +\ ## Improving If one looks at semiconductor ageing there are a few things we can do to improve the stability in the long term. -Firstly, it is possible to lower the current passing trough the reference devices on the die, this in turn will decrease the drift experienced from electromigration. This is the movement of material caused by electons bumping into then. Thus this could be lessened by decreasing the amount of electrons troughout the device by decreasing the amount of current. This coming at the tradeoff of extra noise. +Firstly, it is possible to lower the current passing trough the reference devices on the die, this in turn will decrease the drift experienced from electromigration. This is the movement of material caused by electons bumping into them. Thus this could be lessened by decreasing the amount of electrons troughout the device by decreasing the amount of current. This coming at the tradeoff of extra noise. Secondly and majorly is chemical reactions over time, though stable a chip still exists upon a mixure of chemicals all slowly reacting on oneother. Thus [Arherrius' equation](https://en.wikipedia.org/wiki/Arrhenius_equation) comes into play, where reaction rates increase as temperature rises. Emperically this has been tested to double the drift for every 10degreesC.