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@ -35,6 +35,7 @@ Now the big question with any 3458A project is whether the U180 ASIC at the hear
## Improving ## Improving
If one looks at semiconductor ageing there are a few things we can do to improve the stability in the long term. 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. This coming at the tradeoff of 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 then. Thus this could be lessened by decreasing the amount of electrons troughout the device. 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. 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.
Thus it is interesting lower the setpoint of the LTZ1000 voltage reference setpoint. Well known on the 3458A is the voltage reference being operated at an extremely high oven temperature. As such I have added a resistor to the voltage reference board at designator X413, decreasing the temperature to ___degC. Thus it is interesting lower the setpoint of the LTZ1000 voltage reference setpoint. Well known on the 3458A is the voltage reference being operated at an extremely high oven temperature. As such I have added a 200K resistor to the voltage reference board at designator X411, decreasing the temperature to about 75degC.