Hi Everyone,
I am trying to define the most suitable current source for my application. Essentially, I need a high stability current source to feed Hall probes sensors. The probes' nominal current is 10 mA. A stability of 100 ppm (i.e., 1 uA) for short term (a few hours) is desired. Usually, I can see two main information in the datasheet: the accuracy and the RMS noise. Accuracy is associated with systematic errors, so it should not affect the stability. On the other hand, RMS noise seems to be a good starting to evaluate stability.
Let me use the Keithley 2450 datasheet as an example (see the image attached). For a nominal current of 10 mA, let's suppose I use the range 10 mA. For that range, the noise RMS (< 10 Hz) is 40 nA. My first question is: what exaclty this information means? Does it mean that the output current would have a standard deviation of 40 nA if a sample it in 10 Hz? What if I use a sampling rate of 50 Hz? Would the noise RMS be higher? Can we estimate it?
Last but not least: how would you evaluate whether the instrument meets the 100 ppm stability? Which variables (besides price) would you take into account to make a decision?
Thank you all.
I am trying to define the most suitable current source for my application. Essentially, I need a high stability current source to feed Hall probes sensors. The probes' nominal current is 10 mA. A stability of 100 ppm (i.e., 1 uA) for short term (a few hours) is desired. Usually, I can see two main information in the datasheet: the accuracy and the RMS noise. Accuracy is associated with systematic errors, so it should not affect the stability. On the other hand, RMS noise seems to be a good starting to evaluate stability.
Let me use the Keithley 2450 datasheet as an example (see the image attached). For a nominal current of 10 mA, let's suppose I use the range 10 mA. For that range, the noise RMS (< 10 Hz) is 40 nA. My first question is: what exaclty this information means? Does it mean that the output current would have a standard deviation of 40 nA if a sample it in 10 Hz? What if I use a sampling rate of 50 Hz? Would the noise RMS be higher? Can we estimate it?
Last but not least: how would you evaluate whether the instrument meets the 100 ppm stability? Which variables (besides price) would you take into account to make a decision?
Thank you all.
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