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Number 200

Application Note Understanding Low Voltage
Series Measurements

Introduction Reducing circuit resistance can reduce noise in some
instances. However, it does not diminish problems when sensing
Techniques for making precision, accurate voltage measurements current since it reduces the signal more than the thermal noise.
are fairly well known. But a lot of these methods fall short when For example, reducing the resistance of a current-measuring
resolution must be extended below one microvolt, which is often shunt by a factor of 100 cuts noise by a factor of 10. But from
the case when measuring physical parameters in industry such as Ohm's law, reducing resistance by 100 also cuts the voltage to be
temperature, pressure, force, etc. measured by 100, thus making the noise voltage proportionally
For example, industrial temperature measurements often larger.
require resolution of 0.1