Source measure unit
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The Source–measurement unit (SMU) is a type of test equipment which, as the name indicates, is capable of both sourcing and measuring at the same time.
Overview
The SMU is a special kind of instrument that can work as a constant current source or as a constant voltage source. It simultaneously sources to a pair of terminals at the same time measuring the current or voltage across those terminals. Typically when an SMU sources constant voltage it measures current through the terminals. When it sources constant current through the terminals, it measures the voltage built up across those terminals.
SMUs are typically used in automatic test equipment and they usually come with an interface such as GPIB or USB to enable connection to a computer. However they can also be used in lab bench for characterization purpose. Typically Source meters have four terminals. Two for source and measurement and two more for kelvin connection.