Precision current source

摘要

A current source includes a first current mirror and a second current mirror that share a common current path. The current in the common current path mirrors a current of a current reference connected to the first current mirror. A current in an output current path of the second current mirror mirrors the current of the common current path. A first feedback loop controls the current in the common current path and a second feedback loop matches a voltage of the common current path with an output voltage. The cooperation of the first and second feedback loops ensures that the output current replicates the current of the current reference even when an voltage of the current source is close to the supply voltage. Thus, the voltage swing of the current source output voltage is increased and a precision current source is provided even when the output voltage is close to the supply voltage.