Apparatus and method for a precision bi-directional trim scheme

摘要

A circuit is arranged to enable bi-directional trimming of a reference voltage. A trim current is generated by mirroring a bias current using one or more selectable current source circuits. The selectable current source circuits may each contain transistors that are sized differently from corresponding transistors of the other selectable current source circuits. The sizing may be arranged in a binary chain such that a range of currents may be generated for the trim current while allowing for selection of the level of adjustment for the reference voltage. The current selected for the trim current depends on which of the selectable current sources is enabled. The node corresponding to the trim current is selectively coupled to a load to either increase the voltage across the load or decrease the voltage across the load, providing bi-directional trimming of the reference voltage measured across the load.