High-precision voltage-to-current converters based on single-chip gain-selectable amplifiers

A new application of single-chip gain-selectable amplifiers for Howland current pump circuits is here presented and discussed. LT199x integrated circuits, by Linear Technology, were used for the implementation of extremely accurate voltage-to-current conversion. Circuit performance was evaluated for resistive temperature-sensors biasing and signal conditioning. Experimental results highlight the excellent performance of the fabricated prototypes in terms of linearity and sensitivity. In addition, a ratiometric measurement method can be applied, ensuring virtual nulling of errors caused by the limited absolute accuracy of the voltage supply and/or the voltage reference used for the whole acquisition system.