In this paper a digitally-controlled fully differential low-noise current source is presented. It was developed for sensor excitation, however, the concept is applicable wherever a precise digitally controlled current source is required. The current source is based on a two-stage cascaded Delta-Sigma modulator using a current-steering digital-to-analog converter. The D/A conversion is done by 64 unary current cells that are controlled by a timing optimized switch driver. The buffer stage is implemented using only a single operational amplifier that delivers a filtered and scaled output current. Thus the subsequent signal conditioning amplifier is eliminated, hereby increasing the noise performance significantly.