A new system including circuit and methods are given to realize a dynamic matching of current sources, which are arranged as arrays of sets of current sources with added piecewise switchable trim bit transistors. The matching is achieved during an programmed calibration and trimming step by switching ON/OFF certain trim bit transistors until a required accuracy compared to a master reference is reached. The accuracy of the current source trimming is purely a function of the LSB size, and the trim range a function of the number of trim bits. Applying these new principles the drawbacks with regard to chip space and cost of prior art solutions can be overcome. Making use of modern chip manufacturing technologies allows for a very flexible and adaptive production of large arrays of current sources, as e.g. used in driver ICs for OLED displays.