Analytical determination of output resistance and DC matching errors in MOS current mirrors

A new technique for the analytical determination of output resistance and current ratio or DC matching errors in MOS current mirrors is presented, emphasising, in comparison four types of frequently used circuit: the simple current mirror, the Wilson current mirror, the improved Wilson current mirror and the cascode current mirror. Formulas that precisely describe the performance parameters are derived. The minimum output voltage is also discussed. A review of other types of current mirror configurations is included.