An improved low voltage CMOS current source exploiting positive shunt feedback

A new circuit solution able to increase the output impedance of a CMOS current source is proposed here. Since the technique does not rely on series feedback applied at the output, as usually happens, it is suitable to be employed for very low voltage analog circuits in deep submicron technologies. Performance similar to cascoded current sources can be achieved, without requiring huge length MOS transistors. The proposed approach can be successfully applied to the tail current of differential stages in order to improve their common mode rejection performance, whilst preserving the input common mode dynamic range.