Regulated Cascode Current Mirror with Improved Voltage Swing

Abstract

This paper presents a simple and easy-to-use method allowing to improve output swing of regulated cascode CMOS current mirror with short channel devices. It is based on matched offset voltage generators, implemented simultaneously at the input and output of the current mirror. These voltage generators translate the drain voltages of the reference and source transistors to the saturation voltage VDSAT, i.e. to minimal level, ensuring high output resistance of the cascode. The design aims to provide a nanosecond current generator for optical laser source, with fast short channel devices facilitating the integration. This paper presents a concept of circuit implementation, a mathematical description of the optimal value of voltage offset, and simulation results in 40nm process.