Theory and design of advanced CMOS current mirrors

In this paper continuous time high-performance current mirrors (CMs) based on series and parallel connected unity sized CMOS transistors suitable for low power applications are presented. It is shown that the proposed implementation techniques allow an increased output resistance, from twice the output resistance of the simple current mirror (SCM) up to more than 50 times of the cascode current mirror's output resistance depending on the chosen topology. A complete theory which describes the concept of using series connected transistors is developed and expressed with analytical equations. Furthermore, it is shown that the advanced current mirror (ACM) and the advanced cascode current mirror (ACCM) exhibit a much higher output resistance compared to the simple and the cascode current mirror (CCM). Spectre simulations of the different current mirror implementations built with transistors of IHP 130nm CMOS technology verify the analytical solutions.