An energy efficient sub-threshold to above-threshold level shifter using a modified Wilson current mirror

Abstract

In this article, a new energy efficient level shifter circuit is described for robust sub-threshold to above-threshold voltage conversion. The design is based on a modification of the Wilson current mirror that minimizes the static current and improves the energy efficiency. The proposed level shifter is capable of converting a 200mV signal into a 1V signal and operates correctly across process corners. At the design target ( [GRAPHICS] 200mV, input signal frequency=1MHz), the proposed level shifter exhibits a propagation delay of 20.17ns, a static power dissipation of 11.07nW, and the total energy per transition of 113.2fJ. We compare our results with the design proposed by Lutkemeier and Ruckert (2010). At the design target, the energy delay product of our design is 81.53% that of the reference design and, over all the voltage range of [GRAPHICS] from 160mV to 1V, the proposed circuit shows an average energy reduction of 14.71% compared to the reference design. Thorough variability analysis was performed using HSPICE Monte Carlo simulations for different values of [GRAPHICS] , which reveals the robustness of the proposed design.