A Robust, High-Speed and Energy-Efficient Ultralow-Voltage Level Shifter

This brief presents a robust level shifter design able to convert input voltages from the deep sub-threshold regime (about 100 mV) up to the nominal supply voltage (1.8 V). The proposed circuit is based on a self-biased low-voltage cascode current mirror (CM) topology that features diode-connected PMOS and NMOS transistors to drive the split-input inverting buffer used as output stage with high energy efficiency. Experimental results across corner wafers demonstrate the effectiveness of the proposed level shifter as compared to prior art. The proposed circuit allows a voltage up-conversion from a 0.4-V 100-kHz input pulse to 1.8 V with an average switching delay of 7.6 ns and an average energy per transition of only 69 fJ. This is achieved at an area of 82~\mu \text{m}^{2} for a standard cell-based design.