A 65-nm 25.1-ns 30.7-fJ Robust Subthreshold Level Shifter With Wide Conversion Range

Level shifters (LS) are crucial interface circuits for multisupply voltage designs, and it is challenging to achieve both robust and efficient level conversion from subthreshold to aforementioned threshold. In this brief, we propose two circuit techniques for a novel subthreshold LS with wide conversion range. First, we introduce a novel LS circuit with NMOS-diode-based current limiter for current contention reduction to achieve robust and efficient level conversion. Second, we explore the inverse narrow width effect to increase the drivability of the pull-down devices for delay reduction. When implemented in a commercial 65-nm MTCMOS process, the proposed LS achieves robust conversion from deep subthreshold (sub-100 mV) to nominal supply voltage (1.2 V). For the target conversion from 0.3 to 1.2 V, the proposed LS shows on average 25.1-ns propagation delay, 30.7-fJ energy efficiency, and 2.5-nW leakage power across 25 test chips.