A Single-supply True Voltage Level Shifter

When a signal traverses on-chip voltage domains, a level shifter is required. Inverters can handle a high to low voltage shift with minimal leakage. For a low to high voltage level translation, inverters tend to consume a large amount of leakage power, and hence special circuits have been proposed for this type of translation. This paper reports a novel single-supply "true" (in the sense that it can handle a low to high, or high to low voltage level conversion) voltage level shifter, which can handle low-to-high and high-to-low voltage translation. Such a requirement arises in many modern ICs or systems-on-chip (SoCs). The use of single supply voltage reduces circuit complexity by eliminating the need for routing both supply voltages. The proposed circuit was extensively simulated in a 90 nm technology using SPICE. Simulation results demonstrate that the level shifter is able to perform voltage level shifting with low leakage for both low to high, as well as high to low voltage level translation. We have validated the correct operation of the proposed level shifter under process and temperature variations as well.