Logic design considerations for 0.5-volt CMOS

As the operation supply voltage for commercial CMOS devices falls below 2 V, research activities are underway to develop CMOS integrated circuits that can operate at supply voltages well under 1 V. Although dramatic power reductions can be achieved using low supply voltages in high performance applications, the increased subthreshold leakage that results when transistor threshold voltages are lowered can render some conventional logic circuit systems unusable. Furthermore, some low voltage circuits are not robust when faced with normal variations in threshold voltage. This paper examines the design consideration for logic and memory circuits in very low voltage CMOS and compares simulated behavior with measurements of fabrication test circuits. These circuit examples were closed because they illustrate the unique design challenges of low voltage CMOS.