Quaternary Logic Circuits in 2-μm CMOS Technology

Novel quaternary logic circuits, designed in 2-μm CMOS technology, are presented. These include threshold detector circuits with an improved output voltage swing and a simple binary-to-quaternary encoder circuit. Based on these, the literal circuits, the quaternary-to-binary decoder, and the quaternary register designs are derived. A novel scheme for improving the power-delay product of pseudo-NMOS circuits is developed. Simulations for an inverter indicate a 66% improvement over a conventional pseudo-NMOS circuit. Noise-margin and tolerance estimations are made for the threshold detectors. To demonstrate the utility of these circuits, a quaternary sequential/storage logic array (QSLA), based on the Allen-Givone algebra, has been designed and fabricated. The prototype chip occupies an area of 4.84 mm2, is timed with a 2.2-MHz clock, and consumes 93 mW of power.