Global Placement for Quantum-dot Cellular Automata Based Circuits

Quantum Cellular Automata (QCA) has been proposed as an alternative architecture to CMOS and in principle should permit the implementation of ultra lower-power, nano-scale logic circuitry working at teraflop frequency. QCA is based on a new paradigm for encoding binary logic into electronic circuitry, where binary 1s and 0s are mapped to spatial configurations of electrons rather than magnitudes of electronic currents. The layout rules for QCA based circuits are radically different from those of CMOS based circuits, and design automation tools for QCA circuit layout are hard to find. This paper discusses the first automatic global placement algorithm for QCA-based circuits. We divide the QCA global placement process into zone partitioning and zone placement, and identify the constraints and objectives that are unique to QCA-based circuits as opposed to the conventional CMOS VLSI