Serial Parallel Multiplier Design in Quantum-dot Cellular Automata
Heumpil Cho Qualcomm, Inc. 5775 Morehouse Dr. San Diego, California 92121 Email: hpcho@qualcomm.com Abstract
An emerging nanotechnology, quantum-dot cellular automata (QCA), has the potential for attractive features such as faster speed, smaller size, and lower power consumption than transistor based technology. Quantum-dot cellular automata has a simple cell as the basic element. The cell is used as a building block to construct gates, wires, and memories. Several adder designs have been proposed, but multiplier design in QCA is a rather unexplored research area. This paper utilizes the QCA characteristics to design serial parallel multipliers. Two types of serial parallel multipliers are designed and simulated with several different operand sizes. Those designs are compared in terms of complexity, area, and latency. The serial parallel multipliers have simple and regular structures.
Earl E. Swartzlander, Jr. Department of Electrical and Computer Engineering The University of Texas at Austin Austin, Texas 78712 Email: eswartzla@aol.com
vious adder designs show that complex designs generally incur longer delays in QCA, so a simple structure is a good choice for the starting point. A large word size parallel multiplier has quite a complex structure. Due to the complex wiring, parallel multipliers in QCA are likely to incur long delays. This paper investigates the serial parallel multiplier. Based on FIR lter equations, the serial parallel multiplication equation is derived and using QCA characteristics, optimized serial parallel multipliers are presented. The nal designs show simple and regular structures with an attractive bit slice structure. The paper is organized as follows. In Section 2, the background of QCA technology and the design approaches are presented. Section 3 shows the algorithmic design of multiplication networks based on lter networks and Section 4 discusses multiplier implementation for QCA circuits. Analyses of simulation results and comparisons follow in Section 5 and conclusions are presented in Section 6.

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