An Efficient 4-Bit Processor Design Using Quantum Dot Cellular Automata Technology

Integrated Circuit(IC) fabrication technology is improving, so the internal dimension of semiconductor devices are decreasing day by day. This trend of scaling down dimensions reached its limit in near future. In nanoscale design, Complementary Metal Oxide Semiconductor (CMOS) has certain limitations such as hot electron effect, interconnect crosstalk, power dissipation, operating speed, gate oxide and interconnect scaling. According to the novel nanotechnology Quantum-dot cellular automata (QCA),which provides a better computation platform than traditional CMOS, in which polarization of electrons indicates the digital information. This work relies on an efficient 4 bit processor design based on QCA technology and it is compared with the CMOS technology. The processor mainly consists of a comparator, ALU, accumulator and data memory. The comparator were designed based on Tree-Based(TB) architecture, that is the entire bit is splitted into two halves and computed separately. Finally, it is cascaded together. The ALU consists of arithmetic operations such as full adder, full subtractor and logical operations such as AND and XOR. The data memory is a 4 *4 volatile memory. QCA based design reduces delay, power dissipation and number of cells used. The VHDL language is used for coding and synthesis can be done by means of Xilinx-ISE 13.2