DESIGN OF 4-BIT PROCESSOR UNIT USING VLSI-CAD TOOLS

Abstract

Layout of CMOS 4-bit Processor unit as well as the Schematic of a 4-bit Processor unit gate is drawn using VLSI-CAD Tools (Tanner tool) and performance of Processor unit is compared with MM74HC 181, which is 4-bit processor unit chip. Tanner tool is a powerful CAD package used in the design of VLSI chip. It has utility programs . . such as the spice file compiler, which also work with the Schematic and Layout of the circuit. In the fist stage, the realization of the 4-bit Processor Unit is done then I have calculated the width to length ratio of n-type and p-type transistor] Schematic of CMOS 4-bit processor unit is drawn with the calculated dimension using Schematic editor. Schematic editor is a part of Tanner tool, which is used for drawing a schematic of circuit. Spice file of Schematic is generated by running the spice file compiler. The Schematic performance is then verified by simulating this spice file using T-spice and then Layout is drawn for the Inverter and NAND GATE with the above-calculated channel dimension. Layout of 4-bit Processor Unit is generated using Layout editor. After drawing Layout, the Layout design rule checking is done using design rule checker. Spice file of Layout is generated by running the spice file compiler. Layout performance is then verified by simulating this spice file. In the next step, LVS comparisonsdone using LVS of Tanner tool for verifying the node connection between Schematic and Layout. In the last step, I have compared the output performance of 4-bit Processor unit with the MM74HC 181.