Design and Analysis of Combinational Circuits Using Gate Diffusion Input

The popularity and necessity of portable electronic systems by users have strongly influenced VLSI designers to make great effort for reduced silicon area, improved speeds, long duration battery life, and great reliability. The VLSI designers always try to save power consumption while designing a system.  This technique also reduces the transistor count and thus the area of the circuit. Thus the circuit will be much simpler and easy to manage. To design of an 8 – bit Arithmetic Logic Unit using Gate Diffusion Input (GDI) Technique and also the comparison with other logic styles. Basic Logic Gates, half adders, full adders, multiplexers etc are also designed and performances are compared in terms of power dissipation and transistor count. The ALU design uses 2x1 multiplexers, 4x1 multiplexers, half adders, full adders and OR gates to realise the basic arithmetic and logic functions. The arithmetic functions are Addition, Subtraction, Increment, and Decrement. The logic functions that can be realised are AND, OR, XOR, and XNOR. The simulation tool used is Tanner EDA 13.0 using 250nm technology.