Arithmetic Logic Unit(ALU) is one the most important component of any computing system like microprocessors, embedded chips, super computers, smart phones and sequential circuits. The ALU is present in very complex devices to the daily devices we use. ALU is a combinational circuit and it performs arithmetic and logic operations. For a circuit design, the important aspects are to minimize the delay, power and area as per the application. In this paper we cover various aspects of ALUs like working of 4-bit ALU designs, various approaches on how to optimize delay, how GDI technique is used to optimize delay and power, and its constraints and various techniques on how to test the ALUs.
Here, in this paper we first initially talk about various logic design techniques and we justify why GDI (Gate Diffusion Input) technique is the best compared to others. The files here contain LTSpice models of Logical Block, muliplexers and Arithmetic Block of ALU using GDI technique developed from scratch.
Logical Block components: - AND XOR NOT OR
Arithmetic Block components: - Full Adder
Multiplexers : 4X1 and 2X1
Using TSMC180nm technology
Detailed explanation can be seen in ALU_Digital_VLSI_Design_Project2_Final file