Arithmetic logic unit design implemented using CMOS transistors
This is a 4-bit ALU designed on LT Spice by using CMOS transistors. It has the operations of XOR, XNOR, Addition, Subtraction, Multiplication, Leftshift, Arithmetic left-shift, Arithmetic right-shift, Circular left-shift and right shift, 4-bit magnitude comparator and Equality comparator. Operations of the ALU are selected by the selection inputs, which drive the 4x16 decoder and trigger the 4-bit operations. The truth Table for functional selections is given below
A B C D - Operation
0 0 0 0 - XOR
0 0 0 1 - XNOR
0 0 1 0 - Multiplication
0 0 1 1 - Addition
0 1 0 0 - Subtraction
0 1 0 1 - Arithmetic Shift left
0 1 1 0 - Rotate Shift Right
0 1 1 1 - Rotate Shift Left
1 0 0 0 - Logical shift Left
1 0 0 1 - Arithmetic Right Shift
1 0 1 0 - Magnitude Comparator
1 0 1 1 - Equality Comparator
All the 4-bit Operation Outputs are driven by the 16x1 Multiplexers and give the final output.