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How many 4 input LUTs will a 4-bit comparator require?
For case A>B, if the input is 2bit, the logic utilization is one 4-input LUT. Pretty obvious. A0,A1,B0,B1 inputs and one Y output. But for 4-input comparator, the logic utilization is three 4-input LUTs and MUX.
What is a 4-input LUT?
An n-bit LUT can encode any n-bit Boolean function by modeling such functions as truth tables. This is an efficient way of encoding Boolean logic functions, and LUTs with 4-6 bits of input are in fact the key component of modern FPGAs. Virtex-4 function generators are implemented as 4-input look-up tables (LUTs).
What is a 6-input LUT?
The Xilinx 6-input LUT is a look-up table with a total of 64 bits of logic programming space and 6 independent inputs. It is able to implement any function of 6 inputs and numerous combinations of one or two smaller functions. The 6-input LUT also includes associated carry logic, MUXs, and a flip-flop.
Which is basic comparator?
A digital comparator or magnitude comparator is a hardware electronic device that takes two numbers as input in binary form and determines whether one number is greater than, less than or equal to the other number. Note: An XNOR gate is a basic comparator, because its output is “1” only if its two input bits are equal.
How to create a 4-bit comparator based on 2-bit logic?
Firstly, a 2-bit comparator is implemented based on the logic expressions from the truth table of each output. Next, likewise, it generates a 4-bit comparator by instantiating two models of the 2-bit comparators and some extra logic gates.
How is a magnitude comparator used in logic?
By using these Boolean expressions, we can implement a logic circuit for this comparator as given below: A comparator used to compare two binary numbers each of two bits is called a 2-bit Magnitude comparator. It consists of four inputs and three outputs to generate less than, equal to and greater than between two binary numbers.
Which is the truth table of a 4-bit comparator?
Comparing to the truth table of a 2-bit comparator, a 4-bit comparator will be used 4-bit in input A and 4-bit in input B. Therefore, the truth table of the 4-bit comparator is the following table below. From the table above, the logic expressions of each output are:
How is a cascading comparator used in digital logic?
A comparator performing the comparison operation to more than four bits by cascading two or more 4-bit comparators is called cascading comparator. When two comparators are to be cascaded, the outputs of the lower-order comparator are connected to corresponding inputs of the higher-order comparator.