Block Diagram of a Combinational Circuit

Combinational Circuit

A combinational circuit is a connected arrangement of logic gates with a set of inputs and outputs. At any given time, the binary values of the outputs are a function of the binary combination of the inputs. The n binary input variables come from an external source. The m binary output variables go to an external destination, and in between, there is an interconnection of logic gates.

A combinational circuit transforms binary information from the given input data to the required output data. These circuits employed in digital computers for generating binary control decisions. It also provides the digital components required for data processing.

Block Diagram of Combinational Circuit

A combinational circuit described by a truth table showing the binary relationship between the n input variables and the m output variables. The truth table lists the corresponding output binary values for each of the 2ⁿ input combinations. It can also be specified with m Boolean functions, one for each output variable. Each output function expressed in terms of the n input variables.

The design of combinational circuits starts from the verbal outline of the problem and ends in a logic circuit diagram. The procedure involves the following steps:

1. The problem is stated.
2. The input and output variables assigned letter symbols.
3. The truth table that defines the relationship between inputs and outputs is derived.
4. The simplified Boolean functions for each output obtained.
5. The logic diagram is drawn.