Analyzing a simple 1-to-4 demultiplexer (also known as a 1:4 demux) circuit involves understanding its functionality, truth table, and logic diagram. A 1:4 demux has one data input line, two control input lines (often denoted as A and B), and four output lines (often denoted as Y0, Y1, Y2, and Y3).
Here's a step-by-step breakdown of how to analyze a 1:4 demux circuit:
Truth Table: Start by creating a truth table that shows all possible combinations of the control inputs A and B, along with the corresponding outputs Y0, Y1, Y2, and Y3.
A B Y0 Y1 Y2 Y3
0 0 D 0 0 0
0 1 0 D 0 0
1 0 0 0 D 0
1 1 0 0 0 D
Here, "D" represents the data input value.
Logic Diagram: The logic diagram of a 1:4 demux will include gates to implement the desired output behavior based on the control inputs. It will generally consist of AND gates and NOT gates. The control inputs A and B will directly control the selection of which output line will be active.
Output Equations: Each output line is associated with a specific combination of control inputs. You can derive the output equations for each line from the truth table. For example, for Y0:
Y0 = A' * B' * D
Here, A' and B' are the complements (negations) of control inputs A and B, respectively.
Similarly, you can derive the output equations for Y1, Y2, and Y3.
Functional Analysis: With the truth table, logic diagram, and output equations, you can analyze how the circuit functions. When the control inputs A and B are given specific values, the corresponding output line will carry the data input value while the others will remain at logic 0.
Use Cases: A 1:4 demux can be used for various purposes. For example, it can route a single input signal to one of four output lines based on the control inputs. It can also be used for memory addressing or data distribution in digital systems.
Timing Analysis: Depending on the application, you might need to consider the timing behavior of the demux, especially in larger circuits where signal propagation delays and setup/hold times can impact overall system performance.
Remember that the analysis described here is based on idealized logic gates without taking into account factors like signal propagation delays and power consumption. In real-world applications, these considerations become important, especially in high-speed or low-power designs.