Electronics Simulations #11| Logic Gates implementation on Caneda (with a guide of How-to-build-full-adder)

What Will I Learn?

In this tutorial, reader:

• will be more familiar basic concept of logic gates
• will learn working principle of full-adder
• will learn implementation of full adder on Caneda

Requirements

To complete the tutorial, readers would have:

• basic knowledge about circuit design
• basic knowledge about digital circuit world
• basic knowledge about Caneda software

Difficulty

• Intermediate

Tutorial Contents

In this tutorial, I am going to explain logic gates implementation on circuit simulator software which is called as Caneda, with the help of the construction of full-adder circuit. Firstly, I will give basic idea behind the circuit and then move into construction & observation of the circuit. Let me start with general information about full adder.

- Episode 1: What is full-adder circuit?

In order to understand the concept of full-adder circuit, one may need to know about half adder circuit. General description of half-adder circuit is given below:

With the help of half adder, we can design circuits that are capable of performing simple addition with the help of logic gates.

Overall diagram for the Half-Adder circuit is given below:

_{Source of the image}

Truth table of the circuit is:

_{Source of the image}

After we know the basics of half-adder, reader can understand full adder circuitry. General description of full adder and differences from half adder are given below:

This type of adder is a little more difficult to implement than a half-adder. The main difference between a half-adder and a full-adder is that the full-adder has three inputs and two outputs. The first two inputs are A and B and the third input is an input carry designated as CIN. When a full adder logic is designed we will be able to string eight of them together to create a byte-wide adder and cascade the carry bit from one adder to the next.

The circuit diagram of full-adder circuit is:

_{Source of the image}

The truth table for the full-adder circuit is:

_{Source of the image}

Note that this design is not unique one. From the truth table there are infinitely many designs, but this one is the most shortest and effective one. Now, we are ready to construct circuit on the software.

- Episode 2: Construction of full-adder circuit

In order to construct full-adder circuit in the software, reader should know the basics about logic gates in the software. The main and most critical point is biasing the circuit. Reader can find corresponding logic gates in "CMOS" subtitle in "Components Browser" window as illustrated below.

Note that there are 2 more inputs for logic gates if we compare it with circuit in the image which is given above. "In Caneda software, reader should bias the logic gates before using them". In reality, we also need bias logic gates before using it, so this situation is expected.

Reader should bias upper terminal and ground lower terminal as shown below:

"Please notice that I have used different biasing methods that I have used before. When you port a voltage source with a arbitrary name and create a new port with same name, voltage value stands same. This trick may help the reader to make the circuit more neat & looks simpler"

I have explained the basics about circuit design in my previous tutorial, if reader hasn't cover it yet, I highly recommend to do it before moving into next steps. Overall design of the circuit may look like:

("Note that I have skipped basics of construction steps since I have already explained in before." )

In this case, our three inputs are set to 0,(each one of them are grounded as in the figure), if reader want to give "1" to an input, he/she has to delete the "ground" terminal and "connect Vdd to that line" Next figure shows when A is 1 where B and Cin are both 0.

We have completed construction of a full-adder and ready for the simulation.

- Episode 3: Simulation of full-adder circuit

In order to simulate the circuit, reader just needs to save the file and click simulation button.(Note that the circuit that I have constructed is already have "transient simulation" component, so no need to add it again.)

As I have indicated above, reader can change input as changing the voltage values for the corresponding one, I will give 2 examples of outputs for this circuit, other ones can be tested from the reader.(I will give the corresponding files that I have constructed for this tutorial at the end of this part.)

"When A=0 B=1 Cin=1" (expected result is Cout=1 , S=0 ["Check Truth Table!" ])

"When A=1 B=1 Cin=1" (expected result is Cout=1 , S=1 ["Check Truth Table!" ])

"Note that both signals are over each other so we only see just a line"

I have proven that circuit works as we desire, so we have managed to construct full-adder on Caneda software.

I have provided the files for this tutorial here. I highly recommend that the reader should work on the files that I have provided and try to understand the basics of the circuit & software. It will be benefical he/she.

This is the end for this tutorial.Hope that you like it.

Caneda software is really user-friendly & effective for the one who wants to make simulation. If you have any questions, please feel free to ask me on Discord (Escorn#4114)

Source

Source for the circuit diagrams & expressions that I have cited

Curriculum

I have provided the previous tutorials that I have prepared for the community:

• Part 1
• Part 2
• Part 3
• Part 4
• Part 5
• Part 6
• Part 7
• Part 8
• Part 9

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