# Designing a 2-Input XOR Gate: RL=1KΩ, VDD=1.8V

• jean28
In summary, the task is to design a 2-input XOR gate using transistors with the given specifications, including a 1KΩ load, 1.8V VDD, 0.1V VOL, and 1.7V VOH. The solution may involve considering the ON resistance of FETs and ensuring that the output voltage swing meets the logic 1 or 0 requirements for the next gate.
jean28

## Homework Statement

Design a 2-input XOR with the following specifications:

RL = 1KΩ
VDD = 1.8V
VOL = 0.1V
VOH = 1.7V

## Homework Equations

Triode:
Id = μnCox W/L VDS (VGS - Vt - VDS/2)

Cutoff:
Id = 0.

## The Attempt at a Solution

Searching on my book I found the image attached which is an implementation of an XOR gate with transistors. However, how can I use the voltages given to "design" the transistor? I just don't get it very well.

#### Attachments

• XOR.jpg
23.6 KB · Views: 493
Is the question asking you for an implementation with generic transistors (as in your attached picture), or something involving the design of the transistors themselves (as you imply with your equations)? You can see that you don't need rail-to-rail output (Voh and Vol) and that you need to be able to source enough current to drive a 1k load (i.e. 1.8V / 1k)

FETs have ON resistance that will affect the output voltage delivered to the load. Think of it as a potential divider problem where the output voltage swing must be at least enough to meet the definition of a logic 1 or 0 for the next gate to use as an input.

## 1. What is a 2-Input XOR Gate?

A 2-Input XOR gate is a logic gate that takes in two binary inputs and outputs a single binary signal based on a specific logical operation. In this case, the gate performs an exclusive OR (XOR) operation, which means the output will be 1 only if one of the inputs is 1, but not both.

## 2. What are the components of this XOR gate?

This XOR gate has two inputs, each with a resistor (RL) of 1KΩ, and a voltage supply (VDD) of 1.8V. It also has an output that will be either 1 or 0 depending on the inputs and the operation performed.

## 3. How does the resistor (RL) affect the performance of the XOR gate?

The resistor (RL) helps to limit the current flow in the circuit and ensures that the inputs and outputs are at the desired voltage levels. In this case, the 1KΩ resistor helps to create a voltage divider with the 1.8V supply, which is necessary for the XOR operation to work correctly.

## 4. Can this XOR gate handle different input voltages and resistances?

Theoretically, this XOR gate can handle different input voltages and resistances as long as they are within the specified range (1.8V for VDD and 1KΩ for RL). However, using different values may affect the performance and accuracy of the gate and may require additional adjustments or modifications.

## 5. What are some practical applications of a 2-Input XOR Gate?

XOR gates are commonly used in digital electronics, such as in computers and microcontrollers, to perform logical operations and create more complex circuits. They are also used in encryption and error-detection systems, as well as in mathematical and scientific calculations.

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