# Determining transistor sizes equal to a single inverter

• tdotengineer
In summary, the conversation discusses determining transistor sizes for a 2 input NAND gate so that the worst case pull down and pull up is equivalent to a single inverter with Wn = 1 micro m and Wp= 2 Micro m. The solution involves using the worst case scenario and ensuring that the equivalent W/L for the PDN or PUN of the NAND gate is equal to the Wp or Wn given in the question.

## Homework Statement

Determine transistor sizes for (lets say a 2 input nand gate, my actual question is more complicated but i want to know the basic idea so i can do it myself) so that the worst case pull down and pull up is equivalent to a single inverter with Wn = 1 micro m and Wp= 2 Micro m
All transistor lengths are 0.25 micro meters

## Homework Equations

Basic Mosfet knowledge should do i guess.

## The Attempt at a Solution

i know the solutions, i just don't know how to arrive at it.
My guess was that the equivalent transistor W/L for the PDN or PUN should be the same as the W/L for the PDN or PUN of the inverter. But the numbers don't add up.

Guys i think I've got it but I am not sure

the question said WORST CASE... i was basically missing that part.
so now that I've read it carefully I've found out (with working backwards on the solutions) that using the worst case scenario (slowest timing aka lowest equivalent W/L for PDN or PUN of the nand gate) your equivalent w/l of the worst case scenario should equal to the Wp or Wn given in the question.

## 1. What is the purpose of determining transistor sizes equal to a single inverter?

The purpose of determining transistor sizes equal to a single inverter is to ensure proper functionality and efficiency of the inverter. By determining the appropriate sizes of the transistors, the inverter can perform its function effectively and with minimal power consumption.

## 2. How do you determine the transistor sizes for a single inverter?

There are various methods for determining transistor sizes for a single inverter, but the most common approach is to use the inverter's logic equation and the transistor's specifications to calculate the optimal sizes. This involves considering factors such as voltage, current, and frequency requirements.

## 3. What are the key factors to consider when determining transistor sizes equal to a single inverter?

The key factors to consider when determining transistor sizes include the inverter's input and output voltage levels, the required switching speed, and the maximum current that the inverter can handle. It is also important to take into account the type of transistor being used (e.g. MOSFET or BJT) and its specifications.

## 4. Can transistor sizes for a single inverter be determined using a simulation tool?

Yes, transistor sizes for a single inverter can be determined using simulation tools such as SPICE. These tools allow for the input of various parameters and can provide accurate simulations of the inverter's behavior. This can help in determining the optimal sizes for the transistors.

## 5. How can transistor sizes for a single inverter affect the overall performance of a circuit?

The sizes of the transistors in a single inverter can greatly impact the performance of a circuit. If the sizes are too small, the inverter may not be able to handle the required voltage or current, leading to malfunctions. On the other hand, if the sizes are too large, the circuit may consume more power than necessary. Therefore, proper determination of transistor sizes is crucial for optimal circuit performance.