# Common Source MOSFET Amp problem

• vermin
In summary, the given CS amplifier has a MOSFET with μnCox = 400 μA/V2, W/L = 10, and VA = 10v, and is biased at ID = 0.2mA with RD = 6k. To find Rin, AVO, and RO, we can use the equations VAO = -gm(RD||ro) and Ro = RD||ro. Using the given values, we can find gm and ro and then calculate the required parameters.
vermin

## Homework Statement

A CS amplifier utilizes a MOSFET with μnCox = 400 μA/V2, W/L = 10, and VA=10v. It is biased at ID=0.2mA and uses RD=6k.

Find Rin,AVO,RO

VAO= -gm(RD||ro)

Ro=RD||r0

## The Attempt at a Solution

I drew out the equivalent circuit with hybrid-pi model. Doesn't seem to tell me much.

Not sure where to start. For the relevant equations above I'm missing gm and ro. I have a feeling "it is biased at ID=0.2mA" is a clue but I'm having trouble finding what that implies.

ok nevermind I just figured it out.

Last edited:

## What is a common source MOSFET amplifier?

A common source MOSFET amplifier is a type of electronic circuit that uses a MOSFET (metal-oxide-semiconductor field-effect transistor) to amplify an input signal. It is commonly used in audio amplifiers, and its basic function is to increase the strength of a signal while maintaining its original shape.

## What are the most common problems associated with common source MOSFET amplifiers?

The most common problems include biasing issues, distortion, noise, and thermal instability. These can be caused by improper design, component failure, or external factors such as temperature or power supply fluctuations.

## How can I troubleshoot a common source MOSFET amplifier problem?

The first step is to check the biasing of the MOSFET, as this is a common cause of issues. Then, test the components and connections to ensure they are functioning properly. If the problem persists, it may be necessary to adjust the circuit design or replace components.

## What is thermal instability in a common source MOSFET amplifier?

Thermal instability refers to the tendency of the MOSFET to change its characteristics as it heats up. This can cause the amplifier to become unstable and produce distorted or noisy output. It is important to properly design the circuit and use appropriate heat sinks to prevent this issue.

## Can I use a common source MOSFET amplifier for high power applications?

While common source MOSFET amplifiers are commonly used for low to medium power applications, they are not typically suitable for high power applications. This is because the MOSFET can overheat and become damaged, or the circuit may become unstable. It is best to use other types of amplifiers for high power applications.

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