Noise in a MOSFET — Lesson 2

This lesson covers the noise in the MOSFET and how it is modeled. The lesson explains the behavior of electrons in the channel of a MOSFET, how they jostle for space, and how this activity increases with temperature. It also discusses how the noise current is proportional to the number of electrons available in the channel. The lesson further explains how to model this noise over all regions of operation using a formula involving the Boltzmann constant and the inversion charge. The lesson also touches on the concept of input referred noise and output noise, and how to calculate these using the gain of the system.

Video Highlights

04:20 - MOSFET noise model that works over all regions of operation
15:45 - Impact of the body resistance on the noise voltage and parasitics capacitances
21:17 - Concept of input referred noise
29:21 - How to calculate the input referred noise and total output noise
32:33 - Discussion on the calculation

Key Takeaways

- Noise in a MOSFET is primarily due to the jostling of electrons in the channel, which increases with temperature.
- The noise current is proportional to the number of electrons available in the channel.
- The noise can be modeled over all regions of operation using a formula involving the Boltzmann constant and the inversion charge.
- The concept of input referred noise and output noise is important in understanding the overall noise in a system.
- The input referred noise and output noise can be calculated using the gain of the system.