Noise Model

Good noise models in circuit simulators are critical to analog and RF applications.

Two types of noise, thermal and flicker, are important in a MOSFET.

Flicker Noise

The basic characteristic of flicker noise is a 1/? spectral density.

There are three different theories of flicker models.

1. carrier density fluctuation models
2. mobility fluctuation models
3. correlated carrier and mobility fluctuation models

In the 1) carrier density fluctuation model, the noise is explained by the fluctuation of channel free carriers due to the random capture and emission of carriers by interface traps at the Si-SiO2 interface.

In Bsim3v3, there are 2 flicker noise models.

1. SPICE2 flicker noise model (noiMod=1)
2. Unified flicker noise model (noiMod=2)

The Physical Mechanism of Thermal Noise

The origin of thermal noise in a MOSFET has been found to be related to the random thermal motion of carriers in the channel of the device.

In Bsim3v3, there are 2 thermal noise models.

1. modified SPICE2 thermal model (noiMod=1)
2. BSIM3 thermal noise model (noiMod=2)

Bsim3 学习笔记6