# noise in transitor

Noise in MOSFET Transistor

MOS transistor noise equivalent model

The fundamental concept of noise in MOS is very important for the choice of architecture, circuit analysis and optimization. The noise model for MOS transistor is depicted

Kf is flicker noise coefficients which is dependent on process. ID and gm are the DC drain current and transconductance of the transistor which are determined by the bias condition. The flicker noise is only affected if the frequency at high frequency. ? is a correction factor for short channel device and ? =1 for long channel device.

The noise contribution of noise voltage and noise current are both dependent on the source resistance. A typical RF input source impedence is 50 ohm. Therefore, the noise voltage is the most significant in calculation. The noise formula gives us a tendency of the noise at which frequency of interested.