Equations for modeling BJT thermal, shot, and flicker noise are as follows.
The mean square short-circuit base resistance noise current equation is:
The mean square short-circuit collector resistance noise current equation is:
The mean square short-circuit emitter resistance noise current equation is:
The noise associated with the base current is composed of two parts: shot noise and flicker noise. Typical values for the flicker noise coefficient, KF, are 1e-17 to 1e-12. They are calculated as:
where fknee is noise knee frequency (typically 100 Hz to 10 MHz) and q is electron charge.
The noise associated with the collector current is modeled as shot noise only.
