Section 11
BJT transistors
Computes BJT currents from the circuit model and the stated conditions.
- Small-signal NPN unless stated; stay in the named region.
Computes Current gain alpha from the circuit model and the stated conditions.
- Small-signal NPN unless stated; stay in the named region.
Computes Current gain beta from the circuit model and the stated conditions.
- Small-signal NPN unless stated; stay in the named region.
Computes Relation between beta and alpha from the circuit model and the stated conditions.
- Small-signal NPN unless stated; stay in the named region.
In the active region of the load line IC=β IB with VCE above saturation.
- Small-signal NPN unless stated; stay in the named region.
In cutoff IB≈0 and IC≈0: the Q-point sits at VCE=VCC.
- Small-signal NPN unless stated; stay in the named region.
In saturation VCE sat is small and IC no longer follows β IB.
- Small-signal NPN unless stated; stay in the named region.
The load line joins (VCC,0) to (0,VCC/RC); the Q-point travels cutoff, active and saturation.
- Small-signal NPN unless stated; stay in the named region.
Computes BJT divider bias from the circuit model and the stated conditions.
- Small-signal NPN unless stated; stay in the named region.
Computes BJT transconductance from the circuit model and the stated conditions.
- Small-signal NPN unless stated; stay in the named region.
Computes Small-signal input resistance from the circuit model and the stated conditions.
- Small-signal NPN unless stated; stay in the named region.
Computes BJT as a switch from the circuit model and the stated conditions.
- Small-signal NPN unless stated; stay in the named region.