BJT practice problems
Refresh the page to get a new problem.
An ideal, uniformly doped silicon npn transistor has the following doping and widths.
| NPN | emitter | base | collector |
| doping | NDE = 2.1e+18 cm-3 | NAB = 7.0e+16 cm-3 | NDC = 5.83e+15 cm-3 |
| widths | WE = 3.5 μm | WB = 1 μm | WC = 10 μm |
The BJT area is 200 μm x 200 μm.
Calculate βF and IS for the BJT.
If the BJT is biased in forward active operation, with VBE = 0.85 V, calculate the base, collector, and emitter currents, assuming room temperature operation.
Note: For silicon,
- the intrinsic carrier concentration is ni = 6.0e+9 cm-3
- the electron diffusion coefficient is 35 cm2/s, and
- the hole diffusion coefficient is 10 cm2/s.