BJT practice problems

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An ideal, uniformly doped silicon npn transistor has the following doping and widths.

NPN | emitter | base | collector |

doping | N_{DE} = 4.0e+17 cm^{-3} |
N_{AB} = 2.0e+16 cm^{-3} |
N_{DC} = 4.0e+15 cm^{-3} |

widths | W_{E} = 4 μm |
W_{B} = 2 μm |
W_{C} = 3 μm |

The BJT area is 300 μm x 300 μm.

Calculate β_{F} and I_{S} for the BJT.

If the BJT is biased in forward active operation, with V_{BE} = 0.65 V, calculate the base, collector, and emitter currents, assuming room temperature operation.

Note: For silicon,

- the intrinsic carrier concentration is n
_{i}= 6.0e+9 cm^{-3} - the electron diffusion coefficient is 35 cm
^{2}/s, and - the hole diffusion coefficient is 10 cm
^{2}/s.