ELE533 Bipolar Devices
Final Exam

NAME___________________________________________________________

1. Consider a silicon npn transistor with a base width of 1.0 micron, base doping, Na = 10¹⁷ acceptors/cm³, emitter doping, Nde = 5x10¹⁹ donors/cm³, emitter width is 1.5 microns, electron and hole life times are 10 ^-6 sec. in the emitter and 10 ^-9 sec. in the base, the emitter area is 20 microns by 40 microns.

   Find:

   1. beta________________

   If the collector current is 1 mA, find:
   2. gm__________________

   3. r_pi , the incremental base-emitter resistance_____________

   4. Cd, the base-emitter diffusion capacitance______________

   5. Assume the diffusion capacitance is much greater than the base emitter and base collector junction capacitances and find;

      F_T, the frequency at which the magnitude of beta is one_______________