# Chapter 5: Bipolar Junction Transistors     ## Examples

 A bipolar transistor with an emitter current of 1 mA has an emitter efficiency of 0.99, a base transport factor of 0.995 and a depletion layer recombination factor of 0.998. Calculate the base current, the collector current, the transport factor and the current gain of the transistor. Consider a pnp bipolar transistor with emitter doping of 1018 cm-3 and base doping of 1017 cm-3. The quasi-neutral region width in the emitter is 1 mm and 0.2 mm in the base. Use mn = 1000 cm2/V-s and mp = 300 cm2/V-s . The minority carrier lifetime in the base is 10 ns.Calculate the emitter efficiency, the base transport factor, and the current gain of the transistor biased in the forward active mode. Assume there is no recombination in the depletion region. Calculate the saturation voltage of a bipolar transistor biased with a base current of 1 mA and a collector current of 10 mA. Use aR = 0.993 and aF = 0.2. Consider a bipolar transistor with a base doping of 1017 cm-3 and a quasi-neutral base width of 0.2 mm. Calculate the Early voltage and collector current ideality factor given that the base-emitter capacitance and the base-collector capacitance are 0.2 nF and 0.2 pF. The collector area equals 10-4 cm-2.