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Unformatted text preview: ere VCE , VEB , and VBC are collector-emitter, emitter-base, and basecollector voltages. The BJT can operate in one of three modes: active,
cutoff, and saturation. When transistors operate in the active mode, typically VBE 0.7 V,
IC = αIE B
E (3.29) (a) where α is called the common-base current gain. In Eq. (3.29), α denotes
the fraction of electrons injected by the emitter that are collected by the
IC = βIB B − VCE +
VBE − −
(b) Figure 3.39
1−α v v VCB (3.31) and | + + (3.30) where β is known as the common-emitter current gain. The α and β are
characteristic properties of a given transistor and assume constant values
for that transistor. Typically, α takes values in the range of 0.98 to 0.999,
while β takes values in the range 50 to 1000. From Eqs. (3.27) to (3.30),
it is evident that
IE = (1 + β)IB C | e-Text Main Menu | Textbook Table of Contents | (3.32) The terminal
variables of an npn transistor:
(a) currents, (b) voltages. Problem Solving Workbook Contents 104 PART 1 In fact, transistor...
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This note was uploaded on 07/16/2012 for the course KA KA 2000 taught by Professor Bkav during the Spring '12 term at Cambridge.
- Spring '12