Image from page 434 of "The Bell System technical journal" (1922)
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oting figures on type As, ranges for commensurate fractionsof the total family will be given. In order that symbols and terminology 420 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1952 will be clear, it will be useful to review briefly the method of definingthe linear characteristics of all transistors. In Fig. 10 is shown a gener-alized network representing the transistor in which the input terminalsare emitter-base and the output terminals are collector-base. Then, overa sufficiently small region of the static characteristics, the linear re-lations between the incremental emitter and collector voltages andcurrents may be represented by the pair of linear equations shown.^ 0 MA. \ -1.0 \ -1.5 -2.0 V -2.5 \ -3.0 \ -3.5 -4.0 -4.5j -5.0, \ S \l J / lie-0 MA. -0.5 j -1.0 1 i -1 -2.5, 1 / /// -3.=y -4.0i -4.5 ^^ / / -so, 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Ic IN MILLIAMPERES Fig. 8—Static characteristics of the M1752 junction transistor. PRESENT STATUS OF TRANSISTOR DEVELOPAIKXT ■421
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/ (AMP / / -25 >-50 f-lb -100/ -125 -150 -175 -0.08 0 20 40 60 80 100 120 140 160 180 200 Ic IN MICROAMPERES Fig. 9—Expanded plot of the microwatt region of the static characteristics ofthe M1752 transistor. 422 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1952 The coefficients are simply the open-circuit driving point and trans-fer impedances of the transistor, or the slopes of the appropriatestatic characteristics at fixed dc operating currents. These equationsmay be represented by any one of a large number of equivalent cir-cuits of which the one shown in Fig. 11 is perhaps currently most useful.In this circuit Vg is very nearly the ac forward impedance of the emit-ter barrier, Vc is very nearly the ac reverse impedance of the collectorbarrier, Vb is the feedback impedance of the bulk germanium commonto both, and a is the circuit current gain representing carrier collec-tion and multiplication if any. It turns out this is very nearly equalto the current multiplication factor a of th
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