Image from page 1278 of “The Bell System technical journal” (1922)

Some cool Signal Characterization images: Image from page 1278 of "The Bell System technical journal" (1922) Signal Characterization
Image by Internet Archive Book Images Identifier: bell00systemvol31techniamerrich Title: The Bell System technical journal Year: 1922 (1920s) Authors: American Telephone and Telegraph Company Subjects: Telecommunication Electric engineering Communication Electronics Science Technology Publisher: [Short Hills, N.J., etc., American Telephone and Telegraph Co.] Contributing Library: Prelinger Library Digitizing Sponsor: Internet Archive View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: point contact devices, Tco has beenmeasured as an ap{)i-o.imation. In the idealization, r^ and r^i arc re- lated as, . Uc - Ico) >M = = 1 im The measiuement of 7-^0 is made at a collector voltage which is typicalof the applications in the range of perhaps —10 to —45 volts. A constant dissipation line has been drawn on Fig. 21, which revealsthe desirability of having Vco very large in order to operate at highervoltages and to secure high efficiency through lower dissipation in theOFF or rest condition. UEGIOX II PROPERTIES The Region II low frequency properties are essentially identical tothose of transistors intended for small-signal applications. A possibleexception is the somewhat less attention paid to the base resistance, n ,which is critical to small-signal applications. The characterization con-sists of a normal small-signal set plus dc bias values. UEGIOX III PROPERTIES The Region III properties have been defined largely by a figure of Ir_= -5.5 MACOLLECTOR CURRENT r^= Text Appearing After Image: Vc CONSTANT CONSTANT DISSIPATION Fig. 21—Idealized output characteristic illu.strating parameters. 1244 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1952 merit measurement shown as Fc(3, —5.5) in Fig. 21. This measurementis the voltage from collector to base under the condition that I^ > — {Ic/a). In this instance /j has been chosen to be 3 mA and Ic to be — 5.5 mA. The collector current value is chosen on the basis of thesmallest tolerable value of alpha expected so as to place the point ofmeasurement near the 7^22 knee, but in Region III or overload. The T^c(3, —5.5) measurement is a good measurement for definingthe general behavior. Tc(3, —5.5) taken with the r^o measurementconstitute a very good defining set for checking the transistor as inre-measuring. For design purposes, the Fc(3, —5.5) measurement is notsufficient. It provides an approximate value for Tc , but does not definer/ and r„ . A second dc measurement, the collector to emitter voltagedrop, V,c , has Note About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.
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