Journal ArticleDOI
A theory of transistor cutoff frequency (f T ) falloff at high current densities
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In this paper, it was shown that the observed falloff in the f T of a transistor at high currents is due to the spreading of the neutral base layer into the collector region of the device at high current densities.Abstract:
It is shown that the observed falloff in the f T of a transistor at high currents is due to the spreading of the neutral base layer into the collector region of the device at high current densities. The base layer spreading mechanism derives from an analysis of the effect of the current-dependent buildup of the mobile-carrier space-charge density in the collector transition layer. Calculations show that at sufficiently high collector current levels, the mobile space-charge density in the collector transition layer cannot be considered negligible in comparison to the fixed charge density of that region. The over-all effect of taking the mobile space charge into account in analyzing the collector transition region is that, at high current densities, the transition region boundary adjacent to the neutral base layer is displaced toward the collector metal contact with increasing collector current. The attendant widening of the neutral base layer results in the observed, high-current falloff in f T . The application of this theory to transistor structures of both the alloy and mesa variety yields, in each case, calculated curves of f T vs I c which are in reasonably good agreement with experiment.read more
Citations
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Proceedings ArticleDOI
Effects of negative differential resistance in high power devices and some relations to DMOS structures
TL;DR: In this paper, the effects of negative differential resistance and moving filaments on the formation of electric fields at the n−-n++-junction were investigated in high power devices.
Journal ArticleDOI
InAlAs/InGaAs HBTs with simultaneously high values of F/sub /spl tau// and F/sub max/ for mixed analog/digital applications
TL;DR: In this paper, the design, fabrication, and measurement of InAlAs/InGaAs heterostructure bipolar transistors (HBTs) designed for high speed digital circuits were reported.
Journal Article
HBT Modeling
TL;DR: The combination of a thin base, low base resistance, and low parasitics in particular make HBTs a suitable choice for high frequency applications as discussed by the authors, which can yield higher gain and fmax.
Journal ArticleDOI
Optimum bias conditions for linear broad-band InGaP/GaAs HBT power amplifiers
M. Iwamoto,C.P. Hutchinson,Jonathan B. Scott,T.S. Low,M. Vaidyanathan,Peter M. Asbeck,D.C. D'Avanzo +6 more
TL;DR: In this paper, a design strategy for a linear broadband InGaP/GaAs heterojunction bipolar transistor (HBT) power amplifier is presented, which is based on the bias dependence of the nonlinear base-collector charge, as expressed in the C/sub BC/ versus V/sub CE/ and /spl tau/sub C/ versus I/sub c/
Journal ArticleDOI
The effect of collector resistance upon the high current capability of n-p-ν-n transistors
TL;DR: In this paper, it was shown that the onset of conductivity modulation of the bulk collector resistance causes an abrupt decrease in h FE at high current density and consequently limits the current range in which a transistor exhibits usable gain.
References
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Journal ArticleDOI
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TL;DR: In this article, a method of analyzing transistor behavior for any base-layer impurity distribution is presented, in particular expressions for emitter efficiency, transverse sheet resistance R, transit time, and frequency cut-off f?.
Journal ArticleDOI
Structure-Determined Gain-Band Product of Junction Triode Transistors
TL;DR: In this article, the authors compared the power gain of the junction triode with those of the field effect transistor and the analog transistor and showed that the gain-band product is nearly independent of the particular alpha cutoff frequency selected.