DocumentCode :
913095
Title :
Ultralinear UHF power transistors for CATV applications
Author :
Müller, Otward
Author_Institution :
General Electric Company, Lynchburg, Va.
Volume :
58
Issue :
7
fYear :
1970
fDate :
7/1/1970 12:00:00 AM
Firstpage :
1112
Lastpage :
1121
Abstract :
An investigation of the cross-modulation performance of UHF power transistors and its correlation with the gain parameter curves S21(IC, VCB) shows that such transistors today exhibit an inherent linearity limitation and are not optimized for ultralinear applications. This means that using higher power transistors does not result in a larger output signal with low cross-modulation distortion. Presented measurements clearly demonstrate that the nonlinear products increase, not only with increasing emitter dc current, but also with collector voltage above certain limiting values ICLand VCL, respectively; ICLand VCLare relatively small compared with the corresponding maximum permissible values of ICand VCB. Their existence can be explained by current crowding effects, by the space-charge limitation of the collector current, by the nonuniform thermal conductance, by the temperature gradients, and by the unequal current density distribution across the (large) active areas of power transistors. A correlation between the VCgain parameter falloff effect and the "thermal distortions," has been established. Design and selection criteria for ultralinear transistors needed in CATV amplifers are given. A simple linearity test method is described.
Keywords :
Current measurement; Distortion measurement; Linearity; Nonlinear distortion; Performance gain; Power transistors; Proximity effect; Temperature distribution; Thermal conductivity; Voltage;
fLanguage :
English
Journal_Title :
Proceedings of the IEEE
Publisher :
ieee
ISSN :
0018-9219
Type :
jour
DOI :
10.1109/PROC.1970.7854
Filename :
1449784
Link To Document :
بازگشت