DocumentCode :
3553370
Title :
The effects of internal R. F. attenuation on the power output performance of bipolar transistors
Author :
Hunt, R.E. ; Zoroglu, D.S.
Volume :
17
fYear :
1971
fDate :
1971
Firstpage :
92
Lastpage :
94
Abstract :
In the design of microwave bipolar transistors, there has been extensive utilization of three basic geometries: interdigitated, overlay and mesh emitter. In view of the obvious cost-performance-reliability trade-offs of the geometrical designs, an understanding of attenuation along un-metallized stripes is imperative. This paper summarizes an experimental and theoretical investigation of the variation of output power by the r.f. attenuation along a diffused stripe where current was fed from one end only. The experiments have employed the overlay geometry with 2.5 µm linewidths and 4 µm spaces. Diffused stripe length, Le, was varied while the emitter periphery, Pe, the base area, Ab, and the emitter area, Aewere kept constant. At a frequency of 1 GHz, it was observed that for the same input power, the output power decreased by \\sim 25% in Class C operation and \\sim44% in Class A as Lewas increased from 19 µm to 36 µm. Interestingly, in both modes of operation, no change in output power was noted for Le\´s between 12 µm and 19 µm. The obvious implication is that in these structures r.f. attenuation does not play a dominant role until the stripes reach a length of ∼ 20 µm, allowing the use of quite wide emitter metallization. A simple analysis has been carried out to better understand the r.f. attenuation mechanism and relate it to experimental data. The attenuation constant, a , was calculated using ordinary transmission line theory. Then, the collector current, Ie, was found employing this value of a . Variation of the output power was, then, inferred from the variation of Ie2. Correlation between theory and experiment is satisfactory considering the simplifications introduced into the analysis.
Keywords :
Attenuation; Bipolar transistors; Geometry; Laboratories; Metallization; Microwave transistors; Plasma density; Power generation; Telephony; Transmission line theory;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Electron Devices Meeting, 1971 International
Type :
conf
DOI :
10.1109/IEDM.1971.188410
Filename :
1476748
Link To Document :
بازگشت