Direct Measurement of the Maximum Operating Region in AlGaAs HBTs for RF Power Amplifiers

Akira INOUE
Shigenori NAKATSUKA
Satoshi SUZUKI
Kazuya YAMAMOTO
Teruyuki SHIMURA
Ryo HATTORI
Yasuo MITSUI

Publication
IEICE TRANSACTIONS on Electronics   Vol.E86-C    No.8    pp.1451-1457
Publication Date: 2003/08/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Microwave and Millimeter Wave Technology)
Category: 
Keyword: 
maximum operating region,  measurement,  waveform,  power amplifier,  HBT,  

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Summary: 
A microwave waveform measurement system below 18 GHz was developed and verified with a conventional RF measurement. The current and voltage RF waveforms of AlGaAs HBTs at the fundamental frequency of 1 GHz were directly measured with the system. A new direct method of sweeping and measuring dynamic RF load lines is proposed to measure the operating limits of the device. The maximum operating region was experimentally investigated with this method. The limits with a small input power are found to come from thermal runaway and the avalanche breakdown of the device. With a large input power, the HBT was found to operate beyond the DC limit of thermal runaway. The base ballasting resistance was also found to enhance large signal operating limits beyond those expected from the conventional DC theory.