Composite-Collector InGaP/GaAs HBTs for Linear Power Amplifiers

Takaki NIWA
Takashi ISHIGAKI
Naoto KUROSAWA
Hidenori SHIMAWAKI
Shinichi TANAKA

Publication
IEICE TRANSACTIONS on Electronics   Vol.E88-C    No.4    pp.672-677
Publication Date: 2005/04/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.4.672
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Fundamental and Application of Advanced Semiconductor Devices)
Category: Compound Semiconductor Devices
Keyword: 
HBT,  gallium arsenide,  ruggedness,  breakdown voltage,  linearity,  composite collector,  WCDMA,  

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Summary: 
The linear operation of a HBT with a GaAs/InGaP composite collector structure is demonstrated. The composite collector structure allows for a thin collector design that is suitable for the linear operation of a HBT without critical degradation of the breakdown voltage. The load pull measurements under a 1.95 GHz WCDMA signal have shown that a composite-collector HBT with a 400-nm thick collector layer operates with power-added-efficiency (PAE) as high as 53% at VCE = 3.5 V as a result of improved distortion characteristics. Despite the thin collector design, collector-emitter breakdown voltage of 11 V was achieved even at current density of 10 kA/cm2. The composite-collector HBT has even greater advantage for future low voltage (< 3 V) applications where maintaining PAE and linearity becomes one of the critical issues.