Microwave Class-F InGaP/GaAs HBT Power Amplifier Considering up to 7th-Order Higher Harmonic Frequencies

Masato SEKI  Ryo ISHIKAWA  Kazuhiko HONJO  

IEICE TRANSACTIONS on Electronics   Vol.E89-C    No.7    pp.937-942
Publication Date: 2006/07/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e89-c.7.937
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM2005)
Category: High-Speed HBTs and ICs
microwave,  class-F amplifier,  InGaP/GaAs HBT,  high-efficiency,  PAE,  base-collector capacitance,  

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The first realization of a class-F InGaP/GaAs HBT amplifier considering up to 7th-order higher harmonic frequencies, operating at 1.9-GHz band, is described. A total number of open-circuited stubs for higher harmonic frequency treatment is successfully reduced without changing a class-F load circuit condition, using a low-cost and low-loss resin (tan δ=0.0023) circuit board. In class-F amplifier design at microwave frequency ranges, not only increasing treated orders of higher harmonic frequencies for a class-F load circuit, but also decreasing parasitic capacitances of a transistor is important. Influence of a base-collector capacitance, Cbc, for power added efficiency, PAE, and collector efficiency, ηc, was investigated by using a two-dimensional device simulator and a harmonic balance simulator. Measured maximum PAE and ηc reached 74.2% and 76.6%, respectively, using a fabricated class-F InGaP/GaAs HBT amplifier with collector doping density of 21016 cm-3. In case circuit losses were de-embedded for the experimental results, PAE and ηc were estimated as 78.7% and 81.2%, respectively. These are very close to obtainable maximum PAE for the use of the InGaP/GaAs HBT.