An InGaP/GaAs Merged HBT-FET (BiFET) Technology and Applications to the Design of Handset Power Amplifiers

• Published in: IEEE journal of solid-state circuits Vol. 42; no. 10; pp. 2137 - 2148
• Main Authors: Metzger, A.G., Ramanathan, R., Jiang Li, Hsiang-Chih Sun, Cismaru, C., Hongxiao Shao, Rushing, L., Weller, K.P., Ce-Jun Wei, Yu Zhu, Klimashov, A., Tkachenko, Y.A., Bin Li, Zampardi, P.J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01.10.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amplifiers; Applied sciences; Bias; Bipolar transistor circuits; Circuit properties; Circuits; Corporate acquisitions; Devices; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; FETs; field effect devices; field effect transistor circuits; Gallium arsenide; Gallium arsenides; Heterojunction bipolar transistors; heterojunction bipolar transistors (HBTs); Low voltage; Manufacturability; microwave power amplifiers; modeling; MODFET; Other multijunction devices. Power transistors. Thyristors; Power amplifiers; Radiofrequency amplifiers; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; semiconductor epitaxial layers; semiconductor technology; Signal convertors; Silicon; Telephone sets; Transistors; Performance evaluation; Mobile phone; n channel; Review; semiconductor technology; Voltage control; Modeling; MODFET; Power transistor; Low voltage; Field effect devices; Heterojunction bipolar transistors; Bias circuit; Cost lowering; Microwave power amplifiers; Depletion mode; Large signal behavior; Field effect transistor circuits; Switching; Field effect transistor; Voltage standard; heterojunction bipolar transistors (HBTs); Power amplifier; semiconductor epitaxial layers; Bipolar transistor circuits
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2007.904318

The last decade has seen GaAs HBTs emerge as the dominant technology in wireless handset power amplifiers. Modern application requirements and size limitations have driven industry leaders towards the co-integration of depletion mode n-FET and GaAs HBT. The merger of Bipolar and FET, or BiFET, gives an additional degree of freedom in the design of advanced power amplifiers independent of a silicon controller. This paper provides an overview of the various techniques that can be used to join the two device technologies and then shows how a merged epitaxial structure, where an FET is formed in the emitter layers of an HBT, combines functional versatility with the high volume manufacturability needed to supply millions of power amplifiers at low cost. A large-signal model of the FET structure is developed which takes into account the unique physics and geometries of the device, including voltage-dependant parameters and charges on all four electrical terminals. Specific handset applications that can benefit or be enabled by BiFET are presented, such as on-off switching, low voltage bias controllers , Auto-Bias power amplifiers, and bias circuits with low or no voltage reference. When npn-only bias circuitry is limited to low voltage reference levels, HBT power amplifiers with BiFET bias stages are shown to have superior RF performance to their npn-only counterparts.