A 23-dBm 60-GHz Distributed Active Transformer in a Silicon Process Technology

• Published in: IEEE transactions on microwave theory and techniques Vol. 55; no. 5; pp. 857 - 865
• Main Authors: Pfeiffer, U.R., Goren, D.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amplifiers; Applied sciences; Circuit properties; Computer simulation; Differential amplifiers; Distributed active transformer (DAT); Electric potential; Electric, optical and optoelectronic circuits; Electromagnetic modeling; Electronic circuits; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Feasibility; Frequency; Germanium silicon alloys; Inductors; Magnetic devices; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; millimeter wave; Millimeter wave technology; on-chip power combining; power amplifier (PA); Power amplifiers; Receivers & amplifiers; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon germanides; Silicon germanium; silicon germanium (SiGe); Slabs; Transformations; Transformers; wireless communication; Wires; Performance evaluation; Electric transformer; Output power; Scalability; Differential amplifier; Microwave; silicon germanium (SiGe); Inductor; Implementation; wireless communication; Millimetric wave; Power combiners; Coupling factor; Multistage circuit; Semiconductor alloys; Microwave power amplifiers; power amplifier (PA); Compact design; Cascode connection; Electromagnetic wave; Combiner circuit; millimeter wave; Simulation; Distributed active transformer (DAT); on-chip power combining; Equivalent circuit; Feasibility; Impedance; Gain
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2007.895654

In this paper, a distributed active transformer for the operation in the millimeter-wave frequency range is presented. The transformer utilizes stacked coupled wires as opposed to slab inductors to achieve a high coupling factor of k f =0.8 at 60 GHz. Scalable and compact equivalent-circuit models are used for the transformer design without the need for full-wave electromagnetic simulations. To demonstrate the feasibility of the millimeter-wave transformer, a 200-mW (23 dBm) 60-GHz power amplifier has been implemented in a standard 130-nm SiGe process technology, which, to date, is the highest reported output power in an SiGe process technology at millimeter-wave frequencies. The size of the output transformer is only 160times160 mum 2 and demonstrates the feasibility of efficient power combining and impedance transformation at millimeter-wave frequencies. The two-stage amplifier has 13 dB of compressed gain and achieves a power-added efficiency of 6.4% while combining the power of eight cascode amplifiers into a differential 100-Omega load. The amplifier supply voltage is 4 V with a quiescent current consumption of 300 mA