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Prognostications from the edge.

Prognostications from the Edge

Future predictions are risky at best. However, even a fuzzy version of the future is better than none at all. My belief, with regards to editorial philosophy, is that content should follow a big picture, generic, informative format and leave the reader with warm intellectual feelings. In keeping with that belief, I would like to share my current vision of where the microwave component community is heading. During my ramblings it will become apparent that I believe that GaAs ICs are conquering the microwave circuit world, and, other than situations where large power levels are required, GaAs ICs (MMICs) will be the dominant microwave technology. One short disclaimer is that vacuum devices will be required where truly high power is needed and will become a full partner with MMICs. More specifically, as MMIC power levels increase, the requirement for high gain inside the vacuum envelope can be alleviated, allowing smaller interaction structures. Tubes and ICs can indeed work together synergistically.

Probably the largest external influence on the microwave community will be the deflation of the military budget and readjustment of the military and civilian market place ratio. Much has been written on this, and I will not attempt to broach this subject. Suffice it to say that there will be a shift to the civilian market place with automobile applications, including back-up and blind spot warning radars; and communications, including inter and intra office and mobile telecommunication-to-satellite, leading the way.

As I have already intimated, the dominant technology of the microwave and mm-wave community will continue to be MMICs. The 1980s saw a meteoric advance in technology from the first amplifier on a chip to sophisticated macro-cells with a hundred components on one chip. Chip costs have come down from $20 to $30/square millimeter to the current price of $7 to $9/square and will approach $1 to $2/square millimeter by the mid 1990s. Yield currently averaging 20 percent will increase to 30 percent over this same time frame. Currently, most MMICs are MESFET based, 0.5 [micrometer] minimum feature size and use ion implantation for active layer formation. These devices are frequency limited to the microwave frequency band and even decreasing feature size to 0.25 [micrometer] will not significantly impact V- and W-band performance. However, significant increases in performance will be obtained by implementing the MMIC approach with various alternate superstructures, such as HEMTs, P-HEMTs and lattice matched HEMTs, as well as vertical oriented structures, such as GaAs HBTs. All of these technologies will continue to erode the MESFET base, leading to a significant market share reduction for MESFET MMICs. These noted structures will use an MBE material base as throughput of epitaxial techniques will increase to meet production quantity magnitudes.

One of the most powerful tools for achieving low cost/high yield MMICs is CAD (together with CAM and CAT). Workstations will increase in complexity and cost will decrease to PC levels. Open framework architectures will be available in order that various tools may easily be interconnected through simple interface standards. Powerful electro-magnetic simulators will continue to shrink GaAs real estate size by efficient circuit compacting, and nonlinear simulators will allow modeling of nonlinear devices or systems. Design centering concepts will increase yield, and design to cost will allow cost/yield tradeoffs. New system simulators will allow design of complex systems down to component IC levels.

Testing, which today represents the largest cost portion of the chip/packaging/testing troika, will continue to be refined. Currently, on-chip probe testing is a reality with commercial availability to 40 GHz, and specialty availability to 60 GHz. By the mid 1990s, contact probe systems will be commercially available to 100 GHz with custom applications to 140 GHz. Pulse power testing algorithms today in R&D will be the rule for high power testing on wafer for ICs or hybrid devices at full device operational levels. Non-intrusive testing currently being implemented optically, will be refined to the point where it will be the dominant probing technology by the end of the decade. Qualification of products will be by QML (qualified manufacturer list) rather than QPL with its attendant inefficiencies. Qualification will be in a matter of weeks as opposed to the two-year cycle currently existing under QPL. High reliability, class S MMICs will be available qualified to MIL-M-38510 from multiple vendors. As failure mechanisms are identified, MTTFs for MESFETs, HEMTs and HBTs will approach > [10.sup.7] hours at 125[degrees]C channel temperatures.

Since GaAs is weakly piezo-electric, acoustic wave bulk and surface devices will be integrated on the same chip. Fundamental frequency acoustic oscillators, using thin-film resonators, will be available to Ka-band for exciter applications. Circuit design capture will be through a high level MHDL language. All specification sheets will have MHDL descriptions of the components involved. The obsolescence problem common to the military industry will decrease as MHDL descriptions of circuits become technology independent and easy to emulate in emerging technologies. Dominant GaAs wafer sizes will be 4" with specialty facilities available for 5" and 6". This size will be defined by the economic realities, the market place, rather than technology. Wafer characterization will be by nondestructive optical techniques. High throughput MOCVD reactors will challenge production MBE machines. Precision etching techniques, such as focused ion beam, will be used to fabricate gate recess structures for high yields. The middle of the decade will see the emergence of multifunction ICs (MF-MMICs). The chip architecture will be determined by economics alone.

Well, there you have it. I have the feeling that our industry is going through an exciting decade faintly reminiscent of the 1960s for digital circuits. A very important goal for our industry is that a commercial industrial base be developed. Although I see a stabilized military funding base, by the mid decade, it will be smaller in dollar magnitude. I hope to have the opportunity to make a prediction again for the next decade. I will see you in the 21st century!

Vladimir G. (Walt) Gelnavatch received as BS degree in electronic engineering from Monmouth College, West Long Branch, NJ in 1963 and his MS degree in electrical engineering from New York University in 1966. Since 1963, Gelnovatch has been employed by the US Army Electronics Technology and Devices Laboratory of LABCOM, Ft. Monmouth, NJ. During this time, he has engaged in fabrication of microwave integrated circuit (MIC) components, including original research into the synthesis of transistor amplifiers to cover octave bands in the L-, S- and C-band regions. He also has engaged in the development of reflectometer modeling for the purpose of automated, error-free measurements and has developed closed-form computer solutions and subsequent self-calibration algorithms. Gelnovatch has pioneered the introduction of optimal seeking CAD for MICs and has authored the first of these computer programs, Demon, for which he received the US Army R&D Achievement Award in 1972. Currently, he is director of the Microwave and Signal Processing Devices Division, which is responsible for the development of components for microwave, mm-waves, pulse power conditioning and acoustic signal processing for Army applications. Additionally, he is the Army Deputy Director of the MIMIC Program. From 1968 to 1979, Gelnovatch participated as a member of the Executive and Technical Committee of the International Solid-State Circuits Conference. In 1974, he participated in the IEEE/USSR POPOV Society Exchange Program and visited various Russian technical institutes. He is currently a member of various technical and professional organizations, including participation as army member of the Advisory Group on Electron Devices; past president of IEEE-MTT Society ADCOM; associate editor of the Microwave Journal; member of Industrial Advisory Board of the Electrical Engineering Department; and visiting professor of electrical engineering at the University of Virginia. Gelnovatch recently received the US Army's second highest decoration for Meritorious Civilian Service.
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Title Annotation:future of microwave component technology
Author:Gelnovatch, Vladimir G.
Publication:Microwave Journal
Date:Apr 1, 1991
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