H. Xu, V. Kukshya, and T. S. Rappaport, "Spatial and temporal characteristics of 60-GHz indoor channels," IEEE Journal on Selected Areas in Communications, Vol. 20, No. 3, pp. 620–630, April 2002.

60 GHz RFIC and Antenna Design Initiative

• Research Focus
• Graduate Students
• Recent Papers
• Description of Research
• Current Research Ideas
• Useful References

L. Ragan, A. Hassibi, T. S. Rappaport, C. L. Christianson, “Novel On-Chip Antenna Structures and Frequency Selective Surface (FSS) Approaches for Millimeter Wave Devices,” IEEE 66th Vehicular Technology Conference (VTC), Baltimore, MD, Oct. 1-3, 2007, pp. 2051-2055.

Research Focus

Our research focus is to develop low-power on-chip antennas and to explore novel low-power RF design technologies and position algorithms, as well as a system for location, direction finding, and channel sensing.

Take a look at our RF Integrated Circuits and Millimeter-Wave Lab. - Now available for outside users!

Graduate students working with Prof. Rappaport

• Felix Gutierrez
• James Murdock
• Eshar Ben-Dor

Some Recent 60 GHz Papers

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Description of Research

It is only recently, in the past 5 to 7 years, that worldwide governments have realized that semiconductor technologies may someday be produced at millimeter wave frequencies at reasonable cost. Today, federal governments in the US , Japan , and the EU have allocated spectrum at 60 GHz which has 7 GHz bandwidth available. This allocation offers an unprecedented opportunity to provide high bandwidth wireless connectivity, and is a clear indication that within a decade, it should be possible to provide truly massive bandwidths within local areas, at rates of several to tens of gigabits per second, so that massive information sources may be transmitted wirelessly within seconds or milliseconds. The capabilities of massively broadband wireless devices, operating at carrier frequencies of 60 GHz to 90 GHz, and above, will enable an era of ubiquitous portable content, and will eliminate today's bulky, cumbersome storage devices such as hard drives, large paper texts, and CDs. Based on results of this research project, and the one-time investment in faculty and infrastructure at NYU WIRELESS at New York University and NYU-Poly, bulky present-day storage devices will be replaced with wireless, low-power RF devices that enable incredible wireless data rates to transport the contents of low-cost silicon memory banks. Basic research in RF millimeter wave integrated circuit technology, combined with new theoretical and implementation approaches for new massive bandwidth media access protocols, is critical for US competitiveness, and critical infrastructure is provided through this project.

Prof. Rappaport's research group will work to solve challenging problems to enable accurate design and implementation of low-cost, low-power transceivers in this frequency range of 60 GHz and above.

Advanced CMOS manufacturing, at geometries finer than 0.1 micron, provides active devices which are adequate, with proper matching networks, for 60 GHz wireless applications. Our research will therefore concentrate in the following areas:

1. Characterization of metals on standard CMOS processes at 60 GHz
2. Design of tuning, matching, and combining networks using these metals
3. Innovative combination of active and on-chip passive devices to construct basic transceiver building blocks
4. Interfaces with multi-GHz data streams in modulators and demodulators
5. Adaptive, directive antenna structures
6. Packaging techniques

In addition, faculty with expertise in MAC and Network design layers will explore the memory structures required to pipeline data and to explore multi-user issues at data rates of several Gbps. This research problem requires new thinking in order to allow proper handling and buffering of data at this enormous rate. Furthermore, queue sizes and the power/bandwidth tradeoffs for a network of massively broadband nodes will be unlike any previous problem domain. This interdisciplinary team will address the following additional critical areas:

• Real-time digital pipelining for implementing a digital MAC
• Buffering and media access approach for Massively Broadband data transfers
• Communication protocols and their performance
• Network Architectures for connecting these devices

The pioneering research contemplated here, which will combine RFIC design and semiconductor research capabilities with MAC and Network layer research, will pave the way for basic research that could lead to single chip data transceivers that reliably transfer more than 5 Gb/s data for more than 5 meters in military or commercial applications, at a price of under $5 (at volumes of 5 million per month) in less than 5 years. This will lead to very-low-cost transceivers (under $1) that will enable unprecedented bandwidth networks for military, industries and consumers around the world as the production volumes ramp over the next decade, and as wireless replaces mechanical hard drives and hard media, such as CDs and books.

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"The Emerging World of Massively Broadband Devices: 60 GHz and Above," Keynote Speech, Virginia Tech 2009 Symposium & Wireless Summer School, Blacksburg, VA, June 4, 2009.

FCC Frequency Spectrum Chart

Some of Our Current Research Ideas

On-chip Antennas Using Frequency Selective Surface (FSS)

• Utilizing only the metal interconnect layers of a high-speed integrated circuit process, a proposed structure is expected to result in efficient on-chip antennas and arrays for radio frequency integrated Systems On Chip (SOCs).
• If the shield plane of a semiconductor is patterned with holes to create a mesh, a Frequently Selective Surface (FSS) is produced and can be arranged to provide high wave impedance over a narrow band around the operating frequency. This results in a reflection of the wave from the antenna toward the semiconductor chip in phase with the wave propagating away from the chip.
• Energy is radiated in the half space away from the top surface of the chip where the antenna lies, adding to the energy normally radiated in this direction. This prevents losses in the semiconductor and reduces them substantially in the shield plane, as induced currents are minimized.
• There are various geometries of mesh structures and techniques for designing them that are applicable to the on-chip antenna with FSS configuration. Variable capacitors could be realized with structures in the silicon, such as varactor diodes or MOS capacitors, which can be voltage tuned.
• It may be possible, through careful design, to allow limited interconnect of semiconductor circuits through the FSS, and the FSS could serve as a power or ground plane for other circuitry on the chip.
• Multiple metal layers can be used to realize thick FSS structures, for example a resonant "coil" which would have multiple turns, or a "thick coil" which would be realized on multiple layers parallel connected by vias. One could also utilize multi-layer capacitors in resonant structures for FSS using this technique.
• An "Active FSS" can also exist, where each resonant node of the FSS is enhanced with an on-chip amplifier to compensate for losses in metal and/or variable capacitors, if used.
• After further research and development of design techniques, the projected results are much lower-cost communications and radar systems in the mm-wave portion of the radio frequency spectrum.

Efficient Laptop Antenna Array

• Developed method of inexpensive design for utilizing combination of PWB antennas and PWB FSS in a laptop lid to facilitate one-sided, efficient, easily matched antennas for Multiple Input Multiple Output (MIMO) antennas and/or steerable arrays, with advantages in coverage and data throughput to wireless networks.
• Use of FSS allows for an antenna to be placed in close proximity to a "ground" or "power supply" plane of a printed wiring board with enhanced efficiency of antennas in difficult environment of laptop lid, negating harmful effects of LCD structure.
• FSS structures are inherently narrow band, so providing the necessary bandwidth in the FSS design could become a challenge.
• Applications include enhanced laptop service from wireless networks, offering better range, coverage, and/or data throughput. In the future, the design could be used in any structure to facilitate efficient antennas in the presence of LCD.

Embedded On-chip Antennas and Signal Processing for Futuristic ICs, Including Adaptive and Lossy Structures

• Frequency Selective Surface (FSS) reflects in phase/out of phase with metal sheet behind it. Application is laptop with FSS on the screen. Picture an FSS with lossy dielectric between it and metal. Have different reflectance/reflective at different frequencies. Receiver could be much easier than Transmitter.
• If FSS is passive on a chip, you can switch really quickly because of close proximity of leads and device. Super low power since switching doesn't take much power at all.
• On-chip FSS could be used as RF filter, attenuate a loud interfering signal in nearby band, by using FSS and exploiting its tunabilty as part of an antenna or at high frequency mixer. Use FSS at the antenna to do RF tuning as part of the antenna circuit, which would make 60 GHz and higher frequency devices "tunable" with "filtering" in a cheaper way than conventional down conversion and filtering.
• Use multiple layers of FSS stacked above each other to make different frequencies invisible or visible.
• Put FSS structures (either single or multi-layers on skin of a surface (say an airplane or cell phone) where the FSS can reflect certain frequencies (such as radar or unwanted signals), and that the FSS can be switched to different frequencies through switching of FSS elements.
• On-Chip - control an active angle, detect or sense if RF is there (very low power). Can do on-chip or off-chip, depends on physically the area you have to work with, but we can sense RF coming from different angles with FSS.
• FSS Array - active in the sense that radiation is detected and then we (the FSS device, the chip, the radio, etc.) take some action - reflect, absorb, attenuate, control an antenna steering, or a reconfiguration of the FSS, based on what radiations was sensed.
• Switch at antenna/FSS, on-chip to do down conversion and filtering all at once -- tunable by FSS and switching.
• RFID, remove baseband protocol and now do switching on/off with FSS for synch/identification/communication in close proximity - very low battery drain and enough frequency selectivity/sensitivity to allow it to work in crowded spectrum. Possible applications in key fobs for cars, RFID handshake in grocery stores, etc.
• Harvest power by tuning FSS to grab in-air power at specific "loud" frequencies, and then collect and store that received signal power. FSS will create a tuned/resonant circuit or will change an antenna pattern in order to adjust the device to harvest maximum amount of power due to ambient RF environment in which the FSS device is in. Pervasiveness of RF devices will allow eventual collection of power (switching does not need much power at all to do).
• Sleep mode for Harvesting application, so that there is not a big current drain when not needed.
• Automatic VSWR tuning or antenna matching, using FSS in cell phone -- create an impedance matching circuit in an IC with FSS.
• Simple environment sense capability.
• FSS in the device, say a phone, its sitting there, very cheap. When you put the cell phone down on the metal table, the FSS makes the table "disappear" by reflecting down. Try finite number of FSS settings to block out objects, heads, dielectric surfaces, metal surfaces. FSS built into the case of phone or laptop, with finite combinations of FSS settings for typical usage cases.
• Demodulate with switching, in a low loss fashion. Make the FSS dark to move energy to a sideband. If multiple channels coming in on same carrier, FSS makes one visible, and let the interference be completely attenuate inband, using switch rate matched to modulation of the desired/undesired signals.
• Generalize: Time Dependent, distributed FSS system. Low current switching no control. Binary changes of one or multiple switches.
• Can use active amplifiers on each varactor to get Q multiplier and better Q. Prior art optics has FSS with only 3 cells per wavelength. This helps reduce to practice, may be more viable.
• FSS on array can configure into end-fire antenna pattern, for use/applications in laptop or other dimension in form factor - can steer to edge. Possible use of FSS for MiMo and Beamsteering with end fire pattern.
• Low Profile transmission line antenna (like for 160m in 1985) - use the semiconductor or lossy conductor to serve as a "lossy ground' - this can allow us to do low profile antenna on chip.
• For on chip antenna, tune the loss in the ground or in the material between antenna and ground using FSS, and NOT the physical antenna elements (they stay etched as is). Punch holes in ground to get more loss, get sheet resistivity properly, can tune around the metal antenna element.
• Use metal in process, hot making metal using wire bonds for circuits and antennas.

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Some Useful References on 60 GHz

Propagation:

• Marcus, Michael and Bruno Pattan, "Millimeter Wave Propagation: Spectrum Management Implications," IEEE Microwave Magazine, June 2005.
• Xu, Hao, Vikas Kukshya, T. S. Rappaport, "Spatial Characteristics of 60-GHz Indoor Channels," IEEE Journal on Selected Areas in Communications, Vol. 20, No. 3, April 2002, pp. 620-630.
• C. R. Anderson and T. S. Rappaport, "In-Building Wideband Multipath Measurements at 2.5 and 60 GHz," IEEE Transactions on Wireless Communications, Vol. 3, No. 3, May 2004, pp. 922-928.

PHY:

• F. Gutierrez, T. S. Rappaport, J. Murdock, "Millimeter-Wave CMOS Antennas and RFIC Parameter Extraction for Vehicular Applications," IEEE 72nd Vehicular Technology Conference Fall (VTC), Ottawa, Canada, Sept. 6-9, 2010, pp.1-6. view
• Razavi, Bezad, "A 60GHz Direct-Converstion CMOS Receiver," ISSCC, San Fransisco, CA, February 9, 2005, 3 pp.
• Gunnarsson, Sten E., Camilla Karnfelt, Herbert Zirath, Rumen Kozhuharov, Dan Kuylenstierna, Arne Alping, Cristian Fager, "Highly Integrated 60 GHz Transmitter and Receiver MMICs in a GaAs pHEMT Technology."
• Tsal, Ming-Da, Huel Wang, Jul-Feng Kuan, Chih-Sheng Chang, "A 70GHz Cascaded Multi-Stage Distributed Amplifier in 90nm CMOS Technology."
• Hunag, Ping-Chen, Ming-Da Tsal, Huel Wang, Chun-Hung Chen, Chih-Sheng Chang, "A 114GHz VCO in 0.13um CMOS Technology," ISSCC, San Fransisco, CA, February 9, 2005, 3 pp.
• Floyd, Brian A., Scott K. Raynolds, Ullrich R. Pfeiffer, Thomas Zwick, Troy Beukema, Brian Gaucher, "SiGe Bipolar Transceiver Circuits Operating at 60GHz," IEEE Journal of Solid-State Circuits, Vol. 40, No. 1, January 2005.
• Winkler, Wolfgang, Johannes Borngraber, Bemd Heinemann, Frank Herzel, "A Fully Integrated BICMOS PLL for 60GHz Wireless Applications," ISSCC, San Fransisco, CA, February 9, 2005, 2 pp.

Systems:

• "Giga bits per second wireless at 60GHz: Ultra Wide Band and beyond" view
• Noreus, Jonas, Maxime Flament, Arne Alping, Hebert Zirath, "System Considerations for Hardware Parameters in a 60GHz WLAN" view
• Smulders, Peter, "Exploiting the 60GHz Band for Local Wireless Multimedia Access: Prospects and Future Directions" view
• "60GHz Wireless Systems Advantages and Challenges" view
• Ebert, Jean-Pierre, Eckhard Grass, Ralf Irmer, Rolf Kraemer, Gerhard Fettweis, "Paving the Way for Gigabit Networking" view
• Fettweis, Gerhard, Ralf Irmer, "WIGWAM: system concept development for 1 GBit/s air interface" view
• Doan, Chinh H., Sohrab Emami, David A. Sobel, Ali M. Niknejad, and Robert Brodersen, "Design Considerations for 60GHz CMOS Radios," IEEE Communications Magazine, December 2004.
• R. C. Daniels, J. N. Murdock, T. S. Rappaport, R. W. Heath, "60 GHz Wireless: Up Close and Personal," IEEE Microwave Magazine, Vol. 11, No. 7, December 2010, pp.44-50. view

Standards:

• "Wireless Local Area Networks and Fixed Wireless Access" view
• "WP5, D11 - Spectrum study and standardization status" view
• "Project IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)" view
• "Proposal on Establishment of a New Expert Group on Millimeter-Wave Communication Systems" view
• Pollock, T., K. Saleem, E. Skafidas, C. Liu, "Preliminary 60GHz Channel Measurements," Presentation at 802.15 TG3c Meeting, Vancouver, Canada, November 2005.
• Grass, Eckhard Maxim Piz, Frank Herzel, Rolf Kraemer, "Draft PHY Proposal for 60GHz WPAN," Presentation for IEEE 802.15. view

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This work is sponsored by the Army Research Laboratory, Project W911F-08-0438, the Army Research Office, Project W911NF-05-2-0044, and the Advanced Microelectronics Research Center of The University of Texas at Austin.

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