Abstract-A Standing-Wave Architecture for Scalable and Wideband Millimeter-Wave and Terahertz Coherent Radiator Arrays

 Hossein Jalili,  Omeed Momeni,

http://ieeexplore.ieee.org/document/8089761/

In this paper, we present a new architecture for implementation of millimeter-wave (mm-wave) and terahertz (THz) radiator arrays based on standing-wave properties. This structure is a continuous distributed coherent array that avoids lossy and parasitic coupling networks. Moreover, it can be scaled simply by extending the size of the structure and replicating the unit cell. The absence of coupling parasitics in addition to the unique characteristics of standing waves allows us to extend the tuning range without using varactors. The 0.34-THz four-element radiator array is designed and fabricated in a 130-nm SiGe BiCMOS process using microstrip transmission lines as the standing-wave mediums and on-chip patch antennas to radiate the desired fourth harmonic of the oscillation. The circuit was measured with no post processing or silicon lens and has 5.9% frequency tuning range (332.5-352.8 GHz) with less than 6-dB output power variation across the band. It consumes 425-mW power from 1.8-V supply and the radiated power is -10.5 dBm at center frequency with -98.2 dBc/Hz phase noise at 10-MHz offset frequency.

Architecture Cracks Terahertz Power Generation And Tuning

http://mwrf.com/active-components/architecture-cracks-terahertz-power-generation-and-tuning
My Note: I came across this article yesterday on the Virginia Diodes Facebook page

Nancy Friedric

CMOS circuits have been proven suitable for sub-millimeter-wave and terahertz frequencies from 300 GHz to 3 THz. To realize a complete terahertz system, however, a challenge still remains in the high-power, tunable signal source. When using LC-resonator-based voltage-controlled oscillators (VCOs), performance begins to degrade beyond 100 GHz. While frequency multipliers solve some of these problems, they require a high-power external source—something undesirable in a fully integrated terahertz source. One alternative could lie in a VCO architecture based on coupled oscillators in a loop configuration, which has been created by Yahya M. Tousi and Ehsan Afshari from Cornell University and Omeed Momeni from the University of California at Davis.

To realize a high-power VCO at the sub-millimeter-wave and terahertz band, three requirements must be met. First, the signal source should be able to generate high harmonic power above the device f_max. The generated power also should be efficiently delivered to the output load. Finally, a frequency-tuning mechanism is needed that will not adversely affect the first two requirements.

In this approach, multiple core oscillators are coupled to generate, combine, and deliver their harmonic power to the output node without using varactor diodes. Leveraging the theory of nonlinear dynamics, the researchers are able to control the coupling between the cores. In doing so, they can set their phase shift and frequency.

Because of the new architecture’s approach to frequency control, the tradeoff between frequency tuning and power generation in conventional VCOs is largely resolved. Frequency tuning can therefore be achieved while maintaining high output power in the sub-millimeter-wave frequency range. The engineers’ approach also provides an effective way to generate and combine the harmonics of the fundamental frequency from multiple core oscillators.

The researchers fabricated two high-power terahertz VCOs in a 65-nm low-power (LP) bulk process. According to measurements, the first one provides 0.76 mW output power at 290 GHz with a 4.5% tuning range. The second VCO puts out 0.46 mW at 320 GHz with a 2.6% tuning range. See “A Novel CMOS High-Power Terahertz VCO Based on Coupled Oscillators: Theory and Implementation,” IEEE Journal Of Solid-State Circuits, Dec. 2012, p. 3032.

Abstract-Low-cost Terahertz Signals on Silicon Chips

MY NOTE: This is not new information to readers of this blog, but it was just posted in this format and it's certainly worthy of posting here. 
http://www.flintbox.com/public/project/22315/

Posted:Nov 9, 2012 1:58 PM

A mathematical model was developed to generate and process signals in the terahertz range at 10,000 times more power that previously possible, and all this with the inexpensive CMOS microchip technology used in many everyday electronic devices.
A mathematical model was developed to generate and process signals in the terahertz range at 10,000 times more power that previously possible, and all this with the inexpensive CMOS microchip technology used in many everyday electronic devices. Terahertz radiation, used in airport body scanners, promises a wide range of applications in communications as well as science and medicine, from detecting cancer and tooth decay to inspection food through its packaging. Such applications require a portable, low-power radiation source, but most terahertz sources are still bulky and expensive -- usually involving lasers and vacuum tubes, or more recently, compound semiconductors at lower terahertz frequencies -- none of which are cost-effective or suitable for integration of different digital blocks on the same chip.

The Cornell invention was demonstrated using CMOS technology, which offers low-cost, reliable fabrication of the entire analog/digital system. Remarkably, it can also be applied to other semiconductor processes and materials, with the same benefit of optimizing the output of virtually any circuit topology.               Potential Applications: Medical imaging, e.g. to detect tooth decay, skin cancer, cornea hydration, etc. Radar, e.g. UWB and compact range Communications, including short range, high data rate, broadband wireless access, etc. Remote sensing                                Advantages Maximizes signal power and frequency of circuit elements Compatible with virtually all semiconductor processes and materials (Si, GaN, etc.) Enables cost-effective, compact and portable terahertz radiation sources

  Researchers:   

Omeed Momeni

Ehsan Afshari

Additional Information

Momeni, O.; Afshari, E.; , "High Power Terahertz and Millimeter-Wave Oscillator Design: A Systematic Approach," Solid-State Circuits, IEEE Journal of , vol.46, no.3, pp.583-597, March 2011

Licensing Contact

Martin Teschl
mt439@cornell.edu
(607) 254-4454

CMOS Terahertz and mm-Wave Electronics: Reaching the Fundamental Limits

Date: 

 Wednesday, November 30, 2011 - 4:00pm - 5:00pm

Location: 

 Engineering Hall 2430 - Colloquia Room

http://www.eng.uci.edu/events/2011/11/cmos-terahertz-and-mm-wave-electronics-reaching-fundamental-limits

Center for Pervasive Communication and Computing
and
Nanoscale Communication Integrated Circuits Labs

Speaker :Prof. Omeed Momeni
Host:Payam Heydari 
 

There is a growing interest in terahertz and mm-wave systems for compact, low cost and energy efficient imaging and spectroscopy. Detection of concealed weapons, cancer diagnosis, food quality control, and breath analyses for disease diagnosis are among many examples that will rapidly flourish if compact and on-chip terahertz systems are realized. While CMOS can overcome these challenges, the best reported fmax of CMOS transistors fall well below terahertz frequencies. To overcome these drawbacks, we have introduced systematic methodologies for designing circuits and components operating close to and beyond the conventional limits of the devices. These circuit blocks can effectively generate, combine, and process signals from multiple devices to achieve performances orders of magnitude better than the state of the art. As an example, we show the implementation of a 482 GHz oscillator in a 65 nm CMOS process with an output power of 160 mW (-7.9 dBm), which is ~8,000 times more than any other CMOS sources at this frequency range. Using a similar methodology we design and implement a 107 GHz amplifier with a gain of 12.5 dB and saturated output power of >2.3 dBm in a 130 nm CMOS process. We also show a traveling-wave frequency multiplier for high power and wide-band terahertz and mm-wave signal generation. This signal source has twice the operating frequency and tuning range of the best reported CMOS multiplier. Moreover, to go beyond the conventional limitations of passive circuits, we developed a method to perform signal processing using 2-D electrical lattices. In this way, we introduced an electrical prism that can achieve a filtering quality factor that is orders of magnitude larger than the quality factor of the individual components in terahertz frequencies.

Bio

Omeed Momeni received his PhD degree in Electrical Engineering from Cornell University in 2011. He joined the faculty of Electrical and Computer Engineering Department at University of California, Davis in 2011. He is currently a visiting professor in Electrical Engineering and Computer Science Department at University of California, Irvine. From 2004 to 2006, he was with the National Aeronautics and Space Administration (NASA), Jet Propulsion Laboratory (JPL), to design L-band transceivers for synthetic aperture radars (SAR) and high power amplifiers for Mass Spectrometer applications. His research interests include mm-wave and terahertz integrated circuits and systems.

Terahertz chips could make portable scanners for medicine

http://www.news.cornell.edu/stories/March11/terahertzChip.html

Jason Koski/University Photography

Ehsan Afshari, right, and graduate student Omeed Momeni design microchips that generate terahertz radiation for medical, dental and security applications.

By Bill Steele

Terahertz radiation, used in airport body scanners, promises a wide range of applications in science and medicine, from detecting cancer and tooth decay to inspecting food through its packaging.

Its range of wavelengths -- between microwaves and infrared light -- penetrate cloth, paper and leather and a very short distance into the skin -- all without the damaging effects of X-rays. Terahertz devices also can detect unique signatures of explosives.

Such applications require a portable, low-power radiation source, but most terahertz sources are still bulky and expensive, usually involving lasers and vacuum tubes. Cornell researchers have now demonstrated new ways to generate signals in the lower end of the terahertz range on a microchip at 10,000 times more power than previously possible, with the inexpensive CMOS chip technology used in many everyday electronic devices.

Provided/Afshari Lab

Microphotos of high-frequency CMOS chips developed in Prof. Ehsan AFshari's lab: above, an oscillator circuit; below, a frequency doubler. Large white areas in the images are contact points where external wires are attached to the chip. At radio frequencies, the length of wires is critical A new mathematical analysis enables researchers to design circuit elements to get the best possible performance.

Solid-state terahertz devices could range from hand-held medical scanners to portable weapons scanners for the military, said Ehsan Afshari, assistant professor of electrical and computer engineering, who reported on new approaches to generating high-frequency signals at the 2011 IEEE International Solid-State Circuits Conference Feb. 22 in San Francisco. A paper on related work appears in the March 2011 issue of the IEEE Journal of Solid-State Circuits.

The maximum frequency at which a chip can operate and the power it can put out are limited by the physical characteristics of the material. Oscillator circuits seldom reach the maximum possible frequency or power, said Afshari.

The best previous effort on a CMOS chip generated a signal at 410 GHz with an output power of 20 nanowatts (billionths of a watt). Using new techniques, Afshari has built CMOS oscillators operating at up to 480 GHz with an output of 0.2 milliwatts (thousandths of a watt) -- 10,000 times higher power. These are still very low-power signals, roughly comparable to Bluetooth devices, but enough for medical instruments that might be held close to the skin.

"We broke the record, but it's more important than that," Afshari said. "Nobody can break our record because we have a method that can look at any given process and come up with a topology that can guarantee the maximum power and frequency."

At radio frequencies, the length and shape of wires and other components are critical. Afshari and graduate student Omeed Momeni developed a mathematical analysis to calculate the characteristics of these components that would achieve the highest possible frequency and power on a given chip material.

The next step, Afshari said, will be to work with Cornell researchers who are familiar with gallium nitride, a material capable of operating at much higher frequencies and with power levels up to 2,000 times more than can be handled by silicon. Cornell is considered a world leader in gallium nitride research, he noted. Computer simulations, Afshari said, indicate that a gallium nitride device could generate frequencies up to 1 terahertz with enough power to scan a 1-meter-square area 10 meters away, with resolution down to 1 square centimeter -- more than adequate for a soldier or police officer to scan an approaching stranger for weapons.

The research was supported by the Semiconductor Research Corporation through the Center for Circuit & System Solutions and by the National Science Foundation. Chips were manufactured through the Taiwan Semiconductor Manufacturing Company University Shuttle Program.

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