This tutorial presents an overview of the technological advances in millimeter-wave (mm-wave) circuit components, antennas, and propagation that will soon allow 60-GHz transceivers to provide multigigabit per second (multi-Gb/s) wireless communication data transfers in the consumer marketplace. Our goal is to help engineers understand the convergence of communications, circuits, and antennas, as the emerging world of subterahertz and terahertz wireless communications will require understanding at the intersections of these areas. This paper covers trends and recent accomplishments in a wide range of circuits and systems topics that must be understood to create massively broadband wireless communication systems of the future. In this paper, we present some evolving applications of massively broadband wireless communications, and use tables and graphs to show research progress from the literature on various radio system components, including on-chip and in-package antennas, radio-frequency (RF) power amplifiers (PAs), low-noise amplifiers (LNAs), voltage-controlled oscillators (VCOs), mixers, and analog-to-digital converters (ADCs). We focus primarily on silicon-based technologies, as these provide the best means of implementing very low-cost, highly integrated 60-GHz mm-wave circuits. In addition, the paper illuminates characterization techniques that are required to competently design and fabricate mm-wave devices in silicon, and illustrates effects of the 60-GHz RF propagation channel for both in-building and outdoor use. The paper concludes with an overview of the standardization and commercialization efforts for 60-GHz multi-Gb/s devices, and presents a novel way to compare the data rate versus power efficiency for future broadband devices.

http://faculty.poly.edu/~tsr/wp-content/uploads/publications/abstract17.pdf

State of the Art in 60-GHz Integrated Circuits and Systems for Wireless Communications

The remarkable growth of wireless data traffic in recent times has driven the need to explore suitable regions in the radio spectrum to meet the projected requirements. In pursuance of this, millimeter wave communications have received considerable attention in the research fraternity. Due to the high path and penetration losses at millimeter wavelengths, antenna beamforming assumes a pivotal role in establishing and maintaining a robust communication link. Beamforming for millimeter wave communications poses a multitude of diverse challenges due to the large channel bandwidth, unique channel characteristics, and hardware constraints. In this paper, we track the evolution and advancements in antenna beamforming for millimeter wave communications in the context of the distinct requirements for indoor and outdoor communication scenarios. We expand the scope of discussion by including the developments in radio frequency system design and implementation for millimeter wave beamforming. We explore the suitability of millimeter wave beamforming methods, both, existing and proposed till midyear 2015, and identify the exciting new prospects unfolding in this domain.

Beamforming for Millimeter Wave Communications: An Inclusive Survey

Antenna-on-chip (AoC) and antenna-in-package (AiP) solutions are studied for highly integrated millimeter-wave (mmWave) devices in wireless communications. First, the background, regulations, standard, and applications of 60-GHz wireless communications are briefly introduced. Then, highly integrated 60-GHz radios are overviewed as a basis for the link budget analysis to derive the antenna gain requirement. Next, in order to have deep physical insight into the AoC solution, the silicon substrate's high permittivity and low resistivity effects on the AoC efficiency are examined. It is shown that the AoC solution has low efficiency, less than 12% due to large ohmic losses and surface waves, which requires the development of techniques to improve the AoC efficiency. After that, the AiP solution and associated challenges such as how to realize low-loss interconnection between the chip and antenna are addressed. It is shown that wire-bonding interconnects, although inferior to the flip-chip, are still feasible in the 60-GHz band if proper compensation schemes are utilized. An example of the AiP solution in a low-temperature cofired ceramic (LTCC) process is presented in the 60-GHz band showing an efficiency better than 90%. A major concern with both AoC and AiP solutions is electromagnetic interference (EMI), which is also discussed. Finally, the systems level pros and cons of both AoC and AiP solutions are highlighted from the electrical and economic perspectives for system designers.

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Antenna-on-Chip and Antenna-in-Package Solutions to Highly Integrated Millimeter-Wave Devices for Wireless Communications

The field of terahertz integrated technology has undergone significant development in the past ten years. This has included work on different substrate technologies such as III–V semiconductors and silicon, work on field-effect transistor devices and heterojunction bipolar devices, and work on both fully electronic and hybrid electronic–photonic systems. While approaches in electronic and photonics can often seem distinct, techniques have blended in the terahertz frequency range and many emerging systems can be classified as photonics-inspired or hybrid. Here, we review the development of terahertz integrated electronic and hybrid electronic–photonic systems, examining, in particular, advances that deliver important functionalities for applications in communication, sensing and imaging. Many of the advances in integrated systems have emerged, not from improvements in single devices, but rather from new architectures that are multifunctional and reconfigurable and break the trade-offs of classical approaches to electronic system design. We thus focus on these approaches to capture the diversity of techniques and methodologies in the field. This Review Article examines the development of terahertz integrated electronic and hybrid electronic–photonic systems, considering, in particular, advances that deliver important functionalities for applications in communication, sensing and imaging.

Terahertz integrated electronic and hybrid electronic–photonic systems

The design is presented of aperture-coupled microstrip line-fed patch antennas (ACMPAs) and 4times4 planar arrays on Ferro A6-S low-temperature cofired ceramic (LTCC) substrate operating in the 60-GHz frequency band. In addition to the traditional ACMPA design, air cavities processed inside the LTCC substrate are used to improve the bandwidth and gain of the antennas. The arrays are excited through the microstrip-line feed networks using quarter-wave matched T-junctions and using Wilkinson power dividers. The results show that ACMPAs and arrays can be fabricated with a standard LTCC process even for the millimeter-wave region. Good agreement is achieved between simulations and measurements. The measured S-parameters indicate impedance bandwidths of 9.5% and 5.8% for the array elements with and without an embedded cavity. The measured maximum gains for the 16-element patch arrays (with and without cavity) are 18.2 and 15.7 dBi, respectively.

60-GHz Patch Antennas and Arrays on LTCC With Embedded-Cavity Substrates

The recent advances in 60-GHz radios have called for the parallel development of compact and efficient millimeter-wave antennas. This brief addresses for the first time the design, fabrication, and characterization of on-chip inverted-F and quasi-Yagi antennas for 60-GHz radios. The design was made using the Zeland IE3D software package. The fabrication was realized with the back-end-of-line process of silicon substrates of low resistivity 10 /spl Omega//spl middot/cm. The characterization was conducted on wafer with Cascade Microtech coplanar probes and an HP8510XF network analyzer. The results show that the inverted-F antenna achieved a minimum return loss of 32 dB and a gain of -19 dBi at 61 GHz; while the quasi-Yagi antenna achieved a minimum return loss of 6.75 dB and a gain of -12.5 dBi at 65 GHz. Good agreement has been observed between the measured and simulated results.

/pdf/on-chip-antennas-for-60-ghz-radios-in-silicon-technology-4jpe1wsski.pdf

On-chip antennas for 60-GHz radios in silicon technology

A microstrip bandpass filter using stepped-impedance resonators is designed in low-temperature co-fired ceramic technology for dual-band applications at 2.4 and 5.2 GHz. New coupling schemes are proposed to replace the normal counterparts. It is found that the new coupling scheme for the interstages can enhance the layout compactness of the bandpass filter; while the new coupling scheme at the input and output can improve the performance of the bandpass filter. To validate the design and analysis, a prototype of the bandpass filter was fabricated and measured. It is shown that the measured and simulated performances are in good agreement. The prototype of the bandpass filter achieved insertion loss of 1.25 and 1.87 dB, S11 of -29 and -40 dB, and bandwidth of 21% and 12.7% at 2.4 and 5.2 GHz, respectively. The bandpass filter is further studied for a single-package solution of dual-band radio transceivers. The bandpass filter is, therefore, integrated into a ceramic ball grid array package. The integration is analyzed with an emphasis on the connection of the bandpass filter to the antenna and to the transceiver die

/pdf/dual-band-microstrip-bandpass-filter-using-stepped-impedance-3g3cmbdvzu.pdf

Dual-Band Microstrip Bandpass Filter Using Stepped-Impedance Resonators With New Coupling Schemes

This paper first presents a quasi-cavity-backed, guard-ring-directed, substrate-material-modulated slot antenna. The antenna, intended for use in highly integrated 60-GHz radios, is deliberately designed to exhibit capacitive input impedance to suit low-cost wire-bonding packaging and assembly technique. The antenna implemented in a thin cavity-down ceramic ball grid array (CBGA) package in low-temperature cofired ceramic (LTCC) technology has achieved an acceptable impedance bandwidth from 59 to 65 GHz with an estimated efficiency of 94%. At millimeter-wave (mm-wave) frequency 60 GHz, one of key challenges is how to realize low-loss interconnection between a radio chip and an antenna using wire-bonding technique. This paper then addresses this issue in the framework of antenna-in-package (AiP) design at 60 GHz and proposes a new solution to the challenge. Detailed wirebond design method and results are given. A major concern with AiP is the risk of the antenna coupling to the radio chip. This paper also evaluates this unwanted coupling and shows that the coupling from the in-package antenna to the on-chip inductor is lower than 30 dB for the worst case. These results clearly demonstrate the feasibility and promise of the elegant AiP technology for emerging high-speed short-range 60-GHz wireless communications.

/pdf/antenna-in-package-design-for-wirebond-interconnection-to-32rouctslt.pdf

Antenna-in-Package Design for Wirebond Interconnection to Highly Integrated 60-GHz Radios

A zero-index metamaterial (ZIM) structure is proposed for the gain enhancement of an antipodal tapered slot antenna (ATSA) at 60-GHz bands. The single ATSA loaded with the proposed ZIM cells exhibits a gain enhancement of up to 2.6 dB in the frequency band of 57–66 GHz. A prototype of a two-element ATSA array loaded with the ZIM cells measures a $\vert {\rm S}_{11} \vert$ of less than $-10~{\rm dB}$ and gain of 12–13.2 dBi over 57–66 GHz. The measurement results agree with the simulated ones and the gain enhancement of the ZIM cells is confirmed.

Gain Enhancement of 60-GHz Antipodal Tapered Slot Antenna Using Zero-Index Metamaterial

The propagation mechanisms of radio waves over intra-chip channels was studied with integrated antennas for wireless chip area networks. Test vehicles were designed and fabricated on silicon wafers of both low and high resistivities, respectively, using complementary metal oxide semiconductor (CMOS) processes. On-wafer measurements for propagation of radio waves over intra-chip channels were conducted in the frequency domain from 10 to 110 GHz with a network analyzer. Time-domain analysis was performed to characterize intra-chip radio channels and more importantly to understand the propagation mechanisms. It was found that path loss factor is constantly less than two and propagation delay of the first-arrival wave is significantly longer than that by free-space transmission. Thus, we concluded that the propagation of radio waves over intra-chip channels is mainly realized with surface wave rather than space wave. Surface wave is guided on air-wafer interface. In addition, effects of metal lines, in both parallel and normal placements with respect to wave propagation direction, on signal propagation were also investigated.

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Mei Sun

Papers

On-chip antennas for 60-GHz radios in silicon technology

Dual-Band Microstrip Bandpass Filter Using Stepped-Impedance Resonators With New Coupling Schemes

Antenna-in-Package Design for Wirebond Interconnection to Highly Integrated 60-GHz Radios

Gain Enhancement of 60-GHz Antipodal Tapered Slot Antenna Using Zero-Index Metamaterial

Propagation Mechanisms of Radio Waves Over Intra-Chip Channels With Integrated Antennas: Frequency-Domain Measurements and Time-Domain Analysis