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Zhang Yue Ping

APZhangEL

Prof. Zhang Yue Ping
Professor, School of Electrical & Electronic Engineering
College of Engineering, Nanyang Technological University, Singapore
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Zhang Yue Pingis a full Professor of Electronic Engineering with the School of Electrical and Electronic Engineering at Nanyang Technological University, Singapore, a Distinguished Lecturer of the IEEE Antennas and Propagation Society (IEEE AP-S), and a Fellow of IEEE.

Prof. Zhang was a Member of the Field Award Committee of the IEEE AP-S (2015-2017), an Associate Editor of the IEEE Transactions on Antennas and Propagation (2010-2016), and the Chair of the IEEE Singapore MTT/AP joint Chapter (2012). Prof. Zhang was selected by the Recruitment Program of Global Experts of China as a Qianren Scholar at Shanghai Jiao Tong University (2012). He was awarded a William Mong Visiting Fellowship (2005) and appointed as a Visiting Professor (2014) by the University of Hong Kong.

Prof. Zhang has published numerous papers, including two invited papers in the Proceedings of the IEEE and one invited paper in the IEEE Transactions on Antennas and Propagation. He holds 7 US patents. He received the Best Paper Award from the 2nd IEEE/IET International Symposium on Communication Systems, Networks and Digital Signal Processing, July 18–20, 2000, Bournemouth, U.K., the Best Paper Prize from the 3rd IEEE International Workshop on Antenna Technology, March 21–23, 2007, Cambridge, U.K., and the Best Paper Award from the 10th IEEE Global Symposium on Millimeter-Waves, May 24–26, 2017, Hong Kong, China. He received the prestigious IEEE AP-S Sergei A. Schelkunoff Prize Paper Award in 2012.

Prof. Zhang has made pioneering and significant contributions to the development of the antenna-in-package (AiP) technology that has been widely adopted by chip makers for millimeter-wave applications. His current research interests include the development of antenna-on-chip (AoC) technology and characterization of chip-scale propagation channels at terahertz for wireless chip area network (WCAN).

Millimeter-Wave In-Package Antennas

Antenna-in-package (AiP) technology, in which there is an antenna (or antennas) with a transceiver die (or dies) in a standard surface-mounted device, represents an important antenna technology achievement in recent years. AiP technology has been widely adopted by chip makers for 60-GHz radios and gesture radars. It has also found applications in 77-GHz automotive radars, 94-GHz phased arrays, 122-GHz imaging sensors, and 300-GHz wireless links. It is believed that AiP technology will also provide elegant antenna solutions to fifth generation and beyond operating in the lower millimeter-wave (mm-wave) bands. Thus, one can conclude that AiP technology has emerged as the mainstream antenna technology for various mm-wave applications. This lecture will start with a review of basic packaging ideas for AiP technology. Then it will focus on the co-design of antennas and packages. It will show that the antenna choice is usually based on those popular antennas that can be easily designed for the application; that the package choice is governed by the Joint Electron Device Engineering Council (JEDEC) for automatic assembly; and that the materials and processes choices involve tradeoffs among constraints such as electrical performance, thermo mechanical reliability, compactness, manufacturability, and cost. The talk also shows a probe-based setup to measure impedance and radiation of mm-wave in-package antennas. It goes on to give three AiP examples implemented, respectively, in a low-temperature co-fired ceramic process, an embedded wafer level ball grid array process, and a high-density interconnect process for 60-GHz applications. Finally, the lecture will present some recommendations on research topics to further the state of the art of AiP technology.

Terahertz On-Chip Antennas

An antenna or array plays a crucial role in a terahertz radiation source. Most conveniently, an on-chip antenna or array is used that is directly integrated with the terahertz signal-generation circuit on the same substrate. However, the substrate will inevitably create surface wave modes that result in poor radiation of the on-chip antenna into the air. This problem has been attacked by antenna designers in different ways for many years, with early efforts focused on gallium arsenide and recently on silicon substrates. The simplest solution is to insert a metal ground plane to isolate the antenna from the substrate. However, this is feasible only for a standard semiconductor process at a higher terahertz frequency to avoid the cancelation between the actual antenna and image currents. A similar approach is to use an artificial magnetic conductor to replace the metal ground plane, which allows reducing the coupling effect between the antenna and the substrate at a lower terahertz frequency. A direct but expensive technique is to remove the substrate in the area where the antenna produces high field strength by micromachining. This is important because it not only reduces the substrate loss due to low resistivity and high permittivity but can also reduce the problem of the mechanical stability of the whole chip. An ingenious solution is to cover the antenna with a superstrate made of either meta-film or dielectric. It has been found that the superstrate cannot be limited in area and must be large enough. But perhaps the most unusual method is to take advantage of substrate radiation by coupling energy through a lens on the back of the substrate. The lens should have the same dielectric constant as the substrate, the minimum radius for acceptable operation being one free-space wavelength for silicon. The lens also requires a matching layer to reduce reflection losses at the air– dielectric interface. The technology of quarter-wavelength matching layers is not well developed. This lecture will evaluate all these solutions and highlight their advantages and disadvantages, leading to suggestions on approaches to the design of terahertz on-chip antennas.

Differential Microstrip Antennas

The earliest antennas implemented by Hertz for the discovery of radio waves were of the dipole and loop varieties, which are differential in nature. It was Marconi who introduced the ground concept into antennas and developed single-ended monopole antennas for wireless transmission. Compared with differential antennas, single-ended antennas are smaller and therefore have dominated in antenna designs. Compared with single-ended circuits, differential circuits permit higher linearity and lower offset and make them immune to power supply variations, temperature changes, and substrate noise. As a result, differential circuits have dominated in integrated circuit designs. Differential circuits call for differential antennas. This is particularly essential in highly integrated system-on-chip and system-in-package solutions, where the system ground plane may be much smaller than one free-space wavelength. Differential antennas perfectly marry (match) with differential circuits. No lossy balanced/unbalanced conversion circuit is needed. As a result, the receiver noise performance and transmitter power efficiency are improved. This lecture will focus on differential microstrip antennas. First, the cavity model is expanded to analyze the input impedance and radiation characteristics of these antennas. Then the design formulas to determine the patch dimensions and the location of the feed point for single-ended microstrip antennas are examined to design differential microstrip antennas. It is found that the patch length can still be designed using the formulas for the required resonant frequency, but the patch width calculated by the formula usually needs to be widened to ensure the excitation of the fundamental mode using the probe feeds. The condition that links the patch width, the locations of the probe feeds, and the excitation of the fundamental mode is given. Next, the wide-band techniques for single-ended microstrip antennas are evaluated for differential microstrip antennas. A novel H-slot is proposed for differential microstrip antennas to improve impedance bandwidth. Finally, two differential microstrip antennas are illustrated, one in low-temperature co-fired ceramics for 60-GHz radios and another in CMOS for 650-GHz imagers.