28 research outputs found
Wireless Testing of Integrated Circuits.
Integrated circuits (ICs) are usually tested during manufacture by means of automatic testing equipment (ATE) employing probe cards and needles that make repeated physical contact with the ICs under test. Such direct-contact probing is very costly and imposes limitations on the use of ATE. For example, the probe needles must be frequently cleaned or replaced, and some emerging technologies such as three-dimensional ICs cannot be probed at all. As an alternative to conventional probe-card testing, wireless testing has been proposed. It mitigates many of the foregoing problems by replacing probe needles and contact points with wireless communication circuits. However, wireless testing also raises new problems which are poorly understood such as: What is the most suitable wireless communication technique to employ, and how well does it work in practice?
This dissertation addresses the design and implementation of circuits to support wireless testing of ICs. Various wireless testing methods are investigated and evaluated with respect to their practicality. The research focuses on near-field capacitive communication because of its efficiency over the very short ranges needed during IC manufacture. A new capacitive channel model including chip separation, cross-talk, and misalignment effects is proposed and validated using electro-magnetic simulation studies to provide the intuitions for efficient antenna and circuit design. We propose a compact clock and data recovery architecture to avoid a dedicated clock channel. An analytical model which predicts the DC-level fluctuation due to the capacitive channel is presented. Based on this model, feed-forward clock selection is designed to enhance performance. A method to select proper channel termination is discussed to maximize the channel efficiency for return-to-zero signaling.
Two prototype ICs incorporating wireless testing systems were fabricated and tested with the proposed methods of testing digital circuits. Both successfully demonstrated gigahertz communication speeds with a bit-error rate less than 10^â11. A third prototype IC containing analog voltage measurement circuits was implemented to determine the feasibility of wirelessly testing analog circuits. The fabricated prototype achieved satisfactory voltage measurement with 1 mV resolution. Our work demonstrates the validity of the proposed models and the feasibility of near-field capacitive communication for wireless testing of ICs.PHDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/93993/1/duelee_1.pd
Optical interconnect for integrated circuits
This thesis presents the research pertaining to the development of essential components of optical interconnect between dies in a package, involving both guided and free-space propagation of light. In order to pursue such an objective, it required the development of a simpler approach to the design of planar silica lens pairs; develop the technology for fabricating such lens pairs, and modeling the critical factors, like alignment non-idealities, that affect the optical loss of such a scheme involving both guided and free-space propagation.
A methodology based on the ABCD matrix method has been developed to design and evaluates the performance of a planar silica lens pair system for a prescribed (âidealâ) free-space propagation distance. The optical loss of a designed system under various fabrication and experimental imperfections has been calculated and verified against the simulation results obtained from the commercial beam propagation method (BPM) software, BPM_CAD by Optiwave.
A two-level optical system comprising of a planar silica lens pair and a pair of 45° micromirror, which is equivalent to a chip to chip optical interconnects in a 3D integrated system, has been theoretically analysed for optical loss due to micromirrors deviation from the ideal 45° and an angular tilt between the two levels.
For the implementation of the planar silica lens pair, a hollow cathode PECVD system was used to deposit low stress thick graded index silica film on silicon wafer from a mixture of O2/SiH4/CF4 gases. Technique of depositing low stress thick fluorine doped silica film was developed and films up to 38 ”m thickness with very low compressive stress (16 Mpa) were deposited on silicon substrate. Lens front-face curvature was defined by vertical deep oxide etch using a state of art STSâICP Advanced Oxide Etch (AOE) system.
The planar silica lens pair designed for 200 and 500 ”m of âidealâ free-space propagation distance were fabricated and optically tested. A successful implementation of such a scheme, involving guided and free-space optical propagation has been demonstrated for the first time.
Practical demonstration and optical characterization of in-plane chip to chip optical interconnects has been performed, however, integration of 45° micromirror and practical demonstration of stacked-die optical interconnect based on planar silica lens pair has been left for future work
Topical Workshop on Electronics for Particle Physics
The purpose of the workshop was to present results and original concepts for electronics research and development relevant to particle physics experiments as well as accelerator and beam instrumentation at future facilities; to review the status of electronics for the LHC experiments; to identify and encourage common efforts for the development of electronics; and to promote information exchange and collaboration in the relevant engineering and physics communities
Wireless Terahertz Communications: Optoelectronic Devices and Signal Processing
Novel THz device concepts and signal processing schemes are introduced and experimentally confirmed. Record-high data rates are achieved with a simple envelope detector at the receiver. Moreover, a THz communication system using an optoelectronic receiver and a photonic local oscillator is shown for the first time, and a new class of devices for THz transmitters and receivers is investigated which enables a monolithic co-integration of THz components with advanced silicon photonic circuits
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Polymer waveguide based optical interconnects for high-speed on-board communications
This dissertation presents a study of multimode polymer waveguide technology for use in board-level communication links for future data centres and supercomputers. The motivation for this work comes from the severe interconnection bandwidth challenges faced by the conventional electrical interconnections technology and the potential performance advantages of optical interconnections. This thesis presents the work to address the bandwidth bottleneck by developing high-bandwidth multimode polymer waveguides. The use of multimode waveguides provides relaxed alignment tolerances enabling low-cost assembly tools. Siloxane polymer materials developed by Dow Corning Corporation are chosen to form the waveguides in this work due to their favourable optical properties (optical losses as low as 0.03 dB/cm and the ability to withstand temperatures in excess of 350 °C) that allow the waveguides to be directly integrated on printed circuits boards (PCBs) using conventional manufacturing processes. Useful design rules for the use of the multimode polymer waveguides are theoretically derived while the bandwidth-length products are investigated under various launch conditions. Frequency-domain measurements and ultra-short pulse measurements are then carried out to investigate the bandwidth performance of the polymer waveguides under different launch conditions and with lateral misalignments. The instrument-limited frequency-domain measurements show that these waveguides exhibit bandwidth-length products (BLPs) of at least 35 GHzĂm, while the pulse broadening measurements reveal the actual BLPs to be in excess of 70 GHzĂm under a 50 ÎŒm multimode-fibre (MMF) launch and 100 GHzĂm for a restricted launch across a wide range of input offsets (>±10 ÎŒm). This shows the potential for data transmission rates of 100 Gb/s and beyond over a single waveguide channel. A theoretical model is developed using the measured refractive index profile and good agreement with the above experimental results is found. The effects of graded refractive index profiles on the performance of waveguide components (bends, crossings) are also investigated, demonstrating that appropriate refractive index engineering can provide enhanced waveguide loss performance while exhibiting adequate bandwidth. Waveguide bends with excess loss below 1 dB for a radius >6 mm, crossings with loss less than 0.02 dB/crossing while exhibiting adequate link bandwidth (>47 GHzĂm) can be achieved for a MMF launch. On this basis, advanced modulation formats are investigated across the board-level waveguide links for further increasing the on-board data rates. Record NRZ-based 40 Gb/s and 56 Gb/s PAM-4 based data transmission over a 1 m long multimode polymer spiral waveguide are theoretically and experimentally demonstrated
Advanced Trends in Wireless Communications
Physical limitations on wireless communication channels impose huge challenges to reliable communication. Bandwidth limitations, propagation loss, noise and interference make the wireless channel a narrow pipe that does not readily accommodate rapid flow of data. Thus, researches aim to design systems that are suitable to operate in such channels, in order to have high performance quality of service. Also, the mobility of the communication systems requires further investigations to reduce the complexity and the power consumption of the receiver. This book aims to provide highlights of the current research in the field of wireless communications. The subjects discussed are very valuable to communication researchers rather than researchers in the wireless related areas. The book chapters cover a wide range of wireless communication topics
Wide Bandgap Based Devices
Emerging wide bandgap (WBG) semiconductors hold the potential to advance the global industry in the same way that, more than 50 years ago, the invention of the silicon (Si) chip enabled the modern computer era. SiC- and GaN-based devices are starting to become more commercially available. Smaller, faster, and more efficient than their counterpart Si-based components, these WBG devices also offer greater expected reliability in tougher operating conditions. Furthermore, in this frame, a new class of microelectronic-grade semiconducting materials that have an even larger bandgap than the previously established wide bandgap semiconductors, such as GaN and SiC, have been created, and are thus referred to as âultra-wide bandgapâ materials. These materials, which include AlGaN, AlN, diamond, Ga2O3, and BN, offer theoretically superior properties, including a higher critical breakdown field, higher temperature operation, and potentially higher radiation tolerance. These attributes, in turn, make it possible to use revolutionary new devices for extreme environments, such as high-efficiency power transistors, because of the improved Baliga figure of merit, ultra-high voltage pulsed power switches, high-efficiency UV-LEDs, and electronics. This Special Issue aims to collect high quality research papers, short communications, and review articles that focus on wide bandgap device design, fabrication, and advanced characterization. The Special Issue will also publish selected papers from the 43rd Workshop on Compound Semiconductor Devices and Integrated Circuits, held in France (WOCSDICE 2019), which brings together scientists and engineers working in the area of IIIâV, and other compound semiconductor devices and integrated circuits