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Rao Tummala

Other affiliations: Qualcomm, IBM, AVX Corporation  ...read more
Bio: Rao Tummala is an academic researcher from Georgia Institute of Technology. The author has contributed to research in topics: Interposer & Capacitor. The author has an hindex of 43, co-authored 623 publications receiving 11663 citations. Previous affiliations of Rao Tummala include Qualcomm & IBM.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors measured and analyzed glass interposer power distribution network (PDN) resonance effects on a high-speed through glass via (TGV) channel for the first time.
Abstract: In this paper, we measured and analyzed glass interposer power distribution network (PDN) resonance effects on a high-speed through glass via (TGV) channel for the first time. To verify the glass interposer PDN resonance effects on the TGV channel, glass interposer test vehicles were fabricated. With these test vehicles, glass interposer PDN impedance, channel loss, far-end crosstalk, and eye diagram are measured. Based on these measurements, glass interposer PDN resonance effects on the signal integrity of the high-speed TGV channel are analyzed. Due to low loss of the glass substrate, sharp high PDN impedance peaks are generated at the resonance frequencies. High PDN impedance peaks at the PDN resonance frequencies, which affect return current of the TGV channel, increase channel loss, crosstalks, and PDN noise coupling in the frequency domain and degrade eye diagram in the time domain. To suppress these glass interposer PDN resonance effects, a ground shielded-TGV scheme is proposed. The proposed ground shielded-TGV scheme includes two ground TGVs $200\;{{\mu \text{m}}}$ away from the signal TGV considering the design rules and includes package ground underneath the glass interposer. Effectiveness of the suggested grounding scheme on the resonance effects suppression is verified with three-dimensional electromagnetic simulation. The proposed shielded-TGV design successfully suppressed the glass interposer PDN resonance effects that results in the suppression of insertion loss, shielding of the crosstalk, and improvement of the eye diagram of the high-speed TGV channel.

15 citations

Proceedings ArticleDOI
20 Nov 2014
TL;DR: In this article, the authors proposed that placing the ground vias near the signal vias is the most promising solution for maximizing the advantages of the glass interposers in power distribution networks.
Abstract: D integration using a glass interposer and through glass via technologies is expected to improve the performance of a whole system significantly. However, due to the high quality factor of the glass substrate, the sharp impedance peaks on the Power Distribution Networks arise at the resonances. When the mode resonances occur, performance of a whole system could be degraded. Segmentation based impedance- estimation was used to analyze the PDN impedance and analyzed system degradation at resonance frequencies. To maximize advantages of the glass interposers, the PDN should be carefully designed to suppress the resonances. Considering the current status of the glass fabrication processes, we propose that placing the ground vias near the signal vias is the most promising solution for maximizing the advantages of the glass interposers.

15 citations

Journal ArticleDOI
TL;DR: This article demonstrates a next-generation high-performance 3D packaging technology with smaller form factor, excellent electrical performance, and reliability for heterogeneous integrati...
Abstract: This article demonstrates a next-generation high-performance 3D packaging technology with smaller form factor, excellent electrical performance, and reliability for heterogeneous integrati...

15 citations

Proceedings ArticleDOI
28 May 2013
TL;DR: The 3D IPAC VRM as mentioned in this paper is an ultra-thin glass module with through-vias and double-side integration of active and passive components to form functional modules.
Abstract: This paper presents a new active and passive integration concept called 3D IPAC (Integrated Actives and Passives) to address the power integrity in high-performance and multifunctional systems. The 3D IPAC consists of an ultra-thin glass module with through-vias and double-side integration of ultra-thin active and passive components to form functional modules. By integrating power ICs, storage capacitors and inductors, and high-frequency decoupling capacitors in ultra-thin (30-100 μm) glass substrates, 3D IPAC Voltage Regulator Module (3D IPAC VRM) provides a complete and ultra-miniaturized solution to power integrity. The ultra-thin 3D IPAC allows both actives and passives very close to each other and to the other active dies, resulting in improved performance over conventional SMDs and state-of-art IPDs for decoupling functions. The first part of the paper presents modeling results to show the benefits of the 3D IPAC module as a power integrity solution. The second part of the paper presents the fabrication and characterization of high-k thinfilm capacitors and etched aluminum film capacitors integrated on either sides of a through-via 3D IPAC glass substrate. This paper, therefore, demonstrates the integration of heterogeneous capacitors on a single ultra-thin glass substrate for the first time, and presents its benefits as a complete solution for power integrity.

15 citations

01 Feb 1995
TL;DR: In this paper, the status of electronic manufacturing and packaging technology in Japan in comparison to that in the United States, and its impact on competition in electronic manufacturing in general, is summarized.
Abstract: This report summarizes the status of electronic manufacturing and packaging technology in Japan in comparison to that in the United States, and its impact on competition in electronic manufacturing in general. In addition to electronic manufacturing technologies, the report covers technology and manufacturing infrastructure, electronics manufacturing and assembly, quality assurance and reliability in the Japanese electronics industry, and successful product realization strategies. The panel found that Japan leads the United States in almost every electronics packaging technology. Japan clearly has achieved a strategic advantage in electronics production and process technologies. Panel members believe that Japanese competitors could be leading U.S. firms by as much as a decade in some electronics process technologies. Japan has established this marked competitive advantage in electronics as a consequence of developing low-cost, high-volume consumer products. Japan's infrastructure, and the remarkable cohesiveness of vision and purpose in government and industry, are key factors in the success of Japan's electronics industry. Although Japan will continue to dominate consumer electronics in the foreseeable future, opportunities exist for the United States and other industrial countries to capture an increasingly large part of the market. The JTEC panel has identified no insurmountable barriers that would prevent the United States from regaining a significant share of the consumer electronics market; in fact, there is ample evidence that the United States needs to aggressively pursue high-volume, low-cost electronic assembly, because it is a critical path leading to high-performance electronic systems.

14 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: Shape-memory polymers as discussed by the authors are an emerging class of active polymers that can change their shape in a predefined way from shape A to shape B when exposed to an appropriate stimulus.

1,575 citations

Journal ArticleDOI
14 Feb 2008-Nature
TL;DR: This work establishes a methodology for scavenging light-wind energy and body-movement energy using fabrics and presents a simple, low-cost approach that converts low-frequency vibration/friction energy into electricity using piezoelectric zinc oxide nanowires grown radially around textile fibres.
Abstract: Nanodevices don't use much energy, and if the little they do need can be scavenged from vibrations associated with foot steps, heart beats, noises and air flow, a whole range of applications in personal electronics, sensing and defence technologies opens up. Energy gathering of that type requires a technology that works at low frequency range (below 10 Hz), ideally based on soft, flexible materials. A group working at Georgia Institute of Technology has now come up with a system that converts low-frequency vibration/friction energy into electricity using piezoelectric zinc oxide nanowires grown radially around textile fibres. By entangling two fibres and brushing their associated nanowires together, mechanical energy is converted into electricity via a coupled piezoelectric-semiconductor process. This work shows a potential method for creating fabrics which scavenge energy from light winds and body movement. A self-powering nanosystem that harvests its operating energy from the environment is an attractive proposition for sensing, personal electronics and defence technologies1. This is in principle feasible for nanodevices owing to their extremely low power consumption2,3,4,5. Solar, thermal and mechanical (wind, friction, body movement) energies are common and may be scavenged from the environment, but the type of energy source to be chosen has to be decided on the basis of specific applications. Military sensing/surveillance node placement, for example, may involve difficult-to-reach locations, may need to be hidden, and may be in environments that are dusty, rainy, dark and/or in deep forest. In a moving vehicle or aeroplane, harvesting energy from a rotating tyre or wind blowing on the body is a possible choice to power wireless devices implanted in the surface of the vehicle. Nanowire nanogenerators built on hard substrates were demonstrated for harvesting local mechanical energy produced by high-frequency ultrasonic waves6,7. To harvest the energy from vibration or disturbance originating from footsteps, heartbeats, ambient noise and air flow, it is important to explore innovative technologies that work at low frequencies (such as <10 Hz) and that are based on flexible soft materials. Here we present a simple, low-cost approach that converts low-frequency vibration/friction energy into electricity using piezoelectric zinc oxide nanowires grown radially around textile fibres. By entangling two fibres and brushing the nanowires rooted on them with respect to each other, mechanical energy is converted into electricity owing to a coupled piezoelectric–semiconductor process8,9. This work establishes a methodology for scavenging light-wind energy and body-movement energy using fabrics.

1,473 citations

Journal ArticleDOI
TL;DR: This work demonstrates the vertical and lateral integration of ZnO nanowires into arrays that are capable of producing sufficient power to operate real devices and uses the vertically integrated nanogenerator to power a nanowire pH sensor and a Nanowire UV sensor, thus demonstrating a self-powered system composed entirely of nanowiring.
Abstract: The lateral and vertical integration of ZnO piezoelectric nanowires allows for voltage and power outputs sufficient to power nanowire-based sensors.

1,465 citations

Journal ArticleDOI
TL;DR: In this paper, the authors focus on the important role and challenges of high-k polymer-matrix composites (PMC) in new technologies and discuss potential applications of highk PMC.

1,412 citations