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Integrated Transmitters for Cellular User Equipment?Wideband CMOS Power Amplifiers and Antenna Impedance Tuners - PhD Defence by

Published: 2019-10-21

Titel: Integrated Transmitters for Cellular User Equipment?Wideband CMOS Power Amplifiers and Antenna Impedance Tuners

Autthor: Jonas Lindstrand,  Department of Electrical and Information Technology

Faculty opponent: Professor Timo Rahkonen

When: 8 November at 9:15

Location:   E:1406, , E-Building, Ole Römers väg 3, Lund University, Faculty of Engineering LTH

Thesis for download

Abstract: The digital cellular systems era started about thirty years ago with the release of the first digital cellphones. These first digital cellphones were very different from today?s slim and esthetic cellular pocket computers. They were not mass-produced in million units a day, and they were designed for radio performance rather than appearance. Today, all components are integrated inside the mobile phone to enable a product for the masses and not only the lucky few. For the radio performance this makes a large difference, especially the cellphones interaction with the user, which has a tendency to load the integrated antennas. This loading of the antennas means that the electronics inside the cellphone works sub-optimally, and a decrease in radio performance is inevitable, resulting in increased power consumption and reduced data rates. This problem can, however, be reduced by a concept called adaptive antenna impedance matching. This compensates for antenna loading effects, so that the electronics inside the cellphone can still operate with a close to optimum impedance, although the antenna impedance is changed due to user interaction. For adaptive impedance matching, the key component is the so called impedance tuner, which is studied, designed, and evaluated in this thesis. The requirements on this impedance tuner are very high, with low insertion loss, in-band distortion, out-of-band distortion, high tunability, and good power handling. The cost should also be as low as possible, which means that it should be implemented in a CMOS based technology suitable for mass-production. In this thesis, an impedance tuner is therefore designed and implemented in a CMOS-SOI technology. It has been verified to fulfill the requirements for use in a modern cellphone, with all measurements of key merits indicating high performance. Finally, it is worth to mention that this impedance tuner has also been used in a different project, where adaptive impedance matching was used in MIMO channel measurements with real cellphone users, but that project is outside the scope of this thesis.

The range of frequencies used for cellular communication has increased over the years, and today a large part of the so called sub-6 GHz frequency range is used. Most of the wireless services we have today use this decade wide frequency range (~600-6000 MHz), and although it is a wide frequency range, the spectrum is congested with a high density of communication. The circuits used to communicate in the sub-6 GHz bands must therefore have high RF-performance, and they should also be low cost since a large number of circuits is used to cover the complete frequency range. Difficulties reducing the cost per frequency band has drastically increased the cost of today?s cellphones. This thesis therefore proposes an alternative concept for the power amplifier, the key component in the transmitter of the mobile phone, with the goal to reduce the cost of and the number of power amplifier circuits required to cover the complete sub-6 GHz range. The core of the concept was first designed and verified by measurements, an injection-locked power amplifier with supply modulation and dynamic transistor bias, resulting in high efficiency and bandwidth. To further reduce the cost of the cellphone more of the transmitter functionality, i.e. the frequency up-conversion, was added to the power amplifier circuit, which also improved the overall transmitter performance. Furthermore, a new version of polar modulation is proposed, to reduce the baseband signal bandwidth expansion, which polar modulation is notorious for. The reduction in bandwidth expansion decreases the overall power consumption of the transmitter, since the baseband circuits can then have lower bandwidth and clock-frequency. To further reduce the number of power amplifier circuits needed to cover the entire sub-6 GHz range, the bandwidth of the circuit was improved using a new higher order output matching network, together with a dual output power amplifier, resulting in a circuit that can operate with high performance over the complete sub-6 GHz frequency range. The proposed solutions in this thesis can reduce the number of ICs in cellular devices, which benefits not only the production cost, but also has positive effects on the environment.

When: 2019-11-08 09:15 to 2019-11-08 09:15
Location: E:1406, E-building, Ole Römers väg 3, LTH, Lund University


 


Contributions to Preventive Measures in Cyber Security - PhD Defence by Linus Karlsson

Published: 2019-10-14

Titel: Contributions to Preventive Measures in Cyber Security

Autthor: Linus KarlssonDepartment of Electrical and Information Technology

Faculty opponent: Professor Jan-Erik Ekberg

When: 24 October at 9:15

Location:   E:1406, , E-Building, Ole Römers väg 3, Lund University, Faculty of Engineering LTH

Thesis for download

Abstract: Organizations and individuals maintain and use an ever increasing amount of computer systems, either deployed locally, or in the cloud. These systems often store and handle vast amounts of data, some of which is sensitive and should be kept private. Regardless of where the data is located, there is a need to prevent data from falling into the wrong hands. To this end, this dissertation presents contributions to preventive measures in cyber security.

Trusted computing can be used to attest the integrity of code running on a remote computer, and to store data securely using secure storage, for example in a cloud setting. This dissertation presents contributions regarding the use of the Trusted Platform Module (TPM) in high-availability systems, both for TPM 1.2 and TPM 2.0. It also discusses migration of keys from TPM 1.2 to the backwards-incompatible TPM 2.0, while maintaining the same behaviour with regard to authorization mechanisms. Contributions also include the use of trusted computing to attest the integrity of network elements before they are enrolled into a Software Defined Network, as well as protecting important assets of such network elements by using isolated execution environments.

In the field of cryptography, the dissertation contains contributions regarding the Maximum Degree Monomial (MDM) test, which is related to the construction of distinguishers and nonrandomness detectors. A new generalized algorithm to find subsets for the MDM test is presented, together with evaluations of the algorithm on several different stream ciphers.

The dissertation also contains contributions in the field of vulnerability assessment using recommender systems. First, a recommender system for user-specific vulnerability scoring is presented, which scores vulnerabilities based on implicit and explicit user preferences, together with domain-based information unique to the field of vulnerability assessment. Finally, the dissertation also contains contributions regarding privacy of such recommender systems, by protecting the privacy of user preferences even from the provider of the recommender service.

When: 2019-10-24 09:15 to 2019-10-24 09:15
Location: E:1406, E-building, Ole Römers väg 3, LTH, Lund University


 


Vertical III-V Nanowire MOSFETs - PhD Defence by Olli-Pekka Kilpi

Published: 2019-10-03

Title: Vertical III-V Nanowire MOSFETs

Author: Olli-Pekka Kilpi, Department of Electrical and Information Technology

Faculty opponent:  Professor Shinichi Takagi

When: 11 October at 09:15

Location:  E:1406, E-building, Ole Römers väg 3, LTH, Lund University

Abstract: Vertical III-V nanowire MOSFETs are interesting candidates for future digital and analog applications. High electron velocity III-V materials allow fabrication of low power and high frequency MOSFETs. Vertical vapor-liquid-solid growth enables fabrication of axial and radial heterostructure nanowires. This enables fabrication of novel structures where the band-gap can be engineered in the electron transport direction.

In this thesis, vertical InAs/InGaAs DC and RF MOSFETs on Si are fabricated and characterized. Several novel structures in vertical nanowire MOSFETs have been implemented such as gate-last process, axial/radial heterostructures, sub-30-nm gate-length, optimized RF design and field-plate structures. Several different nanowire compositions, such as InAs, InAs/In0.7Ga0.3As and InAs/In0.4Ga0.6As, were used. The radial heterostructureand the gate-last process enabled a record low access resistance in these devices. The axial heterostructure, on the other hand, allowed a wider band-gap material on the drain side, therefore suppressing the band-to-band tunnelling and impact ionization. This enabled a considerable improvement in the transistor off-state performance and for the first time Ioff < 1 nA/µm was reported in non-planar In(Ga)As MOSFETs.

This work demonstrated several high performance devices, therefore highlighting the potential of the vertical nanowire MOSFETs. We demonstrate Ion = 407 mA/µm at Ioff = 100 nA/µm and VDD = 0.5 V, which is the highest reported Ion on vertical nanowire MOSFETs. We demonstrated gm = 3.1 mS/µm, which is the highest demonstrated gm on any MOSFET on Si. Further, we increased the breakdown voltage on InAs/InGaAs MOSFETs from 0.5 V to 2.5 V and demonstrated vertical nanowire MOSFETs with fT/ fmax > 100 GHz / 100 GHz.

When: 2019-10-11 13:00 to 2019-10-11 13:00
Location: E:1406, E-building, Ole Römers väg 3, LTH, Lund University


 


Digit@LTH breakfast seminar: Creating reliable 5G-communication in the millimeter wave bands by Fredrik Tufvesson

Published: 2019-06-18

Speaker: Prof. Fredrik Tufvesson, Electrical and Information Technology , LTH

Title: Creating reliable 5G-communication in the millimeter wave bands

When: 3 October at 9.00-10.00

Where: E-huset, Ole Römers väg 3. Room E:1406

Abstract: Millimeter wave communication is one of the cornerstones in the upcoming 5G standards. While it is generally accepted that the path loss can be overcome by using array antennas at both the base station and the terminal side, there are still many open topics when it comes to the dynamic behavior of the mm wave channel and details of the multipath structure. In this talk we discuss recent advances in mm wave channel characterization, we treat the dynamic behavior and multipath structure of the mm wave channel and their implications on how to create reliable and efficient communication in the 5G millimeter wave band. 

Please register no later than 1 October 12.00 at: http://www.lth.se/digitalth/events/register-19-10-03


You are welcome to subscribe to this type of public events at: http://www.lth.se/digitalth/subscribe/

When: 2019-10-03 09:00 to 2019-10-03 10:00
Location: E-huset, Ole Römers väg 3. Room E:1406
Contact: Jonas.Wisbrant@cs.lth.se


 


Massive MIMO From a Terminal Perspective - Doctorate defense by Erik L Bengtsson

Published: 2019-09-09

Author: Erik L BengtssonDepartment of Electrical and Information Technology

Location:  E:1406, E-building, Ole Römers väg 3, LTH, Lund University

Faculty opponent:  Professor Nils Torbjörn Ekman

Thesis for download (PDF) 

Abstract

This thesis focuses on the terminal aspects of massive MIMO systems. Based on the degree of freedom a terminal have in a MaMi, different antenna configurations, transceiver topologies with associated transmission schemes, and the underlying algorithms are researched.

The first studied topic concerns multiple-antenna terminals in a massive MIMO system for sub-6 GHz, operated at the center frequency of 3.7 GHz. Simulation environments based on fully-stochastic as well as geometric-stochastic approaches are developed and the results are compared to measured.
For the measurements the Lund University Massive MIMO (LuMaMi) testbed has been used. To enable evaluation of multi-antenna terminals, modifications to the LuMaMi framework have been necessary. Real-time diversity schemes for dual antenna terminals as well as a channel capturing feature have been implemented. The latter, to enable analysis and post processing of measured channels from the multi-antenna terminals.

Multi-antenna terminal prototypes with integrated antennas, based on real Sony Xperia smartphone chassis where designed for the evaluation. The three-dimensional antenna gain-patterns have been characterized in an anechoic chamber to ensure that simulations and measurements have a common ground.

The second topic in this thesis relates to mm-wave massive MIMO systems. As a first step toward evaluation of handsets, a 28 GHz channel sounder has been developed for the measurement of dynamic, highly resolved, in both temporal and spatial domains, propagation channels. To enable measurements, a 256$\times$128 antenna-element system was designed together with a control program to handle the switching and the enormous amount of data.

When: 2019-09-27 09:00 to 2019-09-27 09:00
Location: E:1406, E-building, Ole Römers väg 3, LTH, Lund University


 


Lund Connected Systems and Circuit Design Workshop 2019

Published: 2019-04-08

Welcome to the 2019 Lund Connected Systems and Circuit Design Workshop

When: September 19-20, 2019

Where:
September 19: Grand Hotel, Lund
September 20: E:1406 LTH, Lund University Lund, Sweden

The workshop will offer an overview of research activities in IC design and realted areas at Lund University. Additionally, invited presentations on related subjects will be given by outstanding experts from both academia and industry.

Invited presentations by:

Mikael Nilsson, Björn Bergqvist, Peter Nilsson, Volvo Cars

Oskar Andersson, Oticon

Anders Trana, Future by Lund

Zhixing Zhao, Globalfoundries

Program outline at: http://cdworkshop.eit.lth.se/index.php?gpuid=304&L=1

The workshop is hosted by the
Lund University Excellence Center in System Design on Silicon (SoS).

The workshop is free of charge!
Registration: http://www.lth.se/digitalth/events/register-19-09-19-20/

 

 

When: 2019-09-19 09:00 to 2019-09-20 15:00
Location: Grand Hotel day 1, LTH day 2
Contact: ove.edfors@eit.lth.se


 


AIML@LU WS: AI & ML Technologies

Published: 2019-03-20

This AIML@LU fika-to-fika workshop focuses on the development of the technologies that form the basis of Artificial Intelligence and Machine Learning. Possible topics to discuss are the research front for different types of AI, but also to look at different techniques for machine learning.

When: 30 August at 9.30 - 15.30  

Where: MA:6 Annexet*, Sölvegatan 20, Lund, Sweden, LTH, Lund University

Programme

9.30 Fika and mingle

10.15 Introduction and update regarding the AIML@LU network [VIDEO]

10.30 Ongoing projects

Collaborative reading robotMartin Karlsson, Lund University: Robot Programming by Demonstration Based on Machine Learning [VIDEO]

Abstract: Whereas humans would prefer to program on a high level of abstraction, for instance through natural language, robots require very detailed instructions, for instance time series of desired joint torques. In this research, we aim to meet the robots half way, by enabling programming by demonstration.

Marcus Klang, Lund University:  Finding Things in Strings [VIDEO]

Abstract: Things such as organizations, persons, or locations are all around us, particularly in the news, forum posts, facebook updates, and tweets. With named things, we can introduce background in news articles, summarize articles, build question-answering systems, and much more.  However, it is challenging to find and link them, as they often may be ambiguous. In this work, we aim to enrich the knowledge graph Wikidata with new relations and things only found in the articles of multilingual Wikipedia. The long term goal is the development of a multilingual system that can answer any natural question and improve how we find new relevant information.

Najmeh Abiri, Lund University: Variational Autoencoders [VIDEO]

Deep Recurrent Neural Networks for Video Object SegmentationJoakim Johnander, Linköping University: Deep Recurrent Neural Networks for Video Object Segmentation [VIDEO]

Abstract: Given a video with a target or object marked in the first frame, we aim to track and segment the target throughout the video. A fundamental challenge is to find an effective representation of the target and background appearance. In this work, we propose to tackle this challenge by integrating a probabilistic model as a differentiable and end-to-end trainable deep neural network module.

12.00 Lunch and mingle

13.00 Future trends and interesting examples

Mikael GreebMichael Green, Desupervised2: Bayesian Deep Probabilistic Programming: Are we there yet? [VIDEO]

Abstract: Not many would argue against the Bayesian paradigm being the most useful one in modeling problems where parameter estimations are inherently uncertain. But unfortunately most interesting models, especially the ones we know from deep learning, have been very hard to fit in any reasonable amount of time. When dealing with +10 million parameters and +100 thousand data points, Markov Chain Monte Carlo just isn't a viable option. This is why almost every practitioner in deep learning defaults to maximum likelihood estimates through optimization via stochastic gradient descent, because it's much faster. In this talk we'll explore a promising way of doing full Bayesian inference on large scale models via stochastic black box variational inference.

ErikErik Gärtner, Lund University: Intrinsic Motivation - Curiosity and learning for the sake of learning  [VIDEO]

Abstract: Humans as well as other animals are curious beings that develop cognitive skills on their own without the need for external goals or supervision.
Inspired by this, how can we encourage AIs to learn and solve tasks by themselves?
This talk presents the fascinating area of intrinsic reward in the context of reinforcement learning by showcasing recent articles and results.

14.30 Summary and conclusions

15.00 Fika and mingel

 


Organisation

If you have any questions, suggestions or would like to contribute to the program please contact one of:

* Former known as 'Matteannexet'.

 

More AIML@LU events at http://aiml.lu.se/events/ | Join the AIML@LU Network at: http://aiml.lu.se/nwreg/

When: 2019-08-30 09:30 to 2019-08-30 15:30
Location: Where: MA:6 Annexet*, Sölvegatan 20, Lund, Sweden, LTH, Lund University
Contact: Jonas.Wisbrant@cs.lth.se


 


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