Kalendarium
Thesis defence: Analog-to-Digital Converters for High-Speed Applications
Publicerad: 2024-06-04
This thesis delves into the multifaceted challenges of designing analog-to-digital converters (ADCs) tailored for high-speed and medium accuracy applications, particularly in deeply scaled-down complementary metal-oxide semiconductor (CMOS) technologies across five comprehensive chapters within its Introduction. Conclusively, the Introduction part briefs the challenges, achievements, and contributions of the thesis, offering insights and recommendations for future research trajectories in the realm of high-speed ADC design. Moreover, the thesis ventures into five original papers in its second part, discussing multiple designs and leveraging techniques such as time interleaving, employment of hybrid ADCs, and asynchronous clocking to attain superior performance metrics encompassing speed, resolution, and power efficiency. Notable contributions include techniques to enhance BST-SW linearity, the design of a high-speed comparator, synchronous versus asynchronous SAR ADC comparison and implementation of a 4-channel TI pipelined-SAR ADC in a 22-nm FDSOI CMOS process, capable of operating at a sampling rate of 1.4 GS/s.
Link to thesis i LU Research Portal:
Zoom link. Zoom ID: 67608675506.
När: | 2024-06-14 09:15 till 2024-06-14 13:00 |
Plats: | E-house, E:1406. |
Kontakt: | hamid.karrari@eit.lth.se |
Thesis defence: Frequency Generation and Baseband Filters for mm-Wave 5G and 6G Transceivers
Publicerad: 2024-05-29
In order to keep up with the constant demand for higher data rates, the fifth generation of mobile communication (5G) introduced the use of mm-wave carrier frequencies from 24 to 71 GHz. Plenty of new frequency spectrum then became available, which has allowed for channel bandwidths of several hundreds of MHz. 6G is projected to continue this trend with even higher carrier frequencies and wider bandwidths, reaching carrier frequencies above 100 GHz and bandwidths in the multi-GHz range. However, this creates new challenges for circuit designers, as the performance of radio circuits typically degrades with increasing frequency. Two critical components in radio transceivers whose performance are highly affected by the increase in carrier frequency and bandwidth are frequency generators and baseband filters. The former generates a local oscillator (LO) signal required for frequency translating the data signal to/from the baseband from/to the carrier frequency, and the latter is used to separate the desired signal from undesired interference and noise in a receiver and to prevent leakage of undesired spectrum content to nearby channels in a transmitter. The design of the frequency generation is also made much more complicated due to mm-wave 5G and 6G communication relying on beamforming, in which the signals from multiple antennas are combined to overcome the high path loss at these frequencies. The LO signal must then be distributed to multiple frequency converters while retaining a constant relative
phase shift. If the beamforming is done using so-called LO beamforming, this relative phase shift must also be tunable in a very accurate manner.
In this thesis, five research papers are included; two concern mm-wave frequency generation, two concern multi-GHz integrated baseband filters, and one is about system-level simulations of beamforming receivers. The thesis is divided into two parts, with the first part providing an introduction and context to the conducted research, while the second part consists of the included papers.
Link to thesis i LU Research Portal:
Zoom link. Zoom ID: 66635753300.
När: | 2024-05-30 09:15 till 2024-05-30 13:00 |
Plats: | E-house, E:1406. |
Kontakt: | rikard.gannedahl@eit.lth.se |
Licentiate seminar: Rohon Kundu
Publicerad: 2024-04-10
In this thesis, we address three main security problems related to cryptography and cloud storage. To tackle the challenge posed by a quantum computer, we need encryption that is resistant to quantum computers. This category of cryptography is called post-quantum cryptography. In the first paper, we solve a challenge in one of lattice-based cryptographic protocols called Nth-degree Truncated polynomial Ring Unit (NTRU) namely how to reduce the key size while keeping the security level. We propose a solution that reduces the key size significantly. Our proposed solution allows a practical implementation of NTRU with fast polynomial multiplications.
Next, we move to solve a long-standing problem arising in any cloud storage namely the reduction of storage cost of redundant data and maintaining security and privacy at the same time. Data deduplication is considered to be a tool that can be used to eliminate redundant data and store only one of its copies. But data deduplication also means that the file cannot go through client-side encryption which opens up new possibilities of adversarial threats. In order to tackle this challenge, we propose a new architecture where we perform client-side deduplication along with dynamic erasure protection by introducing a third-party assistant. We also performed an erasure analysis to quantitatively analyze the probability of loss of a file when a large number of replicas are deleted at random.
Finally, we shift our interest to Decentralized Cloud Storage (DCS). DCS solutions like Filecoin, Storj, and Arweave are gaining more popularity in the Web 3.0 ecosystem. But they are not without challenges. The robustness of the DCS protocols remains a challenging ground. Since the file in a DCS protocol is stored in a decentralized manner among different nodes, a Distributed Denial of Service (DDoS) attack would render the system vulnerable to data loss. Therefore, it is important to analyze the robustness of decentralized architecture against DDoS attacks. In our last paper, we perform a similar erasure analysis to that of the second paper but in a decentralized setup, where the adversary aims to disrupt the system by deleting a file from the network. Storj is one of the leading players in the DCS space. We have created an adversarial model capturing the real Storj network scenario and simulated our model using real-time data obtained from the Storj network. We obtain resource budget figures for DDoS on Storj using our model. Also, we propose a better parametric value for the erasure piece distribution in Storj which suits well when there are more unvetted nodes in the network.
När: | 2024-05-15 13:15 till 2024-05-15 15:00 |
Plats: | E-house, E:1406 |
Kontakt: | rohon.kundu@eit.lth.se |