Engineering Commons^™

Characterization And Modeling Of Low-Frequency Noise In Hf-Based High -Kappa Dielectrics For Future Cmos Applications, Purushothaman Srinivasan

Dissertations

The International Technology Roadmap for Semiconductors outlines the need for high-K dielectric based gate-oxide Metal Oxide Semiconductor Field Effect Transistors for sub-45 nm technology nodes. Gate oxides of hafnium seem to be the nearest and best alternative for silicon dioxide, when material, thermal and structural properties are considered. Usage of poly-Si as a gate electrode material degrades the performance of the device and hence gate stacks based on metal gate electrodes are gaining high interest. Though a substantial improvement in the performance has been achieved with these changes, reliability issues are a cause of concern. For analog and mixed-signal applications, …

Automatic Physical Database Design : Recommending Materialized Views, Wugang Xu

Dissertations

This work discusses physical database design while focusing on the problem of selecting materialized views for improving the performance of a database system. We first address the satisfiability and implication problems for mixed arithmetic constraints. The results are used to support the construction of a search space for view selection problems. We proposed an approach for constructing a search space based on identifying maximum commonalities among queries and on rewriting queries using views. These commonalities are used to define candidate views for materialization from which an optimal or near-optimal set can be chosen as a solution to the view selection …

Low Jitter Phase-Locked Loop Clock Synthesis With Wide Locking Range, Adnan Gundel

Dissertations

The fast growing demand of wireless and high speed data communications has driven efforts to increase the levels of integration in many communications applications. Phase noise and timing jitter are important design considerations for these communications applications. The desire for highly complex levels of integration using low cost CMOS technologies works against the minimization of timing jitter and phase noise for communications systems which employ a phase-locked loop for frequency and clock synthesis with on-chip VCO. This dictates an integrated CMOS implementation of the VCO with very low phase noise performance. The ring oscillator VCOs based on differential delay cell …

Reliability Studies Of Tin/Hf-Silicate Based Gate Stacks, Naser Ahmed Chowdhury

Dissertations

Hafnium-silicate based oxides are among the leading candidates to be included into the first generation of high-Κ gate stacks in nano-scale CMOS technology because of their distinct advantages as far as thermal stability, leakage characteristics, threshold stability and low mobility degradation are concerned. Their reliability, which is limited by trapping at pre-existing and stress induced defects, remains to be a major concern.

Energy levels of electrically active ionic defects within the thick high-Κ have been experimentally observed in the context of MOS band diagram for the first time in Hf-silicate gate stacks from low temperature and leakage measurements. Excellent match …

Design And Performance Of Cdma Codes For Multiuser Communications, Radharani Poluri

Dissertations

Walsh and Gold sequences are fixed power codes and are widely used in multiuser CDMA communications. Their popularity is due to the ease of implementation. Availability of these code sets is limited because of their generating kernels. Emerging radio applications like sensor networks or multiple service types in mobile and peer-to-peer communications networks might benefit from flexibilities in code lengths and possible allocation methodologies provided by large set of code libraries.

Walsh codes are linear phase and zero mean with unique number of zero crossings for each sequence within the set. DC sequence is part of the Walsh code set. …

Some Contributions On Mimo Radar, Nikolaus Lehmann

Dissertations

Motivated by recent advances in Multiple Input Multiple Output (MIMO) wireless communications, this dissertation aims at exploring the potential of MIMO approaches in the radar context. In communications, MIMO systems combat the fading effects of the multi-path channel with spatial diversity. Further, the scattering environment can be used by such systems to achieve spatial multiplexing. In radar, a complex target consisting of several scatterers takes the place of the multi-path channel of the communication problem. A target's radar cross section (RCS), which determines the amount of returned power, greatly varies with the considered aspect. Those variations significantly impair the detection …