26 research outputs found

    Testable Design and Testing of High-Speed Superconductor Microelectronics

    Get PDF
    True software-defined radio cellular base stations require extremely fast data converters, which can not currently be implemented in semiconductor technology. Superconductor niobium-based delta ADCs have shown to be able to perform this task. The problem of testing these devices is a severe task, as very little is known about possible defects in this technology. This paper shows an approach for gaining information on these defects and illustrates how BIST can be a solution of detecting defects in ADCs under extreme conditions

    Contribution to the design of continuous -time Sigma - Delta Modulators based on time delay elements

    Get PDF
    The research carried out in this thesis is focused in the development of a new class of data converters for digital radio. There are two main architectures for communication receivers which perform a digital demodulation. One of them is based on analog demodulation to the base band and digitization of the I/Q components. Another option is to digitize the band pass signal at the output of the IF stage using a bandpass Sigma-Delta modulator. Bandpass Sigma- Delta modulators can be implemented with discrete-time circuits, using switched capacitors or continuous-time circuits. The main innovation introduced in this work is the use of passive transmission lines in the loop filter of a bandpass continuous-time Sigma-Delta modulator instead of the conventional solution with gm-C or LC resonators. As long as transmission lines are used as replacement of a LC resonator in RF technology, it seems compelling that transmission lines could improve bandpass continuous-time Sigma-Delta modulators. The analysis of a Sigma- Delta modulator using distributed resonators has led to a completely new family of Sigma- Delta modulators which possess properties inherited both from continuous-time and discretetime Sigma-Delta modulators. In this thesis we present the basic theory and the practical design trade-offs of this new family of Sigma-Delta modulators. Three demonstration chips have been implemented to validate the theoretical developments. The first two are a proof of concept of the application of transmission lines to build lowpass and bandpass modulators. The third chip summarizes all the contributions of the thesis. It consists of a transmission line Sigma-Delta modulator which combines subsampling techniques, a mismatch insensitive circuitry and a quadrature architecture to implement the IF to digital stage of a receiver

    Cuatro Vientos: A Reconsideration of Seven Prehistoric Sites in the Lower Rio Grande Plains of South Texas

    Get PDF
    With this report, Texas Department of Transportation (TxDOT) begins a reconsideration of approaches to the evaluation and treatment of those areas where surface lithic scatters are the main constituent of the archeological record. The reconsideration was inspired by the Cuatro Vientos project in Laredo, Webb County, Texas. The project and the ideas surrounding it developed slowly. The ideas continued to evolve through discussion between SWCA Environmental Consultants (SWCA) and TxDOT as additional work on the project occurred. Because this project proceeded in an idiosyncratic fashion, some words of explanation might be helpful. The following discussion provides an account of how the project developed and where future work might be heading

    Earth resources technology satellite spacecraft system design studies. Volume 2, book 2 - Subsystems studies Final report

    Get PDF
    Developing attitude control, orbit adjust, thermal, power, electrical integration, integration test and launch support subsystems for ERT

    Cuatro Vientos- A Reconsideration Of Seven Prehistoric Sites In The Lower Rio Grande Plains Of South Texas Webb County

    Get PDF
    On behalf of the Texas Department of Transportation (TxDOT), SWCA Environmental Consultants (SWCA) conducted testing investigations on seven prehistoric sites located within the Cuatro Vientos roadway project right-of-way in Webb County, Texas. The test excavations, conducted in June 2005, were performed in compliance with the National Environmental Protection Act (NEPA), National Historic Preservation Act (NHPA), and the Texas Antiquities Code. The work was designed to assess each site’s potential for listing on the National Register of Historic Places (NRHP) and for designation as State Archeological Landmarks (SAL). The work was performed under Texas Antiquities Permit No. 3755 with Kevin A. Miller serving as Principal Investigator. Field investigations were performed under TxDOT Work Authorization No. 573 26 SA007 of the SWCA/ TxDOT General Services Contract 573 XX SA007. The seven tested sites are distributed primarily within the drainage basin of San Idelfonso Creek, a tributary of the Rio Grande in south Texas. The sites, including 41WB441, 41WB572, 41WB577, 41WB578, 41WB621, 41WB622, and 41WB623, are all prehistoric open sites situated in both buried and surficial contexts on terraces and adjacent uplands. The sites principally consist of various prehistoric features and artifacts associated with lithic procurement locales and open occupations. According to the temporal data, the sites contain occupational components from the Middle Archaic through Late Prehistoric, though Late Archaic components are the most prevalent throughout the project area. Because of poor preservation and the lack of integrity, SWCA did not recommend any of the sites as eligible for the NRHP or as SALs. TxDOT, however, did not concur and recommended three as eligible, though all were effectively mitigated by the testing investigations. This difference of opinion formed the basis for developing a different approach to the assessment of the south Texas archaeological record. In essence, this project is a reconsideration of evaluations of significance and research potential of seven sites, specifically addressing the well-known problems with the regional archaeological record, namely erosional or stable settings that create mixed or incomplete assemblages. The proposed solution is the development of a contextual frame of reference, utilization of specific point-plotted data in addition to the site construct, and variable temporal scales

    Cuatro Vientos- A Reconsideration Of Seven Prehistoric Sites In The Lower Rio Grande Plains Of South Texas Webb County

    Get PDF
    On behalf of the Texas Department of Transportation (TxDOT), SWCA Environmental Consultants (SWCA) conducted testing investigations on seven prehistoric sites located within the Cuatro Vientos roadway project right-of-way in Webb County, Texas. The test excavations, conducted in June 2005, were performed in compliance with the National Environmental Protection Act (NEPA), National Historic Preservation Act (NHPA), and the Texas Antiquities Code. The work was designed to assess each site’s potential for listing on the National Register of Historic Places (NRHP) and for designation as State Archeological Landmarks (SAL). The work was performed under Texas Antiquities Permit No. 3755 with Kevin A. Miller serving as Principal Investigator. Field investigations were performed under TxDOT Work Authorization No. 573 26 SA007 of the SWCA/ TxDOT General Services Contract 573 XX SA007. The seven tested sites are distributed primarily within the drainage basin of San Idelfonso Creek, a tributary of the Rio Grande in south Texas. The sites, including 41WB441, 41WB572, 41WB577, 41WB578, 41WB621, 41WB622, and 41WB623, are all prehistoric open sites situated in both buried and surficial contexts on terraces and adjacent uplands. The sites principally consist of various prehistoric features and artifacts associated with lithic procurement locales and open occupations. According to the temporal data, the sites contain occupational components from the Middle Archaic through Late Prehistoric, though Late Archaic components are the most prevalent throughout the project area. Because of poor preservation and the lack of integrity, SWCA did not recommend any of the sites as eligible for the NRHP or as SALs. TxDOT, however, did not concur and recommended three as eligible, though all were effectively mitigated by the testing investigations. This difference of opinion formed the basis for developing a different approach to the assessment of the south Texas archaeological record. In essence, this project is a reconsideration of evaluations of significance and research potential of seven sites, specifically addressing the well-known problems with the regional archaeological record, namely erosional or stable settings that create mixed or incomplete assemblages. The proposed solution is the development of a contextual frame of reference, utilization of specific point-plotted data in addition to the site construct, and variable temporal scales

    Low-Power Design of Digital VLSI Circuits around the Point of First Failure

    Get PDF
    As an increase of intelligent and self-powered devices is forecasted for our future everyday life, the implementation of energy-autonomous devices that can wirelessly communicate data from sensors is crucial. Even though techniques such as voltage scaling proved to effectively reduce the energy consumption of digital circuits, additional energy savings are still required for a longer battery life. One of the main limitations of essentially any low-energy technique is the potential degradation of the quality of service (QoS). Thus, a thorough understanding of how circuits behave when operated around the point of first failure (PoFF) is key for the effective application of conventional energy-efficient methods as well as for the development of future low-energy techniques. In this thesis, a variety of circuits, techniques, and tools is described to reduce the energy consumption in digital systems when operated either in the safe and conservative exact region, close to the PoFF, or even inside the inexact region. A straightforward approach to reduce the power consumed by clock distribution while safely operating in the exact region is dual-edge-triggered (DET) clocking. However, the DET approach is rarely taken, primarily due to the perceived complexity of its integration. In this thesis, a fully automated design flow is introduced for applying DET clocking to a conventional single-edge-triggered (SET) design. In addition, the first static true-single-phase-clock DET flip-flop (DET-FF) that completely avoids clock-overlap hazards of DET registers is proposed. Even though the correct timing of synchronous circuits is ensured in worst-case conditions, the critical path might not always be excited. Thus, dynamic clock adjustment (DCA) has been proposed to trim any available dynamic timing margin by changing the operating clock frequency at runtime. This thesis describes a dynamically-adjustable clock generator (DCG) capable of modifying the period of the produced clock signal on a cycle-by-cycle basis that enables the DCA technique. In addition, a timing-monitoring sequential (TMS) that detects input transitions on either one of the clock phases to enable the selection of the best timing-monitoring strategy at runtime is proposed. Energy-quality scaling techniques aimat trading lower energy consumption for a small degradation on the QoS whenever approximations can be tolerated. In this thesis, a low-power methodology for the perturbation of baseline coefficients in reconfigurable finite impulse response (FIR) filters is proposed. The baseline coefficients are optimized to reduce the switching activity of the multipliers in the FIR filter, enabling the possibility of scaling the power consumption of the filter at runtime. The area as well as the leakage power of many system-on-chips is often dominated by embedded memories. Gain-cell embedded DRAM (GC-eDRAM) is a compact, low-power and CMOS-compatible alternative to the conventional static random-access memory (SRAM) when a higher memory density is desired. However, due to GC-eDRAMs relying on many interdependent variables, the adaptation of existing memories and the design of future GCeDRAMs prove to be highly complex tasks. Thus, the first modeling tool that estimates timing, memory availability, bandwidth, and area of GC-eDRAMs for a fast exploration of their design space is proposed in this thesis
    corecore