ASDTIC control and standardized interface circuits applied to buck, parallel and buck-boost dc to dc power converters

Versatile standardized pulse modulation nondissipatively regulated control signal processing circuits were applied to three most commonly used dc to dc power converter configurations: (1) the series switching buck-regulator, (2) the pulse modulated parallel inverter, and (3) the buck-boost converter. The unique control concept and the commonality of control functions for all switching regulators have resulted in improved static and dynamic performance and control circuit standardization. New power-circuit technology was also applied to enhance reliability and to achieve optimum weight and efficiency

Soft Gamma-ray Detector for the ASTRO-H Mission

ASTRO-H is the next generation JAXA X-ray satellite, intended to carry instruments with broad energy coverage and exquisite energy resolution. The Soft Gamma-ray Detector (SGD) is one of ASTRO-H instruments and will feature wide energy band (40-600 keV) at a background level 10 times better than the current instruments on orbit. SGD is complimentary to ASTRO-H's Hard X-ray Imager covering the energy range of 5-80 keV. The SGD achieves low background by combining a Compton camera scheme with a narrow field-of-view active shield where Compton kinematics is utilized to reject backgrounds. The Compton camera in the SGD is realized as a hybrid semiconductor detector system which consists of silicon and CdTe (cadmium telluride) sensors. Good energy resolution is afforded by semiconductor sensors, and it results in good background rejection capability due to better constraints on Compton kinematics. Utilization of Compton kinematics also makes the SGD sensitive to the gamma-ray polarization, opening up a new window to study properties of gamma-ray emission processes. The ASTRO-H mission is approved by ISAS/JAXA to proceed to a detailed design phase with an expected launch in 2014. In this paper, we present science drivers and concept of the SGD instrument followed by detailed description of the instrument and expected performance.Comment: 17 pages, 15 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray

Design and Characterization of Power Converters and Amplifiers for Supply-Modulation based Transmitter Architectures

The rapid evolution of telecommunication systems has strongly influenced our lives, and the way we communicate and exchange information. Nevertheless, much progress is expected to happen in the next years with the introduction of new generations of wireless communications standards, which require signals with large bandwidth and very high Peak-to-Average Power Ratio (PAPR) in order to enhance the spectral efficiency and maximize the data rate. However, such developments can only take place through the evolution of Radio-Frequency (RF) which should be capable of working at higher frequencies, higher bandwidth and with higher efficiencies than before. In order to meet these demanding specifications, transmitter architectures have to evolve from a single linear RF Power-Amplifier (PA) into more complex architectures. Envelope Tracking (ET) is one of the most promising solutions for the efficiency-enhancement of next generation transmitters. The research described in this thesis aims to provide solutions to enhance the efficiency of the RF PA by means of an ET architecture. To this purpose, a novel discrete level supply modulator is investigated, which is based on a direct digital-to-analog power conversion. This supply modulator is capable of synthesizing eight voltage steps by means of three isolated voltage sources, thus behaving like a Power Digital-to-Analog Converter (Power-DAC). A hybrid version of the Power-DAC exploiting very fast GaN devices is developed and tested with an L-band PA achieving efficiency improvement up to 13% with 10 MHz of bandwidth. Furthermore, a monolithic GaN version of the Power-DAC is prototyped and tested with an X-band PA achieving efficiency improvement up to 20% and bandwidth of 20 MHz. This supply modulator is tested with outphasing PAs showing promising results with modulated signals and efficiency improvement up to 9%. Finally, dispersive phenomena, which affect PAs and switches in supply modulators, are investigated, characterized and modeled

Electronic systems for intelligent particle tracking in the High Energy Physics field

This Ph.D thesis describes the development of a novel readout ASIC for hybrid pixel detector with intelligent particle tracking capabilities in High Energy Physics (HEP) application, called Macro Pixel ASIC (MPA). The concept of intelligent tracking is introduced for the upgrade of the particle tracking system of the Compact Muon Solenoid (CMS) experiment of the Large Hadron Collider (LHC) at CERN: this detector must be capable of selecting at front--end level the interesting particle and of providing them continuously to the back-end. This new functionality is required to cope with the improved performances of the LHC when, in about ten years' time, a major upgrade will lead to the High Luminosity scenario (HL-LHC). The high complexity of the digital logic for particle selection and the very low power requirement of 95% in particle selection and a data reduction from 200 Tb/s/cm2 to 1 Tb/s/cm2. A prototype, called MPA-Light, has been designed, produced and tested. According to the measurements, the prototype respects all the specications. The same device has been used for multi-chip assembly with a pixelated sensor. The assembly characterization with radioactive sources conrms the result obtained on the bare chip

Spatially Coupled Codes and Optical Fiber Communications: An Ideal Match?

In this paper, we highlight the class of spatially coupled codes and discuss their applicability to long-haul and submarine optical communication systems. We first demonstrate how to optimize irregular spatially coupled LDPC codes for their use in optical communications with limited decoding hardware complexity and then present simulation results with an FPGA-based decoder where we show that very low error rates can be achieved and that conventional block-based LDPC codes can be outperformed. In the second part of the paper, we focus on the combination of spatially coupled LDPC codes with different demodulators and detectors, important for future systems with adaptive modulation and for varying channel characteristics. We demonstrate that SC codes can be employed as universal, channel-agnostic coding schemes.Comment: Invited paper to be presented in the special session on "Signal Processing, Coding, and Information Theory for Optical Communications" at IEEE SPAWC 201

A review of advances in pixel detectors for experiments with high rate and radiation

The Large Hadron Collider (LHC) experiments ATLAS and CMS have established hybrid pixel detectors as the instrument of choice for particle tracking and vertexing in high rate and radiation environments, as they operate close to the LHC interaction points. With the High Luminosity-LHC upgrade now in sight, for which the tracking detectors will be completely replaced, new generations of pixel detectors are being devised. They have to address enormous challenges in terms of data throughput and radiation levels, ionizing and non-ionizing, that harm the sensing and readout parts of pixel detectors alike. Advances in microelectronics and microprocessing technologies now enable large scale detector designs with unprecedented performance in measurement precision (space and time), radiation hard sensors and readout chips, hybridization techniques, lightweight supports, and fully monolithic approaches to meet these challenges. This paper reviews the world-wide effort on these developments.Comment: 84 pages with 46 figures. Review article.For submission to Rep. Prog. Phy

Design of a Cost-Efficient Reconfigurable Pipeline ADC

Power budget is very critical in the design of battery-powered implantable biomedical instruments. High speed, high resolution and low power usually cannot be achieved at the same time. Therefore, a tradeoff must be made to compromise every aspect of those features. As the main component of the bioinstrument, high conversion rate, high resolution ADC consumes most of the power. Fortunately, based on the operation modes of the bioinstrument, a reconfigurable ADC can be used to solve this problem. The reconfigurable ADC will operate at 10-bit 40 MSPS for the diagnosis mode and at 8-bit 2.5 MSPS for the monitor mode. The ADC will be completely turned off if no active signal comes from sensors or if an off command is received from the antenna. By turning off the sample hold stage and the first two stages of the pipeline ADC, a significant power saving is achieved. However, the reconfigurable ADC suffers from two drawbacks. First, the leakage signals through the extra off-state switches in the third stage degrade the performance of the data converter. This situation tends to be even worse for high speed and high-resolution applications. An interference elimination technique has been proposed in this work to solve this problem. Simulation results show a significant attenuation of the spurious tones. Moreover, the transistors in the OTA tend to operate in weak inversion region due to the scaling of the bias current. The transistor in subthreshold is very slow due to the small transit frequency. In order to get a better tradeoff between the transconductance efficiency and the transit frequency, reconfigurable OTAs and scalable bias technique are devised to adjust the operating point from weak inversion to moderate inversion. The figure of merit of the reconfigurable ADC is comparable to the previously published conventional pipeline ADCs. For the 10-bit, 40 MSPS mode, the ADC attains a 56.9 dB SNDR for 35.4 mW power consumption. For the 8-bit 2.5 MSPS mode, the ADC attains a 49.2 dB SNDR for 7.9 mW power consumption. The area for the core layout is 1.9 mm2 for a 0.35 micrometer process

Construction and use of an intense positron source at new linac facilities in Germany (- conceptual report -)

In this conceptual report the idea to establish an European Positron Source for Applied Research ("EPOS") based on new LINAC facilities in Germany (ELBE/Rossendorf or TTF-DESY/Hamburg) is considered. The report contains not only the outline of obvious applications in atomic physics, materials science and surface physics, but also several new methodical developments which are only possible with an intense positron beam. This opportunity will also allow the use and further development of imaging techniques being of special interest for industrial applications