Techniques of Energy-Efficient VLSI Chip Design for High-Performance Computing

How to implement quality computing with the limited power budget is the key factor to move very large scale integration (VLSI) chip design forward. This work introduces various techniques of low power VLSI design used for state of art computing. From the viewpoint of power supply, conventional in-chip voltage regulators based on analog blocks bring the large overhead of both power and area to computational chips. Motivated by this, a digital based switchable pin method to dynamically regulate power at low circuit cost has been proposed to make computing to be executed with a stable voltage supply. For one of the widely used and time consuming arithmetic units, multiplier, its operation in logarithmic domain shows an advantageous performance compared to that in binary domain considering computation latency, power and area. However, the introduced conversion error reduces the reliability of the following computation (e.g. multiplication and division.). In this work, a fast calibration method suppressing the conversion error and its VLSI implementation are proposed. The proposed logarithmic converter can be supplied by dc power to achieve fast conversion and clocked power to reduce the power dissipated during conversion. Going out of traditional computation methods and widely used static logic, neuron-like cell is also studied in this work. Using multiple input floating gate (MIFG) metal-oxide semiconductor field-effect transistor (MOSFET) based logic, a 32-bit, 16-operation arithmetic logic unit (ALU) with zipped decoding and a feedback loop is designed. The proposed ALU can reduce the switching power and has a strong driven-in capability due to coupling capacitors compared to static logic based ALU. Besides, recent neural computations bring serious challenges to digital VLSI implementation due to overload matrix multiplications and non-linear functions. An analog VLSI design which is compatible to external digital environment is proposed for the network of long short-term memory (LSTM). The entire analog based network computes much faster and has higher energy efficiency than the digital one

Requirements Study for System Implementation of an Atmospheric Laser Propagation Experiment Program, Volume II

Program planning, ground support and airborne equipment for laser space communication syste

Artefact reduction in photoplethysmography

The use of optical techniques in biomedical monitoring and diagnosis is becoming increasingly widespread, primarily because of the non-invasive nature of optically derived measurements. Physiological analysis is usually achieved by characterisation of the spectral or temporal properties of the interaction between light and the anatomy. Although some optical measurements require complex instrumentation and protocols, recent technological advances have resulted in robust and compact equipment that is now used routinely in a multitude of clinical contexts. Unfortunately, these measurements are inherently sensitive to corruption from dynamic physical conditions or external sources of light, inducing signal artefact. Artefact is the primary restriction in the applicability of many optical measurements, especially for ambulatory monitoring and tele-medicine. The most widely used optical measurement is photoplethysmography, a technique that registers dynamic changes in blood volume throughout the peripheral vasculature and can be used to screen for a number of venous disorders, as well as monitoring the cardio-vascular pulse wave. Although photoplethysmographic devices are now incorporated into many patient-monitoring systems, the prevalent application is a measurement known as pulse oximetry, which utilises spectral analysis of the peripheral blood to estimate the arterial haernoglobin oxygen saturation. Pulse oximetry is well established as an early warning for hypoxia and is now mandatory under anaesthesia in many countries. The problem of artefact is prominent in these continuous monitoring techniques, where it is often impossible to control the physical conditions during use. This thesis investigates the possibility of reducing artefact corruption of photoplethysmographic signals in real time, using an electronic processing methodology that is based upon inversion of a physical artefact model. The consequences of this non-linear artefact reduction technique for subsequent signal analysis are discussed, culminating in a modified formulation for pulse oximetry that not only has reduced sensitivity to artefact but also possesses increased generality. The design and construction of a practical electronic system is then used to explore both the implementation issues and the scope of this technique. The performance of artefact reduction obtained is then quantified under realistic experimental conditions, demonstrating that this methodology is successful in removing or reducing a large proportion of artefact encountered in clinically relevant situations. It is concluded that non-linear artefact reduction can be applied to any photoplethysmographic technology, reducing interpretation inaccuracies that would otherwise be induced by signal artefact. It is also speculated that this technology could enable the use of photoplethysmographic systems in applications that are currently precluded by the inherent severity of artefact

Baseband analog front-end and digital back-end for reconfigurable multi-standard terminals

Multimedia applications are driving wireless network operators to add high-speed data services such as Edge (E-GPRS), WCDMA (UMTS) and WLAN (IEEE 802.11a,b,g) to the existing GSM network. This creates the need for multi-mode cellular handsets that support a wide range of communication standards, each with a different RF frequency, signal bandwidth, modulation scheme etc. This in turn generates several design challenges for the analog and digital building blocks of the physical layer. In addition to the above-mentioned protocols, mobile devices often include Bluetooth, GPS, FM-radio and TV services that can work concurrently with data and voice communication. Multi-mode, multi-band, and multi-standard mobile terminals must satisfy all these different requirements. Sharing and/or switching transceiver building blocks in these handsets is mandatory in order to extend battery life and/or reduce cost. Only adaptive circuits that are able to reconfigure themselves within the handover time can meet the design requirements of a single receiver or transmitter covering all the different standards while ensuring seamless inter-interoperability. This paper presents analog and digital base-band circuits that are able to support GSM (with Edge), WCDMA (UMTS), WLAN and Bluetooth using reconfigurable building blocks. The blocks can trade off power consumption for performance on the fly, depending on the standard to be supported and the required QoS (Quality of Service) leve

A SIX-PORT MEASUREMENT DEVICE FOR HIGH POWER MICROWAVE VECTOR NETWORK ANALYSIS

The changes experienced in technology due to the third industrial revolution have over the years contributed immensely to the development of efficient devices and systems. As a result, solutions have been provided to challenges encountered in the heating industry. However, higher efficiency and better performance has undoubtedly been highly sort after. This paper presents the complete industrial development of a new system of a microwave device for use in S-band networks (2.45 GHz ISM band in this application): a vector network analyzer (VNA). The VNA, which is designed based on the six-port measurement principle, provides accurate measurements of both magnitude and phase of the load reflection coefficient. The device is designed to have high power handling capabilities and works under the full operating conditions of high-power microwave generators. Initial measurements show that the device perform stable and can perform temperature-independent measurements over protracted periods. The system is suited for on-line monitoring and control of network parameters in industrial waveguide applications.

Rocket measurements of electron temperature in the E region

The rocket borne equipment, experimental method, and data reduction techniques used in the measurement of electron temperature in the E region are fully described. Electron temperature profiles from one daytime equatorial flight and two nighttime midlatitude flights are discussed. The last of these three flights, Nike Apache 14.533, showed elevated E region temperatures which are interpreted as the heating effect of a stable auroral red arc