Low Power Budget Research Articles

ACE4k: An analog I/O 64×64 visual microprocessor chip with 7‐bit analog accuracy

AbstractThis paper describes a full‐custom mixed‐signal chip which embeds distributed optical signal acquisition, digitally‐programmable analog parallel processing, and distributed image memory cache on a common silicon substrate. This chip, designed in a 0.5 µm standard CMOS technology contains around 1.000.000 transistors, of which operate in analog mode; it is hence one the most complex mixed‐signal chip reported to now. Chip functional features are: local interactions, spatial‐invariant array architecture; programmable local interactions among cells; randomly‐selectable memory of instructions (elementary instructions are defined by specific values of the cell local interactions); random storage/retrieval of intermediate images; capability to complete algorithmic image processing tasks controlled by the user‐selected stored instructions and interacting with the cache memory, etc. Thus, as illustrated in this paper, the chip is capable to complete complex spatio‐temporal image processing tasks within short computation time (<300 ns for linear convolutions) and using a low power budget (<1.2 W for the complete chip). The internal circuitry of the chip has been designed to operate in robust manner with >7‐bits equivalent accuracy in the internal analog operations, which has been confirmed by experimental measurements. Such 7‐bits accuracy is enough for most image processing applications. ACE4k has been demonstrated capable to implement up to 30 templateσ‐either directly or through template decomposition. This means the 100% of the 3×3 linear templates reported in Roska et al. 1998, [1]. Copyright © 2002 John Wiley & Sons, Ltd.

Unified CORDIC-based chip to realise DFT∕DHT∕DCT∕DST

Frequency analysis using the DFT, the DHT, the DCT or the DST is an obvious choice for the entire image and signal processing domain. A chip has been designed to obtain a unified architecture for the DFT/DHT/DCT/DST called DXT. For the low-power budget of many signal processing requirements, e.g. biomedical signal processing, a parallel and pipelined architecture is adopted for the unified design. The parallelism environment provides a real-time and low-power application of biomedical and other signal processing requirements, whereas the pipelined structure ensures high throughput of the design. The DXT architecture uses a CORDIC unit as the basic processing element. The UMC library (europractice) of 0.25 micron CMOS technology has been used to obtain a DXT chip of transform length ‘7’ for the synchronous design. The total dynamic power was found to be 204.89 mW, with an operating frequency of 160 MHz and an operating voltage of 2.5 V.

Electron density and recombination rate measurements in CO-seeded optically pumped plasmas

Electron production rate and electron density in cold optically pumped CO–Ar and CO–N2 plasmas in the presence of small amounts of O2 and NO have been measured using a Thomson discharge probe and microwave attenuation. Nonequilibrium ionization in the plasmas is produced by an associative ionization mechanism in collisions of highly vibrationally excited CO molecules. It is shown that adding small amounts of O2 or NO (50–100 mTorr) to the baseline gas mixtures at P=100 torr results in an increase of the electron density by up to a factor of 20–40 (from ne<1010 cm−3 to ne=(1.5–3.0)×1011 cm−3). This occurs while the electron production rate either decreases (as in the presence of O2) or remains nearly constant within a factor of 2 (as in the presence of NO). It is also shown that the electron–ion recombination rates inferred from these measurements decrease by two to three orders of magnitude compared to their baseline values (with no additives in the cell), down to β≅1.5×10−8 cm3/s with 50–100 mTorr of oxygen or nitric oxide added to the baseline CO–Ar mixture, and β≅(2 to 3)×10−7 cm3/s with 75–100 mTorr of O2 or NO added to the baseline CO–N2 mixture. The overall electron–ion removal rates in the presence of equal amounts of O2 or NO additives turn out to be very close, which shows that the effect of electron attachment to oxygen at these conditions is negligible. These results suggest a novel method of electron density control in cold laser-sustained steady-state plasmas and open a possibility of sustaining stable high-pressure nonequilibrium plasmas at high electron densities and low plasma power budget.

Reconfigurable Filter Coprocessor Architecture for DSP Applications

Digital Signal Processing (DSP) is widely used in high-performance media processing and communication systems. In majority of these applications, critical DSP functions are realized as embedded cores to meet the low-power budget and high computational complexity. Usually these cores are ASICs that cannot be easily retargeted for other similar applications that share certain commonalities. This stretches the design cycle that affects time-to-market constraints. In this paper, we present a reconfigurable high-performance low-power filter coprocessor architecture for DSP applications. The coprocessor architecture, apart from having the performance and power advantage of its ASIC counterpart, can be reconfigured to support a wide variety of filtering computations. Since filtering computations abound in DSP applications, the implementation of this coprocessor architecture can serve as an important embedded hardware IP.

An Automated DIMM Telescope for Antarctica

AbstractA knowledge of the on-ice seeing is a key requirement for planning future Antarctic observatories. In this paper we discuss the likely negative impact on seeing produced by the development of the deep winter surface temperature inversion (Ekman layer). The Automated Astronomical Site Testing Observatory (AASTO) will deploy, as one of its complement of site-testing instruments, an automated differential image motion monitor (DIMM) telescope designed to generate seeing data throughout the Antarctic winter. Here we describe the multi-aperture concept which has been developed for this mission, and touch upon some of the critical technological considerations associated with the low power budget and with the requirement of autonomous operation at very low temperature (–90°C).

Temperature sensing using a hybrid optoelectronic multivibrating system under full computer control

A multivibrating system whose oscillatory frequency is dependent on temperature has been developed. The system utilizes a segment of a liquid crystal display (LCD) in a novel closed loop configuration which produces spontaneous oscillation. The probe is addressed and energized completely optically, and a very low-power budget is required for operation. The system is under full computer control, which leads to a greater degree of control, and the ability to test a wider range of models which describe the behaviour of the liquid crystals in the system.