A Pulse-Gated, Predictive Neural Circuit

Recent evidence suggests that neural information is encoded in packets and may be flexibly routed from region to region. We have hypothesized that neural circuits are split into sub-circuits where one sub-circuit controls information propagation via pulse gating and a second sub-circuit processes graded information under the control of the first sub-circuit. Using an explicit pulse-gating mechanism, we have been able to show how information may be processed by such pulse-controlled circuits and also how, by allowing the information processing circuit to interact with the gating circuit, decisions can be made. Here, we demonstrate how Hebbian plasticity may be used to supplement our pulse-gated information processing framework by implementing a machine learning algorithm. The resulting neural circuit has a number of structures that are similar to biological neural systems, including a layered structure and information propagation driven by oscillatory gating with a complex frequency spectrum.Comment: This invited paper was presented at the 50th Asilomar Conference on Signals, Systems and Computer

Monolithic optical integrated control circuitry for GaAs MMIC-based phased arrays

Gallium arsenide (GaAs) monolithic microwave integrated circuits (MMIC's) show promise in phased-array antenna applications for future space communications systems. Their efficient usage will depend on the control of amplitude and phase signals for each MMIC element in the phased array and in the low-loss radiofrequency feed. For a phased array contining several MMIC elements a complex system is required to control and feed each element. The characteristics of GaAs MMIC's for 20/30-GHz phased-array systems are discussed. The optical/MMIC interface and the desired characteristics of optical integrated circuits (OIC's) for such an interface are described. Anticipated fabrication considerations for eventual full monolithic integration of optical integrated circuits with MMIC's on a GaAs substrate are presented

A simple mixer for generating the 3rd-order intermodulation products used for HPA predistortion

This paper proposes to use nonlinear mixer circuits to generate the intermodulation (IM) products for high-power amplifier (HPA) predistortion using the difference-frequency technique. The design of a 3rd-order nonlinear circuit is used for illustration purpose. The circuit employs two mixers using Schottky diodes as non-linear devices to generate the differencefrequency signals. The circuit has a simple structure, requires no DC bias or additional filters, and is easy to fabricate and low cost. Simulation and measurement results show that the design has a low conversion loss and a low-frequency spurious. ©2009 IEEE.published_or_final_versionThe 9th International Symposium on Signals, Circuits and Systems (ISSCS 2009), Iasi, Romania, 9-10 July 2009. In Proceedings of the International Symposium on Signals, Circuits and Systems, 2009, p. 1-

Student Performance in First Year, Mathematics, and Physics Courses: Implications for Success in the Study of Electrical and Computer Engineering

Mathematics and physics courses are recognized as a crucial foundation for the study of engineering, and often are prerequisite courses for the basic engineering curriculum. But how does performance in these prerequisite courses affect student performance in engineering courses? This study evaluated the relationship between grades in prerequisite math and physics courses and grades in subsequent electrical engineering courses. Where significant relationships were found, additional analysis was conducted to determine minimum grade goals for the prerequisite courses. Relationships were found between five course pairs: calculus II and differential equations; calculus II and physics I (mechanics); physics II (electricity and optics) and circuits analysis II; physics II (electricity and optics) and signals and systems; and circuits analysis II and signals and systems. The results indicate that a grade of C+ or higher in calculus II, and a grade of B- or higher in physics II and circuits analysis II will lead to higher grades in subsequent mathematics, circuits, and signals and systems courses. This information will be used to aid faculty in making decisions about imposing minimum grade requirements

Basics of RF electronics

RF electronics deals with the generation, acquisition and manipulation of high-frequency signals. In particle accelerators signals of this kind are abundant, especially in the RF and beam diagnostics systems. In modern machines the complexity of the electronics assemblies dedicated to RF manipulation, beam diagnostics, and feedbacks is continuously increasing, following the demands for improvement of accelerator performance. However, these systems, and in particular their front-ends and back-ends, still rely on well-established basic hardware components and techniques, while down-converted and acquired signals are digitally processed exploiting the rapidly growing computational capability offered by the available technology. This lecture reviews the operational principles of the basic building blocks used for the treatment of high-frequency signals. Devices such as mixers, phase and amplitude detectors, modulators, filters, switches, directional couplers, oscillators, amplifiers, attenuators, and others are described in terms of equivalent circuits, scattering matrices, transfer functions; typical performance of commercially available models is presented. Owing to the breadth of the subject, this review is necessarily synthetic and non-exhaustive. Readers interested in the architecture of complete systems making use of the described components and devoted to generation and manipulation of the signals driving RF power plants and cavities may refer to the CAS lectures on Low-Level RF.Comment: 36 pages, contribution to the CAS - CERN Accelerator School: Specialised Course on RF for Accelerators; 8 - 17 Jun 2010, Ebeltoft, Denmar

Synthetic biology and microdevices : a powerful combination

Recent developments demonstrate that the combination of microbiology with micro-and nanoelectronics is a successful approach to develop new miniaturized sensing devices and other technologies. In the last decade, there has been a shift from the optimization of the abiotic components, for example, the chip, to the improvement of the processing capabilities of cells through genetic engineering. The synthetic biology approach will not only give rise to systems with new functionalities, but will also improve the robustness and speed of their response towards applied signals. To this end, the development of new genetic circuits has to be guided by computational design methods that enable to tune and optimize the circuit response. As the successful design of genetic circuits is highly dependent on the quality and reliability of its composing elements, intense characterization of standard biological parts will be crucial for an efficient rational design process in the development of new genetic circuits. Microengineered devices can thereby offer a new analytical approach for the study of complex biological parts and systems. By summarizing the recent techniques in creating new synthetic circuits and in integrating biology with microdevices, this review aims at emphasizing the power of combining synthetic biology with microfluidics and microelectronics