Electrical and Computer Engineering Faculty Publications and Presentations Copyright (c) 2013 Boise State University All rights reserved. http://scholarworks.boisestate.edu/electrical_facpubs Recent documents in Electrical and Computer Engineering Faculty Publications and Presentations en-us Mon, 18 Mar 2013 15:37:58 PDT 3600 Performance Limit for Distributed Detection Under Correlated Observations in Wireless Sensor Networks http://scholarworks.boisestate.edu/electrical_facpubs/223 http://scholarworks.boisestate.edu/electrical_facpubs/223 Tue, 12 Feb 2013 12:56:15 PST In large-scale and dense wireless sensor networks, sensor observations often are correlated and the correlation impacts overall network performance. Another performance limiting factor comes from the non-ideal nature of the wireless links between network nodes. In this paper, we study the detection performance for a distributed detection system with dependent observations under noisy communication channels. In particular, by adopting a novel unified hierarchical independence fusion framework, we derive asymptotic performance limits in terms of error exponents by taking into account the impact of dependent observations and non-ideal channels. The error exponents are investigated under both the Bayesian and the Neyman-Person criteria. Moreover, conditions under which the detection system will result in zero error exponents are also presented in terms of channel capacity requirements.

]]> Ying Lin et al. Reconfigurable Threshold Logic Gates Using Memristive Devices http://scholarworks.boisestate.edu/electrical_facpubs/222 http://scholarworks.boisestate.edu/electrical_facpubs/222 Tue, 12 Feb 2013 12:41:24 PST We present our early design exploration of reconfigurable Threshold Logic Gates (TLG) implemented using Silver-chalcogenide memristive devices combined with CMOS circuits. A variety of linearly separable logic functions including AND, OR, NAND, NOR have been realized in a Matlab-Simulink/Cadence co-simulation using a single-layer TLG. The functionality can be changed between these operations by reprogramming the resistance of the memristive devices.

]]> Thanh Tran et al. Gamma Ray Induced Structural Effects in Bare and Ag Doped Ge–S Thin Films for Sensor Application http://scholarworks.boisestate.edu/electrical_facpubs/221 http://scholarworks.boisestate.edu/electrical_facpubs/221 Fri, 08 Feb 2013 11:47:40 PST We present data on radiation-induced effects in chalcogenide glasses that also trigger radiation induced structural reorganization contributing to silver (Ag) diffusion. To study these effects and silver diffusion, depending on the radiation dose, films were prepared and analyzed using Raman spectroscopy, X-ray diffraction and Energy Dispersion X-ray Spectroscopy. The results show a structural development occurring in films containing 45.4 at.% Ge with increasing radiation dose defined by increase in the edge-sharing/corner-sharing ratio, higher ethane-like unit values and rise of the amount of Ag diffused within the system. Utilizing these effects, a resistance based radiation sensing device has been created. The I–V curves characterizing the sensor operation demonstrate decreased device resistance as a result of the radiation.

]]> M. Mitkova et al. Simulation and Process Flow of Radiation Sensors Based on Chalcogenide Glasses for in situ Measurement Capability http://scholarworks.boisestate.edu/electrical_facpubs/220 http://scholarworks.boisestate.edu/electrical_facpubs/220 Fri, 08 Feb 2013 11:27:44 PST In this work we present data about electronic devices based on a planar structure; inert electrode/nanophase chalcogenide glass/inert electrode in close proximity with a source of silver (Ag) oriented laterally over the chalcogenide glass film. The conductivity of the devices changes with radiation and it can be measured by contacting the two inert electrodes. Spacing of the electrodes was chosen after an in-depth investigation into the electric field (E-field) and E-field energy displacement simulations with the aid of COMSOL multi-physics software. Simulations have been used to enlighten a specific device structure to perform in situ measurements. Bias voltages, inert electrode material and thickness of the films were used as standards for all different types of simulations while only varying the spacing and the geometries to affect the E-fields. It has been established from the experimental results that a 1 V bias is the most appropriate for the device performance and this is the voltage used in the simulations. The key motivation for this research is to find appropriate dimensions and geometry, which do not cause a change in conduction as a direct result of the applied E-field, but rather effectively contribute to the establishment of only the radiation induced change of the device conductivity. The process flow for the device fabrication is described and data from the device performance are presented as well. The radiation induced Ag doping is mapped in the device volume using electron dispersion X-ray spectroscopy (EDS).

]]> Mahesh Ailavajhala et al. Effects of Cobalt-60 Gamma-Rays on Ge-Se Chalcogenide Glasses and Ag/Ge-Se Test Structures http://scholarworks.boisestate.edu/electrical_facpubs/219 http://scholarworks.boisestate.edu/electrical_facpubs/219 Fri, 08 Feb 2013 10:58:56 PST Solid state electrolytes fabricated with chalcogenide glass (ChG) are considered viable candidates for the next generation of non-volatile memory technologies. These glasses, which are composed of group IV and/or group V elements with those of group VI chalcogens (S, Se, and Te), are excellent metal ion conductors. Because of this property, the resistance across structures composed of ChG films sandwiched between active metal (e.g., Ag) and inert metal (e.g., Ni) electrodes can be switched upon the application of sufficient bias, thereby enabling memristive action. In this paper, the effects of 60Co gamma-ray irradiations on Ag/Ge30Se70 test structures are investigated. The results show that exposure to high-energy photons can trigger the transport of Ag+ & ions from an active Ag top layer into an underlying Ge30Se70 ChG film. Post-irradiation annealing experiments also indicate that this “photo-doping” process is reversible once the radiation stress is removed. Numerical simulations which model the mechanisms of radiation-induced photo-doping and recovery are shown to agree well with the data. The results and analysis presented in this paper suggest the ChG-based memristors may be more susceptible to transient radiation effects than cumulative radiation damage.

]]> Y. Gonzalez-Velo et al. Development of DNA Based Active Macro-Materials for Biology and Medicine: A Review http://scholarworks.boisestate.edu/electrical_facpubs/218 http://scholarworks.boisestate.edu/electrical_facpubs/218 Tue, 05 Feb 2013 10:24:28 PST DNA was first discovered as the carrier of genetic information for the majority of the known living organisms, encoding the secret of life. Its delicate design based upon double helical structure and base pairing offers a stable and reliable media for storing hereditary codes, laying the foundation for the central dogma (Watson et al. 2003). The impact of this molecule is far reaching into scientific community and our society, as manifested in many fields, for instance, forensics (Budowle et al. 2003), besides medicine. To date, a great deal of research effort has been directed towards understanding

]]> Frank Xue Jiang et al. A Low-Power Single-Bit Continuous-Time ΔΣ Converter with 92.5 dB Dynamic Range for Biomedical Applications http://scholarworks.boisestate.edu/electrical_facpubs/217 http://scholarworks.boisestate.edu/electrical_facpubs/217 Tue, 18 Dec 2012 10:01:16 PST A third-order single-bit CT-ΔΣ modulator for generic biomedical applications is implemented in a 0.15 µm FDSOI CMOS process. The overall power efficiency is attained by employing a single-bit ΔΣ and a subthreshold FDSOI process. The loop-filter coefficients are determined using a systematic design centering approach by accounting for the integrator non-idealities. The single-bit CT-ΔΣ modulator consumes 110 µW power from a 1.5 V power supply when clocked at 6.144 MHz. The simulation results for the modulator exhibit a dynamic range of 94.4 dB and peak SNDR of 92.4 dB for 6 kHz signal bandwidth. The figure of merit (FoM) for the third-order, single-bit CT-ΔΣ modulator is 0.271 pJ/level.

]]> Sakkarapani Balagopal et al. NO<sub>2</sub> Gas Sorption Studies of Ge<sub>33</sub>Se<sub>67</sub> Films Using Quartz Crystal Microbalance http://scholarworks.boisestate.edu/electrical_facpubs/216 http://scholarworks.boisestate.edu/electrical_facpubs/216 Wed, 28 Nov 2012 12:08:50 PST A study on the NO2 gas sorption ability of amorphous Ge33Se67 coated quartz crystal microbalance (QCM) is presented. The thin films have been characterized before and after sorption/desorption processes of NO2 by energy-dispersive X-ray spectroscopy (EDS), grazing angle X-ray diffraction (GAXRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and atom force microscopy (AFM) measurements. These studies indicated that physisorption occurs when NO2 gas molecules are introduced into the chalcogenide film and the thin film composition or structure do not change. The mass loading due to NO2 gas sorption was calculated by the resonator’s frequency shift. At the conditions of our experiment, up to 6.8 ng of the gas was sorbed into 200 nm thick Ge33Se67 film at 5000 ppm NO2 concentration. It has been established that the process of gas molecules sorption is reversible.

]]> Velichka Georgieva et al. Study of the Sorption Properties of Ge<sub>20</sub>Se<sub>80</sub> Thin Films for NO<sub>2</sub> Gas Sensing http://scholarworks.boisestate.edu/electrical_facpubs/215 http://scholarworks.boisestate.edu/electrical_facpubs/215 Wed, 28 Nov 2012 11:57:53 PST

In this study we investigated the sorption ability of Ge20Se80 thin films applied as active layers of quartz crystal microbalance for NO2 gas sensing. To identify the chalcogenide system appropriate for gas sensing, we provided data for the packing fraction of a number of chalcogenide systems and discussed their suitability. We performed Raman spectroscopy, X-ray photoelectron spectroscopy and atom force microscopy measurements on the thin films both before and after gas absorption, which showed that the introduced gas molecules interact electrostatically with the chalcogen atoms of the host material and initiate some degree of structural changes in it. The weight change due to NO2 gas absorption was measured by the frequency change of the resonator. The absorbed mass increased monotonically with the thickness of chalcogenide films and the NO2 gas concentration. At the conditions of our experiment, up to 11.4 ng of the gas was absorbed into 200 nm thick Ge20Se80 film at 5000 ppm NO2 concentration. The process of gas molecules absorption is found irreversible at the purging conditions.

]]> Ping Chen et al. On Energy Detection for Cooperative Spectrum Sensing http://scholarworks.boisestate.edu/electrical_facpubs/214 http://scholarworks.boisestate.edu/electrical_facpubs/214 Thu, 08 Nov 2012 13:41:17 PST Energy detection has been used almost exclusively in spectrum sensing. This paper studies the potential optimality (or sub-optimality) of the energy detector in spectrum sensing for two systems: one employing a single node and the other using multiple nodes, i.e., cooperative spectrum sensing. We consider both Gaussian channels as well as fading channels with different signaling from the primary user. For a single node case, we show that the energy detector is provably optimal for most cases and for the case when it is not theoretically optimal, its performance is nearly indistinguishable from the true optimal detector. For cooperative spectrum sensing, however, the problem becomes extremely complicated. The presence of the common signal from the primary user introduces dependence among the observations at different nodes; it is well known that for decentralized detection with dependent observations, designing optimal local decision rules typically is an NP problem. Using a recently proposed framework for distributed detection with dependent observations, we establish the optimality of energy detector for several cooperative spectrum sensing systems and point out difficulties for the remaining cases.

]]> Fangrong Peng et al. Teaching Software Defined Radio Using the USRP and LabVIEW http://scholarworks.boisestate.edu/electrical_facpubs/213 http://scholarworks.boisestate.edu/electrical_facpubs/213 Mon, 05 Nov 2012 12:43:55 PST The universal software radio peripheral (USRP) family of products has become a popular platform for hardware-based research and test bed validations conducted by universities in the software defined radio (SDR) and cognitive radio (CR) fields. With the recently released version of National Instruments (NI) LabVIEW, the USRP now offers a scalable, simpler, and easier to use combined platform. The new software support broadens the accessibility of the USRP platform for teaching applications and will spur further adoption within university communication systems classrooms, teaching laboratories, and their natural follow-on coursework. This paper will discuss the utilization of LabVIEW-based virtual instrumentation with the USRP to rapidly create real-time communication systems demonstrations for the classroom and/or laboratory settings. The combination of the USRP, LabVIEW, and Windows support enables implementation and exploration of both foundational and more advanced concepts related to signal processing and communications.

]]> Thad B. Welch et al. Connexions and the SPEN Fellows Program http://scholarworks.boisestate.edu/electrical_facpubs/212 http://scholarworks.boisestate.edu/electrical_facpubs/212 Mon, 05 Nov 2012 12:37:25 PST Texas Instruments (TI) has created the Signal Processing Education Network (SPEN) Fellows program to help identify and fill content gaps within the signal processing content library hosted on the Connexions ecosystem. This paper will overview Connexions, SPEN, the SPEN Fellows program, and review this year's SPEN Fellows project involving Connexions content creation involving real-time DSP (RT-DSP).

]]> Thad B. Welch et al. A 1 GS/s, 31 MHz BW, 76.3 dB Dynamic Range, 34 mW CT-ΔΣ ADC with 1.5 Cycle Quantizer Delay and Improved STF http://scholarworks.boisestate.edu/electrical_facpubs/211 http://scholarworks.boisestate.edu/electrical_facpubs/211 Thu, 25 Oct 2012 11:50:00 PDT A 1 GS/s Continuous-time Delta-Sigma modulator (CT-ΔΣM) with 31 MHz bandwidth, 76.3 dB dynamic range and 72.5 dB signal-to-noise is reported in a 0.13μm CMOS technology. The design employs an excess loop delay (ELD) of more than one clock cycle for achieving higher sampling rate. The ELD is compensated using a fast-loop formed around the last integrator by using a sample-and-hold. Further, the effect of this ELD compensation scheme on the signal transfer function (STF) of a feedforward CT-ΔΣ architecture has been analyzed and reported. In this work, an improved STF is achieved by using a combination of feed-forward, feed-back and feed-in paths and power consumption is reduced by eliminating the adder opamp. This CT-ΔΣM has a conversion bandwidth of 31 MHz and consumes 34 mW from the 1.2V power supply. The relevant design trade-offs have been investigated and presented along with simulation results.

]]> Sakkarapani Balagopal et al. Design of Wideband Continuous-Time ΔΣ ADCs Using Two-Step Quantizers http://scholarworks.boisestate.edu/electrical_facpubs/210 http://scholarworks.boisestate.edu/electrical_facpubs/210 Wed, 24 Oct 2012 14:35:29 PDT Continuous-time delta sigma (CT-ΔΣ) ADCs are established as the data conversion architecture of choice for the next-generation wireless applications. Several efforts have been made to simultaneously improve the bandwidth and dynamic range of ΔΣ ADCs. We proposed using two-step quantizer in a single-loop CT-ΔΣ modulator to achieve higher conversion bandwidth. This paper presents a tutorial for employing the design technique through a 130n CMOS implementation. The proposed 640 MS/s, 4th order continuous-time delta sigma modulator (CT-ΔΣM) incorporates a two-step 5-bit quantizer, consisting of only 13 comparators. The CT-ΔΣM achieves a dynamic range of 70 dB, peak SNDR of 65.3 dB with 32 MHz bandwidth (OSR = 10) while consuming only 30 mW from the 1.2 V supply. The relevant design trade offs have been discussed and presented with simulation results.

]]> Sakkarapani Balagopal et al. Performance and Characteristics of Silicon Avalanche Photodetectors in the C5 Process http://scholarworks.boisestate.edu/electrical_facpubs/209 http://scholarworks.boisestate.edu/electrical_facpubs/209 Fri, 05 Oct 2012 12:34:03 PDT Avalanche photodetectors (APDs) have been fabricated in ON Semiconductor's C5 process without any special process or fabrication steps. The electrical and optical characteristics of APDs, with varying active area and guard ring configurations, are reported in this paper. Also reported are the details and considerations that went into laying out the APDs. It was found that substrate current was negligible and nearly independent of the geometrical shape of the substrate tie-downs around the perimeter of the APD structures. The measured APD breakdown is approximately 14 V. The devices show optical gains in excess of 1,000 at photocurrents of 10 μA.

]]> Dennis Montierth et al. Modeling the Characteristics of an Inductively Coupled Plasma Antenna for Use in a Micro-Propulsion System http://scholarworks.boisestate.edu/electrical_facpubs/208 http://scholarworks.boisestate.edu/electrical_facpubs/208 Fri, 05 Oct 2012 12:05:41 PDT An ion thruster for small satellites is under development. The thruster uses an Inductively Coupled Plasma (ICP) generated by a flat spiral antenna for the ion source. The antenna is fabricated using the Low Temperature Co-Fired Ceramic (LTCC) materials system. The antenna has been modeled using COMSOL Multiphysics® simulation software. The antenna operating frequency range (600 MHz to 1 GHz) in LTCC (εr=7.8) results in a wavelength on the same order of magnitude as the total length of conductor in the antenna. An analysis of the antenna's behavior is presented.

]]> Sonya Shawver et al. Tandem Distributed Detection with Conditionally Dependent Observations http://scholarworks.boisestate.edu/electrical_facpubs/207 http://scholarworks.boisestate.edu/electrical_facpubs/207 Fri, 05 Oct 2012 11:58:24 PDT This paper deals with distributed detection using a tandem network with conditionally dependent observations. Our approach utilizes a recently proposed hierarchical conditional independence model where a hidden variable is introduced and induces conditional independence among sensor observations. If the hidden variable is discrete, optimal local decision rules are reminiscent that of the conditional independence case. For continuous scalar hidden variable, similar results can be obtained when additional monotonicity conditions are imposed.

]]> Pengfei Yang et al. Real World Ultrasonic Signals and Their Application in Teaching Signal Processing http://scholarworks.boisestate.edu/electrical_facpubs/206 http://scholarworks.boisestate.edu/electrical_facpubs/206 Wed, 05 Sep 2012 12:28:09 PDT In our never-ending quest to find ways to interest and motivate our students, we have recently found something new for our "bag of teaching tricks." Ultrasonic signals present a unique andragogical opportunity in any course where signal processing theory and techniques are taught. The authors have recorded (or obtained) a number of naturally occurring ultrasonic signals (e.g., bat echolocation sounds and dolphin whistles) as well as artificially generated ultrasonic signals (e.g., output from a dog whistle and signals from a device from ThinkGeek called an Annoy-a-tron). This paper discusses how these signals can be effectively used to teach, demonstrate, and reinforce the concepts of time dilation/compression, frequency translation, spectral analysis/estimation, and aliasing.

]]> Thad B. Welch et al. It Blinked! Empowering Students with an Improved Microprocessors Course http://scholarworks.boisestate.edu/electrical_facpubs/205 http://scholarworks.boisestate.edu/electrical_facpubs/205 Tue, 04 Sep 2012 15:55:44 PDT Empowering students in understanding microprocessors involves teaching them how a processor works so that they have the skills they need when presented with a different architecture. Allowing the students to participate more fully in the discovery process enhances their ability to tackle projects with little or no help, and provides the sense of accomplishment that leads a student to exclaim "It blinked!" when he succeeds in causing an LED to blink. Soft core processors run on an FPGA development board were used to implement changes to a microprocessors course in order to achieve the desired goals. The use of soft core processors allows configuration changes not possible in traditional microprocessors.

Simplifying the processor, exposing the low level processor interactions, and adjusting the processor configuration as needed to best demonstrate the desired foundational concepts, are integral to the updated microprocessors course at Boise State University. Course enhancements, including development and continuing augmentation of a course reference, are ongoing.

]]> Arlen Planting et al. A Hierarchical Model for Distributed Detection with Conditionally Dependent Observations http://scholarworks.boisestate.edu/electrical_facpubs/204 http://scholarworks.boisestate.edu/electrical_facpubs/204 Tue, 04 Sep 2012 15:21:34 PDT In this paper, we present a unifying framework for distributed detection with dependent or independent observations. This novel framework utilizes an expanded hierarchical model by introducing a hidden variable. Facilitated by this new framework, we identify several classes of distributed detection problems with conditionally dependent observations whose optimal sensor signaling structure resembles that of the independent case. These classes of problems exhibit a decoupling effect on the form of the optimal local decision rules, much in the same way as the conditionally independent case using both the Bayesian and the Neyman-Pearson criteria.

]]> Hao Chen