Browsing by Author "Maundy, Brent"

Now showing 1 - 13 of 13
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    A New 2nd–Order Allpass Filter in 130nm CMOS
    (IEEE, 2016-09) Ahmadi, Peyman; Maundy, Brent; Elwakil, A.S.; Belostotski, Leonid; Madanayake, Arjuna
    This brief presents a novel wide-bandwidth second-order voltage-mode all-pass filter derived from a canonical single transistor bandpass filter. The core of the circuit consists of only one transistor, two resistors, and two energy storage elements. The operation of the proposed filter is validated experimentally. A filter implemented in an IBM 0.13-μm CMOS was measured to have a 55-ps group delay across a 6-GHz bandwidth while consuming 18.5 mW from a 1.5-V supply. This work experimentally demonstrates a CMOS all-pass filter that operates at multigigahertz frequencies and achieves the highest delay-bandwidth product compared to previously published CMOS all-pass filters known to the authors.
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    Approximated Fractional Order Chebyshev Lowpass Filters
    (2015-03-26) Freeborn, Todd; Maundy, Brent; Elwakil, Ahmed S.
    We propose the use of nonlinear least squares optimization to approximate the passband ripple characteristics of traditional Chebyshev lowpass filters with fractional order steps in the stopband. MATLAB simulations of , , and order lowpass filters with fractional steps from  = 0.1 to  = 0.9 are given as examples. SPICE simulations of 1.2, 1.5, and 1.8 order lowpass filters using approximated fractional order capacitors in a Tow-Thomas biquad circuit validate the implementation of these filter circuits.
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    Compact Wide Frequency Range Fractional-Order Models of Human Body Impedance against Contact Currents
    (2016-02-23) Freeborn, Todd J.; Elwakil, Ahmed S.; Maundy, Brent
    Three circuit models using constant phase elements are investigated to represent the human body impedance against contact currents from 40 Hz to 110 MHz. The parameters required to represent the impedance are determined using a nonlinear least squares fitting (NLSF) applied to the averaged human body impedance dataset. The three fractional-order models with 4, 6, and 7 parameters are compared to an already existing integer-order, 11-parameter model. Simulations of the fractional-order models impedance are presented and discussed along with their limitations.
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    Design of Asymmetric Slope Fractional Band Reject Filters
    (2013-10-08) Marathe, Akshay Anant; Maundy, Brent
    In this work, we propose new techniques of designing asymmetric-slope band reject filters. Two new non-conventional transfer functions are presented based on the concept of fractional Laplacian operator, s^(α) where 0 < α < 1. It is possible to achieve asymmetric slopes, large values of notch magnitude up to 90 dB and high Q values for appropriate values of α using these filters. In addition, unlike integer order filters, independent control of slopes above the notch frequency can be achieved by simply changing the values of α. Different circuit realization techniques based on fractional floating inductor, multiple amplifier biquad (MAB) and field programmable analog array (FPAA) are also presented. The operation of these circuits is verified by plotting PSPICE simulation results for different values of α and showing its comparison with experimental results.
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    Electromechanical Shape Memory Alloy Actuators for Blood Extraction
    (2017) Berka, Martin; Mintchev, Martin; Yadid-Pecht, Orly; Maundy, Brent; Dalton, Colin
    This thesis concerns the design, prototyping and testing of a series of compact electromechanical actuators for drawing capillary blood for analysis by the e-Mosquito wearable, autonomous glucose monitoring system for diabetes. All the designs used contracting shape memory alloy wires, fixed geometry and millimetre-scale moving parts, primarily to extend a disposable lancet needle from the device and into the skin. The lancet was to enter the skin at an acute angle that increased to 90° at full extension, with the goal of increasing blood flow. Attention was paid to isolation and replaceability of external parts, improving manufacturability and increasing actuator power. Satisfactory control and extension of the lancet along the intended path were achieved, leading to the conclusion that the increased elastic response of skin makes angled needle insertion impractical and to the investigation of other techniques for blood sampling with autonomous devices.
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    Fast Low Frequency Electrochemical Impedance Spectroscopy Measurement, Modeling, and Analysis Techniques
    (2022-03-30) Al-Ali, Abdulwadood; Maundy, Brent; Fear, Elise; Helaoui, Mohamed; Murari, Kartikeya; Yanushkevich, Svetlana; John, Deepu
    The rapid advancements in technology today have seen more and more attention placed on the automation of many of our daily life's tasks. This is usually achieved through the use of a variety of sensors and actuators. With both hardware and software being pushed beyond the limits of what we ever thought possible, more focus is now being put on the use of these systems, especially in advancing their rapid measurement ability and in interpreting the data they obtain. Electrochemical Impedance Spectroscopy (EIS) has been regarded as one of the most promising technologies in this field owing to its interesting applications across a wide range of industries. EIS has seen a significant leap particularly in its hardware implementation over the last few years, causing the focus of research to expand toward the utilization of this hardware and the modeling and analysis of measured EIS data. This thesis present various EIS measurement, modeling, and analysis techniques that are meant to contribute to integrating the many EIS applications into the market. This is done by proposing an improved phase extraction technique for a previously proposed magnitude-only impedance measurement technique based on a novel non-uniform Kramers-Kronig transform. Additionally, an extension of the double-dispersion models is presented by combining different single dispersion models. These extended models are validated and proven to give more freedom, improving their fitting accuracy. Moreover, a novel generic model that consists of N sections, each having 3 impedances, is proposed. A machine learning-based circuit model identification technique along with a two-stage optimization routine is also put forward. The technique utilizes the same generic impedance model, with the added value of being able to rapidly model EIS data. Finally, multiple wide band signals for fast low-frequency EIS measurements are presented. The first signal is chaotic, while the second is based on the Rudin-Shapiro polynomial. Both signals were tested with discrete RC circuits and in applications with various fruits and vegetables, while the latter was additionally used to monitor the aging of a strawberry.
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    Fractional Resonance-Based Filters
    (2013-02-10) Freeborn, Todd J.; Maundy, Brent; Elwakil, Ahmed
    We propose the use of a fractional order capacitor and fractional order inductor with orders ,  , respectively, in a fractional series circuit to realize fractional-step lowpass, highpass, bandpass, and bandreject filters. MATLAB simulations of lowpass and highpass responses having orders of , 1.5, and 1.9 and bandpass and bandreject responses having orders of 1.5 and 1.9 are given as examples. PSPICE simulations of 1.1, 1.5, and 1.9 order lowpass and 1.0 and 1.4 order bandreject filters using approximated fractional order capacitors and fractional order inductors verify the implementations.
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    Indirect Measurement of Fractional Impedances
    (2013-12-13) Freeborn, Todd; Maundy, Brent
    This thesis investigates the measurement of fractional-order parameters that describe the electrical impedance of tissues and devices without requiring direct impedance measurements. Concepts from fractional calculus are imported to develop fractional circuit theory and derive the voltage and current excited step responses and magnitude responses of the single-dispersion Cole impedance model which is widely used in biomedicine and biology. Using these responses a numerical graph-fitting and non-linear least squares fitting routine have been applied to MATLAB simulations to assess the accuracy of this approach to extract the fractional impedance parameters that describe this model. Experimentally collected data from fruit tissues and ideal Cole models validate these methods. These fractional calculus concepts are further applied to develop the circuit theory to describe the current excited step response and magnitude response of the double-dispersion Cole impedance model. MATLAB and PSPICE simulations of assess the accuracy of this approach to extract the fractional impedance parameters that describe this model. Experimentally collected data from the current-excited step response and voltage excited magnitude response of apples validates these methods. Finally, the fractional circuit theory is applied to develop the expression for the voltage-excited step-response of a fractional model for a supercapacitor which is then used with non-linear least squares method extract the impedance parameters that characterize the model. This method is validated experimentally using results collected from low capacity supercapacitors with manufacturer ratings of 0.33 F, 1 F, and 1.5 F and high capacity supercapacitors with 1500 F and 3000 F manufacturer ratings.
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    Innovative Hardware Implementation for High-Speed HOM/BSM Analysis in a Commercially Viable Quantum Communication System
    (2024-09-10) Ahadi, Amir; Malik, Om; Oblak, Daniel; Maundy, Brent; Barzanjeh, Shabir; Murari, Kartikeya
    With quantum computing advancing, it is vital to safeguard communications from quantum computer threats. Quantum Key Distribution (QKD) emerged as a cutting-edge solution, utilizing quantum principles to establish secure communication channels. However, conventional QKD systems face vulnerabilities, leading to the development of advanced protocols such as Measurement Device Independent Quantum Key Distribution (MDI-QKD). This protocol, employing a time-reversed entanglement approach, enhances security and enables a multi-use quantum communication network. This research addresses the challenge of implementing MDI-QKD efficiently by introducing a novel electronic board designed for real-time processing of time-bin encoded qubits. As the electrical engineer on this interdisciplinary project, the focus is on creating a cost-effective board that seamlessly integrates into commercially viable MDI-QKD systems. The innovation lies in eliminating the need for expensive external hardware and software, making the technology more accessible. The project involves crafting a high-bandwidth logic-level design to handle ultra-fast signals with precision. The board must also synchronize seamlessly with other MDI-QKD components, contributing to the reliability and effectiveness of the quantum communication network. By providing an affordable means of conducting critical analyses, this research accelerates the integration of MDI-QKD technology into real-world applications, contributing to the establishment of a secure communication framework resilient to the evolving landscape of quantum computing.
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    Measurement and Analysis Tools for the Spectroscopy of Cells
    (2022-01-28) Daou, Bechara; Maundy, Brent; Fear, Elise; Dalton, Colin; Murari, Kartikeya
    Biophysical characteristics of cells are commonly used for cell type classification as label-free biomarkers. Changes in cell membrane capacitance and conductance, as well as intracellular water, are essential to study because they can be utilized as an early detection tool for a variety of diseases, including cancer. Under different conditions cells have varying dielectric characteristics, which can be utilized as biomarkers, according to previous research. Using spectroscopy, the goal is to measure and investigate various changes in cells. Such research necessitates the use of expensive and often inaccessible equipment. The purpose of this thesis is to develop a low-cost, low-power system that allows for label-free, non-invasive testing of various cells to extract various dielectric properties and use them to develop cellular biomarkers. A Transimpedance amplifier-based bio-impedance measurement device was developed to investigate the dielectric characteristics of cells at the frequency range of 100 Hz to 1 MHz, as well as a variety of analytical methodologies and a simulation model to verify the findings. The method is then validated by examining changes in cell morphology in a suspension of yeast cells at different osmolarities. To further study water transport in cells the dielectric characteristics of yeast cell suspensions are then measured using an open ended coaxial dielectric probe at the frequency range of 200 MHz to 6 GHz. This thesis shows promising results in using a Transimpedance amplifier-based bio-impedance system to analyze changes in the dielectric characteristics of cells..
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    Motion Aided Inertial Navigation System Calibration for In-Drilling Alignment
    (2022-01) Ursenbach, Nathan Kelly; Mintchev, Martin; Maundy, Brent; Nielsen, Jorgen
    Azimuth survey accuracy is fundamental to directional drilling operations. Industry standard magnetic surveys are limited by interference, and gyroscopic surveys are time intensive or lose accuracy over time due to measurement drift. Alternative solutions are constantly sought. Inertial navigation system (INS) based technologies are not susceptible to external interference, however measurement errors accumulate leading to uncertainty about the true wellbore trajectory to grow exponentially over time. Periodic calibration methods such as zero-velocity update (ZUPT) reduce the rate of error accumulation in INS but with limited success due to a static error model. This work presents a dynamic INS calibration method for measurement-while-drilling (MWD) known as in-drilling alignment (IDA). This method expands on motion aided INS calibration techniques and makes use of controlled motion while the bottom-hole assembly (BHA) is stationary. During this time, linear and rotary motions are induced on the inertial measurement unit (IMU) by electrical actuators. The induced motion is precisely measured by independent sensors. The measured motions and IMU samples become the input to a two-stage inertial navigation system (INS). First, the coarse alignment stage uses equations of motion and the sensor measurements to update the INS states. Next, the extended Kalman filter (EKF) based fine alignment stage takes the measured actuator motion and coarse alignment results to predict the measurement error states in the INS. This work addresses the limitations in industry standard azimuth survey. A method is presented for overcoming these limitations using IDA. The coarse and fine alignment INS stages are presented including a derivation of a novel error model for the EKF. The behavior of the system is investigated using experimental results from a laboratory scale device.
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    Optoelectronic Systems and Applications for In Vivo Fiber Photometry
    (2016) Ronayne, Kathryn; Murari, Kartikeya; Macnab, Chris; Maundy, Brent; Bains, Jaideep; Frayne, Richard
    The emergence of fluorescent reporters has enabled neuroscientists to image neurons in action in live mice. Conventional imaging setups, however, cannot interrogate structures below the surface of the brain, and the animal must be restrained. This work advances fiber photometry, a simple method to monitor the average activity of a population of cells, to enable experiments in freely-moving mice and in deep brain structures. By targeting a small-diameter probe to the structure of interest, single fiber optoelectronic systems may be designed that monitor changes in calcium-mediated fluorescence intensity. The systems are optimized for an application in a CRH-Cre transgenic mouse, with the calcium reporter GCaMP6s, for minimal damage to tissue. This thesis covers: (a) optoelectronic system design, characterization, and refinement (b) application and results in awake and freely-moving mice, (c) investigation into potential artifacts and (d) method and results of an improved targeting protocol.
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    Theory and Applications of Minimal-Transistor Circuits in High-Frequency Communication Systems
    (2021-04-16) Mohamed, Mohamed Balla Elamien; Maundy, Brent; Belostotski, Leonid; Nowicki, Ed; Murari, Kartikeya; El-Sheimy, Naser; Pennisi, Salvatore; Messier, Geoffrey
    The continuous demand for higher data-rate and better quality of service drives the wireless communication industry towards the next generation of technology. The new wireless communication networks such as the fifth-generation (5G) operate at high frequency (e.g. 28 GHz) and with this unprecedented amount of bandwidth comes the potential for much higher-data-rate than other channels. However, such networks face significant challenges in the radio frequency (RF) design. For example, the true-time delay (TTD) beamformer which is a key technology in the 5G networks, requires novel, high-performance and low complexity analog RF circuits such as the CMOS all-pass filters (APFs). Therefore, innovations in analog circuits including filters, oscillators, and amplifiers, are always needed in order to provide a better performance, particularly at these high frequencies, and to overcome other design challenges. Investigating new analog circuits is exhausting when it comes to examining all possible circuits of any given well-defined structure due to the tremendous amount of time needed to perform hand analysis in order to obtain valid circuits. However, with the power of the symbolic math toolboxes available nowadays, and with the help of two-port network models, this problem can be solved in an automated manner with all possible valid circuits found. In this thesis, we present a paradigm shift in the design of the analog minimal-transistor circuits. We systematically synthesize and investigate new designs using two-port network modeling techniques which enable exploiting the power of the symbolic math solvers. Following this new synthesis methodology, we have managed to propose numerous new analog circuits including filters and oscillators. The functionality of the various contributions was validated through extensive simulation results and experimental measurements on fabricated integrated circuits (ICs) in a 65-nm CMOS process. In conclusion, this work unveils a new systematic methodology in minimal-transistor circuit design and provides a window for further design investigation.