An Energy-Efficient, Dynamic Voltage Scaling Neural Stimulator for a Proprioceptive Prosthesis

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Measurement of Electromagnetic Interference Rejection Ratio for Precision Instrumentation Amplifiers

Electro-Magnetic Interference(EMI) degrades the perfomance of electronic systems. So, Amplifiers which are the basic building blocks used in the front-end of analog and mixed-signal Integrated Circuits (ICs) must be evaluated for EMI. This work introduces the most intriguing figure of merit, Electro-Magnetic Interference Rejection Ratio (EMIRR) to measure the EMI immunity of precision Instrumentation Amplifiers (INAs) that helps to select the EMI robust INAs for EMI critical applications. In this work, a new EMIRR measurement setup is implemented to measure the immunity of INAs for conducted EMI ranging from 10 MHz to 3 GHz. The shift in the DC offset voltage generated at the output of the INA due to RF rectification, is used to compute EMIRR. As part of the setup, the hardware evaluation board is designed and an automation test software is developed to run EMIRR measurements. Furthermore, EMIRR measurements are performed on several INAs with different specifications to compare and rank them on their EMI immunity levels. Additionally, with the help of EMIRR metric, suitable INAs for developing EMI-sensitive applications are proposed. Finally, the influence of amplifier bandwidth, the input capacitance, 50 Ω termination at the end of RF input trace, INA package parasitics and EMI filter bandwidth on EMIRR is analyzed with the measurement results

Dual Method Headphone Amplifier

Many high impedance headphones underperform their full potential when directly connected to the audio source. Amplifiers boost the audio signal and provide the headphones with sufficient power to ensure their maximum performance. The invention of transistors caused vacuum tube implementation to decline, leaving many audiophiles unsatisfied with the transistor’s sound signature. Vacuum tubes and transistors both amplify signals, however the distinct “tube sound” has vanished. We have designed and created a product where the user selectively switches between solid-state transistor and tube amplification to compare the sound signatures of each amplification method. The ability to switch between the solid-state and tube amplifiers creates the ability to achieve a more customized sound for individual songs and improve the user’s listening experience. This requires the design of two separate amplifiers and circuitry to switch back and forth between amplification methods without pausing the music or unplugging any device

A Silicon Carbide Power Management Solution for High Temperature Applications

The increasing demand for discrete power devices capable of operating in high temperature and high voltage applications has spurred on the research of semiconductor materials with the potential of breaking through the limitations of traditional silicon. Gallium nitride (GaN) and silicon carbide (SiC), both of which are wide bandgap materials, have garnered the attention of researchers and gradually gained market share. Although these wide bandgap power devices enable more ambitious commercial applications compared to their silicon-based counterparts, reaching their potential is contingent upon developing integrated circuits (ICs) capable of operating in similar environments. The foundation of any electrical system is the ability to efficiently condition and supply power. The work presented in this thesis explores integrated SiC power management solutions in the form of linear regulators and switched capacitor converters. While switched-mode converters provide high efficiency, the requirement of an inductor hinders the development of a compact, integrated solution that can endure harsh operating environments. Although the primary research motivation for wide bandgap ICs has been to provide control and protection circuitry for power devices, the circuitry designed in this work can be incorporated in stand-alone applications as well. Battery or generator powered data acquisition systems targeted towards monitoring industrial machinery is one potential usage scenario

The ATS-6 power system: Hardware implementation and orbital performance

The Applications Technology Satellite-6 power system, a shunt-boost configuration, uses partial shunt regulation of the solar array and a boost regulator for control of battery power. Regulation is provided for three different operating modes: shunt, charge, and boost. This configuration achieves the highest efficiency of power transfer from the solar array to the loads. The excellent dynamic regulation and low output impedance of the power system virtually eliminated the problem of subsystem interactions on the power bus due to conducted interference from load current fluctuations. The performance of the power system continues to be excellent. The solar array degradation (18.5 percent) was less than the specified 20 percent in two years in spite of extreme cycling from -160 C to 60 C. A unique battery cycling regime of discharges varying from 5 percent to 60 percent daily is being encountered. During the second year, noneclipse discharges have occurred twice a day to depths of 35 percent and 45 percent. Battery performance was good with only a small decrease in end-of-discharge voltage. A recent test to evaluate capacity gave 12.4 AH (83% of the nominal capacity of 15 AH) after over 1400 battery discharge cycles. A small increase in the end-of-charge voltage has recently occurred necessitating a change in the charge regime to achieve full charge conditions

Low Voltage CMOS SAR ADC Design

This project centers on the design of a single ended 10-bit successive approximation register analog to digital converter (SAR ADC for short) that easily interfaces to a micro-controller, such as an Arduino. With micro-controller interfacing in mind, the universal data transfer technique of SPI proved an easy way to communicate between the ADC and the micro-controller. The ADC has a range of 1V (highest code value) to 0V (lowest code value) and operates from a single voltage rail value of 1.8V. Typical SPI clock speeds run on the order of 2MHz and with a 10-bit ADC this means a sampling speed of 200k samples per second, though the design could run at faster speeds. While this design does not provide groundbreaking circuit designs or ideas, it does provide an in-depth learning experience for sub-micron (180nm) circuit design

Mini Input Sensor Boards

The objective of this MQP was to use analog and other design techniques to build a circuit using one of Analog Device\u27s new Integrated Circuits. After much thought, research, and collaboration, the project chosen was the Mini PCB Input Sensor and Display Circuits . This project has two parts: the first being a small, inexpensive, and portable circuit designed to be distributed to high school seniors who attend WPI\u27s ECE undergraduate recruitment open houses. The second phase is a more complex version of the portable circuit, and would allow the user to connect to a PC via USB and display the output of the various sensors on a computer monitor

High Voltage DC-DC Converter

This project involved the design of a high-voltage DC-DC converter capable of converting 12VDC into 170VDC and delivering 250W of power. The design is based on a push-pull topology utilizing power MOSFET switches, a custom center-tapped transformer, and an all-analog feedback control system. The design comprised the front-end of a DC-AC sinewave inverter and was implemented using a custom PCB and tested. The control circuitry worked as expected, however the power-side switching posed several issues that remain to be resolved

DIGITAL CONTROL BOARD FOR PHASED ARRAY ANTENNA BEAM STEERING IN ADAPTIVE COMMUNICATION APPLICATIONS

The application of adaptive communication techniques for mobile communications has attracted considerable interest in the last decade. One example of these techniques is spatial filtering through planar antenna array beam forming. This thesis describes the development of a digital system that adaptively controls a phased array antenna. The radiating structure of the phased antenna array is tetrahedral-shaped and contains four antenna elements on each of its three faces. The overall system comprises of a digital control board with an external computer interface, an RF control board, and the phased antenna array. The RF controls the main lobe direction on the phased array antenna. This thesis describes the design and implementation of the digital control board. The digital control board`s primary responsibilities are implementing inter- faces between the external computer and the RF board, which results in two operational modes: the MATLAB graphical user interface (GUI) mode and the adaptive receive mode. The GUI mode allows users to input parameters that provide interactive control of the phased antenna array by interfacing with an external computer and the RF control board. The adaptive receive mode im- plements an algorithm for an adaptive receive station. This algorithm uses a 58-point scanning technique that locates the maximum receive power direction. Test results show that the digital control board successfully manages the RF board control voltage with an nominal error of less than 1%, which subsequently allows for precise control of the antenna`s active face. Additionally, testing of the GUI demonstrated the successful interactive application of various system control parameters