Sensors and analog-to-information converters

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 93-96).Compressed sensing (CS) is a promising method for recovering sparse signals from fewer measurements than ordinarily used in the Shannon's sampling theorem [14]. Introducing the CS theory has sparked interest in designing new hardware architectures which can be potential substitutions for traditional architectures in communication systems. CS-based wireless sensors and analog-to-information converters (AIC) are two examples of CS-based systems. It has been claimed that such systems can potentially provide higher performance and lower power consumption compared to traditional systems. However, since there is no end-to-end hardware implementation of these systems, it is difficult to make a fair hardware-to-hardware comparison with other implemented systems. This project aims to fill this gap by examining the energy-performance design space for CS in the context of both practical wireless sensors and AICs. One of the limitations of CS-based systems is that they employ iterative algorithms to recover the signal. Since these algorithms are slow, the hardware solution has become crucial for higher performance and speed. In this work, we also implement a suitable CS reconstruction algorithm in hardware.by Omid Salehi-Abari.S.M

Software-hardware systems for the Internet-of-Things

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.Cataloged from PDF version of thesis.Includes bibliographical references (pages [187]-201).Although interest in connected devices has surged in recent years, barriers still remain in realizing the dream of the Internet of Things (IoT). The main challenge in delivering IoT systems stems from a huge diversity in their demands and constraints. Some applications work with small sensors and operate using minimal energy and bandwidth. Others use high-data-rate multimedia and virtual reality systems, which require multiple-gigabits-per-second throughput and substantial computing power. While both extremes stress the computation, communications, and energy resources available to the underlying devices, each intrinsically requires different solutions to satisfy its needs. This thesis addresses both bandwidth and energy constraints by developing custom software-hardware systems. To tackle the bandwidth constraint, this thesis introduces three systems. First, it presents AirShare, a synchronized abstraction to the physical layer, which enables the direct implementation of diverse kinds of distributed protocols for loT sensors. This capability results in a much higher throughput in today's IoT networks. Then, it presents Agile-Link and MoVR, new millimeter wave devices and protocols which address two main problems that prevent the adoption of millimeter wave frequencies in today's networks: signal blockage and beam alignment. Lastly, this thesis shows how these systems enable new IoT applications, such as untethered high-quality virtual reality. To tackle the energy constraint, this thesis introduces a VLSI chip, which is capable of performing a million-point Fourier transform in real-time, while consuming 40 times less power than prior fast Fourier transforms. Then, it presents Caraoke, a small, low-cost and low-power sensor, which harvests its energy from solar and enables new smart city applications, such as traffic management and smart parking.by Omid Salehi-Abari.Ph. D

A differential 5th derivative Gaussian pulse generator for UWB transceivers

A differential, all digital, fifth-order derivative Gaussian pulse generator is designed and fabricated in a standard 0.13μm CMOS technology for Ultra wideband (UWB) system. Usage of the differential pulse generator eliminates the need of any extra circuit for feeding differential on-chip antenna. This elimination has an enormous effect on decreasing the power consumption of transceiver. The average power consumption of proposed pulse generator is 1.63mW and 26.4μW at pulse repeating frequency (PRF) of 300MHz and 4MHz respectively with 1.2V power supply voltage. The measured output pulse amplitude is 540mV peak to peak. The proposed pulse generator fully complies with FCC regulation

Comparative study of passive and active correlators for UWB impulse radio

This research is focused on timing correlation of low d ata rate IR-UWB for medical sensor design in Body Area Net-w ork (BAN). A passive and an active correlator are compared by multiplying the incoming pulse with three different templates, namely sine wave, clock and 5 th derivative Gaussian pulse. Their individual performance and resistance to interference have been studied in detail. The intermittent characteristic of UWB pulse makes the passive correlator appropriate to reduce overall power consumption. The Gilbert Cell based active mixer has higher output level with increased power consumption