Ultra-Low-Power Uwb Impulse Radio Design: Architecture, Circuits, And Applications

Recent advances in home healthcare, environmental sensing, and low power computing have created a need for wireless communication at very low power for low data rate applications. Due to higher energy/bit requirements at lower data -rate, achieving power levels low enough to enable long battery lifetime (~10 years) or power-harvesting supplies have not been possible with traditional approaches. Dutycycled radios have often been proposed in literature as a solution for such applications due to their ability to shut off the static power consumption at low data rates. While earlier radio nodes for such systems have been proposed based on a type of sleepwake scheduling, such implementations are still power hungry due to large synchronization uncertainty (~1[MICRO SIGN]s). In this dissertation, we utilize impulsive signaling and a pulse-coupled oscillator (PCO) based synchronization scheme to facilitate a globally synchronized wireless network. We have modeled this network over a widely varying parameter space and found that it is capable of reducing system cost as well as providing scalability in wireless sensor networks. Based on this scheme, we implemented an FCC compliant, 3-5GHz, timemultiplexed, dual-band UWB impulse radio transceiver, measured to consume only 20[MICRO SIGN]W when the nodes are synchronized for peer-peer communication. At the system level the design was measured to consume 86[MICRO SIGN]W of power, while facilitating multi- hop communication. Simple pulse-shaping circuitry ensures spectral efficiency, FCC compliance and ~30dB band-isolation. Similarly, the band-switchable, ~2ns turn-on receiver implements a non-coherent pulse detection scheme that facilitates low power consumption with -87dBm sensitivity at 100Kbps. Once synchronized the nodes exchange information while duty-cycling, and can use any type of high level network protocols utilized in packet based communication. For robust network performance, a localized synchronization detection scheme based on relative timing and statistics of the PCO firing and the timing pulses ("sync") is reported. No active hand-shaking is required for nodes to detect synchronization. A self-reinforcement scheme also helps maintain synchronization even in the presence of miss-detections. Finally we discuss unique ways to exploit properties of pulse coupled oscillator networks to realize novel low power event communication, prioritization, localization and immediate neighborhood validation for low power wireless sensor applications

Ultra-Wideband Transceiver Design And Optimization

University of Minnesota Ph.D. dissertation. July 2015. Major: Electrical Engineering. Advisor: Ramesh Harjani. 1 computer file (PDF); xiii, 128 pages.The technology landscape has quickly changed over the last few years. Developments in personal area networks, IC technology, DSP processing and bio-medical devices have enabled the integration of short range communication into low cost personal health care solutions. Newer technologies and solutions are being developed to cater to the personal operating space(POS) and body area networks(BAN). Health care is driving towards using multiple sensor and therapeutic nodes inside the POS. Technology has enabled remote patient care where the patient has low cost on-body wearables that allow the patient/physician to access vital signs without the patient physically visiting the clinic. Big semiconductor giants want to move into the wearable health monitor space. Along with the developments in fitness based health wearables, there has been a lot of interest towards developing BAN devices catering to the 'mission-critical' wearables and implants. Hearing aids, EKG monitors, neurostimulators are some examples. This work explores the use of the 802.15 ulta wideband (UWB) standard for designing a radio to operate in the a wireless sensor network in the BAN. The specific application targeted is a hearing aid. However, the design in this work is capable of working in a low power low range application with the ability to have multiple data rates ranging from a few kHz to 10's of MHz. The first radio designed by Marconi using spark-gap transmitters was an impulse radio (IR). The IR UWB technology boasts of low power, low cost, high data rates, multiple channels, simultaneous networking, the ability to carry information through obstacles that more limited bandwidths cannot, and also potentially lower complexity hardware design. The inherent timing accuracy associated with the technology gives UWB transmissions immunity to multipath fading and are hence make them more suitable for a cluttered indoor environment. The key difference with the traditional narrowband transceiver is that instead of using continuous wave (CW) transmission, impulses in time are used. The timing accuracy associated with these impulses require synchronization in time, rather than synchronization in frequency for carrier-based CW systems. A complete fully integrated system is presented in thesis. This work presents a low-power noncoherent IR UWB transceiver operating at 5GHz in 0.13um CMOS. A fully-digital transmitter generates a shaped output pulse of 1GHz 3-dB bandwidth. DLLs provide a PVT-tolerant time-step resolution of 1ns over the entire symbol period and regulate the pulse generator center frequency. The transmitter outputs -31dBm (0.88pJ/pulse at 1Mpulse/s) with a dynamic (energy) efficiency of 16pJ/pulse. The transmit out pulse is FCC part 15 compliant over process voltage and temperature (PVT) variations. The transmitter is semi-compliant with IEEE 802.15.6 and IEEE 802.15.4 standards and will become completely compliant with minor modifications. The receiver presented in this work is a non-coherent energy detect IR UWB receiver. The receiver has an on-chip transformer preceding the LNA, which is followed by a super-regenerative amplifier (SRA), envelope detector, sample-and-holds, and a bank of comparators. The design is SRA based energy-detection receiver. Measured results show a receiver efficiency of 0.32nJ/bit at 20.8Mb/s and operation with inputs as low as -70dBm. The SRA based energy-detection receiver utilizes early/late detection for a two-step baseband synchronization algorithm. An integrated solution to the issue of synchronization is also proposed. The system proposed is capable of synchronization and tracking control. The system in this work utilizes early/late detection for a two-step baseband synchronization algorithm. The algorithm is implemented in Matlab and the time to synchronization is observed to be between 250us to a few couple of ms. Measurements have also been made using the receiver and manually implementing the algorithm. This work addresses all aspects time synchronization in an IR transceiver. The initial mismatch is addressed by two methods. Beyond the initial synchronization, the system presented in this system is also capable of tracking. This would mean that once the transceiver has been synchronized, the timing generation would continue to track the phase and the frequency changes depending upon crystal drift over time or movement between the receiver and the transmitter. A test was also performed on the complete transceiver system with two radios talking to each other over a highly attenuated wired channel

Power-efficient Circuit Architectures for Receivers Leveraging Nanoscale CMOS

Cellular and mobile communication markets, together with CMOS technology scaling, have made complex systems-on-chip integrated circuits (ICs) ubiquitous. Moving towards the internet of things that aims to extend this further requires ultra-low power and efficient radio communication that continues to take advantage of nanoscale CMOS processes. At the heart of this lie orthogonal challenges in both system and circuit architectures of current day technology. By enabling transceivers at center frequencies ranging in several tens of GHz, modern CMOS processes support bandwidths of up to several GHz. However, conventional narrowband architectures cannot directly translate or trade-off these speeds to lower power consumption. Pulse-radio UWB (PR-UWB), a fundamentally different system of communication enables this trade-off by bit-level duty-cycling i.e., power-gating and has emerged as an alternative to conventional narrowband systems to achieve better energy efficiency. However, system-level challenges in the implementation of transceiver synchronization and duty-cycling have remained an open challenge to realize the ultra-low power numbers that PR-UWB promises. Orthogonally, as CMOS scaling continues, approaching 28nm and 14nm in production digital processes, the key transistor characteristics have rapidly changed. Changes in supply voltage, intrinsic gain and switching speeds have rendered conventional analog circuit design techniques obsolete, since they do not scale well with the digital backend engines that dictate scaling. Consequently, circuit architectures that employ time-domain processing and leverage the faster switching speeds have become attractive. However, they are fundamentally limited by their inability to support linear domain-to-domain conversion and hence, have remained un-suited to high-performance applications. Addressing these requirements in different dimensions, two pulse-radio UWB receiver and a continuous-time filter silicon prototypes are presented in this work. The receiver prototypes focus on system level innovation while the filter serves as a demonstration vehicle for novel circuit architectures developed in this work. The PR-UWB receiver prototypes are implemented in a 65nm LP CMOS technology and are fully integrated solutions. The first receiver prototype is a compact UWB receiver front end operating at 4.85GHz that is aggressively duty-cycled. It occupies an active area of only 0.4 mm², thanks to the use of few inductors and RF G_m-C filters and incorporates an automatic-threshold-recovery-based demodulator for digitization. The prototype achieves a sensitivity of -88dBm at a data rate of 1Mbps (for a BER of 10^-3), while achieving the lowest energy consumption gradient (dP/df_data=450pJ/bit) amongst other receivers operating in the lower UWB band, for the same sensitivity. However, this prototype is limited by idle-time power consumption (e.g., bias) and lacks synchronization capability. A fully self-duty-cycled and synchronized UWB pulse-radio receiver SoC targeted at low-data-rate communication is presented as the second prototype. The proposed architecture builds on the automatic-threshold-recovery-based demodulator to achieve synchronization using an all-digital clock and data recovery loop. The SoC synchronizes with the incoming pulse stream from the transmitter and duty-cycles itself. The SoC prototype achieves a -79.5dBm, 1Mbps-normalized sensitivity for a >5X improvement over the state of the art in power consumption (375pJ/bit), thanks to aggressive signal path and bias circuit duty-cycling. The SoC is fully integrated to achieve RF-in to bit-out operation and can interface with off-chip, low speed digital components. Finally, switched-mode signal processing, a signal processing paradigm that enables the design of highly linear, power-efficient feedback amplifiers is presented. A 0.6V continuous-time filter prototype that demonstrates the advantages of this technique is presented in a 65nm GP CMOS process. The filter draws 26.2mW from the supply while operating at a full-scale that is 73% of the V_dd, a bandwidth of 70MHz and a peak signal-to-noise-and-distortion ratio (SNDR) of 55.8dB. This represents a 2-fold improvement in full-scale and a 10-fold improvement in the bandwidth over state-of-the-art filter implementations, while demonstrating excellent linearity and signal-to-noise ratio. To sum up, innovations spanning both system and circuit architectures that leverage the speeds of nanoscale CMOS processes to enable power-efficient solutions to next-generation wireless receivers are presented in this work

Energy-efficient, short-range ultra-wideband radio transceivers

Short-range wireless communications continually attract interest from both industry and academia, and it is changing our life in every aspect in the last decade. The design of wireless transceivers is the bottleneck for variety applications, due to RF modeling inaccuracy, stringent FCC regulations over the transmitted power spectrum, interference, multi-path reflections, modulation scheme, receiver sensitivity, and synchronization. In addition, energy efficiency is always one of the most important design goals. Ultra-Wideband(UWB) is found to be very energy-efficient due to its low duty cycle and potentially high data rate due to its wide bandwidth. However, there still remain unsolved issues with UWB transceivers, such as pulse shaping, multi-path reflections, and receiver clock synchronization. To address these, novel techniques such as wireless multi-path equalization, pulse injection-locking for receiver clock synchronization, reconfigurable pulse shaping, low power wireless clock distribution, and an ultra-low-power super-regenerative receiver are implemented and verified on silicon. Three chips are designed and verified: a 3-5GHz Impulse-Radio(IR) UWB transceiver, a 3-60GHz all digital reconfigurable transmitter, and a 402-405MHz MICS/UWB(Sub-GHz) super-regenerative receiver incorporating wireless clock synchronization. A detailed design methodology, measurement results, and discussions are presented

Smart Devices and Systems for Wearable Applications

Wearable technologies need a smooth and unobtrusive integration of electronics and smart materials into textiles. The integration of sensors, actuators and computing technologies able to sense, react and adapt to external stimuli, is the expression of a new generation of wearable devices. The vision of wearable computing describes a system made by embedded, low power and wireless electronics coupled with smart and reliable sensors - as an integrated part of textile structure or directly in contact with the human body. Therefore, such system must maintain its sensing capabilities under the demand of normal clothing or textile substrate, which can impose severe mechanical deformation to the underlying garment/substrate. The objective of this thesis is to introduce a novel technological contribution for the next generation of wearable devices adopting a multidisciplinary approach in which knowledge of circuit design with Ultra-Wide Band and Bluetooth Low Energy technology, realization of smart piezoresistive / piezocapacitive and electro-active material, electro-mechanical characterization, design of read-out circuits and system integration find a fundamental and necessary synergy. The context and the results presented in this thesis follow an “applications driven” method in terms of wearable technology. A proof of concept has been designed and developed for each addressed issue. The solutions proposed are aimed to demonstrate the integration of a touch/pressure sensor into a fabric for space debris detection (CApture DEorbiting Target project), the effectiveness of the Ultra-Wide Band technology as an ultra-low power data transmission option compared with well known Bluetooth (IR-UWB data transmission project) and to solve issues concerning human proximity estimation (IR-UWB Face-to-Face Interaction and Proximity Sensor), wearable actuator for medical applications (EAPtics project) and aerospace physiology countermeasure (Gravity Loading Countermeasure Skinsuit project)

Ultra Wideband

Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption. Our book attempts to present current and emerging trends in-research and development of UWB systems as well as future expectations

Radar detection of cosmic-ray and neutrino induced cascades

An ultra high energy particle, incident upon the earth, will produce a cascade of particles upon interaction. Detection of this cascade holds the key to understanding the properties of the primary-what it was, how much energy it carried, and maybe even where it came from. Of the many strategies developed over the course of the last century to detect such cascades, the radar technique is one of the latest to be explored with interest. For high enough incident energies, the relativistic progression of the cascade through a medium will produce a cloud of ionization that may become dense enough to reflect incident radio-frequency (RF) fields. If so, a broadcasting transmitter and distant receiver could feasibly detect cascades at very long baselines, thereby converting a massive volume of air or ice or sand or salt into a sensitive detector. Such an increase in volume opens up possibility of detecting events which occur on the order of 1km −2 yr −1 or less. In this dissertation, we present a detailed discussion of the radar detection method, focusing specifically on the detection of ultra high energy cosmic rays in the atmosphere, and ultra high energy neutrinos in dense material, such as ice. We will present the history and experimental efforts to date, and include the latest results from recent models and experiments seeking to address the radar problem. Ultimately, we suggest that the radar method is a promising one for the detection of 10 15 eV neutrinos which have interacted in a dense medium, such as the Antarctic ice

10ns start-up techniques for a duty cycled impulse radio receiver

This paper presents fast start-up techniques for duty cycled Impulse Radio receivers. Three different techniques are used to improve the start-up time of individual blocks. DC coupling between the mixer and the VGA is used to ensure a fast start-up time for the whole chain, resulting in an overall start-up time below 10ns. This is the fastest startup time reported for duty cycled Impulse Radio receivers. Moreover, to the best of our knowledge, this is the first paper to detail the start-up techniques that enable ultra-low power consumption in this class of receivers. The measured power consumption is scaling proportionally to the duty cycling rate from 46mW in continuous mode down to 58uW fo

Voyager spacecraft system. Volume A - Preferred design for flight spacecraft and hardware subsystems, part II Final technical report, task B

Hardware subsystems for flight spacecraft, design reliability, interface control, and mission objectives - Voyager projec