A Sub-nW 2.4 GHz Transmitter for Low Data-Rate Sensing Applications

This paper presents the design of a narrowband transmitter and antenna system that achieves an average power consumption of 78 pW when operating at a duty-cycled data rate of 1 bps. Fabricated in a 0.18 μm CMOS process, the transmitter employs a direct-RF power oscillator topology where a loop antenna acts as a both a radiative and resonant element. The low-complexity single-stage architecture, in combination with aggressive power gating techniques and sizing optimizations, limited the standby power of the transmitter to only 39.7 pW at 0.8 V. Supporting both OOK and FSK modulations at 2.4 GHz, the transmitter consumed as low as 38 pJ/bit at an active-mode data rate of 5 Mbps. The loop antenna and integrated diodes were also used as part of a wireless power transfer receiver in order to kick-start the system power supply prior to energy harvesting operation.Semiconductor Research Corporation. Interconnect Focus CenterSemiconductor Research Corporation. C2S2 Focus CenterNational Institutes of Health (U.S.) (Grant K08 DC010419)National Institutes of Health (U.S.) (Grant T32 DC00038)Bertarelli Foundatio

Ultra Low Power FM-UWB Transceiver for High-Density Wireless Sensor Networks

The WiseSkin project aims to provide a non-invasive solution for restoration of a natural sense of touch to persons using prosthetic limbs. By embedding sensor nodes into the silicone coating of the prosthesis, which acts as a sensory skin, WiseSkin targets to provide improved gripping, manipulation and mobility for amputees. Flexibility, freedom of movement and comfort demand unobtrusive, highly miniaturized, low-power sensing capabilities built into the artificial skin, which is then integrated with a sensory feedback system. Wireless communication between the sensor nodes provides more flexibility, better scalability and robustness compared to wired solution, and is therefore a preferred approach for WiseSkin. Design of an RF transceiver tailored for the specific needs of WiseSkin is the topic of this work. The properties of FM ultra-wide band (FM-UWB) modulation make it a good candidate for High-Density Wireless Sensor Networks (HD-WSN). The proposed FM-UWB receivers take advantage of short range to reduce power consumption, and exploit robustness of this wideband modulation scheme. The LNA, identified as the biggest consumer, is removed and signal is directly converted to dc, where amplification and demodulation are performed. Owing to 500 MHz bandwidth, frequency offset and phase noise can be tolerated, and a low-power, free-running ring oscillator can be used to generate the LO signal. The receiver is referred to as an approximate zero-IF receiver. Two receiver architectures are studied. The first one performs quadrature downconversion, and owing to the demodulator linearity, provides the multi-user capability. In the second receiver, quadrature demodulation is replaced by the single-ended one. Due to the nature of the demodulator, sensitivity degrades, and multiple FM-UWB signals cannot be resolved, but the consumption is almost halved compared to the first receiver. The proposed approach is verified through two integrations, both in a standard 65 nm bulk CMOS process. In the first run, a standalone quadrature receiver was integrated. Power consumption of 423 uW was measured, while achieving -70 dBm sensitivity. Good narrow-band interference rejection and multiuser capability with up to 4 FM-UWB channels could be achieved. In the second run, a full transceiver is integrated, with both quadrature and single-ended receivers and a transmitter, all sharing a single IO pad, without the need for any external passive components or switches. The quadrature receiver, with on-chip baseband processing and multi-user support, in this case consumes 550 uW, with a sesensitivity of -68 dBm. The low power receiver consumes 267 uW, and provides -57 dBm sensitivity, at a single FM-UWB channel. The implemented trantransmitter transmits a 100 kb/s FM-UWB signal at -11.4 dBm, while drawing 583 uW from the 1 V supply. The on-chip clock recovery allows reference frequency offset up to 8000 ppm. Since state of the art on-chip RC oscillators can provide below 2100 ppm across the temperature range of interest, the implemented transceiver demonstrates the feasibility of a fully integrated FM-UWB radio with no need for a quartz reference or any external components. In addition, the transceiver can tolerate up to 3 dBm narrow-band interferer at 2.4 GHz. Such a strong signal can be used to remotely power the sensor nodes inside the artificial skin and enable a truly wirelessWiseSkin solution

Communication and energy delivery architectures for personal medical devices

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 219-232).Advances in sensor technologies and integrated electronics are revolutionizing how humans access and receive healthcare. However, many envisioned wearable or implantable systems are not deployable in practice due to high energy consumption and anatomically-limited size constraints, necessitating large form-factors for external devices, or eventual surgical re-implantation procedures for in-vivo applications. Since communication and energy-management sub-systems often dominate the power budgets of personal biomedical devices, this thesis explores alternative usecases, system architectures, and circuit solutions to reduce their energy burden. For wearable applications, a system-on-chip is designed that both communicates and delivers power over an eTextiles network. The transmitter and receiver front-ends are at least an order of magnitude more efficient than conventional body-area networks. For implantable applications, two separate systems are proposed that avoid reimplantation requirements. The first system extracts energy from the endocochlear potential, an electrochemical gradient found naturally within the inner-ear of mammals, in order to power a wireless sensor. Since extractable energy levels are limited, novel sensing, communication, and energy management solutions are proposed that leverage duty-cycling to achieve enabling power consumptions that are at least an order of magnitude lower than previous work. Clinical measurements show the first system demonstrated to sustain itself with a mammalian-generated electrochemical potential operating as the only source of energy into the system. The second system leverages the essentially unlimited number of re-charge cycles offered by ultracapacitors. To ease patient usability, a rapid wireless capacitor charging architecture is proposed that employs a multi-tapped secondary inductive coil to provide charging times that are significantly faster than conventional approaches.by Patrick Philip Mercier.Ph.D

Study and design of an impulse radio UWB synthesizer for 3.1-10.6 GHz band in 28 NM CMOS FD-SOI technology

Orientador: Prof. Ph.D. André Augusto MarianoCoorientador: Prof. Ph.D. Rémy VaucheDissertação (mestrado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia Elétrica. Defesa : Curitiba, 21/03/2022Inclui referências: p. 107-110Resumo: Este trabalho de dissertação de mestrado apresenta o estudo e desenvolvimento de sintetizador de pulsos de radio ultra banda larga para a banda 3,1-10,6 GHz em tecnologia 28 nm CMOS FD-SOI. A primeira utilização dessa banda de frequência foi autorizada pela comissão federal de comunicações dos Estados Unidos em 2002. Visando a explorar essa banda de frequência, o padrão IEEE 802.15.4 escolheu as comunicações baseadas em pulsos de radio em detrimento das comunicações tradicionais de banda estreita. Uma linha importante de pesquisa e o estudo e desenvolvimento de um transmissor ultra banda larga, capaz de endereçar múltiplas bandas e múltiplos padrões diferentes, que e consistido em um sintetizador de pulsos de radio devendo ter a capacidade de cobrir a banda 3,1-10,6 GHz. Para atingir tal objetivo, visa-se a implementação de uma arquitetura versátil baseada em um gerador de pulsos constituído principalmente por um oscilador controlado por tensão, e um circuito de formatação da envoltória do pulso, em que e possível fazer ajuste da duração e da frequência central dos pulsos, e compensar variações PVT (Processo, Tensão e Temperatura). O objetivo principal deste trabalho de dissertação de mestrado e estudo e desenvolvimento de um sintetizador de pulsos baseado nessa arquitetura em tecnologia 28 nm CMOS FD-SOI, de maneira que esse circuito seja capaz de cobrir toda banda 3.1-10.6 GHz e ao mesmo tempo cumprir os requerimentos espectrais estabelecidos pelos padrões IEEE 802.15.4 e IEEE 802.15.6. No projeto do circuito proposto, utilizou-se a técnica de síntese de pulso por transposição de frequência, constituído principalmente por um oscilador local comutado, permitindo a redução do consumo de energia, em que o sinal produzido pelo oscilador e modulado por um pulso em banda base. Em relação a metodologia do projeto, trata-se de um projeto totalmente personalizado, em que se utilizou as logicas CMOS e CML (Logica Diferencial), e se considerou capacitâncias parasitas estimadas no intuito de melhorar o dimensionamento dos transistores. A arquitetura do oscilador escolhida neste projeto foi o oscilador em anel, a qual permite de se obter uma banda de frequência suficientemente alta. Acerca da formatação do pulso, escolheu-se uma envoltória possível de se implementar com circuito digital reprogramável, visando a endereçar os diferentes canais do padrão IEEE 802.15.4 e IEEE 802.15.6. O sistema implementado, em nível de esquemático de transistor considerando capacitâncias parasitas estimadas, apresenta um desempenho satisfatório sobre a toda a banda de frequência de interesse, em que os pulsos gerados respeitam os gabaritos espectrais impostos pelos padrões IEEE, evidenciando a capacidade do circuito prosposto de ser multi-banda e cobrir toda a banda de frequência de interesse. Em relação ao consumo de potência, esse e influenciado pela duração do pulso e sua frequência central. Ademais, obteve-se um consumo de potencia estática 14 µW e um consumo de energia por pulso emitido máximo de 308 pJ, em que para esse caso, o pulso apresenta um energia transmitida de 11,7 pJ por pulso, assim apresentando uma eficiência de 3,8 %.Abstract: This dissertation work concerns the study and design of an impulse radio ultra-wide band synthesizer for 3.1-10.6 GHz frequency band in 28 nm CMOS FD-SOI technology. Indeed, this frequency band exploitation was initially authorized by the federal communications commission of United States in 2002. Targeting to exploit this frequency band, the IEEE 802.15.4 standard has chosen the communications based on impulse radio instead of the traditional narrowband communications. Besides, the impulse radio communications should respect communications standards, like the IEEE 802.15.4 for wireless personal networks, or IEEE 802.15.6 for wireless body networks. These IEEE standards define the generated pulse bandwidth and its central frequency. An important line of research is the study and design of a multi-standard or multi-band UWB transmitter, consisted by a pulse synthesizer that should be able to address all the standardized channels. To accomplish this, a proposed solution reposes on design of versatile architecture based on pulse generator and an envelope shaping circuit, where it is possible to tune the pulse duration and central frequency, and also to compensate PVT variations (Process, Voltage and Temperature). The dissertation work main goal is the study and design of a pulse synthesizer based on this architecture in 28 nm CMOS FD-SOI technology, such that the designed system is capable to cover all the 3.1-10.6 GHz and at same time to comply the spectral requirements established by IEEE 802.15.4 and 802.15.6 standards. In relation of the proposed circuit design, it is applied the pulse synthesis technique based on frequency transposition, that is mainly composed by a local oscillator that can be turned on and off, which allows to reduce the power consumption. The generated oscillation is modulated by a baseband pulse. Concerning the design methodology, it is a full-custom project, where CMOS and CML logics were used, and estimated parasitic capacitances were considered to achieve more reliable transistor sizing. The oscillator architecture chosen is based on ring oscillator, which allows to reach a frequency range sufficiently large. For the pulse shaping, it was chosen a envelope that is feasible to implement with fully digital circuit, targeting to address all IEEE 802.15.4 and IEEE 802.15.6 standard channels. The implemented system presents, in schematic levels considering parasitic capacitances, a satisfactory performance over all the 3.1-10.6 GHz band, where the generated pulses respect the spectral requirements imposed by the IEEE standards, therefore indicating that the proposed circuit is multi-band and able to cover all frequency band of interest. In terms of power consumption, it was achieved a power leakage of 14 µW and a maximal energy per pulse consumption of 308 pJ, where for this case, the pulse has an emitted energy of 11.7 pJ per pulse, therefore a efficiency of 3.8 %

A hardware and software platform for characterization and prototyping of a low-power energy-harvesting SoC

Energy consumption is an important performance indicator for wireless devices. Developing ICs that address this issue for IoT applications is a complex task, which relies not only on design, but also on testing and characterization as a large part of the process. This thesis develops a framework for testing, characterizing and prototyping of an ultra-low power IC developed at Aalto. The framework consists of both hardware and software components. The hardware involves a large four-layer PCB, various components that support the IC’s functions and a smaller PCB which interfaces with a one-bit display, both implemented with Altium Designer, together with a UWBfilter and an impedance matching network. The software part consists of a flexible IC programming and configuration interface written in Python, two LabVIEW VIs for wireless data transmission and reception and a set of measurement automation libraries written in Python. The framework is successfully tested with the one-bit display driver and is used by the researchers for evaluating their IC blocks

Improving RF Localization Through Measurement and Manipulation of the Channel Impulse Response

For over twenty years, global navigation satellite systems like GPS have provided an invaluable navigation, tracking, and time synchronization service that is used by people, wildlife, and machinery. Unfortunately, the coverage and accuracy of GPS is diminished or lost when brought indoors since GPS signals experience attenuation and distortion after passing through and reflecting off of building materials. This disparity in coverage coupled with growing demands for indoor positioning, navigation, and tracking has led to a plethora of research in localization technologies. To date, however, no single system has emerged as a clear solution to the indoor localization and navigation problem because the myriad of potential applications have widely varying performance requirements and design constraints that no system satisfies. Fortunately, recently-introduced commercial ultra-wideband RF hardware offers excellent ranging accuracy in difficult indoor settings, but these systems lack the robustness and simplicity needed for many indoor applications. We claim that an asymmetric design that separates transmit and receive functions can enable many of the envisioned applications not currently realizable with an integrated design. This separation of functionality allows for a flexible architecture which is more robust to the in-band interference and heavy multipath commonly found in indoor environments. In this dissertation, we explore the size, weight, accuracy, and power requirements imposed on tracked objects (tags) for three broadly representative applications and propose the design of fixed-location infrastructure (anchors) that accurately and robustly estimate a tag’s location, while minimizing deployment complexity and adhering to a unified system architecture. Enabled applications range from 3D tracking of small, fast-moving micro-quadrotors to 2D personal navigation across indoor maps to tracking objects that remain stationary for long periods of time with near-zero energy cost. Each application requires careful measurement of the ultra-wideband channel impulse response, and an augmented narrowband receiver is proposed to perform these measurements. The key design principle is to offload implementation complexity to static infrastructure where an increase in cost and complexity can be more easily absorbed and amortized. Finally, with an eye towards the future, we explore how the increasingly crowded RF spectrum impacts current ultra-wideband system design, and propose an alternative architecture that enables improved coexistence of narrowband and ultra-wideband transmissions.PHDComputer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/138642/1/bpkempke_1.pd