Ultra-low power FSK receiver for body area networks with automatic frequency control

In this paper we present an ultra-low-power receiver geared towards body area networks (BAN). The presented wideband-FSK receiver consumes only 382.5µW while achieving a BER of 10-3 at -81dBm sensitivity for 12.5kbps. The bit rate is scalable up to 625kbps, enabling a trade-off between sensitivity and bit rate. Taking advantage of the short-range nature of BAN applications, a mixer-first architecture is proposed, leading to a good dynamic range, given the DC power consumption. To further decrease the power consumption a free-running digitally controlled oscillator (DCO), tunable from 782MHz to 932MHz, is implemented, that is controlled by a data-aided automatic frequency control (AFC) loop, making the receiver resilient against DCO frequency variations

無線センサネットワークのための超低消費電力と高感度CMOS RF受信機に関する研究

Wireless sensor networks (WSN) have been applied in wide range of applications and proved the more and more important contribution in the modern life. In order to evaluate a WSN, many metrics are considered such as cost, latency, power or quality of service. However, since the sensor nodes are usually deployed in large physical areas and inaccessible locations, the battery change becomes impossible. In this scenario, the power consumption is the most important metric. In a sensor node, the RF receiver is one of the communication devices, which consume a vast majority of power. Therefore, this thesis studies ultra low power RF receivers for the long lifetime of the sensor nodes. Currently, the WSNs use various frequency bands. However, for low power target, the sub-GHz frequency bands are preferred. In this study, ultra-low power 315 MHz and 920 MHz receivers will be proposed for short-range applications and long-range applications of the WSNs respectively. To achieve ultra-low power target, the thesis considers some issues in architecture, circuit design and fabrication technology for suitable choices. After considering different receiver architectures, the RF detection receiver with the On-Off-Keying (OOK) modulation is chosen. Then the thesis proposes solutions to reduce power consumption and concurrently guarantee high sensitivity for the receivers so that they can communicate at adequate distances for both short and long-range applications. First, a 920 MHz OOK receiver is designed for the long-range WSN applications. Typically, the RF amplifiers and local oscillators consume the most of power of RF receivers. In the RF detection receivers, the local oscillators are eliminated, however, the power consumption of the RF amplifiers is still dominant. By reducing the RF gain or removing the RF amplifier, the power consumption of the receivers can be reduced drastically. However, in this case the sensitivity is very limited. In order to overcome the trade-off between power consumption and sensitivity, the switched bias is applied to the RF amplifiers to reduce their power consumption substantially while guaranteeing high RF gain before RF detection. As a result, the receiver consumes only 53 W at 0.6 V supply with -82 dBm sensitivity at 10 kbps data rate. Next, an OOK receiver operating at 315 MHz for the short-range WSN applications with low complexity is proposed. In this receiver, the RF amplifier is controlled to operate intermittently for power reduction. Furthermore, taking advantage of the low carrier frequency, a comparator is used to convert the RF signal to a rail-to-rail stream and then data is demodulated in the digital domain. Therefore, no envelope detector or baseband amplifiers is required. The architecture of the receiver is verified by using discrete RF modules and FPGAs before it is designed on CMOS technology. By simulation with the physical layout, the 315 MHz OOK receiver consumes 27.6 W at 200 kbps and achieves -76.4 dBm sensitivity. Finally, the Synchronized-OOK (S-OOK) modulation scheme is proposed and then an S-OOK receiver operating in the 315 MHz frequency is developed to reduce power consumption more deeply. The S-OOK signal contains not only data but also clock information. By generating a narrow window, the RF front-end is enabled to receive signal only in a short period, therefore, power consumption of the receiver is reduced further. In addition, thank to the clock information contained in the input signal, the data and corresponding clock are demodulated simultaneously without a clock and data recovery circuit. The architecture of the S-OOK receiver is also verified by using discrete RF modules and FPGAs, then VLSI design is carried out. Physical layout simulation shows that the receiver can achieve -76.4 dBm sensitivity, consumes 8.39 W, 4.49 W, 1.36 W at 100 kbps, 50 kbps and 10 kbps respectively. In conclusion, with the objective is to look for solutions to minimize power consumption of receivers for extending the lifetime of sensor nodes while guaranteeing high sensitivity, this study proposed novel receiver architectures, which help reduce power consumption significantly. If using the coin battery CR2032 for power supply, the 920 MHz OOK receiver can work continuously in 1.45 years with communication distance of 259 meters; the 315 MHz OOK receivers can work continuously in 2.8 years with approximately 19 meters communication distance in free space. Whereas, the 315 MHz S-OOK receiver with the minimum power consumption of 1.36 W is suitable for batteryless sensor nodes.電気通信大学201

Low Power Circuit Design in Sustainable Self Powered Systems for IoT Applications

The Internet-of-Things (IoT) network is being vigorously pushed forward from many fronts in diverse research communities. Many problems are still there to be solved, and challenges are found among its many levels of abstraction. In this thesis we give an overview of recent developments in circuit design for ultra-low power transceivers and energy harvesting management units for the IoT. The first part of the dissertation conducts a study of energy harvesting interfaces and optimizing power extraction, followed by power management for energy storage and supply regulation. we give an overview of the recent developments in circuit design for ultra-low power management units, focusing mainly in the architectures and techniques required for energy harvesting from multiple heterogeneous sources. Three projects are presented in this area to reach a solution that provides reliable continuous operation for IoT sensor nodes in the presence of one or more natural energy sources to harvest from. The second part focuses on wireless transmission, To reduce the power consumption and boost the Tx energy efficiency, a novel delay cell exploiting current reuse is used in a ring-oscillator employed as the local oscillator generator scheme. In combination with an edge-combiner power amplifier, the Tx showed a measured energy efficiency of 0.2 nJ=bit and a normalized energy efficiency of 3.1 nJ=bit:mW when operating at output power levels up to -10 dBm and data rates of 3 Mbps

Ultra-Low Power Transmitter and Power Management for Internet-of-Things Devices

Two of the most critical components in an Internet-of-Things (IoT) sensing and transmitting node are the power management unit (PMU) and the wireless transmitter (Tx). The desire for longer intervals between battery replacements or a completely self-contained, battery-less operation via energy harvesting transducers and circuits in IoT nodes demands highly efficient integrated circuits. This dissertation addresses the challenge of designing and implementing power management and Tx circuits with ultra-low power consumption to enable such efficient operation. The first part of the dissertation focuses on the study and design of power management circuits for IoT nodes. This opening portion elaborates on two different areas of the power management field: Firstly, a low-complexity, SPICE-based model for general low dropout (LDO) regulators is demonstrated. The model aims to reduce the stress and computation times in the final stages of simulation and verification of Systems-on-Chip (SoC), including IoT nodes, that employ large numbers of LDOs. Secondly, the implementation of an efficient PMU for an energy harvesting system based on a thermoelectric generator transducer is discussed. The PMU includes a first-in-its-class LDO with programmable supply noise rejection for localized improvement in the suppression. The second part of the dissertation addresses the challenge of designing an ultra- low power wireless FSK Tx in the 900 MHz ISM band. To reduce the power consumption and boost the Tx energy efficiency, a novel delay cell exploiting current reuse is used in a ring-oscillator employed as the local oscillator generator scheme. In combination with an edge-combiner PA, the Tx showed a measured energy efficiency of 0.2 nJ/bit and a normalized energy efficiency of 3.1 nJ/(bit∙mW) when operating at output power levels up to -10 dBm and data rates of 3 Mbps. To close this dissertation, the implementation of a supply-noise tolerant BiCMOS ring-oscillator is discussed. The combination of a passive, high-pass feedforward path from the supply to critical nodes in the selected delay cell and a low cost LDO allow the oscillator to exhibit power supply noise rejection levels better than –33 dB in experimental results

Wireless sensor networks for flight applications

Die Prognosen der Marktentwicklung im Luftfahrtbereich sehen sehr positiv aus. In den kommenden 20 Jahren soll sich die Anzahl der Passagierflugzeuge verdoppeln, was sicherlich die Geschäfte im Luftfahrtbereich anregen wird. Jedoch bildet sich neue Konkurrenz in Asien, welche den Wettbewerb erhöhen wird. Um in dieser neuen Marktsituation weiterhin bestehen zu können, müssen Flugzeughersteller vermehrt innovative Flugzeugkonzepte entwickeln, mit welchen sie sich von ihren Konkurrenten absetzen können. Die meisten Innovationen zielen auf eine Reduzierung des Gewichts und auf höhere Energieeffizienz von Flugzeugen ab. Ebenso steht eine Reduzierung der Inbetriebnahme- und Betriebskosten im Fokus. Ein vielversprechender Ansatz diese Ziele zu erreichen, ist der Einsatz von drahtlosen Sensornetzen, um Luftfahrtanwendungen anzubinden. Der Einsatz so eines drahtlosen Sensornetzes kann in vielerlei Hinsicht Nutzen bringen. Verkabelung kann eingespart werden was große Gewichtsreduktionen mit sich bringt. Arbeitsabläufe können verbessert werden, wodurch Inbetriebnahme- und Betriebskosten reduziert werden können. Zusätzlich kann der Einsatz von drahtlosen Sendernetzen dazu beitragen, bisher nicht sinnvoll realisierbare Anwendungen einzuführen, beziehungsweise diese erst zu ermöglichen. In dieser Arbeit werden typische Flugzeuganwendungen identifiziert, welche von dem Einsatz eines drahtlosen Sendernetzes profitieren können. Die Herausforderungen, die der Einsatz so eines drahtlosen Sensornetzes hervorruft, werden beleuchtet, als auch entsprechende Technologien und Protokolle vorgestellt, welche darauf abzielen, diesen Herausforderungen zu begegnen.The market forecast for aircraft manufacturers is very promising; the fleet of passenger aircraft will double. This will clearly generate a strong business for aircraft manufactures. But new competitors arise and, hence, rivalry is increasing. To succeed in this market situation, aircraft manufacturers have to build innovative aircraft to set themselves apart from competitors. Most of the research effort is concentrated on developing lighter, more energy-efficient aircraft which reduce operational costs for airline operators. A very promising approach to accomplish this goal is to introduce wireless sensor networks for flight applications. Such wireless sensor networks can be very beneficial: they can help to reduce weight by saving cabling, they can improve workflows and, hence, reduce commissioning and operational costs, and they can enable new applications which were not feasible or even possible before.In this work, flight applications are investigated to identify the challenges which arise when introducing such a wireless sensor network. Technologies and protocols are presented which aim to tackle these challenges. In particular, the most demanding prerequisites are energy efficiency, transmission reliability, scalability, synchronization, and localization. Four of these demands will be addressed by three different protocols. First, a clock synchronization protocol is presented which uses a special hardware devicea wake-up receiverto achieve synchronization in a very energy-efficient, reliable, and scalable way. Second, using this same technology a clustering protocol is presented which can reduce redundant transmissions. In doing so, it becomes possible to lower the mean energy consumption for hundreds of sensor nodes. Last, a custom-tailored medium access protocol is presented which utilizes spatial diversity to increase transmission reliability while keeping a very low power demand.Tag der Verteidigung: 25.08.2015Paderborn, Univ., Diss., 201