Starved picowatt oscillator for remote sensor wake-up timer

A sub-nanowatt oscillator is described. The oscillator is intended for a wake-up timer for remote sensors and hence trades frequency accuracy for reduced power consumption. It is constructed from a five-stage ring of inverters in which the switching speed is reduced using transistors that are always-off, or starved. Fabricated in a 0.35 μm process, the oscillator and its active load dissipate 80 pW at 1.5 Hz from a 1 V supply at 22°C.J.A. Kitchener and B.J. Phillip

A +10dBm 2.4GHz Transmitter with sub-400pW Leakage and 43.7% System Efficiency

Extreme energy constraints inherent in many exciting new wireless sensing applications (such as [1-3]) virtually dictate that such systems operate with extremely low duty cycles, harvesting and storing energy over long periods of time before waking up to perform brief measurement and communication tasks. However, such duty cycling only works if the sleep power of the system is less than the average power available from the power source, which may only be as much as a few nA. In this work, we present an RF transmitter designed to operate in an extremely low duty-cycle industrial monitoring system. The primary challenges are achieving high efficiency in the active mode while transmitting as high as +10dBm and simultaneously minimizing the leakage during the sleep mode. We address these in a +10dBm Bluetooth Low Energy (BLE) transmitter test-chip through 1) low voltage design (0.68V) for switching power and short-circuit power reduction, 2) extensive power gating of unused blocks and 3) a negative-V[subscript GS] biasing technique for PA leakage reduction without affecting its on-performance.Shell Oil CompanyTexas Instruments Incorporate

Sens-o-Spheres – Mobile, miniaturisierte Sensorplattform für die ortsungebundene Prozessmessung in wässrigen Lösungen

Zur Prozessmessung in Flüssigkeiten wird ein Konzept vorgestellt, das mittels miniaturisierter Sensorkugeln eine ortsveränderliche Aufnahme von Prozessmesssignalen – z. B. der Temperatur – ermöglicht und diese kontinuierlich aus dem Reaktionsvolumen an eine Basisstation überträgt. Das System beinhaltet nicht nur die Miniaturisierung der Messstelle auf einen Kugeldurchmesser von 7,8 mm sondern auch die Abstimmung der Gesamtdichte auf die Prozessbedingungen, um eine gleichmäßige Verteilung der Messpunkte auf das gesamte Reaktionsvolumen zu ermöglichen. Für die Verwendung im Bioprozess wurde eine bio-inerte Kapselung für die gesamte Messelektronik entwickelt und die Funktionstüchtigkeit in mehreren Bioreaktorsystemen demonstriert. Das Messsystem wird mit einer induktiv wieder aufladbaren Energiequelle betrieben und hat eine Reichweite von mehr als 30 cm durch die Flüssigkeitssäule

Spread Spectrum Modulation Investigation Using MATLAB Developed Tool On Automotive Dc-Dc Converter

Electromagnetic Interference (EMI) classified as emission from a device or a system that interrupt normal operation of the own or neighbor system. Generally, EMI is caused by radiation emitted from an external source. The electromagnetic interference classified into conducted emission and radiated emission. Conducted EMI is pass through transmission lines such as wires and PCB traces whereas radiated EMI is caused by induction. Nowadays, spread spectrum concept widely used in design phase of DC-DC converter as a measure to keep emission within automotive EMC defined standard besides filter techniques and PCB designs. In principle, there are many different test measurement setup used in spread spectrum modulation concept for conducted EMI analysis which cause beginners difficult to master the topic. This paper describes a developed MATLAB program for spread spectrum modulation (SSM) techniques with several modulation parameters, profiles, including test measurement setups in EMI analysis

A Fully-Integrated Reconfigurable Dual-Band Transceiver for Short Range Wireless Communications in 180 nm CMOS

© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.A fully-integrated reconfigurable dual-band (760-960 MHz and 2.4-2.5 GHz) transceiver (TRX) for short range wireless communications is presented. The TRX consists of two individually-optimized RF front-ends for each band and one shared power-scalable analog baseband. The sub-GHz receiver has achieved the maximum 75 dBc 3rd-order harmonic rejection ratio (HRR3) by inserting a Q-enhanced notch filtering RF amplifier (RFA). In 2.4 GHz band, a single-ended-to-differential RFA with gain/phase imbalance compensation is proposed in the receiver. A ΣΔ fractional-N PLL frequency synthesizer with two switchable Class-C VCOs is employed to provide the LOs. Moreover, the integrated multi-mode PAs achieve the output P1dB (OP1dB) of 16.3 dBm and 14.1 dBm with both 25% PAE for sub-GHz and 2.4 GHz bands, respectively. A power-control loop is proposed to detect the input signal PAPR in real-time and flexibly reconfigure the PA's operation modes to enhance the back-off efficiency. With this proposed technique, the PAE of the sub-GHz PA is improved by x3.24 and x1.41 at 9 dB and 3 dB back-off powers, respectively, and the PAE of the 2.4 GHz PA is improved by x2.17 at 6 dB back-off power. The presented transceiver has achieved comparable or even better performance in terms of noise figure, HRR, OP1dB and power efficiency compared with the state-of-the-art.Peer reviewe

A miniaturised autonomous sensor based on nanowire materials platform: the SiNAPS mote

A micro-power energy harvesting system based on core(crystalline Si)-shell(amorphous Si) nanowire solar cells together with a nanowire-modified CMOS sensing platform have been developed to be used in a dust-sized autonomous chemical sensor node. The mote (SiNAPS) is augmented by low-power electronics for power management and sensor interfacing, on a chip area of 0.25mm2. Direct charging of the target battery (e.g., NiMH microbattery) is achieved with end-to-end efficiencies up to 90% at AM1.5 illumination and 80% under 100 times reduced intensity. This requires matching the voltages of the photovoltaic module and the battery circumventing maximum power point tracking. Single solar cells show efficiencies up to 10% under AM1.5 illumination and open circuit voltages, Voc, of 450-500mV. To match the battery’s voltage the miniaturised solar cells (~1mm2 area) are connected in series via wire bonding. The chemical sensor platform (mm2 area) is set up to detect hydrogen gas concentration in the low ppm range and over a broad temperature range using a low power sensing interface circuit. Using Telran TZ1053 radio to send one sample measurement of both temperature and H2 concentration every 15 seconds, the average and active power consumption for the SiNAPS mote are less than 350nW and 2.1 μW respectively. Low-power miniaturised chemical sensors of liquid analytes through microfluidic delivery to silicon nanowires are also presented. These components demonstrate the potential of further miniaturization and application of sensor nodes beyond the typical physical sensors, and are enabled by the nanowire materials platform

Ekho: A Tool for Recording and Emulating Energy Harvesting Conditions

Harvested energy makes it possible to deploy sensing devices long-term with minimal required upkeep. However, as devices shrink, unpredictable power supplies make it difficult for system designers to anticipate the behavior of these devices. Ekho is tool that records and emulates energy harvesting conditions in order to enable accurate and repeatable testing of these sensing devices. Ekho uses the concept of I-V curves — curves that describe harvesting current in relation to supply voltage — in order to accurately represent harvesting conditions in a form that is independent of the sensing platform and the type of energy that is being harvested. This paper describes extensions to Ekho; it presents the design and an improved implementation, as well as preliminary testing and results. My role in this project has been to reimplement and to extend Ekho. This software was unmaintainable and considerably limited in its ability to emulate energy harvesting conditions. The first implementation of Ekho was a hardware design for an FPGA, which made use of specialized circuits. I refactored this code for a microcontroller, achieving even better performance than before: this new implementation can record harvesting conditions and can emulate changing I-V curves, and I have added back-end programs to ease processing and formatting of data. Initial results show that Ekho is able to replay I-V surfaces while readjusting to the harvesting conditions as frequently as once in 4.3μs. Ekho is able to emulate changing energy conditions, adapting both to changes in supply voltage and energy availability. Ekho can update the I-V curve, which the I-V controller holds in memory during emulation, as frequently as once per millisecond. These results show that Ekho is responsive to changes in the harvesting current and could be working properly

A 1.1 nW Energy-Harvesting System with 544 pW Quiescent Power for Next-Generation Implants

This paper presents a nW power management unit (PMU) for an autonomous wireless sensor that sustains itself by harvesting energy from the endocochlear potential (EP), the 70-100 mV electrochemical bio-potential inside the mammalian ear. Due to the anatomical constraints inside the inner ear, the total extractable power from the EP is limited close to 1.1-6.25 nW. A nW boost converter is used to increase the input voltage (30-55 mV) to a higher voltage (0.8-1.1 V) usable by CMOS circuits in the sensor. A pW charge pump circuit is used to minimize the leakage in the boost converter. Furthermore, ultralow-power control circuits consisting of digital implementations of input impedance adjustment circuits and zero current switching circuits along with Timer and Reference circuits keep the quiescent power of the PMU down to 544 pW. The designed boost converter achieves a peak power conversion efficiency of 56%. The PMU can sustain itself, and a duty-cyled ultralow-power load while extracting power from the EP of a live guinea pig. The PMU circuits have been implemented on a 0.18- μm CMOS process.Semiconductor Research Corporation. Focus Center for Circuit and System Solutions (C2S2)Interconnect Focus Center (United States. Defense Advanced Research Projects Agency and Semiconductor Research Corporation)National Institutes of Health (U.S.) (Grant K08 DC010419)National Institutes of Health (U.S.) (Grant T32 DC00038)Bertarelli Foundatio

On-Chip Solar Energy Harvester and PMU With Cold Start-Up and Regulated Output Voltage for Biomedical Applications

This paper presents experimental results from a system that comprises a fully autonomous energy harvester with a solar cell of 1 mm 2 as energy transducer and a Power Management Unit (PMU) on the same silicon substrate, and an output voltage regulator. Both chips are implemented in standard 0.18 μm CMOS technology with total layout areas of 1.575 mm 2 and 0.0126 mm 2 , respectively. The system also contains an off-the-shelf 3.2 mm × 2.5 mm × 0.9 mm supercapacitor working as an off-chip battery or energy reservoir between the PMU and the voltage regulator. Experimental results show that the fast energy recovery of the on-chip solar cell and PMU permits the system to replenish the supercapacitor with enough charge as to sustain Bluetooth Low Energy (BLE) communications even with input light powers of 510 nW. The whole system is able to self-start-up without external mechanisms at 340 nW. This work is the first step towards a self-supplied sensor node with processing and communication capabilities. The small form factor and ultra-low power consumption of the system components is in compliance with biomedical applications requirementsThis work was supported in part by the Spanish Government (Ministerio de Ciencia, Innovación y Universidades) under Project RTI2018-097088-B-C32 and Project RTI2018-095994-B-I00 (MICINN/FEDER), in part by the Xunta de Galicia, in part by the Consellería de Cultura, Educación e Ordenación Universitaria (accreditation 2016-2019, ED431G/08 and reference competitive group 2017-2020, ED431C 2017/69) and European Regional Development Fund (ERDF), and in part by the Junta de Extremadura and the ERDF, under Grant IB 18079S