Rf-powered systems using steep-slope devices
22 Jun 2014-pp 73-76
TL;DR: This paper focuses on how steep-slope devices can enhance efficiencies of harvesting ambient RF energy and improve power efficiency of analog and digital computational blocks.
Abstract: Steep-slope tunnel devices promise new opportunities in ultra-low-power computing. This paper focuses on how steep-slope devices can enhance efficiencies of harvesting ambient RF energy and improve power efficiency of analog and digital computational blocks.
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09 Mar 2015
TL;DR: The simulation platform in this paper is calibrated using measured results from a fabricated nonvolatile processor and used to explore the design space for a nonVolatile processor with different architectures, different input power sources, and policies for maximizing forward progress.
Abstract: Energy harvesting has been widely investigated as a promising method of providing power for ultra-low-power applications. Such energy sources include solar energy, radio-frequency (RF) radiation, piezoelectricity, thermal gradients, etc. However, the power supplied by these sources is highly unreliable and dependent upon ambient environment factors. Hence, it is necessary to develop specialized systems that are tolerant to this power variation, and also capable of making forward progress on the computation tasks. The simulation platform in this paper is calibrated using measured results from a fabricated nonvolatile processor and used to explore the design space for a nonvolatile processor with different architectures, different input power sources, and policies for maximizing forward progress.
225 citations
Cites background or methods from "Rf-powered systems using steep-slop..."
...We observe substantial variation in power, even over a few milliseconds for RF in Figure 3a) with the ratio between the maximum and minimum power over this period around 250× [20], [25], [26]....
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...Finally, various circuit and architecturelevel techniques can be applied to reduce the power: adoption of emerging technologies like Tunnel-FET [20], low power sub-threshold circuits, dark silicon-aware architectures [34], clock gating, dynamic-voltage-frequency-scaling (DVFS) and Dynamic-Adjusting Threshold-Voltage Scheme (DATS) [35] etc....
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...Ambient power sources and harvesting techniques Typical ambient energy sources that could be harvested to power an embedded system include solar energy, radiofrequency (RF) radiation, piezoelectric effect and thermal gradients [20]....
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07 Jun 2015
TL;DR: New metrics of nonvolatile processors to consider energy harvesting factors for the first time are proposed and the nonvolatility processor design from circuit to system level is explored.
Abstract: Energy harvesting is gaining more and more attentions due to its characteristics of ultra-long operation time without maintenance. However, frequent unpredictable power failures from energy harvesters bring performance and reliability challenges to traditional processors. Nonvolatile processors are promising to solve such a problem due to their advantage of zero leakage and efficient backup and restore operations. To optimize the nonvolatile processor design, this paper proposes new metrics of nonvolatile processors to consider energy harvesting factors for the first time. Furthermore, we explore the nonvolatile processor design from circuit to system level. A prototype of energy harvesting nonvolatile processor is set up and experimental results show that the proposed performance metric meets the measured results by less than 6.27% average errors. Finally, the energy consumption of nonvolatile processor is analyzed under different benchmarks.
127 citations
Cites background from "Rf-powered systems using steep-slop..."
...Generally, the widely used ambient energy sources include the radio-frequency (RF) signal, piezoelectric energy, photovoltaic cells, and thermoelectric devices [19, 20, 21]....
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05 Jun 2016
TL;DR: This work proposes a 2-transistor (2T) FEFET-based nonvolatile memory with separate read and write paths that achieves non-destructive read and lower write power at iso-write speed compared to standard FE-RAM.
Abstract: Ferroelectric FETs (FEFETs) offer intriguing possibilities for the design of low power nonvolatile memories by virtue of their three-terminal structure coupled with the ability of the ferroelectric (FE) material to retain its polarization in the absence of an electric field. Utilizing the distinct features of FEFETs, we propose a 2-transistor (2T) FEFET-based nonvolatile memory with separate read and write paths. With proper co-design at the device, cell and array levels, the proposed design achieves non-destructive read and lower write power at iso-write speed compared to standard FE-RAM. In addition, the FEFET-based memory exhibits high distinguishability with six orders of magnitude difference in the read currents corresponding to the two states. Comparative analysis based on experimentally calibrated models shows significant improvement of access energy-delay. For example, at a fixed write time of 550ps, the write voltage and energy are 58.5% and 67.7% lower than FERAM, respectively. These benefits are achieved with 2.4 times the area overhead. Further exploration of the proposed FEFET memory in energy harvesting nonvolatile processors shows an average improvement of 27% in forward progress over FERAM.
99 citations
Cites background from "Rf-powered systems using steep-slop..."
...Nonvolatile memories (NVM) are being actively explored with the objectives to achieve zero stand-by leakage and high integration density, and thereby attain a large boost in the energy efficiency and storage capacity of on-chip caches for embedded applications and energy autonomous systems [1-5]....
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TL;DR: This paper pioneers a converter-less PV power system with the maximum power point tracking that directly supplies power to the load without the power converters or the energy storage element and achieves an 87.1% of overall system efficiency during a day.
Abstract: Energy harvesting from natural environment gives range of benefits for the Internet of things. Scavenging energy from photovoltaic (PV) cells is one of the most practical solutions in terms of power density among existing energy harvesting sources. PV power systems mandate the maximum power point tracking (MPPT) to scavenge the maximum possible solar energy. In general, a switching-mode power converter, an MPPT charger, controls the charging current to the energy storage element (a battery or equivalent), and the energy storage element provides power to the load device. The mismatch between the maximum power point (MPP) current and the load current is managed by the energy storage element. However, such architecture causes significant energy loss (typically over 20%) and a significant weight/volume and a high cost due to the cascaded power converters and the energy storage element. This paper pioneers a converter-less PV power system with the MPPT that directly supplies power to the load without the power converters or the energy storage element. The proposed system uses a nonvolatile microprocessor to enable an extremely fine-grain dynamic power management in a few hundred microseconds. This makes it possible to match the load current with the MPP current. We present detailed modeling, simulation, and optimization of the proposed energy harvesting system including the radio frequency transceiver. Experiments show that the proposed setup achieves an 87.1% of overall system efficiency during a day, 30.6% higher than the conventional MPPT methods in actual measurements, and thus a significantly higher duty cycle under a weak solar irradiance.
87 citations
Cites background from "Rf-powered systems using steep-slop..."
...I. INTRODUCTION SOME technical reports predicted that the number of smartsensors will reach to trillions in the near future [1]....
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TL;DR: The capability of obtaining a high PCE at a low RF input power range reveals the superiority of the HTFET RF rectifiers for battery-less energy harvesting applications.
Abstract: Radio-frequency (RF)-powered energy harvesting systems have offered new perspectives in various scientific and clinical applications such as health monitoring, bio-signal acquisition, and battery-less data-transceivers. In such applications, an RF rectifier with high sensitivity, high power conversion efficiency (PCE) is critical to enable the utilization of the ambient RF signal power. In this paper, we explore the high PCE advantage of the steep-slope III-V heterojunction tunnel field-effect transistor (HTFET) RF rectifiers over the Si FinFET baseline design for RF-powered battery-less systems. We investigate the device characteristics of HTFETs to improve the sensitivity and PCE of the RF rectifiers. Different topologies including the two-transistor (2-T) and four-transistor (4-T) complementary-HTFET designs, and the n-type HTFET-only designs are evaluated with design parameter optimizations to achieve high PCE and high sensitivity. The performance evaluation of the optimized 4-T cross-coupled HTFET rectifier has shown an over 50% PCE with an RF input power ranging from -40 dBm to -25 dBm, which significantly extends the RF input power range compared to the baseline Si FinFET design. A maximum PCE of 84% and 85% has been achieved in the proposed 4-T N-HTFET-only rectifier at -33.7 dBm input power and the 4-T cross-coupled HTFET rectifier at -34.5 dBm input power, respectively. The capability of obtaining a high PCE at a low RF input power range reveals the superiority of the HTFET RF rectifiers for battery-less energy harvesting applications.
68 citations
References
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01 May 1946
TL;DR: In this paper, a simple transmission formula for a radio circuit is derived, and the utility of the formula is emphasized and its limitations are discussed, as well as its utility and limitations.
Abstract: A simple transmission formula for a radio circuit is derived. The utility of the formula is emphasized and its limitations are discussed.
1,956 citations
"Rf-powered systems using steep-slop..." refers background in this paper
...where Gt and Gr are the antenna gains with respect to an isotropic radiator of the transmitting and receiving antennas respectively, λ is the wavelength, and ηharvester is the PCE of the power harvester consisting of impedance matching network and RF-to-DC rectifier [16]....
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...(1) with λ/2 dipole antenna [16] 1mW 0....
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...(1) with λ/2 dipole antenna [16] A 40 W cellular station Typical sensitivity range of cellphones: 10~10 μW...
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25 Oct 2010
TL;DR: This review introduces and summarizes progress in the development of the tunnel field- effect transistors (TFETs) including its origin, current experimental and theoretical performance relative to the metal-oxide-semiconductor field-effect transistor (MOSFET), basic current-transport theory, design tradeoffs, and fundamental challenges.
Abstract: Steep subthreshold swing transistors based on interband tunneling are examined toward extending the performance of electronics systems. In particular, this review introduces and summarizes progress in the development of the tunnel field-effect transistors (TFETs) including its origin, current experimental and theoretical performance relative to the metal-oxide-semiconductor field-effect transistor (MOSFET), basic current-transport theory, design tradeoffs, and fundamental challenges. The promise of the TFET is in its ability to provide higher drive current than the MOSFET as supply voltages approach 0.1 V.
1,389 citations
"Rf-powered systems using steep-slop..." refers background in this paper
...A TFET is essentially reverse-biased, gated p-i-n tunnel diode with asymmetrical source/drain doping, whose on-state drain-source current is enabled by gate-controlled band-to-band tunneling, and off-state current is determined by the reverse-biased diode leakage [11][12][13]....
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...Steep-slope TFETs have been proposed to further scale the power supply in ultra-low-power applications [11]....
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...Steep-slope tunnel field-effect transistors (TFETs) have become a promising candidate to replace CMOS FETs with higher power-efficiency for low-voltage digital applications due to the tunneling characteristics at a low power supply [11][12][13]....
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03 Nov 2009
TL;DR: Experimental results show the existence of an optimum transistor size in accordance with the output loading conditions and the peak PCE increases with a decrease in operation frequency and with an increase in output load resistance.
Abstract: A high-efficiency CMOS rectifier circuit for UHF RFIDs was developed. The rectifier has a cross-coupled bridge configuration and is driven by a differential RF input. A differential-drive active gate bias mechanism simultaneously enables both low ON-resistance and small reverse leakage of diode-connected MOS transistors, resulting in large power conversion efficiency (PCE), especially under small RF input power conditions. A test circuit of the proposed differential-drive rectifier was fabricated with 0.18 mu m CMOS technology, and the measured performance was compared with those of other types of rectifiers. Dependence of the PCE on the input RF signal frequency, output loading conditions and transistor sizing was also evaluated. At the single-stage configuration, 67.5% of PCE was achieved under conditions of 953 MHz, - 12.5 dBm RF input and 10 KOmega output load. This is twice as large as that of the state-of-the-art rectifier circuit. The peak PCE increases with a decrease in operation frequency and with an increase in output load resistance. In addition, experimental results show the existence of an optimum transistor size in accordance with the output loading conditions. The multi-stage configuration for larger output DC voltage is also presented.
432 citations
"Rf-powered systems using steep-slop..." refers methods in this paper
...In conventional designs, Schottky diode has thus been utilized because of small turn-on voltage [26]....
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TL;DR: In this paper, a fully integrated programmable biomedical sensor interface chip dedicated to the processing of various types of biomedical signals is presented. But the chip, optimized for high power efficiency, contains a low noise amplifier, a tunable bandpass filter, a programmable gain stage, and a successive approximation register analog-to-digital converter.
Abstract: This paper presents a fully integrated programmable biomedical sensor interface chip dedicated to the processing of various types of biomedical signals. The chip, optimized for high power efficiency, contains a low noise amplifier, a tunable bandpass filter, a programmable gain stage, and a successive approximation register analog-to-digital converter. A novel balanced tunable pseudo-resistor is proposed to achieve low signal distortion and high dynamic range under low voltage operations. A 53 nW, 30 kHz relaxation oscillator is included on-chip for low power consumption and full integration. The design was fabricated in a 0.35 mum standard CMOS process and tested at 1 V supply. The analog front-end has measured frequency response from 4.5 mHz to 292 Hz, programmable gains from 45.6 dB to 60 dB, input referred noise of 2.5 muVrms in the amplifier bandwidth, a noise efficiency factor (NEF) of 3.26, and a low distortion of less than 0.6% with full voltage swing at the ADC input. The system consumes 445 nA in the 31 Hz narrowband mode for heart rate detection and 895 nA in the 292 Hz wideband mode for ECG recording.
390 citations
TL;DR: A noninvasive wireless sensor platform for continuous health monitoring that is wirelessly powered and achieves a measured glucose range of 0.05-1 mM with a sensitivity of 400 Hz/mM while consuming 3 μW from a regulated 1.2-V supply is presented.
Abstract: This paper presents a noninvasive wireless sensor platform for continuous health monitoring. The sensor system integrates a loop antenna, wireless sensor interface chip, and glucose sensor on a polymer substrate. The IC consists of power management, readout circuitry, wireless communication interface, LED driver, and energy storage capacitors in a 0.36-mm2 CMOS chip with no external components. The sensitivity of our glucose sensor is 0.18 μA·mm-2·mM-1. The system is wirelessly powered and achieves a measured glucose range of 0.05-1 mM with a sensitivity of 400 Hz/mM while consuming 3 μW from a regulated 1.2-V supply.
384 citations