A 0.68V 0.68mW 2.4GHz PLL for ultra-low power RF systems

A 2.4GHz PLL consuming 0.68mW has been implemented in 65nm LPCMOS for use in ultra-low power Bluetooth Low Energy (BLE) applications. VCO, charge pump and dynamic flip-flop design optimization allow low voltage operation at 0.68V, bringing down dynamic power. The integer-N PLL covers all BLE channels and has a phase noise of −110dBc/Hz at 1MHz offset. To extend operation to extremely low duty cycles, extensive power gating is applied to bring the leakage power down to 170pW.Shell Oil CompanyTexas Instruments Incorporate

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

Hardware and software for a power-aware wireless microsensor node

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 143-144).This thesis examines important issues in the design of hardware and software for microsensor networks, with particular attention paid to mechanisms for providing power awareness. The [mu]AMPS Revision 1 microsensor node is used as an example. The design of this node implementation is described in detail, including, in particular, the design of the pAMPS processor board and its power-scalable architecture. The operating system and application programming interface for the node is described. Finally, an analysis is made of the power consumed by each of the node's subsystems, and these results are used to assess the degree of power-awareness provided by the [mu]AMPS Revision 1 node.by Nathan J. Ickes.M.Eng

Cancer Curriculum for Appalachian Kentucky Middle and High Schools

Background: Appalachian Kentucky faces the highest cancer incidence and mortality rates in the country due to poor health behaviors and lifestyle choices. These poor health behaviors are facilitated by a lack of cancer education. Youth represent a vulnerable population that could be greatly impacted by increased cancer education. Teachers have the power to facilitate this learning. Purpose: This study examined the need for cancer education curriculum in Appalachian Kentucky middle and high schools from the perspective of educators. Methods: An online survey was conducted with science and health teachers (n=21) in Appalachian Kentucky, consisting of questions that investigated existing cancer education efforts, relevance of cancer education, and feasibility of such curriculum being delivered in the classroom. Content analysis was used to analyze teacher comments. A 3-part cancer education curriculum was developed that is culturally relevant and aligned with science and health education standards. Results: All participating teachers agree that cancer education is important to students’ lives. Teachers also agree that there is an inconsistent amount of cancer education within schools, and qualitative content analysis revealed that cancer education likely fits best in certain course subjects. Cancer education could feasibly be integrated into science and health classrooms, although the perception of needing to teach to the academic standards and having limited time to teach additional lessons outside of the standards are significant barriers. To combat this, a cancer curriculum that aligns with state and national science and health education standards was developed. Implications: Cancer education curriculum could play an important role in improving the cancer outlook in Appalachian Kentucky. Teachers have expressed a desire for increased cancer education in the classroom. By disseminating and implementing cancer curriculum in schools in the region and revising the curriculum -based on teacher and student feedback to better fit their needs, it has the potential to increase cancer literacy and improve related health behaviors and outcomes

A 0.6V, 8mW 3D Vision Processor for a Navigation Device for the Visually Impaired

This paper presents an energy-efficient computer vision processor for a navigation device for the visually impaired. Utilizing a shared parallel datapath, out-of-order processing and co-optimization with hardware-oriented algorithms, the processor consumes 8mW at 0.6V while processing 30 fps input data stream in real time. The test chip fabricated in 40nm is demonstrated as a core part of a navigation device based on a ToF camera, which successfully detects safe areas and obstacles.Texas Instruments Incorporate

The Great Escape: The Role of Self-esteem and Self-related Cognition in Terror Management

Integrating terror management theory and objective self-awareness theory, we propose the existential escape hypothesis, which states that people with low self-esteem should be especially prone to escaping self-awareness as a distal response to thoughts of death. This is because they lack the means to bolster the self as a defense, and the propensity to bolster the self reduces the motivation to escape from self-awareness. Five studies supported this hypothesis. Individuals low, but not high, in self-esteem scored lower on a measure of private self-awareness (Study 1), showed less implicit self-activation (Studies 2 & 3), were more likely to choose to write about others than themselves (Study 4), and consumed more alcohol in a field study at a nightclub (Study 5) in response to mortality reminders. Implications for terror management theory (highlighting an additional route to defend against mortality awareness), self-regulation, physical health and well-being are discussed

Micropower digital signal processing for sensor applications

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.Includes bibliographical references (p. 171-176).Ultra-low power systems, such as wireless microsensor networks or implanted medical devices, are driving the development of processors capable of performing increasingly complicated computations using mere microwatts of power. This thesis describes the design of a micropower DSP intended for medium bandwidth microsensor applications (such as acoustic sensing and tracking) which achieves 4 MIPS performance at 40 [mu]W (10 pJ per instruction) operating at 450 mV and fabricated in 90 nm CMOS. Energy efficiency optimizations include a custom CPU instruction set, a miniature instruction cache with a novel replacement strategy, hardware accelerator cores for FIR filter and FFT operations, and extensive power gating of both logic and memory. The tradeoffs of cache size, line length, and replacement policy for very small (a few hundred words or less) caches are explored, as are the design implications of optimizing the cache for minimum energy without regard to performance (since onchip memory access is already single-cycle). A replacement policy designed to reduce thrashing in miniature instruction caches is presented. Efficient control of power-gated circuits requires consideration of the minimum off time, or break-even time. An energy model for determining the break-even time is developed, which correlates with measurements of the power-gated domains on the DSP. The energy savings obtained from hardware accelerators for FIR filtering and FFT operations are measured, and a model is developed to predict the actual net power reduction in a real system, including factors such as sampling rate, leakage power, latency requirements, and power gating overhead.by Nathan J. Ickes.Ph.D

Instruction Level and Operating System Profiling for Energy Exposed Software

Energy conscious software design can significantly improve the energy efficiency of a portable system. A software energy estimation technique using instruction class profiling is presented. The technique is shown to have an estimation error of less than 3% with trivial runtime overhead, based on a set of application programs evaluated on the StrongARM SA-1100 and Hitachi SH-4 microprocessors. A technique to isolate the switching and leakage energy components of software is outlined. The energy overhead of a real-time operating system is also profiled. The overall impact of system-level software energy management is quantified using the MIT AMPS system as an application example

Physical layer driven protocol and algorithm design for energy-efficient wireless sensor networks

The potential for collaborative, robust networks of microsensors has attracted a great deal of research attention. For the most part, this is due to the compelling applications that will be enabled once wireless microsensor networks are in place; location-sensing, environmental sensing, medical monitoring and similar applications are all gaining interest. However, wireless microsensor networks pose numerous design challenges. For applications requiring longterm, robust sensing, such as military reconnaissance, one important challenge is to design sensor networks that have long system lifetimes. This challenge is especially difficult due to the energyconstrained nature of the devices. In order to design networks that have extremely long lifetimes, we propose a physical layer driven approach to designing protocols and algorithms. We first present a hardware model for our wireless sensor node and then introduce the design of physical layer aware protocols, algorithms, and applications that minimize energy consumption of the system. Our approach prescribes methods that can be used at all levels of the hierarchy to take advantage of the underlying hardware. We also show how to reduce energy consumption of non-ideal hardware through physical layer aware algorithms and protocols. 1