Multi-channel ultra-low-power receiver architecture for body area networks

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 85-91).In recently published integrated medical monitoring systems, a common thread is the high power consumption of the radio compared to the other system components. This observation is indicative of a natural place to attempt a reduction in system power. Narrowband receivers in-particular can enjoy significant power reduction by employing high-Q bulk acoustic resonators as channel select filters directly at RF, allowing down-stream analog processing to be simplified, resulting in better energy efficiency. But for communications in the ISM bands, it is important to employ multiple frequency channels to permit frequency-division-multiplexing and provide frequency diversity in the face of narrowband interferers. The high-Q nature of the resonators means that frequency tuning to other channels in the same band is nearly impossible; hence, a new architecture is required to address this challenge. A multi-channel ultra-low power OOK receiver for Body Area Networks (BANs) has been designed and tested. The receiver multiplexes three Film Bulk Acoustic Resonators (FBARs) to provide three channels of frequency discrimination, while at the same time offering competitive sensitivity and superior energy efficiency in this class of BAN receivers. The high-Q parallel resonance of each resonator determines the passband. The resonator's Q is on the order of 1000 and its center frequency is approximately 2.5 GHz, resulting in a -3 dB bandwidth of roughly 2.5 MHz with a very steep rolloff. Channels are selected by enabling the corresponding LNA and mixer pathway with switches, but a key benefit of this architecture is that the switches are not in series with the resonator and do not de-Q the resonance. The measured 1E-3 sensitivity is -64 dBm at 1 Mbps for an energy efficiency of 180 pJ/bit. The resonators are packaged beside the CMOS using wirebonds for the prototype.by Phillip Michel Nadeau.S.M

Thermal Energy Harvesting for Self-Powered Smart Home Sensors

This paper investigates the use of thermoelectric energy harvesting for embedded, self-powered sensor nodes in smart homes. In particular, one such application is self-powered pressure sensing in vacuum insulation panels for buildings. The panels greatly improve heating and cooling energy use, and the thermal difference developed across them could be used to drive a wireless sensor to monitor their pressure level. We first created a model for the available power using historical weather data. Then, we measured the thermoelectric generator’s actual power output by combining the generator with a vacuum insulation panel and mounting it inside a window for experiments. Finally, we determine the feasibility of using the established thermal gradient to power a sensor node. We show that thermoelectric energy harvesting could enable a new class of embedded, maintenance-free, self-powered sensors for smart homes

A 440pJ/bit 1Mb/s 2.4GHz multi-channel FBAR-based TX and an integrated pulse-shaping PA

A 2.4GHz TX in 65nm CMOS defines three channels using three high-Q FBARs and supports OOK, BPSK and MSK. The oscillators have -132dBc/Hz phase noise at 1MHz offset, and are multiplexed to an efficient resonant buffer. Optimized for low output power ≈-10dBm, a fully-integrated PA implements 7.5dB dynamic output power range using a dynamic impedance transformation network, and is used for amplitude pulse-shaping. Peak PA efficiency is 44.4% and peak TX efficiency is 33%. The entire TX consumes 440pJ/bit at 1Mb/s.Interconnect Focus Center (United States. Defense Advanced Research Projects Agency and Semiconductor Research Corporation

Multi-channel 180pJ/b 2.4GHz FBAR-based receiver

A three-channel 2.4GHz OOK receiver is designed in 65nm CMOS and leverages MEMS to enable multiple sub-channels of operation within a band at a very low energy per received bit. The receive chain features an LNA/mixer architecture that efficiently multiplexes signal pathways without degrading the quality factor of the resonators. The single-balanced mixer and ultra-low power ring oscillator convert the signal to IF, where it is efficiently amplified to enable envelope detection. The receiver consumes a total of 180pJ/b from a 0.7V supply while achieving a BER=10-3 sensitivity of -67dBm at a 1Mb/s data rate.Semiconductor Research Corporation. Interconnect Focus CenterNatural Sciences and Engineering Research Council of Canada (Fellowship

IPTV: Streaming television over the Internet

Abstract only availableIPTV is the process of streaming video over a network connection like the internet. This could be the next step in television evolution. There are currently several programs and boxes that you can buy that use the internet to connect to various servers that broadcast live TV and video on demand. These systems can be expensive and usually come with a monthly fee. Because of the large amount of data required for digital media it is difficult to stream it over common internet connections without lag or a buffering process. This project investigates two ways of solving problems with IPTV technology. The first method uses real-time bitstream switching. This process should reduce the quality of the video by reducing the size of the bitstream thus allowing the video to buffer faster during times of low bandwidth. It should also switch to higher quality during times of increased bandwidth. The second problem that was investigated was how to easily and efficiently change the resolution of a video. Interpolation is the process of increasing or decreasing the size of an image by guessing what the pixels in between known pixels should look like. In video processing, interpolation is required for proper reconstruction of frames in a video using motion vectors with sub-pixel accuracy to calculate the location of most similar pixels from one frame to the next. A third task is to create a GUI implementation for the project. The GUI should have the capability to use picture in picture (PiP) and a multichannel preview. For this project, we used VLC, an open source media player, and the mp4 video file format. After modifying VLC code, we were able to switch between multiple tracks within an mp4 file, where each track has a different bit rate. Using a similar process, we were able to switch between videos at different spatial resolutions. Further modifications to VLC are required to interpolate the image in order for smooth switching of spatial resolutions. The GUI implementation uses visual C# to embed VLC, and allows the user to select video files from a streaming server to watch in a main screen and PiP format.NSF-REU Program in Home Networking Technologie

Prolonged energy harvesting for ingestible devices

Ingestible electronics have revolutionized the standard of care for a variety of health conditions. Extending the capacity and safety of these devices, and reducing the costs of powering them, could enable broad deployment of prolonged-monitoring systems for patients. Although previous biocompatible power-harvesting systems for in vivo use have demonstrated short (minute-long) bursts of power from the stomach, little is known about the potential for powering electronics in the longer term and throughout the gastrointestinal tract. Here, we report the design and operation of an energy-harvesting galvanic cell for continuous in vivo temperature sensing and wireless communication. The device delivered an average power of 0.23 μW mm⁻² of electrode area for an average of 6.1 days of temperature measurements in the gastrointestinal tract of pigs. This power-harvesting cell could provide power to the next generation of ingestible electronic devices for prolonged periods of time inside the gastrointestinal tract.National Institutes of Health (U.S.) (Grant EB-000244

Prolonged energy harvesting for ingestible devices

Ingestible electronics have revolutionized the standard of care for a variety of health conditions. Extending the capacity and safety of these devices, and reducing the costs of powering them, could enable broad deployment of prolonged monitoring systems for patients. Although prior biocompatible power harvesting systems for in vivo use have demonstrated short minute-long bursts of power from the stomach, not much is known about the capacity to power electronics in the longer term and throughout the gastrointestinal tract. Here, we report the design and operation of an energy-harvesting galvanic cell for continuous in vivo temperature sensing and wireless communication. The device delivered an average power of 0.23 μW per mm2 of electrode area for an average of 6.1 days of temperature measurements in the gastrointestinal tract of pigs. This power-harvesting cell has the capacity to provide power for prolonged periods of time to the next generation of ingestible electronic devices located in the gastrointestinal tract

Open Problems and Fundamental Limitations of Reinforcement Learning from Human Feedback

Reinforcement learning from human feedback (RLHF) is a technique for training AI systems to align with human goals. RLHF has emerged as the central method used to finetune state-of-the-art large language models (LLMs). Despite this popularity, there has been relatively little public work systematizing its flaws. In this paper, we (1) survey open problems and fundamental limitations of RLHF and related methods; (2) overview techniques to understand, improve, and complement RLHF in practice; and (3) propose auditing and disclosure standards to improve societal oversight of RLHF systems. Our work emphasizes the limitations of RLHF and highlights the importance of a multi-faceted approach to the development of safer AI systems