John J. Cooley

A 2

This paper describes a prototype micropower instrumentation amplifier intended for chronic sensing of neural field potentials (NFPs). NFPs represent the ensemble activity of thousands of neurons and code-useful information for both normal activity and disease states. NFPs are small - of the order of tens of muV- and reside at low bandwidths that make them susceptible to excess noise. Therefore, to ensure the highest fidelity of signal measurement for diagnostic analysis, the amplifier is chopper-stabilized to eliminate 1/f and popcorn noise. The circuit was prototyped in an 0.8 mum CMOS process and consumes under 2.0 muW from a 1.8 V supply. A noise floor of 0.98 muVrms was achieved over a bandwidth from 0.05 to 100 Hz; the noise-efficiency factor of 4.6 is one of the lowest published to date. A flexible on-chip high-pass filter is used to suppress front-end electrode offsets while maintaining relevant physiological data. The monolithic architect and micropower low-noise low-supply operation could help enable applications ranging from neuroprosthetics to seizure monitors that require a small form factor and battery operation. Although the focus of this paper is on neurophysiological sensing, the circuit architecture can be applied generally to micropower sensor interfaces that benefit from chopper stabilization.

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Per-panel photovoltaic energy extraction with integrated converters can increase overall array tracking efficiency. Also, switched-capacitor (SC) converters have been evaluated for many applications because of the possibility for on-chip integration; applications to solar arrays are no exception. This paper presents a comprehensive system-level look at solar installations, finding possibilities for optimization at and between all levels of operation in an array. Specifically, this paper examines new arrangements and options for applying switched-capacitor circuits at 3 levels: for the panel and sub-panel level, as part of the overall control strategy, and for ensuring stable and robust interface to the grid with the possibility of eliminating or reducing the use of electrolytic capacitors.

100 nV/rtHz Chopper-Stabilized Instrumentation Amplifier for Chronic Measurement of Neural Field Potentials

Switched capacitor multilevel output DC-DC converters are evaluated as panel integrated modules in a solar maximum power point tracking system. The recommended system includes a central input current-controlled ripple port inverter. Potential benefits include per panel MPPT without inter-panel communication, electrolytic capacitors or per panel magnetics. Statistical methods are used to predict average tracking and conversion efficiencies. A particular implementation of the switched capacitor module is studied — the Marx converter. Average total efficiencies (tracking × conversion) greater than 93% are predicted for a simulated 510 W, 3 panel, DC-DC system.

A systems approach to photovoltaic energy extraction

We have developed a proximity sensor that can be integrated with a fluorescent lamp ballast. This sensor measures disturbances in the electric field around the lamp in order to detect the presence and motion of people. Range test data from our preliminary experiments showed detection ranges of 11 ft. between the lamp and the closest edge of a human target. The detector enables fine-grain occupancy measurements in spaces, promising to improve energy efficiency by reducing wasted lighting of unoccupied spaces.

Per panel photovoltaic energy extraction with multilevel output DC-DC switched capacitor converters

This paper presents a retrofit system that exploits a fluorescent lamps own stray electric fields for capacitive sensing. Occupancy detection for demand-side energy management is a key application. The experimental system demonstrates a detection range of 10 ft. between the lamp and the nearest edge of the occupant. A full system model is presented including the simulation of a lumped element capacitive model. The full system model is validated against experimental data.

A Fluorescent Lamp with Integral Proximity Sensor for Building Energy Management

This paper demonstrates the building blocks of a new autonomous demand-side energy management system. The system uses a network of lamp sensors interfaced with frequency-controlled dimming ballasts. The auto-dimming lamps detect occupants and automatically adjust their own brightness levels. These occupancy detections may be used to adjust power consumption of other systems such as heating, ventilation and air-conditioning (HVAC) as well. This paper also demonstrates a quasistatic frequency-modulated (FM) wireless link to network auto-dimming lamps with each other. The wireless link reuses the frequency-controlled action of the dimming ballast to transmit data and the lamp sensor electric field measurement to receive data. All of the electronics are made to fit inside a ballast box with the intent to create a drop-in replacement for standard ballasts. This paper presents critical system characterizations and design strategies as well as a demonstration of an auto-dimming lamp and the wireless link.

A Retrofit Capacitive Sensing Occupancy Detector Using Fluorescent Lamps

This paper describes a proximity detection system that uses a fluorescent lamp as a capacitive sensor. Because of the ubiquity of fluorescent lamps in commercial buildings, public spaces, and households, the potential applications of a capacitive sensor of this nature are numerous. These applications include people counting, real-time people tracking and detection of anomalous objects on a person for security verification. Modeling simulations and calculations of the electric fields under the lamp in the presence of a person as well as circuitry and electrode setups, which can be used to obtain a practical detection range are presented. Real-time tracking data and outputs collected from a working fluorescent lamp sensor are also presented

An autonomous distributed demand-side energy management network using fluorescent lamp sensors

Previous work demonstrated a retrofit proximity detector for fluorescent lamps using the lamps own stray electric fields. This paper extends the retrofit sensor system to a solid-state (LED) lamp. The design and implementation of a suitable driver (“ballast”) for the LED lamp is presented. Design considerations for the ballast include those relevant to lighting (e.g. color cast and dimming levels) as well as those relevant to sensing of human occupants. Two electro-quasistatic modeling approaches for the lamp sensor are discussed. Experimental data from the LED lamp sensor are presented and compared to one of the proposed quasistatic models.

Proximity Detection and Ranging Using a Modified Fluorescent Lamp for Security Applications

A standard 48-inch two-bulb fluorescent lamp was modified to be used as a capacitive sensing system. The lamp sensor system demonstrated the ability to detect the presence and motion of human targets at ranges of up to 10 feet between the lamp and the closest edge of the target. Proof of concept was also demonstrated for metal detection by demonstrating the ability to differentiate between a human target and the same human target carrying conducting (metallic) objects. The lamp sensor shows potential for low-cost and widespread discreet security monitoring and biometric surveillance.

Solid-state lamp with integral occupancy sensor

An analytical modelling approach for fully differential amplifiers is presented and validated through examples. Separation of the analysis into two steps coupled with linear superposition techniques leads to concise mathematical expressions. An added benefit of the two-step approach is that the usual symmetry assumptions are not needed. As a consequence, the results hold for arbitrary element values. The mathematical results are validated by comparison to SPICE simulations and experimental data.