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A Low Power and Fast Tracking Light-to-Frequency Converter with Adaptive Power Scaling for Blood SpO2 Sensing
摘要： This paper presents a monolithic low power and fast tracking light-to-frequency converter for blood SpO2 sensing. Normally, the tracking speed and the power consumption are two contradictory characteristics. However different gain-bandwidth specifications for various ambient light intensities allow the dynamically optimization of the power consumption according to the light intensity. In this paper, the amplifier power consumption is adaptively scaled by the generated light-intensity-positively-correlated control voltage. Thus, the chip total power consumption at low light intensity is significantly decreased. Moreover, the proposed adaptive power scaling is achieved with a continuous analog domain, which does not introduce extra switching noise. The proposed light-to-frequency sensor chip is fabricated by using 0.35 μm CMOS technology with a die area of 1 × 0.9 mm2. The measurement results show that the pulse light response for any light intensity is no longer than two new output square-wave cycles. The maximum total current consumption is 1.9 mA from a 3.3 V supply voltage, which can be adaptively scaled down to only 0.7 mA if the output frequency is about 25 KHz or lower. The minimum operational supply voltage of the proposed sensor chip is 2.5 V in the temperature range of -25 to 80 oC with 4 KV ESD level (HBM).
关键词： light-to-frequency converter,low power,fast tracking,blood oxygen,biomedical sensor
更新于2025-09-23 15:23:52
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Radiation from junctions between two-dimensional plasmonic waveguides
摘要： We propose a digitally controlled injection-locked RF oscillator with an auxiliary loop as an alternative to the conventional capacitive fine-tuning of an LC-tank. The oscillator is injection locked to a time-delayed version of its resonating voltage and its frequency is modulated by manipulating the phase and amplitude of injected current. The injection strength can be programmed for the DCO step size to be as fine as 9 kHz at 4 GHz. Alternatively, with large injection strength, the tuning range can reach up to 200 MHz. The proposed oscillator is experimentally verified in TSMC 40 nm digital CMOS.
关键词： multi-stage noise ΣΔ (MASH),digitally controlled oscillator (DCO),digitally controlled delay (DCD),digital-to-frequency converter (DFC),All-digital PLL (ADPLL),digital phase rotator (DPR)
更新于2025-09-19 17:13:59
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[IEEE IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Lisbon, Portugal (2019.10.14-2019.10.17)] IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - New Approaches for Low Power Photovoltaic Water Pumping Systems
摘要： Photovoltaic water pumping systems are available as kits to supply water where the grid does not go. These kits usually are made by multinationals and based on specific components, making the most of small and very small companies, who usually install these systems, dependent on others. Thankfully these companies can develop their own solutions with standard frequency converters and AC pumps. An alternative is to connect the standard frequency converters to a photovoltaic string with a DC voltage of the order of some hundreds of volts. This implies in more than 2kW of power installed. For many applications, more than 2kW would be oversized. This paper presents a review of photovoltaic water pumping systems based on standard frequency converters and proposes new approaches for low power applications requiring only up to four modules. These approaches are being investigated and evaluated in cooperation with a company.
关键词： Photovoltaic Pumping,AC Pumps,Boost Converter,Frequency Converter,Photovoltaic Energy
更新于2025-09-16 10:30:52