Mahmoud Saadat

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[[Image:Mahmoud Saadat.JPG|left|128x128px|Mahmoud]]  
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[[Image:Mahmoud Saadat.JPG|left|140x140px|Mahmoud]] BSEE, Sharif University of Technology, 2007<br>MSEE, Stanford University, 2009<br>Admitted to Ph.D. Candidacy: 2011-2012
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'''Research Project:''' '''An Energy-Harvesting, Power-Aware Sensor Platform for Wireless Data Acquisition Applications'''
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Email: mahmoud [at] stanford [dot] edu <br> <br>
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BSEE, Sharif University of Technology, 2007<br>MSEE, Stanford University, 2009<br>Admitted to Ph.D. Candidacy: 2011-2012
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Conventional wireless sensor devices utilize batteries as the main power source for the sensing circuits and wireless transceiver. However, it is often desired to eliminate the battery from a system due to its size, cost (mainly maintenance cost), environmental impact, operating limits, and limited capacity and lifetime. Ambient energy harvesting is a viable alternative source for low power, low data-rate wireless sensing applications; where the sensor monitors a physical quantity that changes slowly and needs to be transmitted infrequently. Depending on the application, a sensor node can harvest solar, thermal, vibrational, RF, or other forms of ambient energy.  
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'''Research:''' An Energy-Harvesting, Power-Aware Sensor Platform for Wireless Data Acquisition Applications<br> <br>
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This project involves design and implementation of high performance Power Management Integrated Circuits (PMIC) for ambient energy harvesting. The core of the PMIC is a high-efficiency, ultra-low voltage, low-quiescent current, DC-DC converter which can harvest energy from one or more energy transducers and provide multiple supply rails to power the subsequent blocks and charge a temporary storage component.
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Conventional wireless sensor devices utilize batteries as the main power source for the sensing circuits and wireless transceiver. However, it is often desired to eliminate the battery from the system due to its limited capacity, size, cost (mainly maintenance cost), environmental impact, and operating limits. Ambient energy harvesting has found to be the most viable alternative source for low power, low data-rate wireless sensing applications, where the sensors monitor a physical quantity that changes slowly and needs to be transmitted infrequently. Depending on the application, a sensor node can harvest solar, thermal, vibrational, RF, or other forms of the ambient power.  
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The current phase of this project is the design of a reconfigurable closed-loop switched-capacitor DC-DC converter for sub-mW energy harvesting applications.&nbsp;This design has the following characteristics: First, to support a wide input voltage range, the switched-capacitor converter is designed to be reconfigurable: It adjusts its voltage gain and frequency based on the operating condition of the converter. Second, our design is targeted to operate with DC voltages from 0.5 V to 2.5 V. This range covers operation with solar cells, high voltage thermo-electric generators and rectified AC sources. Finally, since a wireless sensor typically consumes tens to hundreds microwatts of power, we aim at delivering at least one hundred microwatts of power to the load (comprised of sensor circuits). The target output voltage is 1.2 V and the regulation window is from 1 V to 1.4 V.&nbsp; <br> <br>
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<br>This project involves design and implementation of a high performance Power Management IC (PMIC) for ambient energy harvesting. The core of the PMIC is a high-efficiency, ultra-low voltage, low-quiescent current, step-up converter which can harvest energy from one or more energy transducers and provide multiple supply rails to power the subsequent blocks and charge a temporary storage component. A power-aware analog front-end and low-power ADC are operated on a supply line from the PMIC. The sampling rate and resolution of the ADC are adaptively adjusted based on the available energy that is harvested and stored by the PMIC. Once the energy harvesting sensor platform is developed, the ambient energy transducer, micro-controller, and RF transceiver are added to create a complete energy harvesting wireless sensor node. <br><br>
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The following figure shows the block diagram of the reconfigurable closed-loop switched-capacitor DC-DC converter. The power conversion stage is a reconfigurable series-parallel converter. Two gain control and frequency control loops run simulataneously to regulate the output voltage and guarantee high-efficiency operation. This power management circuit has been simulated in a 0.25-μm CMOS process and simulation results confirm that with an input voltage ranging from 0.5 V to 2.5 V, the converter can generate a regulated 1.2 V output rail and deliver a maximum load current of 100 μA. The power conversion efficiency is higher than 80% across a wide range of the input voltage with a maximum efficiency of 88%.  
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[[Image:Mahmoud EnergyHarvestingSoC.JPG|left|Top Level Block Diagram of the Energy Harvesting Sensor Platform]]
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[[Image:Itc10725 blockDiagram.png]]

Latest revision as of 19:40, 30 July 2014

Mahmoud
BSEE, Sharif University of Technology, 2007
MSEE, Stanford University, 2009
Admitted to Ph.D. Candidacy: 2011-2012

Research Project: An Energy-Harvesting, Power-Aware Sensor Platform for Wireless Data Acquisition Applications

Email: mahmoud [at] stanford [dot] edu


Conventional wireless sensor devices utilize batteries as the main power source for the sensing circuits and wireless transceiver. However, it is often desired to eliminate the battery from a system due to its size, cost (mainly maintenance cost), environmental impact, operating limits, and limited capacity and lifetime. Ambient energy harvesting is a viable alternative source for low power, low data-rate wireless sensing applications; where the sensor monitors a physical quantity that changes slowly and needs to be transmitted infrequently. Depending on the application, a sensor node can harvest solar, thermal, vibrational, RF, or other forms of ambient energy.


This project involves design and implementation of high performance Power Management Integrated Circuits (PMIC) for ambient energy harvesting. The core of the PMIC is a high-efficiency, ultra-low voltage, low-quiescent current, DC-DC converter which can harvest energy from one or more energy transducers and provide multiple supply rails to power the subsequent blocks and charge a temporary storage component.


The current phase of this project is the design of a reconfigurable closed-loop switched-capacitor DC-DC converter for sub-mW energy harvesting applications. This design has the following characteristics: First, to support a wide input voltage range, the switched-capacitor converter is designed to be reconfigurable: It adjusts its voltage gain and frequency based on the operating condition of the converter. Second, our design is targeted to operate with DC voltages from 0.5 V to 2.5 V. This range covers operation with solar cells, high voltage thermo-electric generators and rectified AC sources. Finally, since a wireless sensor typically consumes tens to hundreds microwatts of power, we aim at delivering at least one hundred microwatts of power to the load (comprised of sensor circuits). The target output voltage is 1.2 V and the regulation window is from 1 V to 1.4 V. 

The following figure shows the block diagram of the reconfigurable closed-loop switched-capacitor DC-DC converter. The power conversion stage is a reconfigurable series-parallel converter. Two gain control and frequency control loops run simulataneously to regulate the output voltage and guarantee high-efficiency operation. This power management circuit has been simulated in a 0.25-μm CMOS process and simulation results confirm that with an input voltage ranging from 0.5 V to 2.5 V, the converter can generate a regulated 1.2 V output rail and deliver a maximum load current of 100 μA. The power conversion efficiency is higher than 80% across a wide range of the input voltage with a maximum efficiency of 88%.

Itc10725 blockDiagram.png

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