Salah-Eddine Adami

Self-powered ultra-low power DC-DC converter for RF energy harvesting

In this paper, an autonomous low voltage and ultra-low power DC-DC converter is presented. This novel topology is inspired from the classical Armstrong oscillator structure. In addition to be self-powered and autonomous, this converter is suitable for high-impedance sources. Theoretical and simulation-based optimizations are used in order to design the converter. A fabricated prototype is tested. It harvests RF energy from a low power rectenna (rectifying antenna). High output voltage and good performances are achieved in the range of 4μW to 1mW of input power.

Self-starting DC:DC boost converter for low-power and low-voltage microbial electric generators

This paper describes and evaluates an original boost converter able to harvest energy from low-power and low-voltage power sources. Design and sizing are made according to specifications issued from the stringent characteristics of microbial electric generators such as microbial fuel cells and microbial desalination cells. The harvested power is 10mW under input voltage Vin=0.3V (33mA input current). The design of the converter is adapted from a classical boost topology. It includes a self-oscillating circuit for autonomous operation, and a simple analog maximum power point regulation. Measurements of the conceived discrete realization enable evaluation of the circuit. Best global efficiency of 74% is achieved under realistic harvesting conditions.

An Efficient Dual - Circularly Polarized Rectenna for RF Energy Harvesting in the 2 . 45 GHz ISM Band

This paper reports a 2.45 GHz, low power dual circularly polarized (DCP) and dual access rectenna. It contains two dc-recombined rectifiers and a cross-slot coupled square patch antenna fed by a microstrip line. A judicious dc recombination scheme allows to minimize the RF power imbalance between accesses caused by multipath effects and consequently arbitrary polarized incident waves. The proposed rectenna is then able to harvest linearly polarized, right-hand circularly polarized (RHCP) and left-hand circularly polarized (LHCP) electromagnetic waves, with nearly stable performances. The rectenna has been optimized at -15 dBm per access and dedicated to remote and contactless supply low consumption sensors. It has been experimentally tested with very low power densities from 0.057 μW/cm2 (Erms=0.46 V/m) to 2.3 μW/cm2 (Erms=2.95 V/m). At 1.49 μW/cm2 (-15 dBm on each rectifier), the structure exhibits an output dc voltage and a global efficiency of 189 mV and 37.7%, respectively when the azimuthal angle (Φ) of the incident field is equal to 0°. Due to the nearly constant total gain of the DCP antenna and an appropriate dc recombination of the two rectifiers, the global efficiency slightly varies between 37.7% and 41.4% when the azimuthal angle (Φ) varies between -90 and 90°.

Autonomous ultra-low power DC/DC converter for Microbial Fuel Cells

In this paper, an ultra-low voltage and power DC/DC converter is presented. This converter harvests energy from a Microbial Fuel Cell (MFC) in order to feed another circuit such as an autonomous wireless sensor. The MFC behaves as a voltage generator of 475mV open-circuit voltage with a 600Ω serial internal impedance. The maximum delivered power is therefore around 100μW. The DC/DC converter provides output voltage in the range 2–7.5V and performs impedance matching with source. The converter achieves when associated with the MFC, 60% peak efficiency. Furthermore, this DC/DC converter is self-operating without the need for external power source of start-up assistance.

A 140 mV Self-Starting 10 mW DC/DC Converter for Powering Low-Power Electronic Devices from Low-Voltage Microbial Fuel Cells

This paper presents an original self-starting DC/DC converter for low-power and low-voltage applications such as energy harvesting from microbial fuel cells to supply low-power electronic devices. Design is performed according to specifications issued from the stringent characteristics of microbial fuel cells. The harvested power reaches 10 mW under 0.3 V input voltage for the ten 1.3-liter experimental microbial fuel cells connected in parallel. The converter is adapted from a boost topology. It includes a self-oscillating sub-circuit for autonomous operation and a simple analog input-voltage control to harvest maximum energy from the source. The paper presents experimental results from a discrete and low-cost prototype. A global efficiency of more than 73% is achieved for 0.3 V input-voltage and under realistic harvesting conditions for the MFCs and the converter prototype.

Ultra-Low Power, Low Voltage, Self-Powered Resonant DC-DC Converter for Energy Harvesting

This article presents a resonant DC-DC converter suitable for ultra-low power and low voltage sources. This original topology allows a self-starting and a self-operation under harsh conditions of input voltage and power without any additional start-up assistance. A global theoretical modeling of the converter which includes start-up and steady-state phases is presented and a methodology for optimal design is detailed. It is based on the combination of both theoretical calculations and circuit simulations. Experimental tests based on discrete prototypes are carried out in order to demonstrate the good operation of the converter. Experimental tests have been achieved using an RF energy harvesting source. Ultra-low power and low voltage conditions as low as 3 μW and 100 mV respectively can be achieved as demonstrated by the experimental measurements. The input low voltage is stepped-up to a conventional level of some volts, what allows to power autonomously and solely low power circuits from energy harvesting sources.