Frédéric Alicalapa

A Compact Rectenna Device at Low Power Level

This article describes the design and performances of a rectenna that collects low incident power density levels, at a single ISM-band frequency (f0 = 2.45GHz). A new rectenna topology consisting only of an antenna, a matching circuit, a Schottky diode, and a DC filter has been modeled using a global simulation. A circular aperture coupled patch antenna is proposed to suppress the first filter in the rectenna device, and in addition, the losses associated with this filter. The harmonics rejection of the antenna is primarily used to reduce the rectenna size. The implementation of the filter in the antenna structure, combined with a reduction of the rectenna size, gives several advantages in several applications where the size and weight are critical criteria. The maximum energy conversion efficiency in this configuration is 34% and is reached for a load of 9.2 kΩ and a RF collected power of SRF = 17μW/cm2 (≈ −10 dBm RF incident upon the diode).

A power management system for energy harvesting and wireless sensor networks application based on a novel charge pump circuit

ABSTRACT Energy Harvesting circuits are developed as an alternative solution to supply energy to autonomous sensor nodes in Wireless Sensor Networks. In this context, this paper presents a micro-power management system for multi energy sources based on a novel design of charge pump circuit to allow the total autonomy of self-powered sensors. This work proposes a low-voltage and high performance charge pump (CP) suitable for implementation in standard complementary metal oxide semiconductor (CMOS) technologies. The CP design was implemented using Cadence Virtuoso with AMS 0.35μm CMOS technology parameters. Its active area is 0.112 mm2. Consistent results were obtained between the measured findings of the chip testing and the simulation results. The circuit can operate with an 800 mV supply and generate a boosted output voltage of 2.835 V with 1 MHz as frequency.

An improved MOS charge pump circuit for low voltage operations and wireless sensor applications

This paper proposes a new low-voltage and high performance charge pump circuit suitable for implementation in standard CMOS technologies. The proposed MOS charge pumps is an energy harvesting circuit for wireless sensor. This new pump is an improvement of the basic charge transfer switches (CTSs) to generate higher output voltage. The simulation results show that the proposed circuit have high pumping gain and suitable for low-voltage.

Broadband Modelling of a High Efficiency Rectenna for Batteryless RFID Systems

This article presents an equivalent circuit approach used for the modelling of a system consisting of an antenna and a RF/DC rectifying circuit (rectenna). This system is developed for microwave energy transfer to low energy consumption wireless devices at 2.45 GHz. The measurements and simulations steps used for parameter extraction and model validation are presented. It is shown that using this approach, no electromagnetic simulation tool is required for the simulation and optimization of the overall circuit. Furthermore, this method allows for the physical origin of the energy losses in the system to be quantified. Results obtained using this simple example show a good agreement with the experiment on a broad frequency range and can form the basis for further developments of more complex systems.

Improved circuit model of photovoltaic cell for energy harvesting application

This paper mainly focuses on model of photovoltaic cell for energy harvesting application (EHV). This model is developed using the standard simulation software LTspice to explore the effect of electrical and physical parameters on Current-Voltage (I-V) and Power-Voltage (P-V) characteristics of photovoltaic cell (PV). The proposed model is based on mathematical equations and is described through an equivalent circuit. The developed model serves to specify the optimal conditions for operating the PV cell and define the maximum power point (MPP). It also allows the prediction of PV cell behavior as a function of temperature and ambient radiation. To demonstrate the validity of the generated model, an experimental test was performed for a PV cell (of type“ASI” from SCHOTT Company). Experimental and technical data display a good agreement with the simulated findings.

A clustering algorithm based on energy variance and coverage density in centralized hierarchical Wireless Sensor Networks

In Wireless Sensor Network (WSN), the clustering algorithm was developed to reduce the total energy consumption which determines the lifetime of the whole network. As a result, a number of recently-designed energy-efficient routing algorithms stated that clustering approach has an important issue for organizing a network into a connected hierarchy and increasing the network lifetime. This paper proposes a new algorithm to improve the performance of Low Energy Adaptive Clustering Centralized (LEACH-C) by improving the criterion for electing a cluster-head and the determination of optimal number of cluster-heads. Firstly, the optimal number of cluster-heads is based on the density of the covering. The sensor nodes are deployed randomly on the plane area of the sensing field covered by the communication range of the node. Secondly, nodes having the highest remaining energy and the lowest energy variance consumption becomes cluster-heads. The variance parameter keeps energy consumption dispersion, if the considered node is elected as cluster-head. This dispersion highly depends on the relative positioning of the node to the base station. This is useful for predicting node status when elected as cluster-head in the current round in order to balance the network energy. The simulation and analytical results of the proposed algorithm outperform the existing protocols in terms of lifetime of the network.

Forwarding and routing cluster-based protocol for wireless sensor networks

This paper presents Forwarding and Routing Cluster-Based Protocol which aims to prolong wireless network lifetime by balancing energy consumption among all nodes. It avoids the premature death of the closest cluster-head (CH) for multi-hop protocols using hierarchical network clustering. FoRoC introduces two items: first, to take into consideration the nodes local informations during CHs selection steps, such as remaining energy and its coefficient of variation. And secondly, it also combines one-hop and multi-hop elementary path routing methods for data transfer for inter-cluster communication as a unique path. Furthermore, periodically changing the role between CH or end-node, and periodically changing the route between CHs and base-station, balances the CHs energy consumption. For going further towards the ideal energy balance which is illustrated by a coefficient of synchronous death. Simulation results show that the FoRoC shows great performance in terms of energy consumption and the network lifetime. Lifetime is increased by 80% compared to one-hop protocols. Compared to multi-hop protocol, FoRoC reaches a coefficient of synchronous death of 2.09.

PSO-based charge pump chip area minimization

In this paper a solution of the well-known silicon area/performance dilemma and an energy harvesting circuit for wireless sensor nodes are presented. A PSO-based integrated circuit area optimization methodology is proposed. The study is performed on a charge pump circuit, using a 0.35μm Si-CMOS process. The PSO sizing strategy has been implemented using a Spice kernel and Matlab environment. The chip size has been reduced from 583μm2 to 179μm2 after the optimization process. Simulation results from the 0.35μm parameters are given. When driving a capacitive load of 50pF, the output-generated voltage is 4V from a 1.3V input voltage. The simulated pumping gain is 3.1.

DC-pass filter design with notch filters superposition for CPW rectenna at low power level

In this paper the challenging coplanar waveguide direct current (DC) pass filter is designed, analysed, fabricated and measured. As the ground plane and the conductive line are etched on the same plane, this technology allows the connection of series and shunt elements to the active devices without via holes through the substrate. Indeed, this study presents the first step in the optimization of a complete rectenna in coplanar waveguide (CPW) technology: key element of a radio frequency (RF) energy harvesting system. The measurement of the proposed filter shows good performance in the rejection of F0=2.45 GHz and F1=4.9 GHz. Additionally, a harmonic balance (HB) simulation of the complete rectenna is performed and shows a maximum RF-to-DC conversion efficiency of 37% with the studied DC-pass filter for an input power of 10 µW at 2.45 GHz.

Experimental study of rectenna coupling at low power level

The experimental results presented in this paper focus on the performance of a rectenna array by studying the effect of mutual coupling between two rectennas. The measurements in several planes of the space are investigated and used to help us to define the minimum distance for future rectenna arrays that can be used at a low power density level. The single element chosen for the array is composed of a rectifier circuit and a CSPA (Circular Slot Patch Antenna). This study shows that at a distance greater than 6cm (λ/2) between two rectennas in reception, we observe that the DC received voltage is constant in the Y plane, while in the X plane, the DC received voltage remains constant whatever the distance. We deduce that these rectennas are uncoupled in this case. We can consider each rectenna like an independent system.