Now showing 1 - 10 of 39
  • Publication
    Wideband electrostatic Vibration Energy Harvester (e-VEH) having a low start-up voltage employing a high-voltage integrated interface
    This paper reports on an electrostatic Vibration Energy Harvester (e-VEH) system, for which the energy conversion process is initiated with a low bias voltage and is compatible with wideband stochastic external vibrations. The system employs the auto-synchronous conditioning circuit topology with the use of a novel dedicated integrated low-power highvoltage switch that is needed to connect the charge pump and flyback - two main parts of the used conditioning circuit. The proposed switch is designed and implemented in AMS035HV CMOS technology. Thanks to the proposed switch device, which is driven with a low-voltage ground-referenced logic, the e-VEH system may operate within a large voltage range, from a pre-charge low voltage up to several tens volts. With such a high-voltage e-VEH operation, it is possible to obtain a strong mechanical coupling and a high rate of vibration energy conversion. The used transducer/resonator device is fabricated with a batch-processed MEMS technology. When excited with stochastic vibrations having an acceleration level of 0.8 g rms distributed in the band 110-170 Hz, up to 0.75 μW of net electrical power has been harvested with our system. This work presents an important milestone in the challenge of designing a fully integrated smart conditioning interface for the capacitive e-VEHs.
      534Scopus© Citations 17
  • Publication
    Modelling and Verification of Nonlinear Electromechanical Coupling in Micro-Scale Kinetic Electromagnetic Energy Harvesters
    Electromechanical coupling in kinetic energy harvesters is the key aspect of these devices that ensures an effective energy conversion process. When modelling and designing such devices, it is necessary to incorporate electromechanical coupling correctly since it will determine the amount of energy that will be converted during its operation. As the engineering community prefers compact (lumped) models of such devices, the conventional choice of the lumped model for the electromagnetic type of electromechanical coupling is linear damping, proportional to the velocity of the mechanical resonator in a harvester, leading to the idea of maximizing the velocity in order to improve the energy conversion process. In this paper, we show that electromechanical coupling in electromagnetic kinetic energy harvesters is inherently nonlinear and requires a number of aspects to be taken into account if one wants to optimize a device. We show that the proposed model, which is based on first principles of electromagnetics, can be reduced to a nonlinear lumped model that is particularly convenient for analysis and design. The modelling approach and the resulting lumped model are verified using two MEMS electromagnetic harvesters operating over a range of frequencies from 300 to 500 Hz (Harvester A) and from 50 to 70 Hz (Harvester B) generating from mV (Harvester A) to few volts (Harvester B) of RMS voltage, respectively. The proposed modelling approach is not limited to energy harvesters but can also be applied to magnetic sensors or other MEMS devices that utilise electromagnetic transduction.
      598Scopus© Citations 7
  • Publication
    Semianalytical model for high speed analysis of all-digital PLL clock-generating networks
    In this paper, we propose the model of a network consisting of All-Digital Phase-Locked Loop Network in application to Clock-Generating Systems. The method is based on a solution of a system of non-linear finite-difference stochastic equations and allows us to perform high speed simulations of a distributed Clock Network on arbitrary topology. The result of our analysis show a good agreement with experimental measurements of a 65nm CMOS All-Digital Phase-Locked Loop Network.
      430Scopus© Citations 3
  • Publication
    Generation of a Clocking Signal in Synchronized All-Digital PLL Networks
    In this brief, we propose a discrete-time framework for the modeling and studying of all-digital phase-locked loop (ADPLL) networks with applications in clock-generating systems. The framework is based on a set of nonlinear stochastic iterating maps and allows us to study a distributed ADPLL network of arbitrary topology. We determine the optimal set of control parameters for the reliable synchronous clocking regime, taking into account the intrinsic noise from both local and reference oscillators. The simulation results demonstrate very good agreement with experimental measurements of a 65-nm CMOS ADPLL network. This brief shows that an ADPLL network can be synchronized both in frequency and phase. We show that for a large Cartesian network the average network jitter increases insignificantly with the size of the system.
      441Scopus© Citations 10
  • Publication
    FPGA Based Modelling of an ADPLL Network
    This paper introduces and compares the implementation of a number of FPGA based ADPLL network prototyping architectures. Networks are then created using three different ADPLL implementations and tests performed on each. Based on these test results, comparison is made to both the expected performance and role of each ADPLL design as a development tool.
      471Scopus© Citations 2
  • Publication
    Control of MEMS vibration modes with Pulsed Digital Oscillators : Part I — theory
    The aim of this paper is to show that it is possible to excite selectively different mechanical resonant modes of a MEMS structure using Pulsed Digital Oscillators (PDOs). This can be done by simply changing the working parameters of the oscillator, namely its sampling frequency or its feedback filter. A set of iterative maps is formulated to describe the evolution of the spatial modes between two sampling events in PDOs. With this lumped model, it is established that under some circumstances PDO bitstreams related to only one of the resonances can be obtained, and that in the antioscillation regions of the PDO the mechanical energy is absorbed into the electrical domain on average. The possibility of selecting for a given resonant frequency the oscillation and antioscillation behaviour allows one to obtain oscillations at any given resonant mode of the MEMS structure.
      373Scopus© Citations 15
  • Publication
    Synchronized Interconnected ADPLLs for Distributed Clock Generation in 65 nm CMOS Technology
    This brief presents an active distributed clock generator for manycore systems-on-chip consisting of a 10×10 network of coupled all-digital phase-locked loops, achieving less than 38 ps phase error between neighboring oscillators over a frequency range of 700–840 MHz at VDD=1.1 V. The network is highly robust against VDD variations. An energy cost of 2.7 μW /MHz per node is 7 times lower than that in analog implementations of similar architectures and is twice lower than that in conventional H-tree architectures. This is the largest on-chip all-digital phase-locked loop network ever implemented. With clock generation nodes linked only locally, this solution is proven to be scalable. The presented clock generation network does not require any external reference, except for the start-up frequency selection, generating a synchronized signal in fully autonomous mode and maintaining frequency stability within 0.09% during 1700 seconds. Such a network of frequency and phase synchronized oscillators can be used as a source for local clocking areas.
      423Scopus© Citations 3
  • Publication
    Combined mechanical and circuit nonlinearities in electrostatic vibration energy harvesters
    The aim of this paper is to study an electrostatic vibration energy harvester that utilises a nonlinear resonator. A vibration energy harvester represents a system where a mechanical resonator driven by ambient vibrations is coupled with a conditioning electronic circuit, which acts as a damper and converts mechanical energy into electrical. If a nonlinear resonator is embedded into the conditioning circuit, nonlinearity will appear from both mechanical and circuit components of the system. We expand the analytical approach that we developed in our previous works to the case of combined mechanical and circuit nonlinearities. This allow us to analyze steady-state behavior and compare it with the linear case. In addition, we discuss a specific nonlinear phenomena that is introduced by the discontinuity of the system — the sliding bifurcation. We show that the onset of steady-state quasi-harmonic oscillations occur through the disappearance of sliding motion.
      430Scopus© Citations 7
  • Publication
    Modelling of a charge control method for capacitive MEMS
    Charging of dielectric materials in microelectromechanical systems (MEMS) actuated electrostatically is a major reliability issue. In our previous work we proposed a feedback loop control method that is implemented as a circuit and that allows smart actuation for switches and varactors. In this paper we discuss system-level modeling of MEMS devices including all aspects of the system: proposed control method, charging dynamics and realistic models of the mechanical components of MEMS.
      456Scopus© Citations 5
  • Publication
    A Concept of Synchronous ADPLL Networks in Application to Small-Scale Antenna Arrays
    In this paper, we introduce a reconfigurable oscillatory network that generates a synchronous and distributed clocking signal. We propose an accurate model of the network to facilitate the study of its design space and ensure that it operates in its optimal, synchronous mode. The network is designed and implemented in a fully integrated 65-nm CMOS system-on-chip that utilizes coupled all digital phase locked loops interconnected as a Cartesian grid. The model and measurements demonstrate frequency and phase synchronization even in the presence of noise and random initial conditions. This network is proposed for small-scale multiple input multiple-output systems that require complete synchronization both in frequency and in phase.
      358Scopus© Citations 14