Langis Roy
PhD, PEng

Advances in Tunable Microwave Ferrite-LTCC Components

WM04 Workshop on MM-Wave Multilayer MCM/SoP and Heterogeneous Integration Techniques, European Microwave Week

Characterization of GaN-based HEMTs as Varactor Diode Devices

European Microwave Week 2015

A Novel Multi-Layer Electromagnetic Band Gap Structure (EBG) Comprised of 3D Lattice of Square Rings

IEEE International Conference on Numerical Elec­tromagnetic and Multiphysics Modeling and Optimization for RF, Microwave, and Terahertz Ap­plications (NEMO)

Modeling Substrate Integrated Waveguide Structures Using Effective Material Properties

IEEE International Conference on Numerical Elec­tromagnetic and Multiphysics Modeling and Optimization for RF, Microwave, and Terahertz Ap­plications (NEMO),

Modeling and Simulation of a Partially-Magnetized Ferrite LTCC Circulator

IEEE International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization for RF, Microwave, and Terahertz Applications

Circulateur LTCC Ferrite Large-Bande à Structures Empilées en Bande K

19èmes Journées Nationales Microondes

Health Implications of Radio-Wave Exposure

Discovery Café, Blackburn Community Centre

How Safe is Wireless Technology

Innovations in Antenna Engineering, Faculty of Engineering and Design, Carleton University Talks, Ottawa Public Library

Schottky-contact Plasmonic Rectenna for Biosensing

Photonics North 2013

Zero-biased Optically Controlled RF Switch in 0.13μm CMOS Technology

IEEE 2011 International Topical Meeting on Microwave Photonics Conference

A New Optically Controlled CdS-Polymer Capacitor for Tunable Microwave Components

European Microwave Week 2011

A 60 GHz System-on-Package Balanced Antipodal Vivaldi Antenna with Stepped Dielectric Director (BAVA-SDD) in LTCC

European Microwave Week 2011

Electric Energy and Power Educational Programs Development Workshop

118th ASEE Annual Conference and Exposition

60 GHz SoP Active Array Design

The 27th International Review of Progress in Applied Computational Electromagnetics

The Field-Programmable Microwave Substrate

A novel low-loss programmable microwave waveguide is demonstrated, allowing reconfigurable microwave circuits with similar levels of programmability as that seen in field-programmable gate arrays. The waveguide is realized with a field-programmable microwave substrate (FPMS), consisting of small unit cells that can be individually reconfigured to have a range of positive dielectric constants or a negative dielectric constant. Programmable waveguides, amplifiers, and oscillators are demonstrated. The proposed FPMS concept promises a new era of programmable microwave circuit design for cognitive radio, the Internet of things, and self-healing/adaptive systems.

View more - The Field-Programmable Microwave Substrate

Surface Plasmon Enhanced Photodetectors Based on Internal Photoemission

Surface plasmon photodetectors are of broad interest. They are promising for several applications including telecommunications, photovoltaic solar cells, photocatalysis, color-sensitive detection, and sensing, as they can provide highly enhanced fields and strong confinement (to subwavelength scales). Such photodetectors typically combine a nanometallic structure that supports surface plasmons with a photodetection structure based on internal photoemission or electron–hole pair creation.

View more - Surface Plasmon Enhanced Photodetectors Based on Internal Photoemission

Characterization and Analytical Modelling of GaN HEMT-Based Varactor Diodes

Varactor diodes fabricated in 0.5 and 0.15 µm GaN HEMT (high-electron-mobility transistor) processes are modelled. The devices were characterized via DC and RF small-signal measurements up to 20 GHz, and fitted to a simple physical equivalent circuit. Approximate analytical expressions containing empirical coefficients are introduced for the voltage dependency of capacitance and series resistance. The analytical solutions agree remarkably well with the experimentally extracted C–V curves and can be used as a general model to represent the nonlinear behaviour of GaN-based varactors devices.

View more - Characterization and Analytical Modelling of GaN HEMT-Based Varactor Diodes

Study of a Ferrite LTCC Multifunctional Circulator With Integrated Winding

This paper shows a study of a new ferrite low-temperature cofired ceramic (LTCC) circulator with integrated winding. The external magnets used in traditional circulators must be strong to overcome the ferrite's demagnetization factor. The novel circulator presented herein uses an embedded winding within the ferrite to magnetize the material from the inside, thereby significantly reducing the demagnetization effects. Because of the controllability of the bias field, the resulting device is also multifunctional: when the windings are energized by a current, the device operates as a dynamic circulator in which the circulation direction can be changed by switching the direction of the current.

View more - Study of a Ferrite LTCC Multifunctional Circulator With Integrated Winding

Vivaldi Antenna for MM-Wave Communications

The proliferation of portable devices such as smart phones, tablets, and laptops has resulted in an increased demand for mobile broadband wireless, and with the expected growth in the Internet of Things and Machine-to-Machine communications, this increase is expected to exceed the current available capacity, and higher frequency bands will also need to be adopted. Serious consideration is being given to the 60 GHz Industrial, Scientific, and Medical (ISM) band by the Wireless Gigabit Alliance (WiGig) to develop and promote the adoption of multi-gigabit speed wireless communication technology based on the IEEE 802.11ad protocol, and by industry involved in developing fifth generation (5G) communication systems. These systems will require the development of antenna array technology with beam scanning capability, since high-gain (narrow beam) patterns that can be steered to track mobile devices, or change shape to reduce interference will be needed. This paper presents the design of a tapered slot antenna, known as a balanced antipodal Vivaldi antenna, and is seen to be a promising candidate for 60 GHz wireless communications.

View more - Vivaldi Antenna for MM-Wave Communications

A New Hybrid-Polymer Optically Tunable Dielectric and its Measurement Using a Variation of the Split-Post Dielectric Resonator

An apparatus based on the split-post dielectric resonator was designed and verified for the purpose of measuring the microwave properties of optically sensitive materials. The apparatus was then used to confirm that a material consisting of micro sized photoconductive particles added to an insulating polymer would show an increase in the effective dielectric constant while under optical illumination. The semiconductor-polymer composite showed a change in dielectric constant and dielectric loss tangent from 5.5 to 6.1 and 0.05 to 0.09 respectively.

View more - A New Hybrid-Polymer Optically Tunable Dielectric and its Measurement Using a Variation of the Split-Post Dielectric Resonator

1 W, Highly Efficient, Ultra-Broadband Non-Uniform Distributed Power Amplifier in GaN

This letter describes the design and implementation of a highly linear, ultra-broadband non-uniform asymmetric distributed MMIC power amplifier in GaN, delivering 1 W of output power and suitable for operation at frequencies up to 6.5 GHz. The GaN HFETs used here have a gate length of 500 nm, and breakdown-voltages exceeding 100 V while exhibiting an fT of approximately 30 GHz. A non-uniform asymmetric distributed topology is used to achieve ultra-broadband performance. CW measurements carried out at nominal bias between 0.5 GHz and 6.5 GHz yielded a maximum PAE of 38.1% at 0.5 GHz, with PAE higher than 20% over the entire band, while achieving Pout > 30 dBm.

View more - 1 W, Highly Efficient, Ultra-Broadband Non-Uniform Distributed Power Amplifier in GaN

Schottky-Contact Plasmonic Dipole Rectenna Concept for Biosensing

Nanoantennas are key optical components for several applications including photodetection and biosensing. Here we present an array of metal nano-dipoles supporting surface plasmon polaritons (SPPs) integrated into a silicon-based Schottky-contact photodetector.

View more - Schottky-Contact Plasmonic Dipole Rectenna Concept for Biosensing

Ultra Low Power CMOS-Based Sensor for On-Body Radiation Dose Measurements

For the first time, a dosimeter employing two floating gate radiation field effect transistors (FGRADFET) and operating at mere 0.1 V is presented. The novel dosimeter requires no power during irradiation and consumes only 1 during readout. Besides the low power operation, structural changes at the device level have enhanced the sensitivity of the dosimeter considerably as compared to previous designs. The dosimeter is integrated with a wireless transmitter chip, thus eliminating all unwanted communication and power cables. It has been realized monolithically in DALSA's 0.8 complementary metal-oxide-semiconductor process and characterized with X-ray and γ-ray sources.

View more - Ultra Low Power CMOS-Based Sensor for On-Body Radiation Dose Measurements

5 GHz LTCC-Based Aperture- Coupled Wireless Transmitter for SoP Applications

A novel System-on-Package (SoP) implementation is presented for a transmitter (TX) module which makes use of electromagnetic coupling between the TX chip and the package antenna. The TX chip is realized in 0.13 μm CMOS process and comprises an on-chip antenna, which serves as the oscillator's inductor as well. The TX chip is housed in a Low Temperature Co-fired Ceramic (LTCC) package with a patch antenna. The on-chip antenna feeds the LTCC patch antenna through aperture coupling, thus negating the need for RF buffer amplifiers, matching elements, baluns, bond wires and package transmission lines. This is the first ever demonstration of wireless-interconnect between on-chip and package antennas which increases the gain and range of the TX module manyfold with respect to the on-chip antenna alone.

Appointed to the Board of Directors

Appointed to this role for a two-year term from 2017 to 2018, Dr. Roy is committed to the promotion of graduate education and university research through meetings, publications and advocacy. CAGS brings together 58 Canadian universities with graduate programs and the three federal research-granting agencies, as well as other institutions and organizations with an interest in graduate studies.

Appointed to the Strategic Engagement Editorial Board

Dr. Roy has been appointed to this COU board for a two-year term from 2017 to 2018. The board is part of a year-long campaign to engage students and parents in province-wide dialogue about future economic needs across all sectors, and determine how universities can contribute to a brighter future for everyone.

Appointed to the NSERC Advisory Committee on University-Industry Grants (ACUIG)

Dr. Roy has been appointed to the ACUIG for a three-year term, from 2017 to 2019. This multidisciplinary committee has broad experience in university-industry interactions. The ACUIG makes funding recommendations for large scale NSERC Collaborative Research and Development applications as well as Industrial Research Chair applications, taking into account the recommendations of site visit committees and external peer reviews.

Appointed to the NSERC Research Tool and Instrument Selection Committee

An appointed member of this committee from 2016 to 2018, Dr. Roy plays a role in evaluating and awarding Research Tools and Instruments (RTI) grants which foster and enhance the discovery, innovation and training capability of university researchers in the natural sciences and engineering (NSE).

Best Conference Paper Award

Awarded for his co-authored paper entitled, Wireless Interconnect Between On-Chip and LTCC Antennas for System-in-Package Applications, at the EuWiT conference held in Amsterdam, Netherlands.

Institute of Electrical and Electronics Engineers (IEEE)

Ontario Aerospace Consortium

Professional Engineers Ontario