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Muller A.,IMT Bucharest | Neculoiu D.,Polytechnic University of Bucharest | Konstantinidis G.,FORTH IESL MRG Heraklion | Vaha-Heikila T.,VTT Technical Research Center of Finland
NATO Science for Peace and Security Series B: Physics and Biophysics | Year: 2010

A review of recent developments of membrane supported millimeter wave circuits based on GaAs micromachining, performed in authors' labs. is presented. Coupled line band pass filters for 35 GHz, Yagi-Uda antennae for 60 GHz having as support a 2 μm thin GaAs membrane are presented. Also the manufacturing direct, video-type receiver module having the Yagi-Uda antenna and Schottky diode monolithic integrated on the same GaAs membrane is presented. The very good results obtained on the measurements of these circuits have demonstrated the high capabilities of GaAs micromachining in manufacturing of high performances millimeter wave circuits and the potential advantage of these technologies for the sub-millimeter wave frequency range were other solutions are not available. © 2010 Springer Science+Business Media B.V. Source


Stefanescu A.,IMT Bucharest | Muller A.,IMT Bucharest | Konstantinidis G.,FORTH IESL MRG Heraklion | Buiculescu V.,IMT Bucharest | And 4 more authors.
Proceedings of the International Semiconductor Conference, CAS | Year: 2012

We report on new models developed for surface acoustic wave resonators (SAW) on GaN/Si substrate working on frequencies above 5 GHz. The devices are composed of interdigital transducers (IDT) with finger and interdigit spacings 200nm wide. Different examples of modeling these devices, from 1D equivalent circuit to 3D FEM model are presented. The simulations are validated with experimental results for one port SAW and for a two port resonator SAW devicse. © 2012 IEEE. Source


Stefanescu A.,IMT Bucharest | Muller A.,IMT Bucharest | Dinescu A.,IMT Bucharest | Konstantinidis G.,FORTH IESL MRG Heraklion | And 3 more authors.
Proceedings of the International Semiconductor Conference, CAS | Year: 2011

For the integration of surface acoustic wave (SAW) devices with nanostructures, numerical simulations must be employed. This paper describes finite element (FEM) models for a basic periodic cell of two types of SAW devices on GaN/Si devoted for GHz applications. E-beam lithographical techniques have been used for IDT fingers of 200nm wide. On wafer measurements of S parameters have shown a good agreement with the simulation results regarding the operation frequency. © 2011 IEEE. Source


Bunea A.-C.,IMT Bucharest | Neculoiu D.,IMT Bucharest | Dragoman M.,IMT Bucharest | Konstantinidis G.,FORTH IESL MRG Heraklion | Deligeorgis G.,FORTH IESL MRG Heraklion
European Microwave Week 2015: "Freedom Through Microwaves", EuMW 2015 - Conference Proceedings; 2015 45th European Microwave Conference Proceedings, EuMC | Year: 2015

In this paper we present, for the first time, a X band slot antenna with a shorted graphene patch. The graphene patch is biased through the signal and ground of the coplanar waveguide feed. The change in the electric field determines a change of the impedance of the graphene sheet, leading to tuning of the antenna behavior. The 3D electromagnetic design and simulation will be presented. The structures were fabricated on high-resistivity silicon with a 0.3 μm thick silicon oxide layer and a single layer graphene sheet deposited by Graphenea. The experimental results are in good agreement with the simulations and show a tunability of over 20 dB in the minimum of the reflection losses and a 7.5 MHz frequency shift. The measured operating bandwidth (|S11| <-10 dB) is between 9.3-10.435 GHz. © 2015 EuMA. Source


Stefanescu A.,IMT Bucharest | Neculoiu D.,IMT Bucharest | Muller A.,IMT Bucharest | Dinescu A.,IMT Bucharest | And 2 more authors.
Romanian Journal of Information Science and Technology | Year: 2011

This paper proposes an analysis of two types of Surface Acoustic Wave (SAW) resonators composed of interdigital transducers (IDT) of 200 nm wide on GaN/Si devoted for GHz applications. Two finite element (FEM) models for basic periodic cells are given to demonstrate de characteristics of the resonators at different resonance frequencies. E-beam lithographical techniques have been used for the IDT fingers. Experimental measurements of the S parameters have shown a good agreement with the simulation results regarding the resonance frequency. Source

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