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Srinivasa Rao N.,Central University of Costa Rica | Pathak A.P.,Central University of Costa Rica | Sathish N.,Central University of Costa Rica | Devaraju G.,Central University of Costa Rica | And 5 more authors.
Solid State Communications | Year: 2010

Ge nanocrystals embedded in an SiO2 matrix were prepared by the atom beam co-sputtering (ABS) method from a composite target of Ge and SiO 2. The as-deposited films were rapid thermally annealed at the temperatures 700 and 800 °C in nitrogen ambience. The structure of the films was evaluated by using X-ray diffraction (XRD) and Raman spectroscopy. XRD results reveal that as-deposited films are amorphous in nature whereas annealed samples show crystalline nature. Raman scattering spectra showed a peak of GeGe vibrational mode shifted downwards to 297 cm-1, presumably caused by quantum confinement of phonons in the Ge nanocrystals. Rutherford backscattering spectrometry has been used to measure the thickness and Ge composition of the composite films. Size variation of Ge nanocrystals with annealing temperature has been discussed. The advantages of ABS over other methods are highlighted. © 2010 Elsevier Ltd. All rights reserved. Source


Chaturvedi S.,Gallium Arsenide Enabling Technology Center | Koul S.K.,Indian Institute of Technology Delhi
Journal of Electronic Packaging, Transactions of the ASME | Year: 2013

Design, fabrication, and test results of a novel 3-layer RF package using a commonly available high frequency laminate are presented in this paper. The developed package can be manufactured using standard multilayer printed circuit board (PCB) manufacturing techniques making it cost effective for commercial applications. The package exhibits excellent RF characteristics up to 6GHz. © 2013 by ASME. Source


Chaturvedi S.,Gallium Arsenide Enabling Technology Center | Bhalke S.,Gallium Arsenide Enabling Technology Center | Arora V.,Solid State Physics Laboratory | Koul S.,Indian Institute of Technology Delhi
European Microwave Week 2010, EuMW2010: Connecting the World, Conference Proceedings - European Microwave Conference, EuMC 2010 | Year: 2010

We report here the results of study of Glob top encapsulation of an MMIC amplifier and a multi-chip system. A broadband (2.5-5.0 GHz) amplifier MMIC and a VCO+ HPA system working in L-Band were packaged using Glob top encapsulant epoxy. The effect of this encapsulation on the performance of these MMICs was characterized. The alteration in performance is analyzed and method to compensate the alteration is suggested. © 2010 EuMA. Source


Raj M.,Gallium Arsenide Enabling Technology Center | Chaturvedi S.,Gallium Arsenide Enabling Technology Center | Sazid M.,Solid State Physics Laboratory SSPL | Badnikar S.L.,Solid State Physics Laboratory SSPL | Sehgal B.K.,Solid State Physics Laboratory SSPL
IEEE MTT-S International Microwave and RF Conference 2015, IMaRC 2015 | Year: 2015

A broadband FET resistive mixer MMIC on GaAs substrate is described in this paper. A non-linear model of MESFET operating in passive mode (Vds=0V) developed for design and simulation of mixer has also been analyzed. Measured mixer results match closely with the simulations based on the developed model. The on-chip broadband spiral baluns delivered wide frequency range from 230 MHz to 1.8 GHz while the LO/RF frequency coverage was from 2-8 GHz. 10 dB conversion loss was achieved for 500 MHz IF at 5 GHz RF frequency, and 10 dBm LO power. The mixer exhibited >10 dBm input 1dB compression point, 18 dBm input 3rd order intercept point and >30 dB LO-IF and RF-IF isolation. The mixer was realized in compact chip area of 2.8 × 2.6 mm2 through intensive EM simulations using ADS momentum EM simulator and was fabricated using the standard G7A MESFET process at GAETEC. © 2015 IEEE. Source


Chaturvedi S.,Gallium Arsenide Enabling Technology Center | Saravanan G.S.,Solid State Physics Laboratory | Bhat K.M.,Solid State Physics Laboratory | Bhalke S.,Gallium Arsenide Enabling Technology Center
2013 IEEE MTT-S International Microwave and RF Conference, IMaRC 2013 | Year: 2013

Design and development of a planar schottky diode which is process compatible with general planar MESFET process is described here. The device geometry has been designed and optimized keeping in view the applications up to Ku-band. The device was fabricated and characterized to extract the diode model. Two representative application circuits, viz. two types of microwave power limiters were designed, fabricated and tested to show the versatility of the device. © 2013 IEEE. Source

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