NISCAIR Online Periodicals Repository Collection: IJPAP Vol.49(06) [June 2011]
http://nopr.niscair.res.in/handle/123456789/11705
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Low-frequency quadrature sinusoidal oscillators using current differencing buffered amplifiers
http://nopr.niscair.res.in/handle/123456789/11718
Title: Low-frequency quadrature sinusoidal oscillators using current differencing buffered amplifiers
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<br/>Authors: Lahiri, Abhirup
<br/>
<br/>Abstract: This paper proposes
new realizations of low-frequency quadrature sinusoidal oscillators using CDBA
(current differencing buffered amplifier) as the active building block (ABB).
The proposed circuits employ reduced number of components, namely two CDBAs,
four (or five) resistors and two true/virtually grounded capacitors. The
oscillators provide two quadrature voltage outputs and the condition of
oscillation (CO) and the frequency of oscillation (FO) are independently
controllable. Low frequency generation is enabled by the presence of difference
term in the numerator of FO. The non-ideal analysis and sensitivity study of
the circuits have been carried out and the circuits exhibit satisfactory
sensitivity performance. SPICE simulation results are included that validate
the working of the circuit.
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<br/>Page(s): 423-428Sun, 29 May 2011 22:58:59 GMTEffect of structural parameters on 2DEG density and C~V characteristics of Al<sub>x</sub>Ga<sub>1−x</sub>N/AlN/GaN-based HEMT
http://nopr.niscair.res.in/handle/123456789/11717
Title: Effect of structural parameters on 2DEG density and C~V characteristics of Al<sub>x</sub>Ga<sub>1−x</sub>N/AlN/GaN-based HEMT
<br/>
<br/>Authors: Lenka, T R; Panda, A K
<br/>
<br/>Abstract: A new High Electron
Mobility Transistor (HEMT) model is proposed in this paper by introducing a
thin AlN layer in nanoscale range into the conventional Al<sub>0.3</sub>Ga<sub>0.7</sub>N/GaN-based
HEMT keeping the Al content of 30%. The AlN layer is very sensitive towards the
development of polarization charges at the hetero interface and results into
high 2DEG density (<i>n</i><sub>s</sub>). The role of AlN layer is essentially
very much suitable in order to reduce various scattering exist at the hetero
interface of the conventional GaN based devices. The change of various
structural parameters such as Al mole fraction of Al<sub>x</sub>Ga<sub>1−x</sub>N from 0.25 to 0.45, thickness of AlGaN
cap layer, thickness of AlN channel layer, doping concentrations give rise to a
significant change in the 2DEG transport and <i>C</i>~<i>V</i> characteristics
of the device and its detail discussion are presented in this paper. The 2DEG
density with the variation of Al<sub>x</sub>Ga<sub>1−x</sub>N thickness and Al mole fraction (<i>x</i>) are in good
agreement with the experimental results from the literature.
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<br/>Page(s): 416-422Sun, 29 May 2011 22:58:59 GMTAnalysis of space charge field of sheet electron beam for compact high power and high frequency microwave devices
http://nopr.niscair.res.in/handle/123456789/11716
Title: Analysis of space charge field of sheet electron beam for compact high power and high frequency microwave devices
<br/>
<br/>Authors: Panda, Purna Chandra; Srivastava, Vishnu; Vohra, Anil
<br/>
<br/>Abstract: Importance of sheet
beam technology and role of space charge field analysis for success of this
technology have been studied. Space charge field of sheet electron beam has
been investigated in three approaches. At first a simplified infinite width
sheet and line model are given to investigate nature of variation of field,
then analysis is done for finite width beam. Using a theoretical model in OPERA
3-D, simulation has been done to compare space charge field. Space charge field
of sheet electron beam is compared with that for equivalent round beam.
Interpretation is made about nature of space charge field and its impact to
sheet beam transport. Importance of proper optimization of beam height has been
emphasized.
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<br/>Page(s): 410-415Sun, 29 May 2011 22:58:59 GMTSpace charge limited current in Schottky diode with single level traps
http://nopr.niscair.res.in/handle/123456789/11715
Title: Space charge limited current in Schottky diode with single level traps
<br/>
<br/>Authors: Kumar, Pankaj; Jain, Anubha; Shukla, Manju; Chand, Suresh
<br/>
<br/>Abstract: The space charge
limited current (SCLC) in a Schottky diode with a finite injection barrier at
the injecting contact and single level traps in the energy space has been
investigated by mathematical modelling. Solution of coupled Poisson’s and
continuity equations with non-zero Schottky barrier (<img src='http://www.niscair.res.in/jinfo/phi.gif' border=0>)
leaded us to calculate the electric field [<i>F</i>(<i>x</i>)] and the charge carrier <i style="">p</i>(<i style="">x</i>) distribution in the
sample. Considering the boundary conditions, the current density-voltage (<i style="">J-V</i>) characteristics have been
calculated numerically. It is reported here that when Schottky barrier is not
zero, <i style="">J-V</i> characteristics become
Ohmic at infinitely large voltages. The expression of trap filled limit voltage
(<i style="">V<sub>TFL</sub></i>) has also been
derived. The effect of Schottky barrier on the SCLC current in semiconducting
devices has been studied in the present paper.
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<br/>Page(s): 406-409Sun, 29 May 2011 22:58:59 GMT