http://nopr.niscair.res.in/handle/123456789/8204 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/8317 Title: Voltage-mode OTA-based active-C universal filter and its transformation into CFA-based RC-filter <br/> <br/>Authors: Shah, N A; Rather, M F <br/> <br/>Abstract: An absolute minimum component voltage-mode (VM) universal filter, employing two each of operational transconductance amplifiers (OTAs) and capacitors with three inputs and one output, is presented. The circuit can be transformed into CFA-based RC-filter involving two each of current feedback amplifiers (CFAs), capacitors and resistors. OTA-C circuit enjoys electronic tunability of filtering parameters while its CFA-based RC version offers low output impedance which suits cascadability. PSPICE simulation and the experimental results of both the circuits are included. <br/> <br/>Page(s): 402-406 http://nopr.niscair.res.in/handle/123456789/8316 Title: High input impedance all-pass and notch filter configuration <br/> <br/>Authors: Kumar, P; Pal, K; Gupta, G K <br/> <br/>Abstract: A circuit realizing second order all-pass and notch filter, employing current conveyors and operational amplifier/CFA as the active circuit elements is proposed. The circuit uses only two current conveyors, one operational amplifier/current feedback amplifier, four resistors and two grounded capacitors. The current conveyors used in the circuit are replaceable by translinear current conveyors and thus quality factors <i style="">Q</i> and center frequency become controllable through the bias currents of the translinear current conveyors. The filter also displays low incremental parameter sensitivities. The simulation results on the filter support theory. <br/> <br/>Page(s): 398-401 http://nopr.niscair.res.in/handle/123456789/8315 Title: Dielectric study of Ba(Zn_1/3Nb_2/3)O₃ at low temperature <br/> <br/>Authors: Himanshu, A K; Gupta, D C; Sinha, T P <br/> <br/>Abstract: The dielectric study of Ba(Zn_1/3Nb_2/3)O₃ has been studied at low temperature in a frequency range 100 Hz-1 MHz and a temperature range from 145K to room temperature. An analysis of real and imaginary part of dielectric permittivity, impedance (<i style="">Z</i>), conductivity and electric modulus with frequency and temperature is performed, showing the polydispersive nature of the relaxation time in the sample as confirmed by the Cole-Cole plot of the dielectric permittivity and impedance. All these results suggest that the relaxation phenomenon seen in the configuration has been attributable to the damping of dipole oscillators due to the application of the external fields. <br/> <br/>Page(s): 391-397 http://nopr.niscair.res.in/handle/123456789/8314 Title: Lattice dynamical calculations of spinel structure compounds <br/> <br/>Authors: Kushwaha, A K; Shankar, Girija; Kushwaha, S S <br/> <br/>Abstract: <smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="City"><smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> Lattice dynamical calculations have been performed for normal spinel structure compounds using the proposed theoretical model. In this model, the dynamical matrix is split into two parts: (i) the short range part is evaluated by using Taylor’s expansion of the crystal potential energy in the harmonic approximation and (ii) the long range part is evaluated on the basis of screened Coulomb potential. This model is applied to study the zone centre (<img src='/image/spc_char/italic_r.gif' border=0>=0) phonon frequencies of sulphide spinels MCr₂S₄(M= Mn, Fe, Cd). The significant outcome of the present work is that (i) the tetrahedral M-S force constants are smaller than the respective octahedral (Cr-S) ones, (ii) the bending force constants are negligible, and (iii) the effective dynamical charges of the bivalent metal ions are nearly zero. The zone-center phonon frequencies, thus calculated using these parameters are found to be in very good agreement with the observed results. </smarttagtype></smarttagtype> <br/> <br/>Page(s): 385-390