[en] The compact sized cross-shaped metamaterial design is evaluated for single negative, double negative and double positive behavior for a wide range of frequencies to investigate the gap and gapless transition from backward to forward wave propagation near 17 GHz. The metamaterial designed in this study is analyzed for negative index characteristics of permittivity, permeability and refractive index over the broad range of frequencies. The dispersion diagram of the material is also investigated for left or right behavior of the material. The equivalent circuit diagrams along with circuit simulations of the parameters are also presented for detailed analysis and understanding. The designed metamaterial behaves like a double negative material for low frequencies below 17.23 GHz and double positive materials for high frequencies above 17.23 GHz. The design is simulated using CST Microwave studio and obtained results are authenticated using the wave-guide measurement technique. (paper)

[en] Graphene base transistor’s (GBT) analysis has been reviewed in this paper. This study has been focused on work carried out by other authors for GBT physics. Here prominence has been given to material properties and their effects on GBT for VLSI analog circuit design to operate in high frequency range of THz. Various papers in literature have been reported for the implementation of designs with different emitter and collector materials. Materials properties are the controlling parameters to decide cut-off frequency (f_T), trans-conductance, gain and off current (I_off) in GBT. The implemented results of literatures signify that the electron affinity and work function of emitter and collector are the dominant factors for flow of charges from emitter to collector. Dependency of these two parameters on dielectric constant and thickness of emitter-base insulator (EBI) and base collector insulator (BCI) that are tantalum pentoxide (Ta₂O₅), carbon-doped silicon oxide (SiCOH) and SiO₂ has been studied. Effects of collector and BCI thickness have been investigated in detail to scrutinize base leakage current by the virtue of back scattering in collector-BCI interface. Small signal equivalent circuit model for GBT have also been studied by including parasitic capacitance behaviour between graphene Dirac-point potential with respect to graphene fermi level, emitter, EBI, BCI and collector fermi level potential. (author)