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Graphene is a very attractive material for applications in optoelectronic devices such as photodetectors because of fast response and broadband absorption. However, the weak absorption of the graphene layer limits the performance of graphene-based photodetectors. To this end, a high responsivity graphene-based plasmonic photodetector, operating over a wide optical wavelength range, is presented. In order to enhance the light absorption efficiency and, consequently, to improve the responsivity of the photodetector, a graphene layer and a specific plasmonic nanostructure are combined. The numerical simulation results reveal that nearly perfect light absorption is achieved at the wavelength of 1550 nm for the proposed structure and also, this structure is polarization insensitive and enables perfect absorption for TE and TM polarizations at the wavelength of 1550 nm. The circuit model of the structure is presented based on transmission line theory whose results are in very good agreement with the numerical simulation results. Also, the high responsivity of 513 mA/W and the bandwidth of 47 GHz are achieved for this scheme.

Fig 1. Conventional voltage reference circuits based on difference between V GS voltages of (a) an nMOS and a pMOS transistor, and (b) two nMOS transistors Abstract-A CMOS voltage reference based on the difference between the gate-source voltages of pMOS and nMOS transistors operating in subthreshold region is presented. Power consumption is optimized by subthreshold design and minimizing the number of passive elements in any circuit branches from supply to the ground. A reference voltage of 912 mV with a temperature coefficient of 68 ppm/°C from −40 °C to 120 °C is achieved. Proposed voltage reference circuit can operate at supply voltages ranging from 1.5 V to 3.5 V while the current drawn from supply is at most 47 nA. Power supply rejection ratio without any filtering capacitor at 100 Hz and 10 MHz frequencies are about −68 dB and −70 dB respectively.