Graphene based analog circuit design

This thesis presents a model of graphene field effect transistor and its some of applications. Since in 2004, graphene has been widely investigated after its synthesis. In present day silicon based electronics technology is scaling down and has been reaching the ultimate limits day by day, therefore Si loses its stability in smaller scales. In the next future graphene is very promising material to overcome this problem. That's why it is necessary to model graphene based transistors and reveal their characteristic equations. Graphene has outstanding properties such as high carrier mobility and high saturation velocity approximately six times bigger than Si material. Graphene field effect transistors (GFETs) have performed very well in RF during last years and thus have been focused seriously by electronic devices and circuits communities. Meanwhile, analytical models which describe the electrical characteristics of GFETs are evolved quickly. Simplified models make calculations easier and then give positive contribution to circuit design. In literature, high transconductance and current saturation are achieved with a designed top-gated GFET. Starting from this point, analog circuits are simulated with GFETs and the results are analysed. Firstly, a model for graphene field effect transistors is told and it is important to be compatible of the model with SPICE. Mathematical equations for electron and hole conduction available are given in this thesis and with the help of these equations three operating regions of GFETs and boundary voltage conditions, which defines that regions, are expressed. Afterwards GFET model is simulated in SPICE. Some circuits made of graphene transistors and in addition to these circuits simple current mirror and cascode current mirror are simulated. As a result of these simulations it has been shown that graphene based current mirrors can be done and their characteristic properties and operating ways are presented and discussed.