Even-odd symmetry and the conversion efficiency of ideal and practical graphene transistor frequency multipliers

The conversion efficiency of field-effect transistors with even-odd symmetry is elucidated in this work. From symmetry considerations, this work reveals that even symmetry, due to electron-hole symmetry in graphene, affords efficient even-harmonic multiplication. Odd symmetry, associated with linear charge transport, affords suppression of odd-harmonic signals. For the ideal symmetric transistor multiplier, conversion efficiency with relatively large power gain is achievable, while for practical graphene transistors, the efficiency can be substantially less than unity due to non-idealities such as contact resistance, high impurity densities, and low gate capacitance. In the quantum capacitance limit of graphene transistor, near-lossless conversion efficiency is available. (C) 2011 American Institute of Physics. [doi:10.1063/1.3664112]