Simulation of the novel high-frequency FET with an opposed gate-source structure

The opposed gate-source transistor (OGST) is a novel high-frequency field-effect device with a symmetry plane and a distributed interaction mode. The operation principles of the OGST have been analyzed using numerical two-dimensional time-dependent device-simulation techniques. The coupled particle balance, momentum balance, and Poisson equations subject to general boundary conditions are solved with finite-difference methods. Device characteristics are simulated using both quasi-static and "ballistic" high-field transport models. The unique symmetry property of the OGST leads to a new pinchoff and current collection mechanism at the source contact. A 60-GHz design has been analyzed in detail. The simulations predict the lower and upper limits of 290 and 709 mS/mm for the transconductance, and 72 and 214 GHz for the cutoff frequency, respectively, for the intrinsic OGST.