Convergence issues in resonant tunneling diode circuit simulation

Due to its status as the fastest switching semiconductor device and its bistable nature, the resonant tunneling diode (RTD) is considered to be one of the most promising devices for future-generation high-performance VLSI systems. However, popular circuit simulators, such as SPICE, can encounter direct current (DC) and transient convergence problems while simulating RTD-based circuits because of the negative differential resistance (NDR) in the device's current-voltage characteristics. In this paper, we study the nature of these convergence problems and provide several solution techniques that can be easily incorporated into SPICE-like circuit simulators.