Implementation of TFET SPICE Model for Ultra-Low Power Circuit Analysis

We proposed a compact model for tunneling field effect transistors (TFETs), which combines BSIM4. Our proposed model for tunneling current is based on a drift-diffusion model under the gradual-channel approximation. The total charge for the drain current has been described by a weighted sum of the tunneling charge and the oxide charge for gate-to-source overlap region. In order to obtain TFETs compact model for circuit simulation that operates in every voltage region, the operating current under the various gate-to-source voltage and drain-to-source voltage conditions are considered. Verilog-A description for our proposed model are implemented in the circuit simulator. Model parameters are extracted for conventional TFETs structure by comparing with in-house 2-D TCAD simulation results. After the transistor-level verification, the circuit-level simulation of 81-stage ring-oscillator using our proposed model has been performed.