Unified Model for Sub-Bandgap and Conventional Impact Ionization in RF SOI MOSFETs with Improved Simulator Convergence

In this paper, a physics based impact ionization model for silicon MOSFETs is proposed. The proposed impact ionization model specially addresses the physics for the low Vds or sub band gap impact ionization (thermally assisted) along with the conventional (channel field assisted) high Vds impact ionization. The proposed model is implemented in industry standard BSIMSOI model and verified by comparison with experimental data of partially depleted silicon-on-insulator MOSFET. Model shows excellent agreement with the experimental data for low as well as high Vds impact ionization. The proposed unified impact ionization model shows improved convergence problem in standard test circuit simulation.