Geometry and layout dependency of high frequency performance of high speed bipolar transistors

Experimental data on the geometry and layout dependence of the high-frequency performance of single polysilicon bipolar transistors are presented. It is shown that small-signal high-frequency measurements provide quantitative information that can be used for the optimization of device structures and device layout. It is determined that for this technology the optimum emitter sizes are in the range of S_e≈1 μm by L_e=2-4 μm. These results illustrate the importance of accurate small-signal high-frequency characterization as a tool for the optimization of the geometry and layout of bipolar transistors. It quantifies how much one can gain or lose by adopting certain device sizes and design rules