Slide 7 of 64
This slide shows the relative wire driving performance of comparably scaled HMESFET and HBT gates. Delay vs.. wire length is plotted. Clearly the bipolar device degrades less rapidly as a fast device when driving purely capacitive loads. Unfortunately for all devices at room temperature wire resistance gives a quadratic shape to this delay curve. The onset of quadratic behavior shows up for bipolar at much shorter wire lengths than for the FET, but for short wire lengths the bipolar device excels. More layers of bigger wire cross section are needed to sustain this advantage.