Slide 2 of 64
Why is the HBT the most likely device candidate for future computing systems? We can see that this is clearly so simply based on the implications of switching with rise and fall times of 1-15 picoseconds. First we cannot permit currents to be turned on and off as they are in CMOS at these speeds due to inductive kick in signal and power lines. Hence current must be continuous and simply steered through different paths. Second we must reduce the voltage swing so that dynamic power does not become untenable. These things are only possible at room temperature in a bipolar full differential CML circuit. Finally III-V HBTs are needed to get to very thin bases for fast transit times through the devices.