Схемы, платы, компоненты

What’s All This Vbe Stuff, Anyhow?

Part 1

This Vbe topic has come up many, many times since junction transistors were introduced in the 1950s. Usually scholars like to use lots of exponential equations, and they seem to pretend that Is is constant. Then they show the old, trite curve where Ic bends like a hockey stick at Vbe = 0,6 volts on a linear-linear scale. They pretend the transistor has no collector current below Vbe = 0,4 volts. This does not help a user or engineer understand how things change versus Ic or temperature. They ignore the way that the transistor’s current shrinks exponentially, all the way down to just a few millivolts of Vbe, and does not magically stop below a certain “threshold.” This analysis helps me a lot; how about you? Bob Widlar used graphical techniques to design transistor circuits that ran some transistors on a small number of nanoamperes or of millivolts. /rap