Topic 37. Amplifying Signals
In earlier Topics we have seen how to use a BJT for switching. We can use a BJT on its own, or use two BJTs as a Darlington pair or as a Schmitt trigger. A comparator has a similar switching action. In all these uses, the transistor is used in an all-or-nothing way. It is either off or saturated. All of these are amplifiers because a small change in input results in a large change in output.