Complementary transistor emitter follower circuit.

摘要

An emitter follower series-connected pair of complementary transistors (2,3) provide an output signal at the junction (20) between their commonly connected emitters. The NPN transistor (2) of the pair of transistors (2,3) is directly driven by an input signal applied to its base. The PNP transistor (3) of the pair of transistors (2,3) is driven through a series connection ofa NPN transistor (1) and a Schottky diode (4), the base of the NPN transistor (1) also receiving said input signal. The forward voltage of the Schottky diode (4) is less than the voltage Vbe of the PNP transistor (3). The PNP transistor (3) nominally is held off and conducts only on negative-going input signal transitions to discharge the capacitive load (6). The NPN transistor (2) of the pair of transistors conducts only on positive-going input signal transitions to charge the capacitive load (6). The circuit (14) which has a low power dissipation and a fast response for driving capacitive loads can be extended (15,16) to perform NOR logic and to provide a pair of output signals in phase opposition to each othar.