A Self-Protecting Transistor Power Amplifier

OTL Power Amplifiers (See figure 1.) The basic types of configuration evolve around either complementary pairs, or the full or half-bridge configuration. The complementary circuit requires a split power supply and matched PNP-NPN power transistors. The practicalities in procuring germanium pairs in reasonably high power ratings exclude this circuit from consideration for the high-fidelity audio amplifier designer. The half-bridge circuit is in most common use at this writing. The variations in design are in the method of drive and the use of either a split power supply or an output capacitor and a single supply.