| 摘要 |
In a power amplifier, in particular an audio-frequency amplifier for car radios, with two push-pull series circuits (10, 11) disposed in a bridge, operating in B-mode and in each case comprising two complementary transistors (12, 13 or 14, 15) operated as emitter followers on a DC operating voltage (UB), a further transistor (26, 27) is in each case inserted between the upper potential point of the DC operating voltage (UB) and each of the two output terminals (19, 20) located in the bridge diagonal (18), for the purposes of increasing the output power with the same operating voltage and power impedance. The bases of the further transistors (26, 27) operated as emitter followers are in each case connected via a threshold value switch (28, 29) to the bases of the assigned complementary transistors (12, 13 or 14, 15). The threshold values are selected in such a way that the activation of the further transistors (26, 27) occurs only when the assigned complementary transistor (12, 13) is fully activated (Fig. 1). <IMAGE>
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