| 摘要 |
A switching amplifier in a bridge circuit configuration is provided with an improved base drive circuit which is highly efficient. The base drive circuit includes a base current shunting transistor across the base-to-emitter circuit of each high current transistor. The first and second high current transistors have their base-to-emitter circuits connected across the supply voltage terminals of the bridge in series with first and second inductors and in series with a first base current regulating transistor. The current in the first and second inductors increases while the first base current regulating transistor is turned on. The first and second diodes provide respective current paths for current through the first and second inductors and the base-to-emitter circuits of the first and second high current transistors when the first base current regulating transistor is turned off. The base drive circuits for the third and fourth high current transistors are the same as that as those described for the first and second high current transistors. A control circuit is disclosed for the base current regulating transistor to maintain the base drive current at a predetermined value. A load current sensing circuit is disclosed to obtain an accurate indication of the output current of the amplifier.
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