| 摘要 |
In a power amplifier apparatus, a positive output signal of left front output amplifier (2LF), a negative output signal of left rear output amplifier (3LR), a negative output signal of right front output amplifier (3RF), and a positive output signal of right rear output amplifier (4RR) are applied to an adder (9), which selects the signal showing the highest level out of the four signals and generates a voltage corresponding to the selected signal. Switching power source (10) is adapted to operate according to the output signal of the adder (9) and produces a power source voltage to each of the high efficiency amplifiers. The positive output signal of the left front output amplifier and that of the right rear output amplifier are identical and substantially in-phase, whereas the negative output signal of the left rear output amplifier and that of the right front output amplifier are identical and substantially in-phase. Thus, a power source voltage is generated for each of the high efficiency amplifiers while providing fewer adders than the number of loads.
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