| 摘要 |
An amplifier circuit includes a bias control feedback loop. A sensing transistor (105) is matched to one or more power transistors (101a, 101b, 101c) and is correspondingly biased. The difference between collector voltage of the sensing transistor (105) and a reference voltage amplified by a differential amplifier (111, 114) provides the base bias voltage for the power transistors (101a, 101b, 101c) and the sensing transistor (105). The gain of the amplifier is controlled by applying a control voltage to a resistor (110) connected to the collector of the sensing transistor (105).
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