| 摘要 |
An amplifier circuit ( 1 ) includes an amplifying transistor (QØ) and an impedance-controllable dc bias circuit ( 2 ) for biasing the amplifier transistor (QØ) to obtain a conduction angle of at least about 180°. The dc bias circuit ( 2 ) includes a self-bias boosting circuit having separate current sources (Ibias, Iclass) for independently controlling the output impedance of the dc bias circuit ( 2 ) and the quiescent current of the amplifier transistor (QØ), and has a Wilson current-mirror (Q 4 , Q 5 , Q 6 , Q 7 ) integrated with a cascode current-mirror circuit (Q 2 , Q 3 , Q 8 ) to form an extended Wilson current-mirror circuit (Q 2 -Q 8 ) having an output coupled to a control terminal of the amplifying transistor (QØ) by a resistor (R 1 ), and a capacitor (C 2 ) coupled from the extended Wilson current-mirror circuit (Q 2 -Q 8 ) to a common terminal (Gnd).
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