| 摘要 |
PROBLEM TO BE SOLVED: To provide a power amplifier which operates thermally stably and has low distortion. SOLUTION: This power amplifier has a bypass path formed for high-frequency components having passed through 1st and 2nd impedance circuits Z1 and ZZ on the both ends of a resistor RB connected between the base terminal B of a bipolar transistor Q1 and a base bias voltage supply terminal VB. A portion of the AC component of a base current flowing from the base bias voltage supply terminal VB to a resistor RB is therefore allocated to the bypass path. An increase in the voltage drop across the resistor RB is effectively suppressed to suppress gain compression and the power amplifier can operate in low-distortion operation. Further, at least one of the 1st and 2nd impedance circuits Z1 and ZZ has its impedance open to the DC component and is conductive to the AC component, so an increase of base current due to a temperature rise can be suppressed by the voltage drop across the resistor RB. COPYRIGHT: (C)2004,JPO
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