| 摘要 |
An amplifier comprises a power amplifying circuit including FET's and operable when supplied with a first power source and a drive circuit operable when supplied with a second power source for driving the power amplifying circuit and including a bias circuit for providing bias voltages for the FET's. Upon turning on the power switch, the first power source builds up quickly while the second power source builds up with some time delay. Switch-over circuits connect the power lines of the drive circuit to the first power source initially and to the second power source after the build-up of the latter, thereby starting the supply of the bias voltages to the FET's at the build up of the first power source to prevent an excessively large current or rush current from flowing through the FET's, thus avoiding the breakage or characteristic deterioration of the FET's. |
