| 摘要 |
The present invention is directed to an automatic power control circuit for a signal power amplifier which maintains the output power to one of a plurality of output power levels. The output power level is controlled by an externally-generally level control signal which is used by a square wave signal generating circuitry for controlling the duty cycle of the generated square wave. The square wave is integrated by a filter network to produce a reference voltage level. The output voltage level of the RF amplifier is compared with the reference voltage level, and the difference between the two signals is used to control a drive circuit for generating the proper control voltage for controlling the RF amplifier so that the desired output power level is maintained.
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