| 摘要 |
PURPOSE: To always keep a maximum efficiency and to prevent the phase deviation by controlling a bias voltage in accordance with the change of an input RF power and controlling the phase change accompanying the change of the bias voltage. CONSTITUTION: The input RF power level is detected by a detection circuit 2 and passes an integrating circuit 7 and is converted to a digital value by an A/D converter 8. It is stored in storage circuits 9, 12, and 15 and is converted by conversion, tables preliminarily stored there and is converted back to an analog value by D/A converters 10, 13, and 16. Bias control circuits 11, 14, and 17 are operated by this analog value. Analog outputs of converters 13 and 16 drive bias control circuits 14 and 17 to control the gate bias voltage and the drain bias voltage of a power amplifier 5 so that an amplifier 5 is always operated most efficiently. The output of the converter 10 drives the circuit 11 to control the bias voltage of a phase shift circuit 3 so that the phase deviation due to the variance of the bias voltage is cancelled. |
