| 摘要 |
PROBLEM TO BE SOLVED: To precisely control an RF carrier amplifier gain by generating a reference voltage corresponding to an output voltage corresponding to an operating temperature measured by the RF carrier amplifier, generating a precise voltage corresponding to the reference voltage, converting the precise voltage to a precise current and controlling the gain by impressing the precise current to the RF carrier amplifier. SOLUTION: A temperature sensor diode (D2) 24 changes the output voltage of a temperature sensor operational amplifier 23 according to the temperature of the temperature sensor diode (D2) 24. The operating temperature of an RF carrier amplifier 12 is measured using a temperature measuring circuit provided with the temperature sensor operational amplifier 23 and the temperature sensor diode (D2) 24. The reference voltage is generated corresponding to the output voltage generated by the temperature measuring circuit. Corresponding to the reference voltage, the precise voltage is generated by a D/A converter 31. The precise voltage is converted to the precise current by a current control operational amplifier 21. The quantity of attenuation is controlled by impressing the precise current to plural PIN diodes 1.5 of a gain control circuit.
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