| 摘要 |
PROBLEM TO BE SOLVED: To make a transmission level constant simply over a wide frequency band without storing correction data with respect to a frequency characteristic of a detector in advance to prevent a transmission level deviation due to the frequency characteristic of the detector in the transmission power automatic control circuit of a radio transmitter. SOLUTION: A differential amplifier 9 detects a differenceΔV between a detection voltage (Vf0 ) with a transmission frequency (f0 ) being a reference to correct a frequency characteristic of a detection sensitivity of a detector 6 and a detection voltage Vd at a transmission frequency desired to be in use to generate a correction voltage. Furthermore, a hold circuit 10 holds only a revision value of a detection voltage and provides an output at a frequency change by using a frequency setting signal fset as a trigger to output the correction voltage only at a frequency change. The correction voltage is added to an output level setting voltage VR of a transmission power control loop to suppress fluctuation in the transmission power at frequency revision.
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