| 摘要 |
PROBLEM TO BE SOLVED: To suppress loop vibration of the gain control voltage of a gain control amplifier 12, when the gain gradient of the amplifier is large and when the gain control voltage range is wide. SOLUTION: This automatic gain control circuit is equipped with an amplifier 12, an A/D(analog-to-digital) converter 14, an error detection part 16, 1st and 2nd coefficient multipliers 30 and 32, an integrator 20, an adder 38, and a D/A converter 22. The error detection part 16 compares the output signal of the A/D converter 14 with a reference signal to detect an error, the 1st and 2nd coefficient multipliers 30 and 32 multiply the detected value by power coefficients k1 and k2, the integrator 20 integrates the output value of the 1st coefficient multiplier 30, the adder 38 adds the output value of the 2nd coefficient multiplier 39 to the integral value of the adder 38, and the D/A converter 22 converts the addition value to an analog signal and outputs it as a gain control voltage to the amplifier 12. Consequently, the output value of the 2nd coefficient multiplier 32 is outputted as the gain control voltage to the amplifier 12 not through the integrator 20, and the response speed of the gain control voltage fed back to the amplifier 12 is increased to suppress the loop vibration.
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