| 摘要 |
PURPOSE:To eliminate the asymmetry of step response, by adding a logarithm converter in the feedback loop of AGC. CONSTITUTION:An input signal is attenuated by a step attenuator 1 so as not to be satuated at an A/D converter 2. The control of the step attenuator 1 is performed by the output of a register 6 scaled to F/N at the second scaler 3b. The output of the A/D converter 2 is scaled by the first scaler 3a, and only an amplitude component is taken out by an absolute value circuit 4. The logarithm of the amplitude component is outputted by a logarithm converter 8, and a threshold constant lnK is subtracted by a subtractor 5, and a differential output is sent to an accumulator circuit consisting of an adder 7, and the register 6, and is integrated until the output of the A/D convert 2 arrives at a certain level. Thus, an AGC feedback characteristic is linearized, and the asymmetry of the step response can be eliminated.
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