| 摘要 |
PURPOSE:To set a desired AGC characteristic easily by applying A/D conversion to an input average value and using a digitized data so as to adjust the gain or the titled amplifier. CONSTITUTION:An average value detecting circuit 3 detects an absolute value or a half wave rectified value of an input signal Vi, averages it and an A/D converter 4 converts an output Vf of the circuit 3 into a digital signal Di. The gain of a variable gain amplifier 6 is controlled by a digital signal D0 from an ROM5 outputting digital signal taking the signal Di as an address. Thus, the desired AGC characteristic is realized by taking the content of the ROM5 as a value corresponding to its characteristic and the AGC characteristic is changed by having only to change the content of the ROM5 without changing the circuitry. |
