| 摘要 |
PURPOSE:To obtain constitution suitable to IC-implementation by using digital elements by comparing the output of a variable gain control amplifier with specific reference levels by two comparators, and ORing their outputs exclusively. CONSTITUTION:The output of the variable gain amplifier 12 is supplied to comparators CMPs 21 and 22. The CMPs 21 and 22 compares the output of the amplifier with maximum amplitudes +m and -m (0<m<1) of the amplifier 12 as reference levels, and the comparison outputs of the CMPs 21 and 22 are ORed 23 exclusively to input the result to a D type FF24. The D.FF24 samples an input signal with a control clock from a clock generating circuit 25 and inputs the output to an up/down counter 26, and the amplifier 12 is controlled with the signal generated by D/A-converting 27 the input signal. The output level of a converter 27 is high or low according to the input signal level to the amplifier 12 is high or low, and the gain of the amplifier 12 is controlled to a low or large level to output a constant-level signal from a terminal 15. |
