Patent ID: 7298212
Filing Date: 2007-11-20
Classification: H03G

Abstract:
1. An automatic level control circuit comprising: a gain controllable amplifier which amplifies an input signal according to an established gain; a comparing and outputting circuit which compares a level of an output signal from the gain controllable amplifier with a reference level, and outputs a result of comparison as a comparison result signal; a circuit which generates a mask signal which is used, when the comparison result signal obtained in a period between one zero crossing point and another zero crossing point of the input signal is output over a predetermined output time, for restricting the comparison result signal output during the over period; and an outputting circuit of an attack detecting and outputting signal which, when the comparison result signal is output over the predetermined output time, restricts the comparison result signal output from the comparing and outputting circuit during the period over the predetermined output period and outputs the restricted comparison result signal as an attack detecting and outputting signal in accordance with the mask signal, and which, during the predetermined output period, outputs the comparison result signal as an attack detecting and outputting signal.