Patent ID: 6107879
Filing Date: 2000-08-22
Classification: H03G

Abstract:
An automatic dynamic range control circuit comprising:fixed-gain first circuit means (111 or 211 or 311);variable-gain second circuit means (112-114 or 212-214 or 312-314) with propagation delay substantially equal to that of the first circuit means;peak value hold means (116, 117 or 216, 217 or 316, 317) for holding the peak value of the input signal;comparison means (120 or 220 or 320) for comparing the value held by the peak value hold means with a preset reference signal level; andfirst selection means (115 or 215 or 315) which on the basis of the result of the comparison by the comparison means, selects the first circuit means when the value held by the peak value hold means is smaller than the reference signal level, and selects the second circuit means when the value held by the peak value hold means exceeds the reference signal level;said automatic dynamic range control circuit being characterized in that:it comprises second selection means (118 or 218 or 318) which on the basis of the result of the comparison by the comparison means, selects the reference signal when the value held by the peak value hold means is smaller than the reference signal level, and selects the value held by the peak value hold means when this value exceeds the reference signal level, and outputs the selected value as a control signal for setting the gain of the second circuit means; andthe maximum output level of the second circuit means is limited by the aforesaid control signal, its output level being kept substantially fixed when the value held by the peak value hold means is input as the control signal, and the second circuit means operating with a fixed gain substantially equal to that of the first circuit means when the reference signal is input as the control signal.