| 摘要 |
A differentiation signal DF differentiated by a differentiation unit is inputted to a slice level generation unit and to comparators. A first peak-hold circuit and a voltage division circuit generate a slice level having a slice ratio SLR that is constant to a peak value VDF of the differentiation signal DF. A second peak-hold circuit generates a slice level the slice ratio SLR of which changes in accordance with the peak value VDF. The slice level generation unit outputs their synthetic slice level SLL, which is compared by the comparators with the level of the differentiation signal DF, outputting thereby binarized signals W-GATE and B-GATE. When the level of the differentiation signal DF is high, the slice level SLL approaches the peak value VDF. Therefore, noise components contained in the differentiation signal DF cannot exceed the slice level SLL. When the level of the differentiation signal DF is low, the slice level SLL has a constant ratio to the peak value VDF. Consequently, the peak value of the amplitude of the differentiation signal DF can be detected reliably.
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