| 摘要 |
PURPOSE:To always obtain an output signal biased to a stable level by clamping an output signal biased by an average bias level clamp system, at the time of abnormality that a bias is not generated. CONSTITUTION:In a state that a pulse is contained in the output signal of a signal processing system 3, a selection circuit 8 selects the output of a clamp level detection circuit 7 by the detection output of a state detection circuit 12, and the said output and a reference voltage are compared by a comparison circuit 5, and a comparison output is fed back to the signal processing system 3. In the case that the pulse is not contained in the output signal of the signal processing system 3, the selection circuit 8 selects the output of an average bias level detection circuit 4 by the detection output of the state detection circuit 12, and this output and the reference voltage are compared by the comparison circuit 5, and the comparison output is fed back to the signal processing system 3, and the average level of the output signal is fixed at the reference voltage value.
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