| 摘要 |
PURPOSE:To attain DC restoration with high accuracy and less interference between codes in response to an input signal form by obtaining a maximum value and a minimum value of an input signal amplitude, comparing its intermediate value with a reference signal to obtain the difference of the both and applying negative feedback control to the input signal. CONSTITUTION:A circuit composing of a diode D, a capacitor C1 and a resistor R1 detects a maximum amplitude of an input signal VI1 and a circuit composing of a diode D2, a capacitor C2 and a resistor R2 detects a minimum amplitude of the input signal VI1. After the impedance is converted from a high to a low from each detection value by buffer circuits Bu1, Bu2, the result is given to division resistors R3, R4. The division resistors R3, R4 add the maximum amplitude and the minimum amplitude, outputs an intermediate signal of both the amplified values from the connecting point and the value is given to a differential amplifier Am. The differential amplifier Am obtains a difference between the intermediate signal and a reference voltage VR, the difference is amplified by a prescribed amplification factor set by resistors R3-R5 and its comparison signal is outputted. A transistor Q superimposes a bias signal onto the input signal VI1 via a resistor R7. |
