| 摘要 |
PURPOSE:To apply automatic control to the ternary APD so that the multiplication factor is not much decreased because the band width is rapidly reduced when the multiplication factor of the ternary APD is too much decreased. CONSTITUTION:An optical signal to be inputted is converted into an optical current signal by a ternary APD 1, subject to current voltage conversion by a preamplifier circuit 2, amplified by an equalization amplifier circuit 3, a high frequency component in an output signal of the equalization amplifier circuit 3 is extracted by a high pass filter 4 and a peak detection circuit 5 detects a peak level of a high frequency signal. A reverse bias control circuit 6 controls a reverse bias application circuit 7 so that the detected peak signal is less than a set threshold level thereby preventing the multiplication factor M of the ternary APD 1 from being much decreased. Thus, it is not required to make adjustment in matching with each characteristic of the ternary APD, the man-hour is reduced and even when the characteristic of the ternary APD is subject to secular change, since automatic control is always applied, the deterioration in the dynamic range of the optical receiver is not deteriorated. |
