| 摘要 |
PROBLEM TO BE SOLVED: To minimize group delay characteristic degradation within a prescribed frequency band and to provide prescribed group delay characteristics by optimizing the characteristic impedance of a transmission line in an increasing direction proportionally to the length of the transmission line for connecting plural high frequency circuits and the input/output matching characteristics of the high frequency circuits. SOLUTION: Optical signals are converted to electric signals in a photodetector 1 and signals low-noise-amplified in a preamplifier 2 are transmitted to a post-amplifier 4 through the transmission line 3, amplified to a prescribed output level and outputted. In this case, corresponding to the length of the transmission line 3 for connecting the preamplifier 2 and the post-amplifier 4 and the input/output matching characteristics of the post-amplifier 4, the characteristic impedance of the transmission line 3 is optimized (enlarged) within the range of not losing the characteristics and stability of the pre-amplifier 2 and the post-amplifier 4. Thus, the influence of reflected waves passed through the transmission line 3 is reduced, the degradation of the group delay characteristics by the reflected waves is suppressed and a light receiver provided with the excellent group delay characteristics is obtained. |
