Optical receiver

Abstract

There is provided an optical receiver in which, between an optical receiver sub-assembly and a pre-amplifier on a main printed circuit board, two transmission lines on a flexible printed circuit board for connecting an optical receiver module with the main printed circuit board, a balanced-type attenuator circuit composed of four resistor elements, and two capacitor elements connected in parallel with the balanced-type attenuator circuit are provided.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view depicting main parts of an optical receiver;

FIG. 2 is a circuit diagram for explaining the optical receiver from a photodiode to a post-amplifier;

FIGS. 3A and 3B are graphs showing characteristics of a frequency characteristic compensating circuit;

FIGS. 4A and 4B are graphs explaining effects and showing frequency characteristics; and

FIG. 5 is a circuit diagram for explaining an optical receiver from a photodiode to a post-amplifier.

Claims

1. An optical receiver comprising: a light receiving element for converting an optical signal into an electrical signal;a first amplifier for amplifying an output signal from the light receiving element; anda second amplifier for further amplifying an output from the first amplifier,wherein there is provided a frequency characteristic compensating circuit between said first amplifier and said second amplifier, the frequency characteristic compensating circuit being configured by a plurality of passive elements.

2. The optical receiver according to claim 1, wherein said frequency characteristic compensating circuit is configured by a balanced-type attenuator circuit composed of four resistor elements and by two capacitor elements connected in parallel with the balanced-type attenuator circuit.

3. The optical receiver according to claim 1, wherein said frequency characteristic compensating circuit is configured by a balanced H-type attenuator circuit composed of five resistor elements and by two capacitor elements connected in parallel with the balanced H-type attenuator circuit.

4. An optical receiver comprising: an optical receiver sub-assembly including a light receiving element for converting an optical signal into an electrical signal and a first amplifier for amplifying an output signal from the light receiving element; anda main printed circuit board mounting a second amplifier for further amplifying an output from said first amplifier,wherein said optical receiver sub-assembly and said main printed circuit board are connected through a flexible printed circuit board for transmitting the electrical signal amplified by said first amplifier, andthere is provided a frequency characteristic compensating circuit between a flexible printed circuit board connected portion and said second amplifier on said main printed circuit board, the frequency characteristic compensating circuit being configured by a plurality of passive elements.

5. The optical receiver according to claim 4, wherein said frequency characteristic compensating circuit is configured by a balanced-type attenuator circuit composed of four resistor elements and by two capacitor elements connected in parallel with the balanced-type attenuator circuit.

6. The optical receiver according to claim 4, wherein said frequency characteristic compensating circuit is configured by a balanced H-type attenuator circuit composed of five resistor elements and by two capacitor elements connected in parallel with the balanced H-type attenuator circuit.

7. The optical receiver according to claim 4, wherein two microstrip lines for differential signals are provided on said flexible printed circuit board.