JPH04252624A - Optical receiver - Google Patents

Abstract

PURPOSE:To prevent the degradation of characteristic and to reduce a plane occupancy area by mounting an analog circuit on one face of an earthed conductor plate and mounting a digital circuit on the other face at the time of using the analog circuit and the digital circuit to constitute an optical receiver. CONSTITUTION:A first substrate 1a whose upper face is mounted with a photodetector 2 and an analog circuit 3 and a second substrate 1b whose lower face is mounted with a digital circuit 4 are put one over the other with a conductor plate 6 between them. The conductor plate 6 is made slightly larger than the first and second substrates 1a and 1b and is earthed. Thus, the conductor plate 6 functioning as the electromagnetic shield is interposed between the analog circuit 3 and the digital circuit 4 constituting the optical receiver, and the electromagnetic noise generated from the circuit 4 is cut off by the conductor plate 6 and does not reach the circuit 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical receiver. More specifically, the present invention relates to a novel configuration of an optical receiver configured by combining an analog circuit and a digital circuit.

0002

2. Description of the Related Art An optical transmitter used for optical communication, etc. includes at least a light receiving element that converts a received optical signal into an electrical signal, and an electric circuit that shapes the waveform of the electrical signal output from the light receiving element. There is. Furthermore, since signals handled in the field of optical communications are generally digital signals, a digital signal processing circuit is often also included for purposes such as synchronizing received signals.

FIG. 2 is a plan view showing the configuration of a conventional general optical receiver.

As shown in the figure, this optical receiver is composed of a light receiving element 2 mounted on a substrate 1, an analog circuit 3, and a digital circuit 4.
and the digital circuit 4 are connected to a common GND island 5 for necessary grounding.

In the optical receiver configured as described above, after converting the optical signal received by the light receiving element 2 into an electrical signal, the analog circuit 3 shapes the electrical signal, and the digital circuit 4 further converts the obtained electrical signal into an electrical signal. After performing processing such as synchronizing the signals, the reproduced signals are output to the outside.

[0006]

[Problem to be Solved by the Invention] However, as shown in Figure 2, when an analog circuit and a digital circuit are mounted on one board, the noise generated by the digital circuit in particular affects the operation of the analog circuit. It is known that That is, it has been pointed out that the characteristics of the analog circuit directly connected to the light receiving element deteriorate due to the radiation of electromagnetic waves from the digital circuit, resulting in problems such as deterioration of the reception sensitivity of the optical receiver.

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned problems of the prior art and provides an optical receiver including an analog circuit and a digital circuit. The purpose is to provide a new optical receiver configuration that can suppress the

[0008]

[Means for Solving the Problems] According to the present invention, in an optical receiver including an analog circuit and a digital circuit, a grounded conductor plate, an analog circuit loaded on one surface of the conductor plate, An optical receiver is provided, comprising a digital circuit loaded on the other surface of the conductor plate.

[0009]

[Operation] The main feature of the optical receiver according to the present invention is that an analog circuit and a digital circuit are arranged separately on the front and back sides of a single grounded conductor plate.

That is, in conventional optical receivers, analog circuits and digital circuits coexist on the same surface of one substrate. However, in such a configuration, the analog circuit is seriously affected by noise generated from the digital circuit, and the characteristics of the optical receiver are inevitably deteriorated.

On the other hand, in the optical receiver according to the present invention, an analog circuit is mounted on one surface of a conductor plate which is grounded and serves as an electromagnetic shield, and a digital circuit is mounted on the other surface. Therefore, noise generated in the digital circuit does not reach the analog circuit.

Further, in the optical receiver according to the present invention, since the circuit is mounted on both sides via a conductor plate, there is an effect that the area occupied by the optical receiver as a circuit is reduced.

[0013] Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the following disclosure is merely an example of the present invention, and is not intended to limit the technical scope of the present invention in any way.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view showing a specific example of the configuration of an optical receiver according to the present invention.

As shown in the figure, this optical receiver includes a first substrate 1a on which a light receiving element 2 and an analog circuit 3 are mounted on the upper surface, and a second substrate 1b on which a digital circuit 4 is mounted on the lower surface. , are constructed by overlapping each other with a conductor plate 6 interposed therebetween. The conductor plate 6 is connected to the first and second substrates 1a, 1
It is slightly larger than b and is grounded.

In the optical receiver configured as described above, since the conductive plate 6 as an electromagnetic shield is interposed between the analog circuit 3 and the digital circuit 4, the electromagnetic wave noise generated from the digital circuit 4 is It is blocked by the conductor plate 6 and does not reach the analog circuit 3.

[0017]

[Effects of the Invention] As explained above, the optical receiver according to the present invention has a double-sided mounting configuration in which the analog circuit and the digital circuit are separated, so that the electromagnetic wave noise generated in the digital circuit does not affect the analog circuit. This prevents the possibility of harm. Therefore, deterioration of the characteristics of the optical receiver due to the installation of a digital circuit is prevented. Also,
Since it has a double-sided mounting configuration, it occupies less planar space and contributes to the miniaturization of the optical receiver.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a configuration example of an optical receiver according to the present invention.

FIG. 2 is a plan view showing the configuration of a conventional optical receiver.

[Explanation of symbols]

1, 1a, 1b board, 2 Photo-receiving element, 3. Analog circuit, 4 Digital circuit, 5 GND Island, 6 Conductor plate

Claims (1)

[Claims] Claim 1: An optical receiver including an analog circuit and a digital circuit, comprising: a grounded conductor plate; an analog circuit loaded on one side of the conductor plate; and an analog circuit loaded on the other side of the conductor plate. An optical receiver comprising a loaded digital circuit.