Optical waveguides – Integrated optical circuit
Reexamination Certificate
2000-03-17
2002-05-28
Healy, Brian (Department: 2874)
Optical waveguides
Integrated optical circuit
C385S039000, C385S131000
Reexamination Certificate
active
06396967
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to optoelectronic integrated circuit devices, and, more particularly, to an optoelectronic integrated circuit device which performs light signal transmission between integrated circuit devices.
2. Description of the Related Art
In recent years, smaller and higher-performance electronic apparatuses of various types have been produced with the use of highly integrated, high-speed, large-scale integrated circuits (LSI). In a large-scale electric circuit such as computer, LSIs are generally mounted on a multi chip module (MCM) substrate, as shown in
FIGS. 1A and 1B
.
FIG. 1A
is a plan view of MCM substrates
120
mounted onto a system board
110
, and
FIG. 1B
is a side view of the MCM substrates
120
.
A plurality of integrated circuit chips
130
are mounted on each of the MCM substrates
120
, which electrically connect the integrated circuit chips
130
. The MCM substrates
120
are mounted onto the system board
110
by inserting I/O (Input/Output) pins
160
into MCM sockets
150
. The MCM substrates
120
are provided with heat radiation fins
140
, if necessary. The system board
110
electrically connects the MCM substrates
120
with lead wires. Accordingly, the MCM substrates
120
and the integrated circuit chips
130
are electrically connected to one another, so that the system board
110
can have various functions.
Japanese Laid-Open Patent Application No. 5-67769 discloses such an optoelectronic integrated circuit which performs signal transmission between the integrated circuit chips
130
. This optoelectronic integrated circuit is characterized by three-dimensionally arranged substrates to achieve high-speed performance and high density. In this arrangement, the substrates are perpendicular to one anther. The substrates are made of a material through which light signals can pass, so that light signal transmission can be carried out through the substrates.
Even higher speed performance is expected in an electronic apparatus provided with the MCM substrates
120
and the integrated circuit chips
130
. However, the connection between the MCM substrates and the integrated circuit chips
130
are electric connection by means of lead wires patterned from a metallic material. Because of this, the signal transmission speed is limited.
As the integrated circuit chips
130
perform at higher speed, proportionally longer transmission delay time is caused in signal transmission between the MCM substrates
120
and the integrated circuit chips
130
. As a result, synchronized signal transmission becomes difficult. For instance, in electric signal transmission, a transmission delay time of 70 ps/cm is caused. In
FIG. 1B
, a signal transmission path
170
between integrated circuit chips
130
-
1
and
130
-
2
and a signal transmission path
180
between integrated circuit chips
130
-
1
and
130
-
6
have different transmission delay times. Between the signal transmission paths
170
and
180
, the difference in transmission delay time becomes too large to ignore in an operation with an operation clock speed of 5 GHz, for instance.
Also, signal damping and transmission loss are caused by the stray capacity and impedance due to the lead wires patterned from a metallic material between the MCM substrates
120
and the integrated circuit chips
130
. As a result, signal transmission becomes difficult.
Meanwhile, in an optoelectronic integrated circuit for light signal transmission, light loss cannot be avoided when a light signal passes through substrates, even if the substrates are made of a material that is supposed to cause little light loss. The result is transmission loss. Such transmission loss leads to transmission errors, thereby reducing reliability in the signal transmission.
SUMMARY OF THE INVENTION
A general object of the present invention is to provide optoelectronic integrated circuit devices, in which the above disadvantages are eliminated.
A more specific object of the present invention is to provide an optoelectronic integrated circuit device which has less signal damping and transmission loss.
Another specific object of the present invention is to provide an optoelectronic integrated circuit device in which signal transmission delay time is shorter than in the prior art.
The above objects of the present invention are achieved by an optoelectronic integrated circuit device comprising a first optoelectronic integrated circuit and a second optoelectronic integrated circuit each of which includes an electric circuit unit, an optical output terminal unit having a plurality of light emitting elements connected to the electric circuit unit, and an optical input terminal unit having a plurality of light receiving elements connected to the electric circuit unit. In this optoelectronic integrated circuit device, the first optoelectronic integrated circuit and the second optoelectronic integrated circuit are arranged in such a manner that each optical output terminal unit faces each corresponding optical input terminal unit. In this arrangement, light signal transmission can be carried out between each optical output terminal unit and each corresponding optical input terminal unit of the first optoelectronic integrated circuit and the second optoelectronic integrated circuit.
Accordingly, light signal transmission can be carried out between the first optoelectronic integrated circuit and the second optoelectronic integrated circuit. Also, since each optical output terminal unit faces each corresponding optical input terminal unit, light signal transmission can be carried out without wrong transmission between substrates. Thus, signal damping and transmission loss can be reduced.
The above objects of the present invention are also achieved by a stacked optoelectronic integrated circuit device which comprises a plurality of optoelectronic integrated circuit devices each having the above structure. The plurality of optoelectronic integrated circuit devices are stacked up and bonded to each other via electrode pads.
In the stacked optoelectronic integrated circuit device having this structure, signal transmission can be carried out between the optoelectronic integrated circuit devices via the electrode pads.
The above objects of the present invention are also achieved by a multiple stacked optoelectronic integrated circuit device which comprises a plurality of stacked optoelectronic integrated circuit devices each having the above structure. The plurality of stacked optoelectronic integrated circuit devices are optically connected.
With the multiple stacked optoelectronic integrated circuit device, signal transmission delay time can be shortened, and signal damping and transmission loss can be reduced.
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4894699 (1990-01-01), Hayashi et al.
patent: 5061027 (1991-10-01), Richard
patent: 5101460 (1992-03-01), Richard
patent: 5200631 (1993-04-01), Austin et al.
patent: 5408547 (1995-04-01), Lebby et al.
patent: 5652811 (1997-07-01), Cook et al.
patent: 5848214 (1998-12-01), Haas et al.
patent: 37 27 177 (1993-11-01), None
patent: 196 52 030 (1998-06-01), None
patent: 5-67769 (1993-03-01), None
patent: 6-268194 (1994-09-01), None
Copy of German Patent Office Action for corresponding German Patent Application No. 123PAT429-DE dated Jul. 18, 2001 with partial translation.
Suzuki Osamu
Watanabe Takayuki
Armstrong Westerman & Hattori, LLP
Fujitsu Limited
Healy Brian
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