Transceiver package

The invention is a transceiver package with reduced overall width and optical pitch. Separate circuit boards are provided for the laser with its associated circuitry and the photodetector with its associated circuitry. The boards are mounted to the sidewalls of the package housing so that they are essentially perpendicular to the base of the package and to the major surface of the mother board.

FIELD OF THE INVENTION 
This invention relates to optoelectronics, and in particular to transceiver 
packages having a narrow optical pitch. 
BACKGROUND OF THE INVENTION 
As a result of the drive for ever-increasing packing densities, optical 
packages, especially transceiver packages, will desirably have smaller 
footprints, narrow widths, and utilize connectors with very narrow optical 
pitch. For example, a standard design utilizes the optical components and 
electronics on a single printed circuit board which is parallel to the 
mother board to which the package is mounted. Such designs use 1 inch wide 
transceiver packages with an optical pitch (the center-to-center distance 
between the laser and detector ports) 0.5 inches. While presently 
adequate, future designs call for a 0.54 inch width and 0.246 inch optical 
pitch. Meeting these stringent requirements was thought to require new 
types of optical components and/or optical fiber stubs. However, it is 
desirable to meet these requirements with commercial optical components 
and utilizing standard assembly techniques. 
SUMMARY OF THE INVENTION 
The invention is a transceiver package including a housing having first and 
second opposing side walls and a base portion adapted for mounting to a 
printed circuit mother board so that the base portion is essentially 
parallel to a major surface of the mother board. A first hybrid integrated 
circuit comprising a first circuit board and a laser is mounted to the 
first sidewall, and a second hybrid integrated circuit comprising a second 
circuit board and a photodetector is mounted to the second sidewall so 
that the first and second circuit boards are essentially perpendicular to 
the base portion.

It will be appreciated that, for purposes of illustration, these figures 
are not necessarily drawn to scale. 
DETAILED DESCRIPTION 
FIG. 1 illustrates a transceiver package, 10, in accordance with an 
embodiment of the invention. The package includes a dielectric housing, 
11, having first and second opposing side walls, 12 and 13, and a base 
portion, 14, adapted for mating with a printed circuit mother board, 15. A 
first hybrid integrated circuit, 20, comprising a first circuit board, 21, 
and a laser module, (22 of FIG. 2) is mounted on the first sidewall, 12, 
and a second hybrid integrated circuit, 30, comprising a second circuit 
board, 31, and a photodetector module (32 of FIG. 3) is mounted on the 
second sidewall, 13, so that the first and second circuit boards are 
essentially perpendicular to the base portion, 14. (A laser module 
typically includes a laser and an aligned lens, and a photodetector module 
typically includes a preamplifier, PIN photodiode and aligned lens.) 
In more detail, the dielectric housing, 11, typically comprises a 
thermoplastic material, and in this embodiment has a width, w, of 
approximately 0.540 inches (13.71 mm). As further illustrated in FIG. 2, 
the transmitter hybrid circuit, 20, includes the laser module, 22, mounted 
near one end of the printed circuit board, 21 and extending beyond it, and 
electronic circuitry, illustrated by block 24, which comprises the laser 
drive circuitry, formed on the remainder of the board. A plurality of 
conductive leads, e.g., 25, is attached to respective metalized contact 
pads, e.g. 26, by standard means such as soldering to provide electrical 
connection to the circuitry, 24, which in turn drives the laser module, 
22. A standard type of optical connector receptacle, 23, such as an 
LC-type receptacle, is molded as an integral part of the housing, 11. The 
receptacle, 23, includes an optical port, 27, for receiving an optical 
connector, 28, which connects to an optical fiber 29, so that light from 
the laser can be transmitted. (The optical port, 23, can alternatively be 
an integral part of the module 22.) The transmitter hybrid circuit, 20, is 
mounted to a mother board, 15, by insertion of the conductive leads, e.g., 
25, into corresponding holes in the mother board. A mounting post, 41, 
extending from the circuit board, can also be inserted in the mother board 
to relieve stresses in the components. The board, 21, may be mounted to 
the sidewall, 12, by pin-in-hole attachment techniques. (See, e.g., R. K. 
Wolf, U.S. patent application Ser. No. 09/069,128 filed Apr. 29, 1998 and 
incorporated by reference herein) 
In an exemplary embodiment, the laser module is a 1310 nm MQW edge emitting 
laser such as the Lucent 370-type laser, although other light emitting 
devices may be employed. Other types of standard receptacle, 23, can be 
employed in place of the LC-type of receptacle. The conductive leads, 
e.g., 25, can be solder plated BeCu and can be attached to the bonding 
pads, 26, by spring force or other means. (See, e.g., Wolf application 
cited previously). 
As further illustrated in FIG. 3, the receiver hybrid circuit, 30, includes 
the photodetector module, 32, mounted near one end of the printed circuit 
board, 31, and extending beyond it, and electronic circuitry, illustrated 
by block 34, which comprises the signal recovery circuitry, formed on the 
remainder of the board. A plurality of conductive leads, e.g., 35, is 
attached to respective metalized pads, e.g. 36, by standard means such as 
soldering to provide electrical connection to the circuitry, 34, which in 
turn recovers the signal received by the detector, 32. A standard type of 
optical connector receptacle, 33, such as an LC-type receptacle, is molded 
as an integral part of the housing, 11. The receptacle, 33, includes an 
optical port, 37, for receiving an optical connector, 38, which connects 
to an optical fiber 39, so that light from the fiber can be received by 
the detector, 32. (Again, the port 37 could be integral with the module 
32.) The receiver hybrid circuit, 30, is also mounted to the mother board, 
15, by insertion of the conductive leads, e.g., 35, into corresponding 
holes in the mother board. The board, 31, may be mounted to the sidewall, 
13, by pin-in-hole attachment techniques in the same manner as the 
transmitter hybrid circuit. 
In an exemplary embodiment, the photodetector module can be a preamplifier 
and PIN such as the Lucent 170-type detector, but other types may be 
employed. Again, other types of standard receptacle, 23, can be employed 
in place of the LC-type of receptacle. The conductive leads, e.g., 35, 
can, again, be solder plated BeCu and can be attached to the metalized 
pads, 36, by spring force or other means. 
As illustrated in FIG. 1, the package, 10, is mounted to the mother board, 
15, such that the base portion, 14, is essentially parallel to the major 
surface, 40, of the mother board, and the hybrid circuit boards, 21 and 
31, are essentially perpendicular to the surface, 40, of the mother board. 
This orientation results in an overall width, w, of the package which is 
considerably less than standard packages where all components are placed 
on a single hybrid circuit board which is parallel to the surface of the 
mother board. In particular, the width of the package in this example is 
approximately 0.540 inches (13.71 mm). The present invention also reduces 
the optical pitch, s, to a value of approximately 0.246 inches (6.25 mm) 
which is significantly less than could be achieved with the prior art 
design. Thus, the package conforms to requirements for the next generation 
transceiver package without requiring new components or new processes. 
Further, the separation of the electronics, 24 and 34, for the laser and 
detector onto two boards, 21 and 31, reduces crosstalk between the 
electronics which is more critical of data rates greater than 1 Gigabit 
per second.