Patent Publication Number: US-6705879-B2

Title: Pluggable electrical transceiver module with high density form factor

Description:
BACKGROUND 
     The present invention pertains to networking systems and pertains particularly to a pluggable electrical transceiver module with a high density form factor. 
     Switches, routers and other networking devices often require many ports for connection to additional devices. The size and number of connectors for which ports are required can have an influence on size and shape of the network devices. 
     For example, switches that utilize the Gigabit Ethernet protocol can have 48, 60 or more ports. Within each port can be placed a transceiver module that includes a connector, printed circuit board (PCB) and housing. The transceiver module translates the data from a format suitable for the cable to a format suitable for the host system, and vice versa. Transceiver modules for use with fiber optic cable are known as “electro-optic transceiver modules”. Electro-optic transceiver modules translate optical signals to electrical signals and vice-versa. Transceiver modules for use with electrical cable are known as “electrical transceiver modules”. Electrical transceiver modules translate electrical signals from an electrical format suitable for electrical cable to another electrical format suitable for the host system, and vice versa. Typically, for the Gigabit Ethernet protocol, an electrical or optical cable with a suitable connector is used to connect to the switch, router or other network device. 
     Optical connectors that have a relatively narrow circumference, such as an MTRJ or LC optical connector, allow for network devices to have densely arranged ports. However, for switches that use electrical connectors that are larger in size, such as RJ 45 connectors, larger, less densely arranged ports have been required. This can result in network devices that require additional space to accommodate the bigger port size. 
     SUMMARY OF THE INVENTION 
     In accordance with the preferred embodiment of the present invention, a transceiver module is presented. The transceiver module is adapted to be plugged into a port cage within a host system. The transceiver module includes transceiver electronics and a connector attached to the transceiver electronics. The transceiver electronics are sized to fit within the port cage. The connector includes a module portion and a connector jack attached to the module portion. The module portion is sized to fit along with the transceiver electronics within the port cage. The connector jack is sized with dimensions too big to fit within the port cage. The connector jack remains out of the port cage when the transceiver module is placed within the port cage. The connector jack occupies an area larger than an opening of the port cage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a simplified drawing of a host system such as a network switch. 
     FIG. 2 shows an electrical transceiver module in accordance with a preferred embodiment of the present invention. 
     FIG. 3 shows an expanded view of the electrical transceiver module shown in FIG. 2 in accordance with a preferred embodiment of the present invention. 
     FIG. 4 shows an alternate view of a connector portion of the electrical transceiver module shown in FIG. 2 in accordance with a preferred embodiment of the present invention. 
     FIG. 5 shows section view of the connector shown in FIG. 4 in accordance with a preferred embodiment of the present invention. 
     FIG. 6 is a simplified drawing of electrical transceiver modules inserted in a host system in accordance with a preferred embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a simplified drawing of a host system. For example, host system is a networking switch, router, or some other networking device. Host system  11  has a number of ports  12 . The ports are implemented as cages designed to receive an electro-optic transceiver module with a small form factor, such as an electro-optic transceiver module used to hold an MTRJ or LC or other type of electro-optic connector, or as an electrical transceiver module used to hold an RJ 45 or another type of electrical connector. 
     FIG. 2 shows an electrical transceiver module  20  that can be placed in a port of a host system, for example, one of ports  12  of host system  11 . Electrical transceiver module  20  passes data from a cable to its host system. 
     Electrical transceiver module  20  includes an opening  27  within an RJ-45 jack  21  into which a cable fits. For example, the cable is a category (CAT) 5 cable. Alternatively, the cable can be, for example, a category 3, 5e or 6 cable for Ethernet, fast Ethernet or gigabit Ethernet applications. 
     For example, electrical transceiver module  20  is a “small-form pluggable” transceiver. The small form-factor allows for a high density of transceivers, so a maximum number of modules can fit into a given system. 
     A portion  22  of electrical transceiver module  20  is placed within a port cage of the host system. A latching mechanism  23  secures electrical transceiver module  20  in the port cage. A delatch  24  is shown inserted within latching mechanism  23 . RJ-45 jack  21  sticks out of the cage of the host system. 
     FIG. 3 shows an expanded view of electrical transceiver module  20 . Electrical transceiver module  20  includes a connector  31 , a printed circuit board (PCB)  33  and a housing  32 . Housing  32  includes electro-magnetic interference (EMI) shielding. Connector  31  also includes EMI shielding over RJ 45 jack  21  and over a module side  25  of connector  31 . In addition to reducing EMI, the shielding also reduces cross-talk. The EMI shielding is connected to chassis ground. 
     Module side  25  of connector  31  includes a 10-pin connector  26  for connection to PCB  33 . Delatch  24  is shown removed from latching mechanism  23 . PCB  33  implements a transceiver. 
     FIG. 4 shows an alternate view of connector  31 . The alternate view allows a clear view of latching mechanism  23  being integrated as part of connector  30 . 10-pin connector  26  is also clearly seen. 
     FIG. 5 shows a section view of connector  31 . A magnetic circuit  51  is included within module side  25  of connector  31 . All incoming and outgoing signals communicated through connector  31  pass through magnetic circuit  51 . For example, magnetic circuit  51  consists of a transformer for electrical isolation between the cable within RJ 45 jack  21  and the transceiver implemented by PCB  33 . Magnetic circuit  51  also includes a common mode choke and a common mode termination. 
     FIG. 6 is a simplified drawing showing electrical transceiver modules  61  inserted in a host system. The jack portions of the electrical transceiver modules extend out of ports  12  allowing for a dense arrangement of ports  12 . The small form-factor allows for a high density of transceivers, so a maximum number of modules can fit into a given system. This results in minimal impact on the ability of host system  11  to house a high density of electrical transceiver modules. 
     The foregoing discussion discloses and describes merely exemplary methods and embodiments of the present invention. As will be understood by those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.