This disclosure relates to electrical connectors and specifically concerns over high frequency small signal connectors.
It can be desirable for high frequency electrostatic damage (ESD) protectors to have short physical lengths. ESD protector solutions based on slotted semi-rigid coaxial cable structures, such as shown in
The ESD protection device 100 as shown in
A very high failure rate was found when the cable length was shortened and the bent section removed to fit the form factor requirements of a sampling oscilloscope product line such as an external time-domain reflectometer (TDR) module protector. The shortened ESD protection device 200 fails because the fragile active components in active component slots 102 are torn apart due to a center cable conductor of the ESD protection device 200 is rotated from its original position, which tears the active components in the active component slots 102. A shortened cable does not have enough PTFE, or Teflon, to hold the center conductor in place. As a result, the cable center conductor will rotate along with the soldered on connector center pin as it rotated by a user. Rotation of this center conductor drags one of the attached arms of the active components in the active components slot 102 and rips them apart because each of the active components' arms are still attached to the stationary outer conductor. It turns out that center pin rotation on SMA (SubMiniature version A) style high frequency connectors has historically been a problem and troubled the industry for some time. The triggering action is that users usually often inadvertently rotate the body of the mating parts instead of just rotating the connector coupling nut as the user should when engaging the connectors. This causes the active components in the active component slots 102 to tear in the shortened ESD protection device 200. As discussed above, the bend shown in
Accordingly, a need remains for an ESD protection device 200 which is short in length and does not include the bend of the ESD protection device 100, but that prevents tearing of the active components in the active component slots 102 when connected to a cable.
Certain embodiments of the disclosed technology include a cable assembly, comprising a coaxial cable having active components mounted thereon, a housing substantially surrounding the coaxial cable, and a launch connector mounted to the outside of the housing and in connection with the coaxial cable.
Other embodiments of the disclose technology include a system, comprising a device under test; a test and measurement instrument; and a cable assembly. The cable assembly includes a coaxial cable having active components mounted thereon; a housing substantially surrounding the coaxial cable; and two launch connectors mounted to the outside of the housing and in connection with the coaxial cable. One of the launch connectors attaches the cable assembly to the device under test and the other launch connector attaches the cable assembly to the test and measurement instrument.
In the drawings, which are not necessarily to scale, like or corresponding elements of the disclosed systems and methods are denoted by the same reference numerals.
The disclosed technology relates to a special technique to incorporate a slip joint between a launch connector pin receptacle and an inner conductor of a coaxial cable so that rotation of a center pin of the launch connectors does not result in rotation of the inner conductor of the coaxial cable. The coaxial cable includes parallel mounted fragile active components in the active component slots 102. The fragile active components in the active component slots 102 may be, for example, diodes (not shown).
In the disclosed technology, instead of using a solder on connector like typical coaxial cables do, a cable assembly 300 is divided into three sections. The cable assembly 300, as shown in
Preferably, the launch connectors 306 are standard edge launch connectors, such as 2.4 mm connectors sold by Southwest Microwave, Inc. Launch connectors 306 used in the disclosed technology are preferably launch connectors designed for microwave transmission from a coaxial cable environment to a stripline or micro strip line. Any launch connection, however, may be used. Launch connectors usually have various diameter launch pins available. In the disclosed technology, however, the launch pins are not used with the launch connector 306, as will be described more fully below. The launch connector 306 does not have to take the shape of that shown in
The coaxial cable 302, shown in more detail in
The portion of the inner conductor 404 located outside the housing fits inside the launch pin receptacle 500 of the launch connector 306, shown in
As shown in
When a cable, such as an SMA cable, is attached to the cable assembly 300, the cable's connecting nut is screwed on to the launch connector 306. Because the inner conductor 402 and 404 is located within the launch pin receptacle 500 of the launch connector 306, the inner conductor 402 and 404 can rotate freely relative to the launch pin receptacle 500 and not follow the rotational movement of the launch pin receptacle 500. This prevents the inner conductor 402 and 404 from rotating separately from the outer conductor 400 which in turn prevents the fragile active components in active component slots 102 on the coaxial cable 302 from tearing when the cable assembly 300 is attached to another mating connector of a cable or an instrument. That is, the launch pin receptacle 500 of the launch connector 306 and the inner conductor 402 and 404 of the coaxial cable 302 can rotate separately from each other.
The inner conductor 404 located outside the housing is plated with at least 30 micro inches thick gold and a 50 micro inches nickel barrier under the gold. Further, the end portions of the outer conductor 302 are also plated as well with at least 30 micro inches thick gold and a 50 micro inches nickel barrier under the gold. This plating ensures that while the exact contacting point is slipping along between the launch pin receptacle 500 and the inner conductor 404, a reliable low resistance path is always maintained between the two bodies. High frequency ESD protectors built with this slip joint comprised of the cable assembly 300 and the launch connectors 306 have proven to be reliable in maintaining good electrical contacts and very effective in suppressing tearing failures of the active components within the active component slot 102.
Although the housing has been substantially in a rectangular shape, one of ordinary skill in the art will understand that the housing can take on other shapes as well, such as cylindrical.
Having described and illustrated the principles of the disclosed technology in a preferred embodiment thereof, it should be apparent that the disclosed technology can be modified in arrangement and detail without departing from such principles. We claim all modifications and variations coming within the spirit and scope of the following claims.
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