Patent Application
20170270071
This application claims priority of Taiwanese Application No. 105108661, filed on Mar. 21, 2016.
The disclosure relates to a network device, and more particularly to a network device for interfacing network communication between equipment and a cable.
A conventional network device for interfacing network communication between equipment and a cable is illustrated in
The isolation transformer 86 includes a primary winding 861 and a secondary winding 862. Each of the primary winding 861 and the secondary winding 862 has a first winding segment 863, a second winding segment 864, and a center tap 865 between the first winding segment 863 and the second winding segment 864. Each of the two noise filtering modules 87 is connected to the center tap 865 of a respective one of the primary winding 861 and the secondary winding 862 for grounding common-mode noise accompanying the signal.
The center tap 865 is implemented as illustrated in
Therefore, an object of the disclosure is to provide a network device for interfacing network communication between equipment and a cable, and for filtering common-mode noise without changing winding inductances.
According to the disclosure, the network device includes an equipment port configured to be electrically connected to the equipment, a cable port configured to be electrically connected to the cable, and a signal transmission unit.
The signal transmission unit includes a primary channel electrically connected to the equipment port for transmission of a signal, a secondary channel coupled to the primary channel and electrically connected to the cable port for transmission of the signal, an isolation transformer electrically connected between the primary channel and the secondary channel for coupling the signal from the primary channel to the secondary channel, and a noise filtering module electrically connected to one of the primary channel and the secondary channel for grounding common-mode noise.
Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiments with reference to the accompanying drawings, of which:
Before the disclosure is described in greater detail, it should be noted that where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics. In addition, when two elements are described as being “coupled in series,” “connected in series” or the like, it is merely intended to portray a serial connection between the two elements without necessarily implying that the currents flowing through the two elements are identical to each other and without limiting whether or not an additional element is coupled to a common node between the two elements. Essentially, “a series connection of elements,” “a series coupling of elements” or the like as used throughout this disclosure should be interpreted as being such when looking at those elements alone.
Referring to
The network device includes an equipment port 1 configured to be electrically connected to the equipment, a cable port 2 configured to be electrically connected to the cable, and two signal transmission units 3 and 3′ each of which includes a primary channel 31 electrically connected to the equipment port 1 for transmission of a signal, a secondary channel 32 electrically connected to the cable port 2 for transmission of the signal, an isolation transformer 33 electrically connected between the primary channel 31 and the secondary channel 32 for coupling the signal from the primary channel 31 to the secondary channel 32, and two noise filtering modules 34 and 34′ electrically connected to a respective one of the primary channel 31 and the secondary channel 32 for grounding the common-mode noise.
The isolation transformer 33 includes a primary winding 331 electrically connected to the primary channel 31, and a secondary winding 332 electrically connected to the secondary channel 32. The primary channel 31 has a forward path 311 and a return path 312 each of which is electrically connected between the equipment port 1 and the isolation transformer 33, and electrically connected to a respective one of two ends of the primary winding 331 so that the forward path 311, the primary winding 331 and the return path 312 are connected in series. The secondary channel 32 has a forward path 321 and a return path 322 each of which is electrically connected between the cable port 2 and the isolation transformer 33, and electrically connected to a respective one of two ends of the secondary winding 332 so that the forward path 321, the secondary winding 332, and the return path 322 are connected in series. By coupled magnetic flux between the primary winding 331 and the secondary winding 332, a network signal is able to be coupled from the primary channel 31 to the secondary channel 32. Moreover, since the primary winding 331 and the secondary winding 332 are isolated from each other, the equipment and the cable may be protected from high voltage surges resulting from lightning strikes.
In this embodiment, the noise filtering module 34 is electrically connected between the forward path 311 and the return path 312 of the primary channel 31, and the noise filtering module 34′ is electrically connected between the forward path 321 and the return path 322 of the secondary channel 32. Because implementation of the noise filtering module 34 is similar to that of the noise filtering module 34′, only details of the noise filtering module 34 will be described.
The noise filtering module 34 includes two first bypass capacitors 341 each of which is electrically connected to a respective one of the forward path 311 and the return path 312, and a second bypass capacitor 344 electrically connected between each of the first bypass capacitors 341 and ground. Specifically, each of the first bypass capacitors 341 has a first end 345 electrically connected to a respective one of the forward path 311 and the return path 312, and a second end 346 electrically connected to one end of the second bypass capacitor 344 opposite to the ground.
The second bypass capacitor 344 is a high voltage isolation capacitor, which is capable of isolating the network device from the ground when lightning strikes occur, so that the first bypass capacitors 341 are prevented from influence of high voltage surges resulting from lightning strikes.
Since frequency of the network signal is lower than that of the common-mode noise, impedance of the first bypass capacitors 341 of the noise filtering module 34 is relatively high for the network signal, but relatively low for the common-mode noise. Similar situation applies to the noise filtering module 34′ as well. Consequently, the network signal would not flow through the noise filtering modules 34 and 34′ but is instead coupled by the isolation transformer 33 as shown in
Comparatively, since the first bypass capacitors 341 of the noise filtering modules 34 and 34′ serve as short circuits for the common-mode noise due to the relatively high frequency thereof, the common-mode noise would not flow through the isolation transformer 33 but instead is grounded by the noise filtering modules 34 and 34′ as shown in
Each of the first bypass capacitors 341 is designed to block the network signal but to allow passage of the common-mode noise to the ground. For example, given that the frequency of the network signal is 100 MHz, capacitance of each of the first bypass capacitors 341 may be designed to be 5 pF to block the network signal but to allow passage of the common-mode noise, which is of relatively higher frequency compared with the network signal, to the ground.
Because the noise filtering module 34 is connected between the forward path 311 and the return path 312 of the primary channel 31, and the noise filtering module 34′ is connected between the forward path 321 and the return path 322 of the secondary channel 32, the winding turns of the primary winding 331 and the secondary winding 332 would not be affected. That is to say, winding inductances of the isolation transformer 33 is not changed, and thereby errors would not be introduced while the primary winding 331 and the secondary winding 332 are inductively coupled.
In practice, the signal transmission unit 3 is a transmitter circuit, and the signal transmission unit 3′ is a receiver circuit. The transmission unit 3 as a transmitter circuit is able to transmit the network signal from the equipment to the cable. The transmission unit 3′ as a receiver circuit is able to receive the network signal from the cable and to transmit the network signal to the equipment. Therefore, a signal loop is formed.
It should be noted that in this embodiment, a total number of the signal transmission units 3 and 3′ is two, but the total number may be greater than two in other embodiments. Alternatively, the network device may include only one signal transmission unit 3 of the disclosure and a conventional signal transmission unit. In addition, a total number of the noise filtering modules 34 and 34′ in each signal transmission unit is two in this embodiment, but inclusion of only one noise filtering module is also feasible in other embodiments. Moreover, implementation of the noise filtering modules 34 and 34′ is not limited to this embodiment and may be combinations of other electronic components, such as combinations of inductors, diodes, or transistors.
By the design of the isolation transformer 33 in combination with the noise filtering modules 34 and 34′, the common-mode noise could be reduced by the noise filtering modules 34 and 34′ without affecting the winding turns of the primary winding 331 and the secondary winding 332, so that the errors of inductive coupling would be alleviated and the quality of the network signal may be improved. In addition, the design of the second bypass capacitor 344 protects the first bypass capacitors 341 from influence of lightning strikes.
A second embodiment of the network device of this disclosure is illustrated in
Because implementation of the common-mode choke module 35′ is similar to that of the common-mode choke module 35, only details of the common-mode choke module 35 will be described for the sake of brevity. The common-mode choke module 35 includes a first winding 351 electrically connected in series with the forward path 311, and a second winding 352 electrically connected in series with the return path 312.
Since magnetic flux caused by common-mode current in the primary winding 351 and magnetic flux caused by common-mode current in the secondary winding 352 are combined, a high impedance is presented by the common-mode choke, so that the common-mode noise is suppressed. Therefore, the design of the common-mode choke modules 35 and 35′ in cooperation with the noise filtering modules 34 and 34′ is capable of improving the quality of the network signal by reducing the common-mode noises of various frequencies.
It is noted that a total number of the common-mode choke modules 35 and 35′ in each of the signal transmission units 3 and 3′ is two in this embodiment. However, the total number may be one in other embodiments. Implementation of the common-mode choke is not limited to the embodiment disclosed herein.
In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects.
While the disclosure has been described in connection with what are considered the exemplary embodiments, it is understood that this disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 105108661 | Mar 2016 | TW | national |
