Patent Application
20170194928
1. Field of the Invention
The present invention relates to a network filtering circuit, and more particularly to a network filtering circuit for use with the so-called UPOE (Universal Power Over Ethernet) circuit network.
2. Description of Related Arts
Chinese Patent No. CN204733134U issued on Oct. 28, 2015, discloses a network filtering circuit including a cable side, a physical side, and a plurality of differential pair transmission channels connected therebetween. Each of the transmission channels includes an autotransformer, two first capacitors, and a CMC (Common Mode Choke). Each differential pair transmission channel includes a first transmission line and a second transmission line with the autotransformer connected between the first transmission line and the second transmission line. The two first capacitors is respectively linked with the corresponding first transmission line and second transmission line in series connection. The CMC includes a first coil connected with the first transmission line, and a second coil connected with the second transmission line, wherein the center taps of the first, second and third transmission channels are initially linked together in parallel connection and successively linked with the resistor and the capacitor to reach the grounding node while the autotransformer of the fourth channel is connected to another ground node through another capacitor. With such an arrangement, it is asserted that such a filtering circuit may be used in the printed circuit board complying with POE standard.
Anyhow, in such an arrangement only three transmission channels are equipped with the corresponding resistors and capacitors, and the remaining transmission channel only has the capacitor, thus failing to efficiently implement the current POE circuit, needless to say using in the UPOE circuits
Accordingly, an object of the present invention is to provide network filtering circuit for use with the UPOE standard. The invention includes a cable side for connection with a network cable, a physical side for connection with a mother board, and a plurality of differential pair transmission channels connected between the cable side and the physical side. Each of the transmission channels includes an autotransformer, two first capacitors, and a CMC. Each of the transmission channels includes a first transmission line, a second transmission line with the autotransformer connected therebetween. The two first capacitors are linked with the corresponding first transmission line and second transmission line, respectively. The CMC includes a first coil and a second coil coupled with each other and respectively connected to the corresponding first transmission line and second transmission line in series connection. The autotransformer is equipped with center taps. The filtering circuit further includes a second capacitor, the resistor, the third capacitor wherein the second capacitor is connected with the center taps, the third capacitor is connected to the ground node, the second capacitor and the corresponding center tap are equipped with an external power line therebetween so as to provide at least 60 Watts for those four transmission channels.
Compared with the prior arts, the network filtering circuit has the features including provision of the second capacitors connected to the center taps, the resistors connected with the second capacitors, the third capacitors linked between the resistors and the ground node. The second capacitor and the corresponding center tap are equipped with an external power line so as to have all four transmission channels provided with power, thus meeting the requirement of power provision in the UPOE circuit under a low cost. Notably, combining the autotransformer with the UPOE circuit may achieved the desired return loss and the lower cost.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Reference will now be made in detail to some preferred embodiments of the present invention.
Referring to
Each of the transmission channels 60 includes an autotransformer 20, two first capacitors 30 and a CMC 40. Each transmission channel 60 includes a first transmission wire/line 601 and a second transmission wire/line 602 for transmitting a pair of different signals, and the corresponding autotransformer 20 linked between the first transmission line 601 and the second transmission line 602. The CMC 40 includes a first coil 401 and a second coil 402 coupled with each other wherein the first coil 401 is linked to the first transmission line 601 and the second coil 402 is linked to the second transmission line 602 in series connection.
The autotransformer 20 includes a center tap 202 located between and respectively connected to the first connection end 201 of the first transmission line 601 and the second connection end 203 of the second transmission line 602. A second capacitor 71 and the resistor 72 are linked to the corresponding center tap 202 in series connection wherein the second capacitor 71 is directly connected to the center tap 202. All four resistors 72 are connected together in parallel connection and commonly linked to a same third capacitor 73 which is directly connected to a ground node 80. A power supply line 90 is provided between the center tap 202 and the corresponding second capacitor 71 so as to provide at least 60 Watts loading, thus meeting the UPEO criteria.
The autotransformer 20 is located closer to the cable side 10 while the CMC 40 is closer to the physics side 50. The two first capacitors 30 are located between the CMC 40 and the autotransformer 20.
The value of the resistor 72 is 75 Ω. The value of the second capacitor 71 is 0.022 uF. The value of the third capacitor 73 is 1000 pF. The value of the first capacitor 30 is 0.1 uF.
In brief, the second capacitor 71, the resistor 72 and the third capacitor 73 are linked with one another in series connection wherein the second capacitor 72 is directly connected to the center tap 202, the third capacitor 73 shared by four transmission channels 60 is directly connected to the ground node 80, and the power supply lines 90 respectively connect to the corresponding transmission channels 60 at a position between the corresponding autotransformer 20 and the corresponding second capacitor 71. Each of all four transmission channels 60 has its own second capacitor 71, the resistor 72 and the power supply line 90 while sharing the same third capacitor 73 before reaching the ground node 90. This arrangement allows the UPOE circuit and the autotransformer circuit to be combined together for achieving the desired return loss and the low cost.
It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201511013369.7 | Dec 2015 | CN | national |
