SE545950C2

SE545950C2 - A signal transmission device

Info

Publication number: SE545950C2
Application number: SE2250858A
Authority: SE
Inventors: Anders Hansson
Original assignee: Anders Hansson
Priority date: 2022-07-07
Filing date: 2022-07-07
Publication date: 2024-03-26
Also published as: SE2250858A1

Abstract

A signal transmission device (100b) comprising a first signal conductor (102b), for transferring a first signal wherein the voltage of the first signal continuously changes over time; a dielectric layer (104a, 104b) embedding the first signal conductor (102b); a first guard conductor (106b) embedded in the dielectric layer, said first guard conductor (106b) being arranged to transfer a first guard signal corresponding to the first signal and said first guard conductor (106b) extending along the extension of the first signal conductor (102b) a first shielding layer (108b), at least partly enclosing the first signal conductor (102b), and protecting the first guard signal and the first signal from radiated electromagnetic fields. The dielectric layer comprises a first dielectric layer (104a) interposed between the first signal conductor (102b) and the first guard conductor (106b), and a second dielectric layer (104b) separating the first shielding layer (108b) and the first signal conductor (102b).

Description

A signal transmission device Technical field The present disclosure relates to a signal transmission device. More specifically, the disclosure relates to a signal transmission device as defined in the introductory parts ofthe independent claims.

Background art A problem with the solutions of the prior art is that signal transmission devices have performance losses, i.e., dielectric losses, because ofthe polarization which occur between a signal conductor and an necessary shielding layer e.g., a conductive layer, around the conductor, which act as protecting for electromagnetic shielding from the outside of the signal transmission device. The above stated problem is especially noticeable in the field of high demanding transmission of for example sound signals, e.g., low level analog signal.

Known solutions to the above stated problem is to use material with low dielectric losses, both when designing electric cables as well as in printed circuit boards, PCB. However, the choice of choosing may be balance between performance, cost and environmental effects.

There is thus a need for improved the performance ofthe signal transmission devices.

Summary lt is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem.

According to a first aspect there is provided a signal transmission device comprising a first signal conductor, for transferring a first signal wherein the voltage of the first signal continuously changes over time. The signal transmission device also comprising a dielectric layer embedding the first signal conductor; a first guard conductor embedded in the dielectric layer. The first guard conductor being arranged to transfer a first guard signal corresponding to the first signal and the first guard conductor extending along the extension of the first signal conductor. The signal transmission device comprising further comprising a first shielding layerwhich least partly enclosing at least the first signal conductor, and protecting the first guard signal transferred by the first guard conductor and the first signal transferred by the first signal conductor from radiated electromagnetic fields. The dielectric layer comprises a first dielectric layer interposed between the first signal conductor and the first guard conductor, and a second dielectric layer. The second dielectric layer is separating the first shielding layer and the first signal conductor.

This has the advantage that the polarization which occur in a dielectric layer in contact with the signal conductor is substantially reduced. This leads to that the dielectric losses in the first dielectric layer is reduced and the performance of the transmission signal device is improved. ln other words, the guarding signal transferred in the first guard conductor reduces the dielectric losses by having a guard signal corresponding to the first signal transferred in the first signal conductor.

Put differently, the effect of connecting each signal conductor transferring a first signal to a guard conductor transferring a corresponding guard signal is that said guard signal is configured to reduce the dielectric losses in the dielectric layer encapsulating the first signal conductor.

According to some embodiments, wherein the second dielectric layer is separating the first shielding layer and the first signal conductor, and wherein the second dielectric layer is gas housed by the first shielding layer.

The advantage of having gas as the second dielectric layer is that a guard signal is not needed, since gas, e.g., air, does not give rise for the polarization leading to dielectric losses. ln one example, this may be used when designing a multi-layer PCB. The integrated conductive layers may comprise a dielectric layer different than gas, and therefore need a corresponding guard conductor transferring a corresponding guard signal.

According to some embodiments, wherein the second dielectric layer is separating the first shielding layer and the first signal conductor, said signal transmission device further comprising a second guard conductor which is located betweenšrasšde the second dielectric layer.ln some scenarios, for example in a multi-layer PCB, or in an electric cable, gas is not feasible and/or suitable as dielectric material in the dielectric layer. ln such scenarios, the dielectric layer may comprise a solid material e.g. polymer, for example polytetrafluoroethylene, PTFE. Thereby electrical insulation is provided. As disclosed above, dielectric layer will experience dielectric losses. By having a guarding signal transferred by a guard conductor, at least partly enclosing the dielectric layer which encloses signal conductor, said dielectric losses will be reduced. ln one example the guard conductor is placed on a nearby layer, in another example the at least guard conductors are placed on different, preferably opposite, sides of the signal conductor.

According to some embodiments, the signal transmission device comprising a third dielectric layer located between the first shielding layer and the second guard conductor.

According to some embodiments, the dielectric layers may be any dielectric material since the guarding signal transferred in a guarding conductor is reducing the polarization in said dielectric layer and thereby the dielectric losses. The guarding signal thereby reduce the challenge of choosing an insulation/dielectric material with low dielectric losses with respect to choosing an insulation/dielectric layer with low dielectric losses with respect to cost and/or environmental considerations. The guard conductor and its corresponding guarding signal enable any dielectric material to be utilized.

According to some embodiments, the signal transmission device comprising a second signal conductor for transferring a second signal, the voltage of the second signal continuously changing over time, wherein the first signal conductor and the second signal conductor extending parallel to each other along the extension ofthe first guard conductor. ln some scenarios it may be advantaged to have at least a first and a second signal conductor, i.e., at least two signal conductors. When the first signals transferred in the first and second signal conductors follow each other, e.g., extends parallel to each other, the corresponding guarding signal transferred in a guard conductor also follows said first and second signal conductor, no electric field interfere with said signal conductors. This has the effect of reducing the dielectric losses in the dielectric layer enclosing said signal conductor.

According to some embodiments, the signal transmission device comprises a second signal conductor for transferring a second signal wherein the voltage of the second signal 4 continuously changes over time, and a second guard conductor extending along the extension of the second signal conductor.

According to some embodiments, the first signal transferred by the first signal conductor and the second signal transferred by the second signal conductor is the same signal.

According to some embodiments, the first signal conductor and the second signal conductor are enclosed by the first guard conductor. For example, if the first signal conductor and the second signal conductor is transferring the same signal, they may be encapsulated by one common guard conductor.

According to some embodiments, the first signal and the second signal transferred by the first signal conductor and the second signal conductor respectively, are the different signals.

According to some embodiments, the first signal conductor and the second signal conductor are enclosed by different guard conductors. For example, if the first signal conductor and the second signal conductor is transferring different signals, they should be encapsulated by different guard conductors, transferring different guard signals corresponding to each ofthe first signal and second signal.

According to some embodiments, each signal conductor and its corresponding guard conductor are configured to be connected to a common signal source. ln one example the connection is utilized by one or more capacitor, resistor and/or via. The one or more capacitor, resistor and/or via may be arrange in combination with any of the above mentioned embodiments.

According to some embodiments, each guard conductor is open at its distal end in the direction ofthe of the signal path.

According to some embodiments, the signal transmission device is a printed circuit board, PCB.

According to some embodiments, the signal transmission device transmits sound signals.

According to a second aspect there is provided a signal transmission system comprising the signal transmission device according to the first aspect of the invention, and at least a first signal source for transmitting a first signal to the first signal conductor and the first guard conductor.

According to some embodiments the signal transmission system further comprises at least a second signal source for transmitting a second signal to the second signal conductor and the second guard conductor.

According to some embodiments the signal transmission system transmits sound signals.

The present disclosure will become apparent from the detailed description given below. The detailed description and specific examples disclose preferred embodiments of the disclosure by way of illustration only. Those skilled in the art understand from guidance in the detailed description that changes and modifications may be made within the scope of the disclosure.

Hence, it is to be understood that the herein disclosed disclosure is not limited to the particular component parts of the device described or steps of the methods described since such device and method may vary. lt is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. lt should be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more ofthe elements unless the context explicitly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps.

Terminology The term Printed Circuit Board, PCB, is to be interpreted as a laminated sandwich structure of conductive and insulating layers. A PCB may be single-sided, one conductive layer, double-sided, two conductive layers, on both sides of one dielectric layer, or multi-layer, i.e., outer and inner layers of conducive, alternating with layers of dielectric layer.

Brief descriptions of the drawings The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

Figure la shows a cross-sectional view of an exemplary non-clamed embodiments of the signal transmission device.

Figure lb shows a side view of an exemplary signal transmission device according to the invention.

Figure 2 shows a side view of another example of a signal transmission device according to the invention.

Figure 3 shows side view of yet another example of a signal transmission device according to the invention.

Figure 4 shows a cross-sectional view of another non-clamed embodiment of the signal transmission device.

Figure 5 shows a cross-sectional view of still another non-claimed embodiment of the signal transmission device.

Figure 6 shows a perspective view of an exemplary non-claimed embodiment of the signal transmission device in the form of a shielded cable.

The present disclosure will now be described with reference to the accompanying drawings, in which preferred example embodiments of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed embodiments. The disclosed embodiments are provided to fully convey the scope of the disclosure to the skilled person.

Figure 1a-1b shows a signal transmission device 100a; 100b comprising a first signal conductor 102a; 102b for transferring a first signal. The voltage of the first signal continuously changes over time. The signal transmission device 100a;100b also comprising a dielectric layercomprising a first dielectric layer l04a and a second dielectric layer l04b. The dielectric layer l04a, l04b are embedding the first signal conductor l02a; l02b and a first guard conductor l06a; l06b also embedded in the dielectric layer l04a, l04b. The first guard conductor l06a; l06b is arranged to transfer a first guard signal corresponding to the first signal. This means that the voltage of the first guard signal is the same as the voltage of the first signal. The first guard conductor l06a; l06b extends along the extension of the first signal conductor l02a; l02b. Shown is also a first shielding layer l08a; l08b which is at least partly enclosing at least the first signal conductor l02a; l02b. The first shielding layer l08a; l08b protects the first guard signal transferred by the first guard conductor l06a; l06b and the first signal transferred by the first signal conductor l02a; l02b from radiated electromagnetic fields. The dielectric layer l04a, l04b comprises a first dielectric layer l04a interposed between the first signal conductor l02a; l02b and the first guard conductor l06a; l06b and a second dielectric layer l04b.|n the example illustrated in figure la, the signal transmission device is a cable. The second dielectric layer l04b is separating the first shielding layer l08a and the first guard conductor l06a. ln the example illustrated in figure lb, the signal transmission device lOOb is a Printed Circuit Board, PCB. ln the PCB, the second dielectric layer l04b is separating the first shielding layer l08b, and the first signal conductor l02b and the second dielectric layer l04b comprises gas, e.g. air, (not illustrated) housed by the first shielding layer l08b.The embodiment disclosed in Fig. lb, can also comprise a second guard conductor llO which -is--åeeateal--bet-wfeen ' is located inside the second dielectric layer l04b. ln the figure, the second dielectric layer is thereby located on either side ofthe second guard conductor llO (dotted line). For ease of reading, the upper part of the second dielectric layer l04b is denoted a third dielectric layer l04c.

Fig.2 shows a signal transmission device 200 being a PCB. The signal transmission device 200 differs from the signal transmission device lOOb illustrated in Fig. lb in that the signal transmission device 200 is having a solid second dielectric layer 204b, i.e., not gas e.g., air, and a second guard conductor 2l0 (dotted line). The second dielectric layer 204b is separating the first shielding layer 208 and the first signal conductor 202. Since the second dielectric layer 204b is not gas, the second dielectric layer 204b experience dielectric losses. 8 The signal transmission device 200 therefore comprises the first guard conductor 206 (dashed line) and the second guard conductor 210 (dotted line).

The second guard conductor 210 is located betwaenmthe second dielectric layer 204b and a third dielectric layer 204c. The first guard conductor 206 is located between the first dielectric layer 204a and a fourth dielectric layer 204d. The third dielectric layer 204c is located between the first shielding layer 208 and the first guard conductor 210. Fig.2 also show that the fourth dielectric layer 204d located on the opposite side of the first guard conductor 206 in relation to the first dielectric layer 204a. The fourth dielectric layer 204d aim to insulate the first guard conductor 206. ln one example, the dielectric layers may be ofthe same dielectric material. ln another example, at least two of the dielectric layers may be of different dielectric materials.

As stated above, the signal transmission device 200 as exemplified in fig 2 is a PCB, i.e., a laminated sandwich structure of conductive and insulating layers. A PCB may be single-sided, one conductive layer, double-sided, two conductive layers, on both sides of one dielectric layer, or multi-layer, i.e., outer and inner layers of conducive, alternating with layers of dielectric layer. ln the example illustrated in Fig. 2, the PCB is a multi-layer PCB having a first signal conductor 202 and two guard conductors 206, Fig. 3 shows a signal transmission device 300 being a PCB. The signal transmission device 300 differs from the signal transmission device 200 illustrated in Fig. 2 in that the signal transmission device 300 comprises a second signal conductor 314 for transferring a second signal wherein the voltage of the second signal continuously changes over time. The first signal conductor 302 and the second signal conductor 314 extend parallel to each other along the extension ofthe first guard conductors 306. The second guard conductors 310 extend along the extension ofthe second signal conductor 314. Shown in the figure is that the first signal conductor 302 is located between two first guard conductors 306 (dotted lines), and that the second signal conductor 314 is located between two second guard conductors 310 (dashed lines). ln other words, the first signal conductor 306 is sandwiched between the two first guard conductors 306, the second signal conductor 314 is sandwiched between the two second guard conductors 310, 9 Thus, fig. 3 shows a multi-layer PCB comprising a first signal conductor 202, second signal conductor 314. Each of said signal conductors 306, 310 is having two corresponding guard conductors 306, 310 respectively.

The signal transmission device 300 enables that when the first signal conductor and the second signal conductor are transferring different signals, said signal conductors are encapsulated by different guard conductors which are transferring different guard signals. The first guard signal and the second guard signal corresponds to the first signal and second signal respectively. ln other words, the first signal is guarded by a matching first guard signal and the second signal is guarded by a matching second guard signal. This means that the voltage of the each guard signal is the same as the voltage of the corresponding signal. ln a further example ofthe signal transmission device 300 (not shown) there may be more than one first signal conductor and/or more than one second signal conductor. lf the first signal conductor and the second signal conductor is transferring the same signal, they may be encapsulated by one common guard conductor.

Fig. 4 shows a signal transmission device 400 being a cable. The signal transmission device 400 differs from the signal transmission device 100 illustrated in Fig. 1a in that the signal transmission device 400 further comprises a plurality of second signal conductors 414 for transferring a plurality of second signals, and a third guard conductor 411. ln the illustrated example, the third guard conductor 411 is formed along a central axis of the cable. The first guard conductor is in the illustrated example arranged coaxially with the third guard conductor 411. The first guard conductor 406 forms in the illustrated example a hollow tube. The third guard conductor 411 extends within the thus formed hollow tube. The inner surface of the first guard conductor 406 and the exterior surface form a space occupied by the first dielectric layer 104a. Further, a plurality of signal conductors 414 (five in the shown example) extend in parallel with the first guard conductor and third guard conductor. However, this is only an example, the third guard conductor 411 may enclose one or a plurality of signal conductors. ln case the third guard conductor 411 may enclose for example two or three signal conductors, said signal conductors is preferably distributed evenly around the third guard conductor. The third guard conductors 411 are located inside the first dielectric layer 104a. Thus, in accordance with this example the first signal conductor 402 and the second signal conductors 414 is transferring the same signal, i.e., the first signal and the second signals transferred by the first signal conductor 402 and the second signal conductors 414 is the same signal. This means that both the first signal conductor 402 and the second signal conductors 414 are connected to the same signal source. ln this case, the first signal conductor 402 and the second signal conductor 414 may be enclosed by the first guard conductor Fig. 5 shows an exemplary signal transmission device 500 being a cable. The signal transmission device 500 differs from the signal transmission device 100 illustrated in Fig. 1a in that the signal transmission device 500 further comprises a second signal conductor 514 for transferring a second signal. The first signal and the second signal transferred by the first signal conductor 502 and the second signal conductor 514 respectively, are different signals. This means that both the first signal conductor 502 and the second signal conductor 514 are connected to different signal sources. ln this case, the first signal conductor 502 and the second signal conductor 514 both are enclosed by different guard conductors, e.g., the first guard conductor 506 and the second guard conductor 510. ln the figure another signal conductor 516 is shown just for the purpose of illustrating that some signal conductor may not be guarded by a guard connector.

Fig. 6 shows an example of a signal transmission device 600 being a cable comprising at least one signal conductor 602 (only one is shown in the figure), a first dielectric layer 604a, and a second dielectric layer 604b. Each signal conductor 602 and its corresponding guard conductor 606 are configured to be connected to a common signal source. The connection 620 is utilized by one or more capacitor and/or resistor per signal.

Fig. 6 further show that each guard conductor 606 is open at its distal end in the direction ofthe ofthe signal path. The signal transmission device is a shielded cable, wherein the second dielectric layer 604b is interposed between the first guard conductor 606 and the first shielding layer The first guard conductor 606 and/or at least one second guard conductor (not shown) is shaped as an open, tube circumventing the associated signal conductor. ln some examples (illustrated in Fig.1b, 2 and 3) the signal transmission device 100b; 200; 300 is a printed circuit board, PCB. 11 The person skilled in the art realizes that the present disclosure is not limited to the examples described above. The person skilled in the art further realizes that modifications and variations are possible within the scope ofthe appended claims.

Claims

Claims A signal transmission device (100b; 200; 300) comprising a first signal conductor (102b; 202; 302) for transferring a first signal, wherein the voltage of the first signal continuously changes over time; a dielectric layer (104; 104a;_; 104b) embedding the first signal conductor (102b; 202; 302); a first guard conductor (106b; 206; 306) embedded in the dielectric layer, said first guard conductor (106b; 206; 306) being arranged to transfer a first guard signal corresponding to the first signal and said first guard conductor (106b; 206; 306) extending along the extension of the first signal conductor (102b; 202; 302); a first shielding layer (108b;_; 208; 308) at least partly enclosing at least the first signal conductor (102b; 202; 302), and protecting the first guard signal transferred by the first guard conductor (106b; 206; 306) and the first signal transferred by the first signal conductor (102b; 202; 302) from radiated electromagnetic fields, wherein the dielectric layer comprises a first dielectric layer (104a; 204a; 304a) interposed between the first signal conductor (102b; 202; 302) and the first guard conductor (106b; 206; 306), and a second dielectric layer (104b; 204b; 304b), wherein the second dielectric layer (104b; 204b; 304b) is separating the first shielding layer (108b;,~ 2083,- 308) and the first signal conductor (102b; 202; 302) wherein the signal transmission device is a printed circuit board, PCB, wherein the PCB is a laminated sandwich structure of conductive and insulating layers. The signal transmission device (100b; 200; 300) according to claim 1, wherein the second dielectric layer (lﬁflb- 204b; šüfib-íêﬁfša) is separating the first shielding layer (108b, 208, )zo 2 308) and the first signal conductor (102b; 202; 302) and wherein the second dielectric layer is gas housed by the first shielding layer (108a; 108b¿; 208,1; 308;). The signal transmission device (100b; 200; 300) according to claim 1 wherein the second dielectric layer (104b¿; 204b¿; 304b) is separating the first shielding layer (108a; 108b¿; 208,1; 308,) and the first signal conductor (102b; 202; 302), said signal transmission device further comprising a second guard conductor (110) which is located inside the second dielectric layer (104b¿; 204b;_; 304b). The signal transmission device (100b; 200; 300) according to claim 3, further comprising a third dielectric layer (104c, 204c¿; 304c) located between the first shielding layer (108b, 208, 308) and the second guard conductor. 93- The signal transmission device (300) according to any of the claims, further comprising a second signal conductor (314) for transferring a second signal wherein the voltage of the second signal continuously changing over time. The signal transmission device ( 300) according to claim ššå, wherein the first signal conductor (302) and the second signal conductor (314) extending parallel to each other along the extension of the first guard conductor (306). The signal transmission device ( 300) according to any of the claims â--å- ål, further comprising a second guard conductor (310) extending along the extension of the second signal conductor (314). The signal transmission device (100b; 200; 300) according to claim ê5_-82, wherein the first signal transferred by the first signal conductor (102b; 202; 302;) and the second signal transferred by the second signal conductor (314) is the same signal. . The signal transmission device (300) according to claim åå-åj, wherein the first signal and the second signal transferred by the first signal conductor (302) and the second signal conductor (314) respectively, are the different signals.The signal transmission device (300) according to claim aëfàg, wherein the first signal conductor (302) and the second signal conductor (314) are enclosed by different gua rd conductors. åfäë. The signal transmission device (100b; 200; 300) according to any ofthe preceding 5 claims, wherein each signal conductor (102b; 202; 302) and its corresponding guard conductor are configured to be connected to a common signal source. The signal transmission device (100a; 100b; 200; 300; 400; 500) according to any of the preceding claims, wherein the each guard conductor (106a; 106b; 206; 306;110;111) is open at its distal end in the direction of the of the signal path.