WO2021118564A1

WO2021118564A1 - Shunt choke circuits

Info

Publication number: WO2021118564A1
Application number: PCT/US2019/065871
Authority: WO
Inventors: Dan E. Rothenbuhler
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2021-06-17

Abstract

In some examples, a circuit can include a common mode choke, a load connected to the common mode choke, and a shunt choke connected between the common mode choke and the load, the shunt choke including a first winding having a first set of terminals and a second winding having a second set of terminals, where the second set of terminals are connected to the circuit in an inverted manner relative to the first set of terminals such that the shunt choke operates in a differential mode.

Description

SHUNT CHOKE CIRCUITS

Background

[0001] Differential signaling can be used for cabling between electronic equipment. A differential circuit can utilize two signals to transmit information from one point to another. Differential signaling can allow for faster transmission times of information between electronic equipment relative to non-differential signaling techniques.

Brief Description of the Drawings

[0002] Figure 1 is an example of a shunt choke circuit consistent with the disclosure.

[0003] Figure 2 is an example of a shunt choke circuit consistent with the disclosure.

[0004] Figure 3 is an example of a shunt choke circuit and a source consistent with the disclosure.

[0005] Figure 4 is an example of a shunt choke circuit and a source consistent with the disclosure.

Detailed Description

[0006] Certain electronic devices may utilize differential signaling to transmit information. Differential signaling can utilize two conductive pathways to transmit information via two complementary signals from one point to another. As used herein, the term “differential signaling” refers to a technique to transmit the same electrical signal as a differential pair of signals, each in its own conductor.

[0007] Certain electronic devices can utilize differential signaling to transmit information faster than non-differential signaling techniques, as well as to minimize electromagnetic interference with other equipment. For example, computing devices, other such electronic devices, and/or electronic device components may utilize differential signaling techniques for faster transmission of information and to shield from electromagnetic interference with other equipment.

[0008] Differential signaling can involve differential mode signals and/or common mode signals. As used herein, the term “differential signals” refer to signals that flow in opposite directions in a pair of lines. Additionally, as used herein, the term “common mode signal" refers to signals that flow in a same direction in a pair of lines.

[0009] Differential signaling can, in some instances, experience common mode noise. As a result, devices utilizing differential signaling can experience radio- frequency interference and/or electromagnetic interference, which in some instances can cause the devices to function improperly.

[0010] Suppression of common mode noise can be difficult. A single common mode choke (CMC) can provide some degree of common mode signal attenuation but can be limited in attenuation capacity. Additionally, ferrite cores on input/output (I/O) cables for electronic devices utilizing differential signaling can provide some degree of common mode signal attenuation, but such cores can be expensive. Further, the I/O cables have to include special molding in order for the ferrite cores to be utilized. As a result, common mode noise on differential signals can be difficult and/or expensive to suppress, which can make regulatory approval of such products difficult.

[0011] Shunt choke circuits, according to the disclosure, can allow for a circuit to include a CMC as well as a shunt choke. The shunt choke can operate in a differential mode in order to provide attenuation of common mode noise of differential signals on the circuit. Accordingly, shunt choke circuits can provide a low-cost solution to suppression of common mode noise.

[0012] Figure 1 is an example of a shunt choke circuit 100 consistent with the disclosure. The shunt choke circuit 100 can include a common mode choke (CMC) 102, a load 104, a shunt choke 106, and ground 124.

[0013] As illustrated in Figure 1, the shunt choke circuit 100 can include a

CMC 102. As used herein, the term “common mode choke (CMC)" refers to a magnetics device to block common mode current in a circuit while allowing differential mode current in a circuit within an effective frequency range of the device. For example, the CMC 102 can block common mode current in the shunt choke circuit 100 while allowing differential mode current in the shunt choke circuit 100. In some examples, the CMC 102 can include two coils of wire wound on a magnetic core, although examples of the disclosure are not so limited.

[0014] A load 104 can be connected to the CMC 102. As used herein, the term “load” refers to a component or portion of a circuit that consumes electric power. For example, the load 104 can be a component of the shunt choke circuit 100. The load 104 can consume electric power generated by a power source, as is further described in connection with Figure 3.

[0015] As illustrated in Figure 1, the load 104 can be connected to the CMC 102 in series. For example, the load 104 can be connected to the CMC 102 along a conductive path.

[0016] The shunt choke circuit 100 can include a shunt choke 106. As used herein, the term “shunt” refers to a device connected to two portions of a circuit through which current may be diverted. The shunt choke 106 can be connected to the shunt choke circuit 100 between the CMC 102 and the load 104. For example, the shunt choke 106 can be a device through which current may be diverted in the shunt choke circuit 100, as is further described herein.

[0017] The shunt choke 106 can be a power magnetics device to block differential mode current in a circuit while allowing common mode current in the circuit. Similar to the CMC 102, the shunt choke 106 can include two coils of wire (e.g., windings) wound on a magnetic core, as is further described herein.

[0018] The shunt choke 106 can include a first winding 108. As used herein, the term “winding” refers to a wire wound on a magnetic core. The first winding 108 can be, for example, a wire wound on a magnetic core of the shunt choke 106.

[0019] The first winding 108 can include a first set of terminals 110. As used herein, the term “terminal” refers to a point at which a conductor can be connected to an external circuit. For example, the first set of terminals 110 can be points at which the first winding 108 of the shunt choke 106 can connect to the shunt choke circuit 100.

[0020] The shunt choke 106 can include a second winding 116. The second winding 116 can be, for example, a wire wound on the same magnetic core of the shunt choke 106 as the first winding 108.

[0021] The second winding 116 can include a second set of terminals 118.

For example, the second set of terminals 118 can be points at which the second winding 116 of the shunt choke 106 can connect to the shunt choke circuit 100. [0022] In some examples, the shunt choke 106 can be a common mode choke. For example, similar to the CMC 102, the shunt choke 106 can be a common mode choke to block common mode current in a circuit (e.g., shunt choke circuit 100) while allowing differential mode current in the circuit (e.g., shunt choke circuit 100).

[0023] The second set of terminals 118 can be connected to the shunt choke circuit 100 in an inverted manner relative to the first set of terminals 110. For example, the second set of terminals 118 can be connected to the shunt choke circuit 100 such that the shunt choke 106 operates in a differential mode. In other words, the shunt choke 106 can be connected to the shunt choke circuit 100 in a manner such that current flowing through the shunt choke 106 can flow in opposite directions through the first winding 108 and the second winding 116, as is further described in connection with Figures 2 and 3.

[0024] As illustrated in Figure 1, the shunt choke 106 can be connected in parallel between the CMC 102 and the load 104. For example, the shunt choke 106 can be connected to the shunt choke circuit 100 between the CMC 102 and the load 104 such that current flowing through the shunt choke circuit 100 is able to be split between the load 104 and the shunt choke 106.

[0025] Additionally, as illustrated in Figure 1 , the shunt choke 106 can be connected to ground 124. The shunt choke 106 can be connected to ground 124 via a capacitor, as is further described in connection with Figures 2-4.

[0026] Figure 2 is an example of a shunt choke circuit 200 consistent with the disclosure. The shunt choke circuit 200 can include a first CMC 202, a load 204, a second CMC 206, a capacitor 226, and ground 224.

[0027] The shunt choke circuit 200 can include a first CMC 202 and a load 204. The load 204 can be connected to the first CMC 202 in series.

[0028] The shunt choke circuit 200 can include a second CMC 206. The second CMC 206 can be analogous to the shunt choke 106 (e.g., previously described in connection with Figure 1). For example, the second CMC 206 can be a choke to act as a shunt in the shunt choke circuit 200. That is, the second CMC 206 can be a device through which current may be diverted in the shunt choke circuit 200, as is further described herein. The second CMC 206 can be connected between the first CMC 202 and the load 204 in parallel. [0029] The second CMC 206 can include a first winding 208 and a second winding 216. The first winding 208 and the second winding 216 can be, for example, wires wound on a magnetic core of the second CMC 206.

[0030] As previously described in connection with Figure 1 , the first winding 208 can include a first set of terminals. The first set of terminals can include a first terminal 212 and a second terminal 214. As illustrated in Figure 2, the first terminal 212 can be connected to the shunt choke circuit 200 between the first CMC 202 and the load 204. The second terminal 214 can be connected to ground 224 via a capacitor 226, as is further described herein.

[0031] Additionally, as previously described in connection with Figure 1, the second winding 216 can include a second set of terminals. The second set of terminals can include a third terminal 220 and a fourth terminal 222. The terminals 220, 222 of the second winding 216 can be connected to the shunt choke circuit 200 in an inverted manner relative to the first terminal 212 and the second terminal 214. For example, the third terminal 220 can be connected to ground 224, and the fourth terminal 222 can be connected to the shunt choke circuit 200 between the first CMC 202 and the load 204.

[0032] Connecting the third terminal 220 and the fourth terminal 222 of the second winding 216 in such an inverted manner relative to the first terminal 212 and the second terminal 214 of the first winding 208 can cause the second CMC 206 to operate in a differential mode. For example, the second CMC 206 can have current (e.g., signals) that flow in opposite directions through the first winding 208 and the second winding 216 as a result of the inverted connection of the third terminal 220 and the fourth terminal 222 relative to the first terminal 212 and the second terminal 214.

[0033] As a result, while the first CMC 202 operates as a common mode choke in the shunt choke circuit 200, the second CMC 206 operates as a differential mode choke. The first CMC 202 can, therefore, provide a high impedance to a common mode signal generated by a source (e.g., not illustrated in Figure 2) and a low impedance to a differential signal generated by the source. Further, the second CMC 206 can provide a high impedance to the differential signal and a low impedance to the common mode signal to attenuate the differential signal. For example, the common mode signal can be attenuated by 20 decibels (dB) in the shunt choke circuit 200. Accordingly, the shunt choke circuit 200 can be utilized as a common mode filter in certain electronic devices utilizing differential signaling.

[0034] While the common mode signal is described above as being attenuated by 20 dB, examples of the disclosure are not so limited. For example, the shunt choke circuit 200 may include more or fewer components, and the first CMC 202 and/or the second CMC 206 may include different inductance values that may lead to more than 20 dB attenuation of the common mode signal or less than 20 dB of the common mode signal.

[0035] As illustrated in Figure 2, the second terminal 214 and the third terminal 220 can be connected to a capacitor 226. As used herein, the term “capacitor” refers to a device that stores electrical energy. The capacitor 226 can be connected to ground 224. The capacitor 226 can be, for example, a 100 nanoFarad (nF) capacitor.

[0036] Although the capacitor 226 is described above as being a 100 nF capacitor, examples of the disclosure are not so limited. For example, the capacitor 226 can be greater than a 100 nF capacitor or less than a 100 nF capacitor.

[0037] The capacitor 226 can be utilized to prevent a driver circuit (e.g., not illustrated in Figure 2) from being shorted. For instance, in some examples a direct current (DC) bias may have to be utilized by a driver circuit, and the capacitor 226 in such an instance can be utilized to prevent the driver circuit from being shorted. [0038] Although the capacitor 226 is illustrated in Figure 2 as being connected between the second CMC 206 and ground 224, examples of the disclosure are not so limited. For example, the shunt choke circuit as previously illustrated and described in connection with Figure 1 may not include a capacitor. For instance, certain devices (e.g., an ethemet cable) may not have to utilize a DC bias, and the shunt choke (e.g., shunt choke 106) may be connected directly to ground. In some examples, certain devices may include a sustained differential signal, as is further described in connection with Figure 4.

[0039] Although illustrated in Figure 2 as including a single capacitor 226, examples of the disclosure are not so limited. For example, the second terminal 214 and the third terminal 220 can each be connected to a respective capacitor, as is further described in connection with Figure 4. [0040] Figure 3 is an example of a shunt choke circuit 300 and a source 328 consistent with the disclosure. The shunt choke circuit 300 can include a first CMC 302, a load 304, a second CMC 306, a capacitor 326, ground 324, and source 328. [0041] As previously described in connection with Figures 1 and 2, the shunt choke circuit 300 can include a first CMC 302 and a load 304. The load 304 can be connected in series with the first CMC 302. The first CMC 302 can be connected to the source 328.

[0042] As illustrated in Figure 3, the shunt choke circuit 300 can include the source 328. As used herein, the term “source” refers to an origination point of electrical energy. For example, the source 328 can provide energy in electrical form to the load 304 via the shunt choke circuit 300.

[0043] The shunt choke circuit 300 can include a second CMC 306. The second CMC 306 can be connected between the first CMC 302 and the load 304 in parallel. The second CMC 306 can be connected to the positive source line 330 and the negative source line 332, as is further described herein.

[0044] As described above, an electronic device utilizing differential signaling can utilize two conductive pathways to transmit information via two complementary signals from one point to another. Accordingly, the source 328 can be connected to a positive source line 330 and a negative source line 332. As used herein, the term “source line” refers to a conductive pathway. For example, the positive source line 330 and the negative source line 332 can be conductive pathways that can transmit information from the source 328 to the load 304.

[0045] The second CMC 306 can include a first winding 308. The first winding 308 can include a first terminal 312 and a second terminal 314. Additionally, the second CMC 306 can include a second winding 316. The second winding 316 can include a third terminal 320 and a fourth terminal 322.

[0046] The first terminal 312 can be connected to the positive source line 330. For example, the first terminal 312 can be connected between the first CMC 302 and the load 304 to the positive source line 330. The second terminal 314 can be connected to ground 324 via the capacitor 326.

[0047] The fourth terminal 322 can be connected to the negative source line

332. For example, the fourth terminal 322 can be connected between the first CMC 302 and the load 304 to the negative source line 332. The third terminal 320 can be connected to ground 324 via the capacitor 326. [0048] As a result of the connection of the third terminal 320 to ground 324 and the fourth terminal 322 to the negative source line 332, the second CMC 306 can operate in a differential mode. For example, the inverted connections of the third terminal 320 to ground 324 and the fourth terminal 322 to the negative source line 332 relative to the first terminal 312 and the second terminal 314 can cause current to flow through the first winding 308 in an opposite direction to that of current flowing through the second winding 316. Accordingly, the second CMC 306 can be utilized as a common mode filter to attenuate the common mode signal in the shunt choke circuit 300 generated by the source 328.

[0049] Figure 4 is an example of a shunt choke circuit 400 and a source 428 consistent with the disclosure. The shunt choke circuit 400 can include a first CMC 402, a load 404, a second CMC 406, ground 424, and source 428.

[0050] As previously described in connection with Figures 1-3, the shunt choke circuit 400 can include a source 428, a first CMC 402, a load 404, and a second CMC 406. The load 404 can be connected in series with the first CMC 402 and the source 428. The second CMC 406 can be connected in parallel between the first CMC 402 and the load 404.

[0051] The first terminal 412 of the first winding 408 of the second CMC 406 can be connected to the positive source line 430 and the fourth terminal 422 of the second winding 416 of the second CMC 406 can be connected to the negative source line 432.

[0052] As illustrated in Figure 4, the shunt choke circuit 400 can include a first capacitor 434 and a second capacitor 436. The second terminal 414 of the first winding 408 of the second CMC 406 can be connected to the first capacitor 434, and the first capacitor 434 can be connected to ground 424. Additionally, the third terminal 420 of the second winding 416 of the second CMC 406 can be connected to the second capacitor 436, and the second capacitor 436 can be connected to ground 424.

[0053] The first capacitor 436 can be, for example, a 100 nF capacitor. Additionally, the second capacitor 438 can be, for example, a 100 nF capacitor. However, examples of the disclosure are not so limited. For example, the first capacitor 436 can be greater than a 100 nF capacitor or less than a 100 nF capacitor. Additionally, the second capacitor 438 can be greater than a 100 nF capacitor or less than a 100 nF capacitor. Moreover, although the capacitance of the first capacitor 436 and second capacitor 438 are the same capacitance, examples of the disclosure are not so limited. For example, the first capacitor 436 and the second capacitor 438 can include different capacitance values.

[0054] The first capacitor 436 and the second capacitor 438 can be utilized to prevent differential signals from being shorted. For instance, in some examples, certain devices (e.g., universal serial bus (USB) devices) may include a sustained differential signal. The first capacitor 436 and the second capacitor 438 can be utilized to prevent the differential signals from being shorted in an event the second CMC 406 is not able to sustain voltages for an amount of time when the inductive field of the CMC 406 collapses.

[0055] Shunt choke circuits, according to the disclosure, can allow for a circuit utilizing differential signaling to shield against radio-frequency interference and/or electromagnetic interference by utilizing a first common mode choke and a second common mode choke. The second common mode choke can be connected to the circuit such that the second common mode choke operates in a differential mode. Such an operation in differential mode by the second common mode choke can suppress common mode noise without expensive cabling and/or ferrite cores, which can suppress such noise an easy and cost-effective way. Additionally, regulatory approval of products having such differential signaling can become easier.

[0056] In the foregoing detailed description of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration how examples of the disclosure may be practiced. These examples are described in sufficient detail to enable those of ordinary skill in the art to practice the examples of this disclosure, and it is to be understood that other examples may be utilized and that process, electrical, and/or structural changes may be made without departing from the scope of the disclosure. Further, as used herein, “a" can refer to one such thing or more than one such thing.

[0057] The figures herein follow a numbering convention in which the first digit corresponds to the drawing figure number and the remaining digits identify an element or component in the drawing. For example, reference numeral 102 may refer to element 102 in Figure 1 and an analogous element may be identified by reference numeral 202 in Figure 2. Elements shown in the various figures herein can be added, exchanged, and/or eliminated to provide additional examples of the disclosure. In addition, the proportion and the relative scale of the elements provided in the figures are intended to illustrate the examples of the disclosure, and should not be taken in a limiting sense.

[0058] It can be understood that when an element is referred to as being "on," "connected to", “coupled to”, or "coupled with" another element, it can be directly on, connected, or coupled with the other element or intervening elements may be present. In contrast, when an object is “directly coupled to” or “directly coupled with" another element it is understood that are no intervening elements (adhesives, screws, other elements) etc.

[0059] The above specification, examples and data provide a description of the method and applications, and use of the system and method of the disclosure. Since many examples can be made without departing from the spirit and scope of the system and method of the disclosure, this specification merely sets forth some of the many possible example configurations and implementations.

Claims

What is claimed is:

1. A circuit, comprising: a common mode choke; a load connected to the common mode choke; and a shunt choke connected between the common mode choke and the load, the shunt choke including a first winding having a first set of terminals and a second winding having a second set of terminals, wherein the second set of terminals are connected to the circuit in an inverted manner relative to the first set of terminals such that the shunt choke operates in a differential mode.

2. The circuit of claim 1 , wherein the shunt choke is connected to ground.

3. The circuit of claim 1 , wherein the shunt choke is connected in parallel between the common mode choke and the load.

4. The circuit of claim 1 , wherein the shunt choke is a common mode choke.

5. The circuit of claim 1 , wherein: the common mode choke is to provide a high impedance to a common mode signal generated by a source and a low impedance to a differential signal generated by the source; and the shunt choke is to provide a high impedance to the differential signal and a low impedance to the common mode signal to attenuate the differential signal.

6. The circuit of claim 1 , wherein the shunt choke is connected to at least one capacitor, and the at least one capacitor is connected to ground.

7. A circuit, comprising: a first common mode choke (CMC); a load connected to the first CMC; and a second CMC connected between the first CMC and the load and having a first winding and a second winding, wherein: the first winding includes a first terminal and a second terminal connected to the circuit; and the second winding includes a third terminal and a fourth terminal connected to the circuit in an inverted manner relative to the first terminal and the second terminal such that the second CMC operates in a differential mode.

8. The circuit of claim 7, wherein: the first terminal is connected between the first CMC and the load; and the second terminal is connected to ground.

9. The circuit of claim 7, wherein: the third terminal is connected to ground; and the fourth terminal is connected between the first CMC and the load.

10. The circuit of claim 7, wherein the second terminal and the third terminal are connected to a capacitor which is connected to ground.

11. The circuit of claim 7, wherein: the second terminal is connected to a first capacitor; the third terminal is connected to a second capacitor; and the first capacitor and the second capacitor are connected to ground.

12. A differential mode signaling device, comprising: a first common mode choke (CMC) connected to a source; a load connected to the first CMC; and a second CMC connected between the first CMC and the load and having a first winding and a second winding, wherein: the first winding includes a first terminal connected between the first CMC and the load and a second terminal connected to ground; and the second winding includes a third terminal connected to ground and a fourth terminal connected between the first CMC and the load such that the second CMC operates in a differential mode.

13. The differential mode signaling device of claim 12, wherein the first terminal is connected to a positive source line from the source between the first CMC and the load.

14. The differential mode signaling device of claim 12, wherein the fourth terminal is connected to a negative source line from the source between the first CMC and the load.

15. The differential mode signaling device of claim 12, wherein the load is connected to the first CMC in series.