Circuit with counter-rotating circuit path

Abstract

A circuit having a counter-rotating circuit path. A circuit includes two current path circuits, a first current path circuit and a second current path circuit, where current flows in opposite rotational directions in a current flow plane. This will induce an opposing counter-rotating current in each current path circuit if the same differential voltage is applied across the first current path circuit and the second current path circuit. Even if the first voltage and / or the second voltage is changing, this is done. Thus, the reverse flow at least partially cancels electromagnetic interference across the frequency range.

Description

Background Technology

[0001] When a changing current flows through a conductor, the conductor emits a changing electromagnetic field. Sometimes, the frequency and amplitude of the emitted electromagnetic field can cause it to interfere with the normal operation of surrounding circuits. In this case, the emitted changing electromagnetic field can be referred to as electromagnetic interference (EMI).

[0002] One method for controlling EMI is to at least partially surround the conductor with a shield that blocks most of the EMI from escaping out of the shield. Other methods involve adding filters to filter out interfering frequencies. As an example, this filter might be a circuit network including inductors and capacitors—also known as an "LC circuit." Yet another method involves varying the circuit itself so that it does not have varying currents within a frequency range that could potentially interfere with surrounding circuitry.

[0003] The subject matter claimed herein is not limited to embodiments that address any shortcomings or operate only in environments such as those described above. Rather, this background is provided merely to illustrate an exemplary technical field in which some of the embodiments described herein can be practiced. Summary of the Invention

[0004] This overview is provided to present, in a simplified form, the concept choices further described below in the detailed description. This overview is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter.

[0005] The embodiments described herein relate to a circuit comprising two current path circuits—a first current path circuit and a second current path circuit. The first current path circuit has a first voltage supply node and a second voltage supply node. The first current path circuit is structured such that when current flows from the first voltage supply node to the second voltage supply node, the current flowing through the first current path circuit is in a first rotational direction in the current flow plane. Conversely, the second current path circuit has a third voltage supply node and a fourth voltage supply node. The second current path circuit is structured such that when current flows from the third voltage supply node to the fourth voltage supply node, the current flowing through the second current path circuit is in a second rotational direction in the current flow plane, the second rotational direction being opposite to the first rotational direction in the current flow plane.

[0006] Therefore, if the same first voltage is applied to the first and third voltage supply nodes, and the same second voltage is applied to the second and fourth voltage supply nodes, the current will flow in a different direction of rotation in the first current path circuit compared to the second current path circuit, thus attenuating electromagnetic interference. For example, if the current flows clockwise in the first current path circuit, it will flow counterclockwise in the second current path circuit, and vice versa. This is true even if the first and / or second voltages vary. Therefore, the reverse flow at least partially cancels out electromagnetic interference across the frequency range.

[0007] Additional features and advantages will be set forth in the following description and will be apparent in part from the description, or may be learned by practicing the teachings herein. The features and advantages of the invention can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. The features of the invention will become more fully apparent from the following description and the appended claims, or may be learned by practicing the invention as set forth below. Attached Figure Description

[0008] To describe how the aforementioned and other advantages and features can be obtained, a more specific description of the subject matter briefly described above will be presented by referring to specific embodiments illustrated in the accompanying drawings. It is understood that these drawings depict only typical embodiments and should not be considered as limiting the scope; the embodiments will be described and explained with additional specificity and detail using the accompanying drawings, in which: Figure 1 A circuit is illustrated, which is only an example of a circuit consistent with the principles described herein, and the circuit includes two current path circuits having flow paths in opposite directions of rotation in order to at least partially cancel electromagnetic interference. Figure 2 The diagram illustrates the meaning. Figure 1 The example circuit is shown, but it uses a high electron mobility transistor (HEMT) to implement the current path circuit. Figure 3 The diagram includes Figure 2 The integrated circuit of the circuit example, wherein the capacitor is formed on the same integrated circuit as HEMT; Figure 4 The diagram includes Figure 2 An integrated circuit example of a circuit, wherein the capacitor is packaged together with the integrated circuit containing the HEMT; Figure 5 The diagram includes Figure 2The circuit example is an integrated circuit, and wherein the capacitor and the package including the integrated circuit are on the same circuit board, the integrated circuit comprising a HEMT; Figure 6 The diagram illustrates an example circuit with four transistors, each of which can be configured as follows: Figure 2 It is structured as described in HEMT and can be used as part of a buck converter circuit. Figure 7 The diagram illustrates an example circuit with four transistors, each of which can be configured as follows: Figure 2 It is structured as described in HEMT and can be used as part of a bidirectional switch, where the transistor is in a common drain configuration; Figure 8A The diagram illustrates a circuit representing a cascode configuration of an enhancement-mode HEMT with low-voltage transistors to simulate a depletion-mode HEMT. Figure 8B The diagram illustrates a circuit representing a direct drive configuration of an enhancement-mode HEMT with low-voltage transistors to simulate a depletion-mode HEMT; and Figure 9 The illustration shows an embodiment of a buck converter circuit, which is... Figure 6 The circuit is an extension, but the inductor-capacitor network also has an additional set of reverse rotating currents to at least partially cancel out the EMI generated in the inductor-capacitor network. Detailed Implementation

[0009] The embodiments described herein relate to a circuit comprising two current path circuits—a first current path circuit and a second current path circuit. The first current path circuit has a first voltage supply node and a second voltage supply node. The first current path circuit is structured such that when current flows from the first voltage supply node to the second voltage supply node, the current flowing through the first current path circuit is in a first rotational direction in the current flow plane. Conversely, the second current path circuit has a third voltage supply node and a fourth voltage supply node. The second current path circuit is structured such that when current flows from the third voltage supply node to the fourth voltage supply node, the current flowing through the second current path circuit is in a second rotational direction in the current flow plane, the second rotational direction being opposite to the first rotational direction in the current flow plane.

[0010] Therefore, if the same first voltage is applied to the first and third voltage supply nodes, and the same second voltage is applied to the second and fourth voltage supply nodes, the current will flow in a different direction of rotation in the first current path circuit compared to the second current path circuit, thus attenuating electromagnetic interference. For example, if the current flows clockwise in the first current path circuit, it will flow counterclockwise in the second current path circuit, and vice versa. This is true even if the first and / or second voltages vary. Therefore, the reverse flow at least partially cancels out electromagnetic interference across the frequency range.

[0011] Figure 1 Circuit 100 is illustrated, which is only an example of a circuit consistent with the principles described herein. Circuit 100 includes a first current path circuit 101 and a second current path circuit 102. The first current path circuit 101 includes a first voltage supply node 111 and a second voltage supply node 112. The second current path circuit 102 includes a third voltage supply node 113 and a fourth voltage supply node 114.

[0012] The first current path circuit 101 is structured such that when current flows from the first voltage supply node 111 to the second voltage supply node 112, the current flowing through the first current path circuit 101 is in a first rotational direction A in the current flow plane. Referring to coordinate system 150, the current flow plane is in the xy plane. On the other hand, the second current path circuit 102 is structured such that when current flows from the third voltage supply node 113 to the fourth voltage supply node 114, the current flowing through the second current path circuit 102 is in a second rotational direction B in the current flow plane, the second rotational direction B being opposite to the first rotational direction A in the current flow plane.

[0013] Therefore, if the same first voltage (e.g., Figure 1 V1) is applied to the first voltage supply node 111 and the third voltage supply node 113, and if the same second voltage (e.g., Figure 1 If V2 is applied to the second voltage supply node 112 and the fourth voltage supply node 114, the current will flow in the opposite rotational direction in the first current path circuit 101 compared to the second current path circuit 102.

[0014] If the current in the first current path circuit 101 is clockwise, such as... Figure 1 If the rotation direction A is such that this causes an electromagnetic field a, which extends in the negative z direction within the current flow circle (reference coordinate system 150), then the current flow in the second current path circuit 102 is counterclockwise. Figure 1The rotation direction is B. Therefore, this will generate an electromagnetic field b, which will extend into the positive z-direction within the current flow circle. Figure 1 The representation of the electromagnetic field generated by the flow of electric current is simplified. In reality, the electromagnetic field would be quite complex and would change over time. However, the principle in this paper is that the counter-rotating current flow will generate an electromagnetic field that cancels each other out at least partially at each instant.

[0015] If the first current path circuit 101 and the second current path circuit 102 are symmetrical in the x-direction, then the counter-rotating currents will be largely mirror images of each other in amplitude and frequency. Furthermore, in the illustrated embodiment, although not required, the first current path circuit 101 includes a capacitor 121 configured as shown, with one terminal connected to a first voltage supply node 111 and the other terminal connected to a second voltage supply node 112. Additionally, in this embodiment, the second current path circuit 102 includes a capacitor 122 configured as shown, with one terminal connected to a third voltage supply node 113 and the other terminal connected to a fourth voltage supply node 114. This allows for more complete rotational flow, particularly at AC frequencies where the capacitors provide very little impedance. Therefore, capacitors 121 and 122 also provide more complete mutual cancellation of the electromagnetic fields generated by the first current path circuit 101 and the second current path circuit 102.

[0016] The wide frequency range across the differential voltage (V1 minus V2) will be as follows. This is because the first input voltage V1 is shared by voltage supply nodes 111 and 113, while the second input voltage V2 is shared by voltage supply nodes 112 and 114. Therefore, the current flow (and the resulting electromagnetic field) have the same spectrum, but their amplitudes are opposite at any given time. Consequently, the current flow in the first current path circuit 101 and the second current path circuit 102 will generate an electromagnetic field that is partially canceled out by destructive interference across the wide frequency range of the differential voltage.

[0017] Although circuit 100 can be any circuit in which the flow of current is useful for operation, it will be discussed below regarding Figure 6 In one embodiment described in detail, circuit 100 forms part of a buck converter, a boost converter, or any other circuit that includes a high voltage supply and a low voltage supply. Figure 7 A second example is shown, where the circuit forms part of a bidirectional switch. However, Figure 6 and Figure 7 The application is just one example among many that utilize the flow of electric current.

[0018] Figure 2An example circuit 200 is illustrated, which represents only one of a wide variety of embodiments considered to fall within the scope of the broadest principles described herein. Circuit 200 is an integrated circuit formed by epitaxial stacking and includes four high electron mobility transistors, also known as "HEMTs". Specifically, the circuit includes HEMT 201, HEMT 202, HEMT 203, and HEMT 204, each formed from different portions of the same epitaxial stack. Thus, HEMTs 201 through 204 are monolithically formed on the same integrated circuit.

[0019] Each HEMT includes two channel nodes, which, depending on the application, can be either drain or source nodes, as will be discussed further below. Figure 6 and Figure 7 The description is provided by way of example. Specifically, HEMT 201 includes channel nodes 210A and 210B, HEMT 202 includes channel nodes 220A and 220B, HEMT 203 includes channel nodes 230A and 230B, and HEMT 204 includes channel nodes 240A and 240B.

[0020] Conductive components reside above HEMTs 201 to 204 (i.e., in the positive z-direction). Such conductive components are indicated by dashed borders. For example, a first voltage supply node 211 is conductively contacted with a first channel node 210A of HEMT 201, a second voltage supply node 212 is conductively contacted with a second channel node 220B of HEMT 202, a third voltage supply node 213 is conductively contacted with a first channel node 230A of HEMT 203, and a fourth voltage supply node 214 is conductively contacted with a second channel node 240B of HEMT 204. A switch output node 215 is conductively contacted with a second channel node 210B of HEMT 201, a first channel node 220A of HEMT 202, a second channel node 230B of HEMT 203, and a first channel node 240A of HEMT 204.

[0021] Voltage supply nodes 211 to 214 are respectively Figure 1 Examples of voltage supply nodes 111 to 114. HEMT 201 and 202 are at least partially turned on when both HEMT 201 and 202 are... Figure 1An example of the first current path circuit 101. In this case, if the voltage at the first voltage supply node 211 is higher than the voltage at the second voltage supply node 212, current will flow from the first voltage supply node 211 through the first HEMT 201 from its first channel node 210A to its second channel node 210B, through the switch output node 215, through the second HEMT 202 from its first channel node 220A to its second channel node 220B, and to the second voltage supply node 212. This represents a clockwise current flow in the current flow plane (as indicated by arrow 251), in this case, the current flow plane is the xy plane of coordinate system 250, which is perpendicular to the epitaxial growth direction in which the epitaxial stack of HEMTs 201 to 204 is formed. Figure 2 (in the positive z direction).

[0022] Similarly, when both HEMT 203 and 204 are at least partially turned on, HEMT 203 and 204 are Figure 1 An example of the second current path circuit 102. In this case, if the voltage at the third voltage supply node 213 is higher than the voltage at the fourth voltage supply node 214, current will flow from the third voltage supply node 213, through the third HEMT 203 from its first channel node 230A to its second channel node 230B, through the switch output node 215, through the fourth HEMT 204 from its first channel node 240A to its second channel node 240B, and to the fourth voltage supply node 214. This represents a counterclockwise current flow in the current flow plane, as indicated by arrow 252.

[0023] as Figure 1 The circuit is the same as 100. Figure 2 Circuit 200 can be any circuit in which current flow is useful for operation. See below for more information. Figure 6 In one embodiment described, circuit 200 forms part of a buck converter, a boost converter, or any other circuit that includes a high voltage supply and a low voltage supply. Figure 7 A second example is shown, in which circuit 200 forms part of a bidirectional switch. However, Figure 6 and Figure 7 The applications described herein are merely examples of the many uses of current flow. The principles described herein are not limited to what reverse current is used for.

[0024] Capacitors 121 and 122 are not in Figure 2 As shown, because the positions of capacitors 121 and 122 with respect to the current path circuit are not important, and as previously mentioned, the most general principle described herein does not require capacitors 121 and 122 at all. However, Figure 3 The diagram includesFigure 2 The integrated circuit 300 of example 301 of circuit 200. That is, example 301 includes Figure 3 The four HEMTs 201 to 204. In this case, voltage sources 311 to 314 are... Figure 2 Examples of the corresponding voltage supply nodes 211 to 214, and capacitors 321 and 322 are Figure 1 Corresponding examples of capacitors 121 and 122 are provided. Here, capacitors 321 and 322 are also formed on the same integrated circuit 300 using the same epitaxial stack, such as example 301 of circuit 200 including HEMT. As an example, capacitors 321 and 322 may each be formed of two conductive layers planar to the xy plane, and have a dielectric layer between them.

[0025] As an alternative Figure 4 The diagram illustrates package 400, which encapsulates integrated circuit 401. Here, integrated circuit 401 represents... Figure 2 An example of circuit 200, which includes four HEMTs 201 to 204. In this case, voltage sources 411 to 414 are... Figure 2 Examples of the corresponding voltage supply nodes 211 to 214, and capacitors 421 and 422 are Figure 1 Corresponding examples of capacitors 121 and 122. Here, capacitors 421 and 422 are not within the same integrated circuit 401 as HEMT, but within the same package 400.

[0026] As yet another alternative. Figure 5 The diagram illustrates a circuit board 500 in which a package 502 is mounted, wherein the package 502 contains representations of... Figure 2 The example of circuit 200 is integrated circuit 501. In this case, voltage sources 511 to 514 are... Figure 2 Examples of the corresponding voltage supply nodes 211 to 214, and capacitors 521 and 522 are Figure 1 Corresponding examples of capacitors 121 and 122. Here, capacitors 521 and 522 are not in the same integrated circuit 501 as the HEMT, nor are they packaged in the same package 502 as the HEMT, but are on the same circuit board as the HEMT. In one example, the current flow plane is the plane of the circuit board, although that is not required.

[0027] again, Figure 1 Circuit 100 and Figure 2 Circuit 200 can be any circuit in which the flow of current is useful for operation. As an example only, Figure 6The illustration shows an example circuit 600, in which there are four HEMTs 601 to 604, each of which can be configured as follows: Figure 2 The HEMTs 201 through 204 are structured as described. In this case, the drain of each of HEMTs 601 and 603 is connected to the voltage source VIN, and the source of each of HEMTs 602 and 604 is connected to ground GND, which is a voltage lower than VIN. The drain of HEMT 602 is connected to the source of HEMT 601 and the switching output node with voltage VOUT. Similarly, the drain of HEMT 604 is connected to the source of HEMT 603 and the switching output node with voltage VOUT. Therefore, in Figure 6 In this embodiment, HEMTs 601 and 603 will be referred to as high-side HEMT 601 and high-side HEMT 603. Similarly, HEMTs 602 and 604 will be referred to as low-side HEMT 602 and low-side HEMT 604.

[0028] In this case, if HEMT 601 to 604 are Figure 2 For each corresponding instance of HEMT 201 to 204, channel nodes 210A and 210B of HEMT 201 will be the corresponding drain and source of HEMT 201, channel nodes 220A and 220B of HEMT 202 will be the corresponding drain and source of HEMT 202, channel nodes 230A and 230B of HEMT 203 will be the corresponding drain and source of HEMT 203, and channel nodes 240A and 240B of HEMT 204 will be the corresponding drain and source of HEMT 204.

[0029] exist Figure 6 In this circuit, circuit 600 regulates the voltage VOUT between GND and VIN by controlling the duty cycles of high-side HEMTs 601 and 603 and low-side HEMTs 602 and 604. Most of the time, when high-side HEMTs 601 and 603 are on, low-side HEMTs 602 and 604 are off, and vice versa. To obtain a higher output voltage VOUT, the duty cycle of high-side HEMTs 601 and 603 is increased, while the duty cycle of low-side HEMTs 602 and 604 is decreased. To obtain a lower output voltage VOUT, the duty cycle of high-side HEMTs 601 and 603 is decreased, while the duty cycle of low-side HEMTs 602 and 604 is increased. Of course, in a buck converter, there is an inductor-capacitor network (…). Figure 6 (Not shown in the diagram) is connected to the output switching node to stabilize the output voltage VOUT. That is, Figure 6The circuit 600 can also be implemented in a boost converter or any other circuit that includes a high voltage supply and a low voltage supply.

[0030] Since the gate voltages applied to the high-side HEMTs 601 and 603 are identical, with their drains connected to each other and their sources connected to each other, the high-side HEMTs 601 and 603 behave as a single high-side HEMT (except for the EMI cancellation properties caused during transitions, as will be briefly described). Furthermore, since the gate voltages applied to the low-side HEMTs 602 and 604 are identical, with their drains connected to each other and their sources connected to each other, the low-side HEMTs 602 and 604 behave as a single low-side HEMT (except for the EMI cancellation properties).

[0031] During the transition period, high-side HEMTs 601 and 603 are turned on, while low-side HEMTs 602 and 604 are turned off, or high-side HEMTs 601 and 603 are turned off, while low-side HEMTs 602 and 604 are turned on. Within this brief transition period, there will be a short interval where current flows from VCC1 to GND1 through HEMTs 601 and 602, and current flows from VCC2 to GND2 through HEMTs 603 and 604. Furthermore, during this transition period, the current and voltage changes at various nodes of the circuit can be quite rapid, resulting in high-frequency power variations, thus allowing EMI to be emitted in the high-frequency range.

[0032] However, according to the principles described herein, the current flowing through HEMT 601 and 602 is a current path with a rotational direction in the current flow plane (see again). Figure 1 and 2 The current flowing through HEMT 603 and 604 is another current path with opposite rotational directions. Therefore, high-frequency emissions will be largely canceled out. Thus, the principles described herein can be applied to buck converters, boost converters, or any other circuit with high and low voltage supplies to limit EMI emissions during the transition phase. Therefore, circuit 600 can form part of a buck converter, boost converter, or any other circuit with low EMI emissions.

[0033] Figure 7 A second example circuit 700 is shown, in which four HEMTs 701 to 704 are present, each of which can be configured as follows: Figure 2 It is structured as described in HEMT 201 to 204. (and) Figure 6 Different from China Figure 7A HEMT with a common drain configuration is shown, and in addition to its EMI cancellation properties, it can behave as a bidirectional switch. In this case, the source of each of HEMTs 701 and 703 is connected to voltage source V1, and the source of each of HEMTs 702 and 704 is connected to another voltage source V2.

[0034] When the bidirectional switch is turned on, if voltage V1 is higher than voltage V2, then... Figure 7 In the first current path, current flows from V1 down through HEMTs 701 and 702 and to voltage V2, and current flows down through HEMTs 703 and 704 and to voltage V2 in the second current path. In this case, if HEMTs 701 to 704 are... Figure 2 In the example of HEMTs 201 to 204, the first current path will be clockwise, and the second current path will be counterclockwise. On the other hand, when the bidirectional switch is on, and if voltage V1 is lower than voltage V2, current flows upward from V2 through HEMTs 702 and 701 in the first current path and to voltage V1, and current flows upward through HEMTs 704 and 703 in the second current path and to voltage V2. In this case, if HEMTs 701 to 704 are... Figure 2 In the case of HEMT 201 to 204, the first current path will be counterclockwise, and the second current path will be clockwise. In either case, EMI will be largely canceled out.

[0035] The HEMTs described above can each be either enhancement-mode (normally off) HEMTs or depletion-mode (normally on) HEMTs. However, if normally off HEMT behavior is desired, a normally on HEMT can be used in conjunction with another low-voltage transistor to perform normally off behavior. For example, Figure 8A The diagram illustrates a circuit 800A, which includes a normally open HEMT 801A and a low-voltage transistor 802A (such as, but not limited to, a MOSFET) connected in series between a high-voltage source V1 and ground. The gate of the normally open HEMT 801A is connected to the source of the low-voltage transistor 802A, and only the gate of the low-voltage transistor is actively driven (e.g., by driver 812A) to control the current flow from the high-voltage source V1 to ground. This configuration is referred to herein as a “cascode configuration of enhancement-mode HEMTs”.

[0036] Figure 8BAnother circuit 800B is illustrated, in which normally-off behavior is simulated by connecting a normally-open HEMT 801B and a low-voltage transistor 802B in series between a first voltage source V1 and a second voltage source V2. Here, both the HEMT 801B and the low-voltage transistor 802B are actively driven. That is, the HEMT 801B is driven by driver 811B, while the low-voltage transistor 802B is driven by driver 812B. This configuration is referred to herein as the "direct-drive configuration of the enhancement-mode HEMT".

[0037] Therefore, circuit 800A or circuit 800B can be used for the above-mentioned... Figures 2 to 6 Any HEMT described. If the low-voltage transistor is formed on the same integrated circuit as the HEMT, then circuit 800A or circuit 800B can be used as... Figure 3 The HEMT in integrated circuit 300. However, if the low-voltage transistor is more precisely a silicon MOSFET, then the silicon MOSFET can be packaged together with the HEMT (e.g., in...). Figure 4 It can be housed within package 400, but not on integrated circuit 401, or it can be on the same board as HEMT (e.g., board 500).

[0038] Figure 9 The illustration shows an embodiment of a buck converter circuit 900, which is Figure 6 The circuit 600 is an extension. That is, transistors 901 to 904 can be... Figure 4 Examples of corresponding HEMTs 601 to 604. Alternatively, as just described, transistors 901 to 904 can be any of circuits 800A or 800B. Furthermore, capacitor 921 is also shown as allowing a first current path 951 (in... Figure 9 (shown as having clockwise rotation), and capacitor 922 is also shown as allowing a second current path 952 (in Figure 9 (As shown in the diagram, rotating counterclockwise). These current paths are active during the brief periods when the buck converter circuit 900 is transitioning between on and off, thus generating high-frequency EMI, which is at least partially canceled out by the counterclockwise rotational nature of the two current paths 951 and 952.

[0039] However, as previously mentioned, buck converters include an inductor-capacitor network, which allows for the generation of a stable output voltage VOUT. This network is also used to provide another example of reverse-rotating current flow occurring at a lower frequency.

[0040] Specifically, inductor 931 is coupled between the common node of transistors 901 and 902 and the output node carrying voltage VOUT. Output capacitor 923 is connected between the output node carrying voltage VOUT and the ground node carrying voltage GND. This results in a clockwise rotation of current path 961, which has a lower frequency component but can still be considered EMI for many surrounding circuits. The larger path represented by the combination of current paths 951 and 961 is represented by current path 971.

[0041] Furthermore, inductor 932 is coupled between the common node of transistors 903 and 904 and the output node carrying voltage VOUT. Again, output capacitor 923 is connected between the output node carrying voltage VOUT and the ground node carrying voltage GND. This results in a counter-clockwise rotation of current path 962, which has a lower frequency component but can still be considered EMI for many surrounding circuits. However, the EMI emitted by rotating paths 961 and 962 is largely mirror-image of each other, and therefore the resulting EMI is largely canceled out. The larger path represented by the combination of current paths 952 and 962 is represented by current path 972.

[0042] Since inductors 931 and 932 are relatively large components that are difficult to fabricate efficiently on a chip, they can be more effectively implemented on a circuit board in which they are mounted. Furthermore, capacitor 923 may be larger than capacitors 921 and 922 because it will have sufficient capacitance to stably maintain voltage VOUT and sufficiently low impedance to maintain the flow of current paths 961 and 962, even though current paths 961 and 962 operate at frequencies lower than current paths 951 and 952. Therefore, capacitor 923 can be implemented on a circuit board.

[0043] Therefore, a circuit has been described comprising two current path circuits—a first current path circuit and a second current path circuit—where current flows in opposite directions of rotation in the current flow plane. If the same differential voltage is applied across the first and second current path circuits, this will induce opposing rotating currents in each current path circuit. This is true even if the first and / or second voltages vary. Therefore, the reverse flow at least partially cancels out electromagnetic interference across the frequency range.

[0044] Literal declaration support section Clause 1. A circuit comprising: a first current path circuit having a first voltage supply node and a second voltage supply node, the first current path circuit being structured such that when current flows from the first voltage supply node to the second voltage supply node, the current flowing through the first current path circuit is in a first rotational direction in a current flow plane; and a second current path circuit having a third voltage supply node and a fourth voltage supply node, the second current path circuit being structured such that when current flows from the third voltage supply node to the fourth voltage supply node, the current flowing through the second current path circuit is in a second rotational direction in a current flow plane, the second rotational direction being opposite to the first rotational direction in the current flow plane.

[0045] Clause 2. The circuit according to Clause 1 is structured such that if the same first voltage is applied to the first voltage supply node and the third voltage supply node, and if the same second voltage is applied to the second voltage supply node and the fourth voltage supply node, the current will flow in a different rotational direction in the first current path circuit compared to the second current path circuit, thereby attenuating electromagnetic interference.

[0046] Clause 3. According to Clause 1, the first current path circuit includes a first high electron mobility transistor (HEMT) formed from a portion of an epitaxial stack and a second HEMT formed from a portion of an epitaxial stack, the current flow plane being perpendicular to the epitaxial growth direction of the epitaxial stack. The first HEMT has a first channel node connected to a first voltage supply node and a second channel node connected to a switching output node of the circuit. The second HEMT has a first channel node connected to a switching output node of the circuit and a second channel node connected to a second voltage supply node. The first current path circuit includes a first high electron mobility transistor (HEMT) formed from a portion of an epitaxial stack and a second HEMT formed from a portion of an epitaxial stack, the current flow plane being perpendicular to the epitaxial growth direction of the stack. Perpendicular to the epitaxial growth direction of the epitaxial stack, the first HEMT has a first channel node connected to a first voltage supply node and a second channel node connected to a switch output node of the circuit, the second HEMT has a first channel node connected to a switch output node of the circuit and a second channel node connected to a second voltage supply node, and the second current path circuit includes a third HEMT formed by a portion of the epitaxial stack and a fourth HEMT formed by a portion of the epitaxial stack, the third HEMT has a first channel node connected to a third voltage supply node and a second channel node connected to a switch output node of the circuit, and the second HEMT has a first channel node connected to a switch output node of the circuit and a second channel node connected to a fourth voltage supply node.

[0047] Clause 4. In the circuit described in Clause 3, the first channel node of the first HEMT is the drain node of the first HEMT, the second channel node of the first HEMT is the source node of the first HEMT, the first channel node of the second HEMT is the drain node of the second HEMT, the second channel node of the second HEMT is the source node of the second HEMT, the first channel node of the third HEMT is the drain node of the third HEMT, the second channel node of the third HEMT is the source node of the third HEMT, and the first channel node of the fourth HEMT is the drain node of the fourth HEMT, the second channel node of the fourth HEMT is the source node of the fourth HEMT.

[0048] Clause 5. The circuit described in Clause 4 is a buck converter circuit or a boost converter circuit, such that if the same first voltage is applied to the first voltage supply node and the second voltage supply node, the same second voltage is applied to the third voltage supply node and the fourth voltage supply node, the same first gate control signal is applied to the first HEMT and the third HEMT, and the second gate control signal is applied to the second HEMT and the fourth HEMT, then the circuit outputs an output signal at the switching output node.

[0049] Clause 6. The circuit described in Clause 3 is a bidirectional switch, wherein the first channel node of the first HEMT is the source node of the first HEMT, the second channel node of the first HEMT is the drain node of the first HEMT, the first channel node of the second HEMT is the drain node of the second HEMT, the second channel node of the second HEMT is the source node of the second HEMT, the first channel node of the third HEMT is the source node of the third HEMT, the second channel node of the third HEMT is the drain node of the third HEMT, and the first channel node of the fourth HEMT is the drain node of the fourth HEMT, and the second channel node of the fourth HEMT is the source node of the fourth HEMT.

[0050] Clause 7. A circuit comprising: a first current path circuit having a first voltage supply node, a second voltage supply node, a first high electron mobility transistor (HEMT) formed by a portion of an epitaxial stack, and a second HEMT formed by a portion of an epitaxial stack, the current flow plane being perpendicular to the epitaxial growth direction of the epitaxial stack, the first HEMT having a first channel node connected to the first voltage supply node and a second channel node connected to a switching output node of the circuit, the second HEMT having a first channel node connected to the switching output node of the circuit and a second channel node connected to the second voltage supply node, the first current path circuit being structured such that when current flows from the first voltage supply node through the first HEMT, the second HEMT, and to the second voltage supply node, the current flows along a first current flow plane in a first rotational direction. The flow path includes a third voltage supply node, a fourth voltage supply node, a third HEMT formed by an epitaxial stack, and a fourth HEMT formed by an epitaxial stack. The third HEMT has a first channel node connected to the third voltage supply node and a second channel node connected to a switch output node of the circuit. The fourth HEMT has a first channel node connected to the switch output node of the circuit and a second channel node connected to the fourth voltage supply node. The second current path circuit is structured such that when current flows from the third voltage supply node through the third HEMT, the fourth HEMT, and to the fourth voltage supply node, the current flows in the second flow path in a second rotational direction in the current flow plane, the second rotational direction being opposite to the first rotational direction in the current flow plane.

[0051] Clause 8. The circuit described in Clause 7, wherein the first HEMT, the second HEMT, the third HEMT, and the fourth HEMT are formed on an integrated circuit comprising an epitaxial stack.

[0052] Clause 9. The circuit according to Clause 8, the first circuit path further includes: a first capacitor having a first terminal connected to a first voltage supply node and a second terminal connected to a second voltage supply node; and a second capacitor having a first terminal connected to a third voltage supply node and a second terminal connected to a fourth voltage supply node.

[0053] Clause 10. In the circuit described in Clause 9, the first capacitor and the second capacitor are also formed on the integrated circuit.

[0054] Clause 11. The circuit described in Clause 9 further includes a package containing an integrated circuit.

[0055] Clause 12. The circuit described in Clause 11, the package further includes a first capacitor and a second capacitor, each not formed on the integrated circuit.

[0056] Clause 13. The circuitry described in Clause 11 further includes a circuit board connected to the package.

[0057] Clause 14. In the circuit described in Clause 13, at least one of the first HEMT, the second HEMT, the third HEMT, or the fourth HEMT is configured with a low-voltage transistor in a cascode configuration, the low-voltage transistor being located outside the package and on a circuit board.

[0058] Clause 15. In the circuit described in Clause 13, at least one of the first HEMT, the second HEMT, the third HEMT, or the fourth HEMT is configured with a low-voltage transistor in a cascode configuration, the low-voltage transistor being outside the package and on a circuit board.

[0059] Clause 16. In the circuit described in Clause 13, the first capacitor and the second capacitor are on a circuit board outside the package.

[0060] Clause 17. The circuit described in Clause 7, wherein the first flow path circuit and the second flow path circuit form a buck converter.

[0061] Clause 18. The circuit described in Clause 7, wherein the first flow path loop and the second flow path loop form a bidirectional switch.

[0062] Clause 19. A circuit board comprising: a first current path circuit having a first voltage supply node and a second voltage supply node, the first current path circuit being configured such that when current flows from the first voltage supply node to the second voltage supply node, the current flowing through the first current path circuit is in a first rotational direction in a current flow plane perpendicular to a plane extending therefrom of the circuit board; and a second current path circuit having a third voltage supply node and a fourth voltage supply node, the second current path circuit being configured such that when current flows from the third voltage supply node to the fourth voltage supply node, the current flowing through the first current path circuit is in a second rotational direction in the current flow plane, the second rotational direction being opposite to the first rotational direction in the current flow plane.

[0063] Clause 20. The circuit board according to Clause 17 further includes: a first capacitor mounted to the board of the circuit board and having a first terminal connected to a first voltage supply node and a second terminal connected to a second voltage supply node, the first capacitor being connected to the circuit board; and a second capacitor mounted to the board and having a first terminal connected to a third voltage supply node and a second terminal connected to a fourth voltage supply node.

[0064] Although the subject matter has been described in language specific to structural features and / or methodological actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the described features or actions, or the order of the described actions. Rather, the described features and actions are disclosed as exemplary forms of implementing the claims.

[0065] This disclosure may be embodied in other specific forms without departing from its essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. All variations from the meaning and scope of equivalents of the claims are to be included within their scope.

[0066] When elements are introduced in the appended claims, the articles “a,” “an,” “the,” and “the” are intended to mean the presence of one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and to mean that additional elements may be present in addition to the listed elements.

Claims

1. A circuit, comprising: a first current path circuit having a first voltage supply node and a second voltage supply node, the first current path circuit structured such that when current flows from the first voltage supply node to the second voltage supply node, the current flowing through the first current path circuit is in a first rotational direction in a current flow plane; and a second current path circuit having a third voltage supply node and a fourth voltage supply node, the second current path circuit structured such that when current flows from the third voltage supply node to the fourth voltage supply node, the current flowing through the second current path circuit is in a second rotational direction in the current flow plane, the second rotational direction opposite the first rotational direction in the current flow plane.

2. The circuit of claim 1, the circuit structured such that if a same first voltage is applied to the first voltage supply node and the third voltage supply node, and if a same second voltage is applied to the second voltage supply node and the fourth voltage supply node, then current will flow in a different rotational direction in the first current path circuit compared to the second current path circuit, thereby attenuating electromagnetic interference.

3. The circuit of claim 1, the first current path circuit includes a first high electron mobility transistor (HEMT) formed from a portion of an epitaxial stack and a second HEMT formed from a portion of the epitaxial stack, the current flow plane perpendicular to an epitaxial growth direction of the epitaxial stack, the first HEMT having a first channel node connected to the first voltage supply node and a second channel node connected to a switching output node of the circuit, the second HEMT having a first channel node connected to the switching output node of the circuit and a second channel node connected to the second voltage supply node, and the first current path circuit includes a first high electron mobility transistor (HEMT) formed from a portion of an epitaxial stack and a second HEMT formed from a portion of the epitaxial stack, the current flow plane perpendicular to an epitaxial growth direction of the epitaxial stack, the first HEMT having a first channel node connected to the first voltage supply node and a second channel node connected to a switching output node of the circuit, the second HEMT having a first channel node connected to the switching output node of the circuit and a second channel node connected to the second voltage supply node, and the second current path circuit includes a third HEMT formed from a portion of the epitaxial stack and a fourth HEMT formed from a portion of the epitaxial stack, the third HEMT having a first channel node connected to the third voltage supply node and a second channel node connected to the switching output node of the circuit, the second HEMT having a first channel node connected to the switching output node of the circuit and a second channel node connected to the fourth voltage supply node.

4. The circuit of claim 3, the first channel node of the first HEMT is a drain node of the first HEMT, the second channel node of the first HEMT is a source node of the first HEMT, the first channel node of the second HEMT is a drain node of the second HEMT, the second channel node of the second HEMT is a source node of the second HEMT, and the first channel node of the third HEMT is a drain node of the third HEMT, the second channel node of the third HEMT is a source node of the third HEMT, the first channel node of the fourth HEMT is a drain node of the fourth HEMT, and the second channel node of the fourth HEMT is a source node of the fourth HEMT.

5. The circuit of claim 4, the circuit being a buck converter circuit or a boost converter circuit, such that if the same first voltage is applied to the first voltage supply node and the second voltage supply node, the same second voltage is applied to the third voltage supply node and the fourth voltage supply node, the same first gate control signal is applied to the first HEMT and the third HEMT, and the second gate control signal is applied to the second HEMT and the fourth HEMT, then the circuit outputs an output signal on the switch output node.

6. The circuit of claim 3, the circuit being a bidirectional switch, the first channel node of the first HEMT is a source node of the first HEMT, the second channel node of the first HEMT is a drain node of the first HEMT, the first channel node of the second HEMT is a drain node of the second HEMT, and the second channel node of the second HEMT is a source node of the second HEMT, and the first channel node of the third HEMT is a source node of the third HEMT, the second channel node of the third HEMT is a drain node of the third HEMT, the first channel node of the fourth HEMT is a drain node of the fourth HEMT, and the second channel node of the fourth HEMT is a source node of the fourth HEMT.

7. A circuit, comprising: a first current path circuit having a first voltage supply node, a second voltage supply node, a first high electron mobility transistor (HEMT) formed from a portion of an epitaxial stack, and a second HEMT formed from a portion of the epitaxial stack, a current flow plane being perpendicular to an epitaxial growth direction of the epitaxial stack, the first HEMT having a first channel node connected to the first voltage supply node and a second channel node connected to a switch output node of the circuit, the second HEMT having a first channel node connected to the switch output node of the circuit and a second channel node connected to the second voltage supply node, the first current path circuit being structured such that when current flows from the first voltage supply node through the first HEMT, the second HEMT, and to the second voltage supply node, the current flows in a first flow path in the current flow plane in a first rotational direction; and a second current path circuit having a third voltage supply node, a fourth voltage supply node, a third HEMT formed from a portion of the epitaxial stack, the third HEMT having a first channel node connected to the third voltage supply node and a second channel node connected to a switch output node of the circuit, and a fourth HEMT formed from a portion of the epitaxial stack, the fourth HEMT having a first channel node connected to the switch output node of the circuit and a second channel node connected to the fourth voltage supply node, the second current path circuit structured such that when current flows from the third voltage supply node, through the third HEMT, the fourth HEMT, and to the fourth voltage supply node, the current flows in the second flow path in a second rotational direction in a current flow plane, the second rotational direction opposite the first rotational direction in the current flow plane.

8. The circuit of claim 7, the first HEMT, the second HEMT, the third HEMT, and the fourth HEMT formed on an integrated circuit comprising the epitaxial stack.

9. The circuit of claim 8, the first circuit path further comprising: a first capacitor having a first terminal connected to the first voltage supply node and a second terminal connected to the second voltage supply node; and a second capacitor having a first terminal connected to the third voltage supply node and a second terminal connected to the fourth voltage supply node.

10. The circuit of claim 9, the first capacitor and the second capacitor also formed on the integrated circuit.

11. The circuit of claim 9, further comprising a package containing the integrated circuit.

12. The circuit of claim 11, the package further containing the first capacitor and the second capacitor, each not formed on the integrated circuit.

13. The circuit of claim 11, further comprising a circuit board connected to the package.

14. The circuit of claim 13, at least one of the first HEMT, the second HEMT, the third HEMT, or the fourth HEMT in a cascode configuration with a low voltage transistor, the low voltage transistor outside the package and on the circuit board.

15. The circuit of claim 13, at least one of the first HEMT, the second HEMT, the third HEMT, or the fourth HEMT in a cascode configuration with a low voltage transistor, the low voltage transistor outside the package and on the circuit board.

16. The circuit of claim 13, the first capacitor and the second capacitor on the circuit board outside the package.

17. The circuit of claim 7, the first flow path circuit and the second flow path circuit forming a buck converter.

18. The circuit of claim 7, the first flow path circuit and the second flow path circuit forming a bidirectional switch.

19. A circuit board comprising: ​ a first current path circuit having a first voltage supply node and a second voltage supply node, the first current path circuit being structured such that, when current flows from the first voltage supply node to the second voltage supply node, the current flowing through the first current path circuit is in a first rotational direction in a current flow plane, the current flow plane being perpendicular to a plane in which the circuit board extends; and a second current path circuit having a third voltage supply node and a fourth voltage supply node, the second current path circuit being structured such that, when current flows from the third voltage supply node to the fourth voltage supply node, the current flowing through the first current path circuit is in a second rotational direction in the current flow plane, the second rotational direction being opposite to the first rotational direction in the current flow plane.

20. The circuit board of claim 17, further comprising: a first capacitor mounted to the board of the circuit board and having a first terminal connected to the first voltage supply node and a second terminal connected to the second voltage supply node, the first capacitor being connected to the circuit board; and a second capacitor mounted to the board and having a first terminal connected to the third voltage supply node and a second terminal connected to the fourth voltage supply node.

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