Enhancement Mode III-Nitride Switch
According to one exemplary embodiment, an efficient and high speed E-mode N/Schottky switch includes a silicon transistor coupled with a D-mode III-nitride device, where the silicon transistor causes the D-mode III-nitride device to operate in an enhancement mode. The E-mode III-N/Schottky switch further includes a Schottky diode coupled across the silicon transistor so as to improve efficiency, recovery time, and speed of the E-mode III-N/Schottky switch. An anode of the Schottky diode can be coupled to a source of the silicon transistor and a cathode of the Schottky diode can he coupled to a drain of the silicon transistor. The Schottky diode can be integrated with the silicon transistor. In one embodiment the III-nitride device is a GaN device.
The present application claims the benefit of and priority to a pending provisional patent application entitled “Power Factor Correction Boost Circuit using Enhanced Mode III-Nitride Power Device,” Ser. No. 61/050,730 filed on May 6, 2008. The disclosure in that pending provisional application is hereby incorporated fully by reference into the present application.
FIELD OF THE INVENTIONThe present invention is generally in the field of switching circuits. More particularly, the invention is in the field of high voltage switching circuits.
BACKGROUND ARTHigh voltage circuits, such as power conversion circuits, typically require fast switches that are capable of handling high voltages without breaking down. Conventionally, silicon devices, such as high voltage silicon diodes and transistors, have been utilized to provide high voltage switches. For example, a high voltage silicon field effect transistor (FET), such as a high voltage metal oxide semiconductor FET (MOSFET), has been utilized as a high voltage switch in a power factor correction boost circuit.
When silicon devices, such as high voltage silicon diodes and transistors, are utilized as switches in high voltage circuits, such as power conversion circuits, they (i.e. the silicon devices) can store a large amount of charge when conducting current. When the silicon devices are turned off, the stored charge must be dissipated. However, the large amount of charge stored by the silicon devices, such as high voltage silicon diodes and transistors, can undesirably limit their efficiency and operating frequency. Consequently, the efficiency and operating frequency of high voltage circuits, such as power conversion circuits, can be undesirably limited by the use of silicon devices, such as high voltage silicon diodes and transistors, as high voltage switches.
SUMMARY OF THE INVENTIONEnhancement mode III-nitride switch with increased efficiency and operating frequency, substantially as shown in and/or described in connection with at least one of the figures, and as set forth more completely in the claims.
The present invention is directed to an enhancement mode III-nitride switch with increased efficiency and operating frequency. The following description contains specific information pertaining to the implementation of the present invention. One skilled in the art will recognize that the present invention may be implemented in a manner different from that specifically discussed in the present application. Moreover, some of the specific details of the invention are not discussed in order not to obscure the invention.
The drawings in the present application and their accompanying detailed description are directed to merely exemplary embodiments of the invention. To maintain brevity, other embodiments of the present invention are not specifically described in the present application and are not specifically illustrated by the present drawings.
As shown in
In E-mode III-N switch 116, silicon transistor 124 is coupled in series with D-mode III-nitride device 126, wherein the gate of D-mode III-nitride device 126 is coupled to the source of silicon transistor 124 and the drain of silicon transistor 124 is coupled to the source of D-mode III-nitride device 126. Silicon transistor 124 can be, for example, a low voltage silicon transistor, such as a silicon FET. In one embodiment, silicon transistor 124 can be a low voltage silicon MOSFET. D-mode III-nitride device 126 can comprise a group III nitride semiconductor compound, such as aluminum nitride (AlN), indium nitride (InN), gallium nitride (GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN), or indium aluminum gallium nitride (InAlGaN). The aforementioned semiconductor compounds have a relatively wide direct bandgap that permits highly energetic electronic transitions to occur. D-mode III-nitride device 126 is a high voltage device and has reduced charge storage and a high mobility conduction channel, which enables it (i.e. D-mode III-nitride device 126) to conduct high current. As a result of reduced charge storage, D-mode III-nitride device 126 provides increased efficiency and increased operating frequency.
D-mode III-nitride device 126 is a normally on device. However, by coupling silicon transistor 124 in series with D-mode III-nitride device 126 as discussed above, silicon transistor 124 causes D-mode III-nitride device 126 to operate in an enhancement mode (E-mode). For example, when silicon transistor 124 is turned on, D-mode III-nitride device 126 is also turned on, thereby allowing current to flow through silicon transistor 124 and D-mode III-nitride device 126. When silicon transistor 124 is turned off, D-mode III-nitride device 126 turns off as a result of a voltage that develops across silicon transistor 124. By including the series-coupled combination of silicon transistor 124 and D-mode III-nitride device 126, E-mode III-N switch 116 provides reduced charge storage, thereby providing increased efficiency and increased operating frequency.
In normally off switch 118, Schottky diode 128 is coupled in series with D-mode III-nitride device 130. In particular, the anode of Schottky diode 128 is coupled to the gate of D-mode III-nitride device 130 and the cathode of Schottky diode 128 is coupled to the source of D-mode III-nitride device 130. Schottky diode 128 can be a low voltage silicon diode in an embodiment of the present invention. D-mode III-nitride device 130, which is a high voltage device, can comprise similar group III nitride semiconductor compounds and provides similar advantages as D-mode III-nitride device 126. D-mode III-nitride device 130 is a normally on device. However, by coupling Schottky diode 128 in series with D-mode III-nitride device 130 as discussed above, Schottky diode 128 causes D-mode III-nitride device 130 to turn off when it (i.e. Schottky diode 128) is in a reverse mode (i.e. when current flows from cathode to anode).
For example, in a forward mode (i.e. when current flows from anode to cathode), Schottky diode 128 is turned on and D-mode III-nitride device 130 is also turned on. The voltage drop across Schottky diode 128 in the forward mode has a negligible effect on D-mode III-nitride device 130, which is a high voltage device. In the reverse mode, D-mode III-nitride device 130 turns off as a result of a voltage that develops across Schottky diode 128. Thus, the combination of Schottky diode 128 and D-mode III-nitride device 130 can operate as a high voltage diode, where the anode of Schottky diode 128 can be an “anode” of the high voltage diode and the drain of D-mode III-nitride device 130 can be a “cathode” of the high voltage diode. By including the series-coupled combination of Schottky diode 128 and D-mode III-nitride device 130, normally off switch 118 provides reduced charge storage, thereby providing increased efficiency and increased operating frequency.
Further shown in
During operation of PFC boost circuit 100, controller 114 provides a PWM (pulse width modulated) signal to the gate of silicon transistor 124 to control the on/off time of E-mode III-N switch 116. When E-mode III-N switch 116 is turned on, current flows in a loop including E-mode III-N switch 116 and normally off switch 118, thereby causing charge to be stored in E-mode III-N switch 116 and normally off switch 118. When E-mode III-N switch 116 is turned off, the stored charge stored in E-mode III-N switch 116 and normally off switch 118 needs to be dissipated. This stored charge, however, is significantly less than the stored charge if, in place of switches 116 and 118, conventional switches were used—which resulted in significantly limiting the efficiency and operating frequency of, for example, a conventional PFC boost circuit.
In a conventional PFC boost circuit, a high voltage MOSFET is typically utilized in place of E-mode III-N switch 116 and a high voltage silicon diode is typically utilized in place of normally off switch 118. However, the high voltage MOSFET stores significantly more charge than E-mode III-N switch 116 and the high voltage silicon diode stores significantly more charge than normally off switch 118. Thus, by utilizing E-mode III-N switch 116 and normally off switch 118, an embodiment of the invention's PFC boost circuit 100 can significantly reduce the amount of stored charge that needs to be dissipated compared to a conventional PFC boost circuit. By reducing the amount of stored charge that needs to be dissipated, E-mode III-N switch 116 and normally off switch 118 cause PFC boost circuit 100 to provide an increased efficiency and an increased operating frequency compared to the conventional PFC boost circuit.
Also, by operating at a higher frequency, PFC boost circuit 100 can utilized smaller size passive components, such as capacitors and inductors, which can advantageously reduce the footprint of PFC boost circuit 100, thereby advantageously reducing manufacturing cost.
As shown in
D-mode III-nitride device 226 is a normally on device. However, by coupling silicon transistor 224 with D-mode III-nitride device 226 as discussed above, silicon transistor 224 causes D-mode III-nitride device 226 to operate in an enhancement mode (E-mode). For example, when silicon transistor 224 is turned on, D-mode III-nitride device 226 is also turned on, thereby allowing current to flow through silicon transistor 224 and D-mode III-nitride device 226. When silicon transistor 224 is turned off, D-mode III-nitride device 226 turns off as a result of a voltage that develops across silicon transistor 224. By including the combination of silicon transistor 224 and D-mode III-nitride device 226. E-mode III-N/Schottky switch 216 provides reduced charge storage, thereby providing increased efficiency and increased operating frequency.
Schottky diode 246 also provides reduced charge storage, which provides increased efficiency and operating frequency. In addition, Schottky diode 246 provides reduced reverse recovery time (i.e. a faster reverse recovery). Thus, an embodiment of the invention's E-mode III-N/Schottky switch 216 provides a high speed, high voltage switch having reduced charge storage, which provides increased efficiency and operating frequency, and also provides a faster reverse recovery time. Thus, E-mode III-N/Schottky switch 216 can be advantageously utilized in high voltage applications, such as power conversion applications, to advantageously provide increased efficiency, increased operating frequency, and increased reverse recovery time compared to a high voltage silicon FET, such as a high voltage silicon MOSFET.
By utilizing E-mode III-N/Schottky switches 416a and 416b, an embodiment of the invention provides a half-bridge configuration that advantageously provides increased efficiency and operating frequency and faster recovery time compared to a conventional half-bridge configuration that utilizes switches comprising high voltage silicon transistors, such as high voltage MOSFETs.
By utilizing E-mode III-N/Schottky switches 516a, 516b, 516c, and 516d, an embodiment of the invention provides a full-bridge configuration that advantageously provides increased efficiency and operating frequency and faster recovery time compared to a conventional full-bridge configuration that utilizes switches comprising high voltage silicon transistors, such as high voltage MOSFETs.
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From the above description of the invention it is manifest that various techniques can be used for implementing the concepts of the present invention without departing from its scope. Moreover, while the invention has been described with specific reference to certain embodiments, a person of ordinary skill in the art would appreciate that changes can be made in form and detail without departing from the spirit and the scope of the invention. Thus, the described embodiments are to be considered in all respects as illustrative and not restrictive. It should also be understood that the invention is not limited to the particular embodiments described herein but is capable of many rearrangements, modifications, and substitutions without departing from the scope of the invention.
Claims
1. An efficient and high speed E-mode III-N/Schottky switch comprising:
- a silicon transistor coupled with a D-mode III-nitride device, said silicon transistor causing said D-mode III-nitride device to operate in an enhancement mode;
- a Schottky diode coupled across said silicon transistor;
- said E-mode III-N/Schottky switch thereby achieving improved speed, efficiency, and reverse recovery time.
2. The E-mode III-N/Schottky switch of claim 1, wherein two of said E-mode III-N/Schottky switches are coupled between a supply voltage and a ground to form a half-bridge configuration.
3. The E-mode III-N/Schottky switch of claim 1, wherein four of said E-mode III-N/Schottky switches are coupled between a supply voltage and a ground to form a full-bridge configuration.
4. The E-mode III-N/Schottky switch of claim 3, wherein a first and a second of said E-mode III-N/Schottky switches are coupled between said supply voltage and respective first and second terminals of an inductor and a third and a fourth of said E-mode III-N/Schottky switches are coupled between said respective first and second terminals of said inductor and said ground.
5. The E-mode III-N/Schottky switch of claim 1, wherein a first said E-mode III-N/Schottky switch is coupled with a second said E-mode III-N/Schottky switch across a DC power source to form a buck circuit.
6. The E-mode III-N/Schottky switch of claim 5, wherein a buck inductor and a buck capacitor are coupled across said first said E-mode III-N/Schottky switch.
7. The E-mode III-N/Schottky switch of claim 1, wherein said silicon transistor is a low voltage FET.
8. The E-mode III-N/Schottky switch of claim 1, wherein said D-mode III-Nitride device is a GaN device.
9. The E-mode III-N/Schottky switch of claim 1, wherein an anode of said Schottky diode is coupled to a source of said silicon transistor and a cathode of said Schottky diode is coupled to a drain of said silicon transistor.
10. The E-mode III-N/Schottky switch of claim 1, wherein said Schottky diode is integrated with said silicon transistor.
11-20. (canceled)
21. An E-mode III-N/Schottky switch comprising:
- a silicon transistor coupled with a D-mode III-nitride device, said silicon transistor causing said D-mode III-nitride device to operate in an enhancement mode;
- a Schottky diode coupled across said silicon transistor;
- said E-mode III-N/Schottky switch configured as a power switch in a power conversion circuit.
22. The E-mode III-N/Schottky switch of claim 21, wherein two of said E-mode III-N/Schottky switches are coupled between a supply voltage and a ground to form a half-bridge configuration.
23. The E-mode III-N/Schottky switch of claim 21, wherein four of said E-mode III-N/Schottky switches are coupled between a supply voltage and a ground to form a full-bridge configuration.
24. The E-mode III-N/Schottky switch of claim 21, wherein a first said E-mode III-N/Schottky switch is coupled with a second said E-mode III-N/Schottky switch across a DC power source to form a buck circuit.
25. The E-mode III-N/Schottky switch of claim 24, wherein a buck inductor and a buck capacitor are coupled across said first said E-mode III-N/Schottky switch.
26. The E-mode III-N/Schottky switch of claim 21, wherein said D-mode III-Nitride device is a GaN device.
27. An E-mode III-N/Schottky switch comprising:
- a silicon transistor coupled with a D-mode III-nitride device, said silicon transistor causing said D-mode III-nitride device to operate in an enhancement mode;
- a Schottky diode coupled across said silicon transistor;
- said E-mode III-N/Schottky switch configured as a power switch in a power conversion circuit;
- wherein a gate of said D-mode III-nitride device is connected to a source of said silicon transistor.
28. The E-mode III-N/Schottky switch of claim 27, wherein two of said E-mode III-N/Schottky switches are coupled between a supply voltage and a ground to form a half-bridge configuration.
29. The E-mode III-N/Schottky switch of claim 27, wherein a first said E-mode III-N/Schottky switch is coupled with a second said E-mode III-N/Schottky switch across a DC power source to form a buck circuit.
30. The E-mode III-N/Schottky switch of claim 27, wherein said D-mode III-Nitride device is a GaN device.
Type: Application
Filed: Feb 11, 2015
Publication Date: Jun 4, 2015
Inventors: Tony Bahramian (Torrance, CA), Jason Zhang (Monterey Park, CA)
Application Number: 14/619,485