Cascaded device with one or more normally open gates

Abstract

A switching device includes: a first power transistor die including a normally-on transistor having at most half a maximum rated drain-to-source voltage of the switching device; a second power transistor die including a normally-off transistor having at most half the maximum rated drain-to-source voltage of the switching device, where a drain of the normally-off transistor is electrically connected to a source of the normally-on transistor to form a splice device; a voltage blocking device electrically connected between a gate of the normally-on transistor and a source of the normally-off transistor, and configured to block a portion of the voltage across the switching device when the splice device is open; and the overvoltage protection device is configured to disconnect the normally-on transistor when the normally-off transistor is disconnected, so that the splicing device is actively controlled only through the grid electrode of the normally-off transistor. Additional switching device embodiments are described.

Description

Background Art

[0001] Many buffer layers are required in GaN (gallium nitride) technology to withstand at least 1.2kV, making it difficult to implement a single discrete or bidirectional switch device with a breakdown voltage of at least 1.2kV in GaN. Therefore, it is currently difficult to implement higher rated voltage applications such as 3-phase matrix converters and 3-phase current source inverters using GaN technology. For discrete devices, a 1.2kV switch can be implemented by stacking two (2) rated 650V devices. This scheme has two active gates, which requires both gates to be driven exactly at the same time. Otherwise, one 650V device may be subjected to greater stress than another 650V device. For a bidirectional blocking device, two (2) discrete bidirectional switches can be arranged back-to-back to block in both directions, while driving the two gates from the same driver or using two individual drivers (but provided from the same auxiliary power supply). However, two (2) 1.2kV discrete devices must be arranged back-to-back to implement a 1.2kV bidirectional blocking device. This results in an inefficient use of the two devices, where only one device blocks in one voltage direction, but current conducts through the semiconductor material of both devices. In addition, this approach is expensive compared to discrete components of the same RDSon (on-state resistance) rating because the required die size is now approximately four (4) times larger.

[0002] Therefore, there is a need for an improved 1.2 kV or higher discrete or bidirectional switch using GaN technology. Summary of the invention

[0003] According to an embodiment of the switching device, the switching device includes: a first power transistor die, including a normally-on transistor, the normally-on transistor having at most half of the maximum rated drain-to-source voltage of the switching device; a second power transistor die, including a normally-off transistor, the normally-off transistor having at most half of the maximum rated drain-to-source voltage of the switching device, wherein the drain of the normally-off transistor is electrically connected to the source of the normally-on transistor to form a cascode device; a voltage blocking device, electrically connected between the gate of the normally-on transistor and the source of the normally-off transistor, and configured to block a portion of the voltage across the switching device when the cascode device is disconnected; and an overvoltage protection device, configured to disconnect the normally-on transistor when the normally-off transistor is disconnected, so that the cascode device is actively controlled only through the gate of the normally-off transistor.

[0004] According to another embodiment of the switch device, the switch device comprises: a first bidirectional switch, comprising a first source, a second source, a normally-off gate and a normally-on gate; a second bidirectional switch, comprising a first source, a second source, a normally-off gate and a normally-on gate, electrically connected to the second source of the first bidirectional switch to form a stacking device; a first voltage blocking device, electrically connected between the first source of the first bidirectional switch and the normally-on gate of the second bidirectional switch, and configured to block a portion of the voltage across the switch device when the stacking device is disconnected; a first overvoltage protection device, configured to disconnect the normally-off gate of the second bidirectional switch when the normally-off gate is disconnected. The normally-on gate of the first bidirectional switch is passively controlled by the normally-off gate of the second bidirectional switch; a second voltage blocking device is electrically connected between the second source of the second bidirectional switch and the normally-on gate of the first bidirectional switch, and is configured to block a portion of the voltage across the switching device when the stacking device is disconnected; and a second overvoltage protection device is configured to disconnect the normally-on gate of the second bidirectional switch when the normally-off gate of the first bidirectional switch is disconnected, so that the normally-on gate of the second bidirectional switch is passively controlled by the normally-off gate of the first bidirectional switch.

[0005] According to another embodiment of the switch device, the switch device comprises: a first bidirectional switch, comprising a first source, a second source, a normally-off gate and a normally-on gate; a second bidirectional switch, comprising a first source, a second source, a first normally-on gate and a second normally-on gate electrically connected to the second source of the first bidirectional switch to form a first part of a stacking device; a third bidirectional switch, comprising a first source, a second source, a first normally-on gate and a second normally-on gate electrically connected to the second source of the second bidirectional switch to form a second part of the stacking device; a first voltage blocking device, electrically connected to the first source of the first bidirectional switch a first overvoltage protection device, configured to disconnect the first normally-on gate of the second bidirectional switch when the normally-off gate of the first bidirectional switch is disconnected, so that the first normally-on gate of the second bidirectional switch is passively controlled by the normally-off gate of the first bidirectional switch; a second voltage blocking device, electrically connected between the first source of the third bidirectional switch and the normally-on gate of the first bidirectional switch, and configured to block a portion of the voltage across the switch device when the stacking device is disconnected; a second overvoltage protection device, configured to disconnect the normally-on gate of the first bidirectional switch when the first normally-on gate of the second bidirectional switch is disconnected; a third voltage blocking device, electrically connected between the second source of the third bidirectional switch and the second normally-on gate of the second bidirectional switch, and configured to block a portion of the voltage across the switch device when the stacking device is disconnected; a third overvoltage protection device, configured to disconnect the second normally-on gate of the second bidirectional switch when the normally-off gate of the third bidirectional switch is disconnected, so that the normally-off gate of the second bidirectional switch is passively controlled by the normally-off gate of the first bidirectional switch; The normally-off gate of the third bidirectional switch and the second normally-on gate of the second bidirectional switch are passively controlled; a fourth voltage blocking device, electrically connected between the normally-on gate of the third bidirectional switch and the first source of the second bidirectional switch, and configured to block a portion of the voltage across the switching device when the stacking device is disconnected; and a fourth overvoltage protection device, configured to disconnect the normally-on gate of the third bidirectional switch when the second normally-on gate of the second bidirectional switch is disconnected, so that the normally-on gate of the third bidirectional switch is passively controlled through the second normally-on gate of the second bidirectional switch.

[0006] According to another embodiment of the switching device, the switching device includes: a first normally-off switch; a second normally-off switch; at least two bidirectional switches, electrically connected between the first normally-off switch and the second normally-off switch in a stacked configuration, each bidirectional switch including a first normally-on gate and a second normally-on gate; a voltage blocking device, electrically connected to one of the normally-on gates of each bidirectional switch, and configured to block a portion of the voltage across the switching device when the switching device is disconnected; a first overvoltage protection device, configured to disconnect the first normally-on gate of each bidirectional switch when the first normally-off switch is disconnected, so that the first normally-on gate of each bidirectional switch is passively controlled by the first normally-off switch; and a second overvoltage protection device, configured to disconnect the second normally-on gate of each bidirectional switch when the second normally-off switch is disconnected, so that the second normally-on gate of each bidirectional switch is passively controlled by the second normally-off switch.

[0007] According to another embodiment of the switching device, the switching device includes: at least two bidirectional switches, which are electrically connected in a stacked configuration, wherein a first bidirectional switch and a second bidirectional switch of the at least two bidirectional switches each have a normally-on gate and a normally-off gate, wherein any remaining bidirectional switch of the at least two bidirectional switches stacked between the first bidirectional switch and the second bidirectional switch has a first normally-on gate and a second normally-on gate, wherein the switching device is actively controlled by the normally-off gate of the first bidirectional switch and the normally-off gate of the second bidirectional switch, wherein each normally-on gate of the at least two bidirectional switches is electrically connected to a source of another bidirectional switch of the at least two bidirectional switches by a voltage blocking device, and the voltage blocking device is configured to block a portion of the voltage across the switching device when the switching device is disconnected.

[0008] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The elements of the drawings are not necessarily drawn to scale relative to each other. Like reference numerals designate corresponding similar parts. The features of the various illustrated embodiments may be combined unless they exclude each other. The embodiments are depicted in the drawings and detailed in the following description.

[0010] Figure 1A A circuit diagram of an embodiment of a unidirectional stacking switch device is shown.

[0011] Figure 1B The circuit diagram of FIG. 1 is shown with superimposed voltages at different nodes of the circuit.

[0012] Figure 2A and 2B Corresponding waveform diagrams of the voltage and load current shown in FIG. 1 are illustrated during operation of the switching device of FIG. 1 .

[0013] Figure 3 The unidirectional stacked switch device of FIG. 1 is shown with stray inductance.

[0014] Figure 4 Graphical Mitigation Figure 3 A circuit schematic diagram of an embodiment of a stray inductance circuit is shown in FIG.

[0015] Figure 5 Graphical Mitigation Figure 3 A circuit schematic diagram of another embodiment of a stray inductance circuit is shown in FIG.

[0016] Figure 6 FIG. 2 is a circuit diagram of another embodiment of a unidirectional stacking switch device.

[0017] Figure 7 The picture is Figure 6 Waveform diagram of voltage and load current during operation of the switching device.

[0018] Figure 8 FIG. 1 is a circuit diagram of an embodiment of a bidirectional stacked switch device based on an asymmetric bidirectional switch.

[0019] Fig. 9 A circuit diagram of an embodiment of a bidirectional stacked switch device based on a pair of asymmetric bidirectional switches and at least one symmetric bidirectional switch is shown.

[0020] Fig.10 A circuit schematic diagram of an embodiment based on a symmetric bidirectional bidirectional stacked switch device stacked between low voltage MOS switch devices in a stacked configuration is shown. DETAILED DESCRIPTION

[0021] Embodiments described herein provide 1.2 kV or higher rated switch devices implemented using discrete and / or bidirectional switch devices having lower (<1.2 kV) breakdown voltages while maintaining the same number of active gates as a single high voltage device and using the entire device in terms of voltage blocking and current conduction. In the case of a 1.2 kV rated switch device, the discrete and / or bidirectional switch device used to implement the switch device has a breakdown voltage of 650 V. However, the embodiments described herein may be applied to voltage levels other than 650 V, and the resulting switch device may have a blocking voltage greater than 1.2 kV. More generally, the switch devices disclosed herein may have a breakdown voltage of at least 1.2 kV, and depending on the number of devices arranged in a stacked configuration, may be implemented using discrete and / or bidirectional switch devices having a breakdown voltage of up to half of the breakdown voltage of the switch device.

[0022] Next, exemplary embodiments of the switch device are described with reference to the accompanying drawings.

[0023] Figure 1A An embodiment of a switch device 100 is shown. According to this embodiment, the switch device 100 is a unidirectional stacked discrete device based on: a first power transistor die (chip) 102, including a normally-on (i.e., depletion mode) transistor Q1; and a second power transistor die 104, including a normally-off (i.e., enhancement mode) transistor Q2. Both the normally-on transistor Q1 and the normally-off transistor Q2 have at most half of the maximum rated drain-to-source (D-to-S) voltage of the switch device 100.

[0024] For the normally-on transistor Q1, in the absence of any voltage applied to the gate terminal G1 of the normally-on transistor Q1, a current conduction channel exists between the drain and source terminals D1, S1 of the normally-on transistor Q1. For the normally-off transistor Q2, in the absence of a suitable voltage applied to the gate terminal G2 of the normally-off transistor Q2, a current conduction channel does not exist between the drain and source terminals D2, S2 of the normally-off transistor Q2.

[0025] In one embodiment, the normally-on transistor Q1 is a normally-on GaN transistor, the normally-off transistor Q2 is a normally-off GaN transistor, and the maximum rated drain-to-source voltage of the switching device 100 is 1.2 kV. In GaN technology, the polarization difference between the GaN channel layer and the AlGaN barrier layer produces a 2-dimensional (2D) "sheet" of uncompensated charge. The 2D charge sheet is usually positive and causes a 2D electron gas to be formed even in the absence of doping. Therefore, GaN devices are often normally-on devices unless additional device engineering techniques (such as doping with acceptor barriers, gate engineering, etc.) are applied to make the device normally-off.

[0026] The drain D2 of the normally-off transistor Q2 is electrically connected to the source S1 of the normally-on transistor Q1 to form a cascaded device. According to this configuration, the drain D1 of the normally-on transistor Q1 forms the drain D of the cascaded switch device 100, and the source S2 of the normally-off transistor Q2 forms the source S of the cascaded switch device 100. The cascaded switch device 100 has a single actively controlled (driven) gate G, which is formed by the gate G2 of the normally-off transistor Q2.

[0027] In order to maximize the use of the two transistor devices Q1, Q2, Figure 1A The switch device 100 in further includes a voltage blocking device 106 electrically connected between the gate G1 of the normally-on transistor Q1 and the source S2 of the normally-off transistor Q2. When the stacked device formed by Q1 and Q2 is disconnected, the voltage blocking device 106 blocks a portion of the drain-to-source voltage "VDS" across the switch device 100. In one embodiment, the voltage blocking device 106 is a capacitor C1 having: a first terminal 108 electrically connected to the gate G1 of the normally-on transistor Q1; and a second terminal 110 electrically connected to the source S2 of the normally-off transistor Q2. If the transistors Q1 and Q2 are rated for 650V, the voltage blocking capacitor C1 may be in the pF range.

[0028] Figure 1A The switch device 100 in the embodiment further comprises: an overvoltage protection device 112, which protects the gate G1 of the normally-on transistor Q1 from an overvoltage condition in the negative direction when the normally-off transistor Q2 is disconnected. When the normally-off transistor Q2 is disconnected, the overvoltage protection device 112 disconnects the normally-on transistor Q1, so that the stacked device formed by Q1 and Q2 is actively controlled only by the gate G2 of the normally-off transistor Q2. Therefore, only the normally-off gate G2 is actively controlled (driven) to control the stacked structure, and synchronous driving of the normally-on gate G1 is not required.

[0029] In one embodiment, the overvoltage protection device 112 includes one or more diodes connected in series between the gate G1 of the normally-on transistor Q1 and the source S1 of the normally-on transistor Q1. The number of diodes depends on the total forward voltage of the overvoltage protection device 112, which should be greater than the negative threshold voltage of the normally-on transistor Q1 in an absolute sense to turn off the normally-on transistor Q1. Therefore, the overvoltage protection device 112 may include a single diode having: an anode AN1 electrically connected to the source S1 of the normally-on transistor Q1; and a cathode CTN electrically connected to the gate G1 of the normally-on transistor Q1. In the case of multiple diodes connected in series, for example, Figure 1AAs shown in , the anode AN1 of the first diode in the series chain is electrically connected to the source S1 of the normally-on transistor Q1, and the cathode CTN of the last diode in the series chain is electrically connected to the gate G1 of the normally-on transistor Q1. For example, the diode(s) (e.g., the ESD (electrostatic discharge) structures(s)) may be monolithically integrated with the normally-on transistor Q1 in the same die 102.

[0030] Figure 1B Shown are a drain-to-source voltage “VDS” of the switching device 100 , a voltage “VM” across the normally-off transistor Q2 , and a gate-to-source voltage “NONVGS” of the normally-on transistor Q1 . Figure 2A is a plot of these voltages and the load current IL during operation of the switching device 100. In this example, when the switching device 100 is open (blocking), VDS is 1.2 kV.

[0031] like Figure 2A As shown in , when the normally-off transistor Q2 is turned off by actively reducing the gate-to-source voltage applied to gate G2 to below the threshold voltage of Q2, the voltage "VM" across the normally-off transistor Q2 and the drain-to-source voltage "VDS" of the switching device 100 both begin to rise. As the voltage "VM" across the normally-off transistor Q2 rises, the voltage across the overvoltage protection device 112 also rises. Eventually, the voltage across the overvoltage protection device 112 rises high enough so that the gate-to-source voltage "NONVGS" of the normally-on transistor Q1 reaches the negative threshold voltage (in this example, -6V), and the normally-on transistor Q1 is safely turned off before experiencing an overvoltage condition.

[0032] The distribution of the drain-to-source voltage "VDS" of the switching device 100 is controlled by the value of the voltage blocking device 106. How fast the voltage across the overvoltage protection device 112 rises determines when the normally-on transistor Q1 turns off. This speed depends on the size of the capacitor C1. The choice of capacitor size also affects the voltage "VM" across the normally-off transistor Q2, as shown in FIG. Figure 2B As shown in Figure 2B In FIG. 1 , C1 = 14 pF produces VM1 of about 560 V, C2 = 17 pF produces VM2 of about 610 V, and C3 = 20 pF produces VM3 of about 670 V. In each case, when the normally-off transistor Q2 turns off, the gate-to-source voltage “NONVGS” of the normally-on transistor Q1 goes negative and turns off the normally-on transistor Q1.

[0033] Although the distribution of the voltage across the stacked structure formed by transistors Q1 and Q2 can be modified based on a single parameter (the value of C1), the stability of this value must be carefully considered in order to achieve stable performance. Figure 1AThe stacked structure shown in FIG. 1 uses two individual (discrete) dies 102 , 104 , so additional parasitic effects will exist due to the inter-die connections required to form the switch device 100 .

[0034] One parasitic effect that affects the switching performance is the stray inductance “Lp” between the gate G1 of the normally-on transistor Q1 and the capacitor C1 of the voltage blocking device 106, such as Figure 3 This stray inductance "Lp" can create oscillations which may require further protection of the gate G1 of the normally-on transistor Q1.

[0035] Figure 4 The illustrated embodiment, according to which an additional diode D_AP (such as an anti-parallel ESD diode) is electrically connected between the gate G1 of the normally-on transistor Q1 and the source S1 of the normally-on transistor Q1, and is anti-parallel to the diode(s) of the overvoltage protection device 112. The cathode CD2 of the additional diode D_AP is electrically connected to the anode AN1 of the first diode of the overvoltage protection device 112, and the anode AD2 of the additional diode D_AP is electrically connected to the cathode CTN of the last diode of the overvoltage protection device 112.

[0036] Figure 5 An illustrated embodiment is shown, according to which the capacitor C1 of the voltage blocking device 106 is replaced by another component with capacitive behavior. This component should block 650V for the 1.2 kV example and have sufficient capacitance for this function. For example, the component with capacitive behavior can be a gate-controlled diode device MGD1, such as a MOS gate-controlled diode. The gate-controlled diode device MGD1 has: a drain D3, which is electrically connected to the gate G1 of the normally-on transistor Q1. The gate G3 and the source S3 of the gate-controlled diode device MGD1 are both electrically connected to the source S2 of the normally-off transistor Q2. The gate-controlled diode device MGD1 can be integrated with the normally-off transistor Q2 in the same die 104, thereby reducing Figure 3 This may be due to the nonlinearity of the output capacitance of the gate controlled diode device MGD1.

[0037] Figure 6 Another embodiment of a unidirectional stacked discrete switch device 100 is shown. Figure 6 In FIG. 1 , the stacked configuration is extended to include a third power transistor die 114, which includes an additional normally-on transistor Q3. The source S3 of the additional normally-on transistor Q3 is electrically connected to the drain D1 of the first normally-on transistor Q1.

[0038] The additional voltage blocking device 116 is electrically connected between the gate G3 of the additional normally-on transistor Q3 and the source S1 of the first normally-on transistor Q1, for blocking a portion of the voltage across the switching device 100 when the stacking device is disconnected. In one embodiment, the additional voltage blocking device 116 is a capacitor C2 having: a first terminal 118 electrically connected to the gate G3 of the additional normally-on transistor Q3; and a second terminal 120 electrically connected to the source S1 of the first normally-on transistor Q1. The distribution of the drain-to-source voltage of the switching device 100 is controlled by the respective values ​​of the voltage blocking devices 106, 116, as previously described herein, and may be in the pF range for the rated 650V transistors Q1, Q2, Q3. In another embodiment, the additional voltage blocking device 116 is a gate-controlled diode device, such as Figure 5 In this case, the drain of the gated diode arrangement is electrically connected to the gate G3 of the additional normally-on transistor Q3 and both the gate and the source of the gated diode arrangement are electrically connected to the source S1 of the first normally-on transistor Q1.

[0039] In order to ensure that the additional normally-on transistor Q3 is protected from overvoltage conditions in the negative direction when the first normally-on transistor Q1 is disconnected, an additional overvoltage protection device 118 is provided. When the first normally-on transistor Q1 is disconnected, the additional overvoltage protection device 118 disconnects the additional normally-on transistor Q3 so that the cascade formed by the transistors Q1, Q2 and Q3 is actively controlled only through the gate G2 of the normally-off transistor Q2. In one embodiment, the additional overvoltage protection device 118 includes one or more diodes connected in series between the gate G3 of the additional normally-on transistor Q3 and the source S3 of the additional normally-on transistor Q3. The number of diodes depends on the total forward voltage of the additional overvoltage protection device 118, as explained above.

[0040] The anode AN1_b of the first diode of the additional overvoltage protection device 122 is electrically connected to the source S3 of the additional normally-ON transistor Q3. The cathode CTN_b of the last diode of the additional overvoltage protection device 122 is electrically connected to the gate G3 of the additional normally-ON transistor Q3. If a single diode provides the desired total forward voltage of the additional overvoltage protection device 122, the first diode and the last diode may be the same diode, or alternatively, the first diode and the last diode are different diodes electrically connected in series.

[0041] The additional diode may be electrically connected between the gate G3 of the additional normally-on transistor Q3 and the source S3 of the additional normally-on transistor Q3 and in anti-parallel with the diode(s) of the additional overvoltage protection device 122, for example, Figure 4This is shown for the first normally-on transistor Q1 to prevent stray inductances which could otherwise create oscillations at the gate G3 of the additional normally-on transistor Q3.

[0042] Figure 7 Diagram Figure 6 The simulation waveform of the unidirectional stacked discrete switch device 100 is shown in FIG. Figure 7 , "VDS3" is the fully blocked voltage of the switch device 100 switching at 1.8 kV in the basic chopper primitive configuration, "VDS2" is the voltage across the first normally-on transistor Q1 blocked at approximately 1.2 kV, and "VDS1" is the voltage across the normally-off transistor Q2. Figure 7 As shown in FIG. 1 , the gate-to-source voltage “NONVGS2” of the first normally-on transistor Q1 and the gate-to-source voltage “NONVGS3” of the additional normally-on transistor Q3 are almost completely synchronized to disconnect the entire cascade chain. Figure 6 The load current “IL” provided by the switching device 100 is also shown in Figure 7 middle.

[0043] In such Figure 6 In the case where the three transistors Q1, Q2, Q3 shown in the figure form a stacked structure, each transistor Q1, Q2, Q3 may have at most one-third (1 / 3) of the maximum rated drain-to-source voltage of the switching device 100. For example, if each transistor Q1, Q2, Q3 has a drain-to-source breakdown voltage of 650V, the switching device 100 will have a drain-to-source breakdown voltage of 1.95kV. The unidirectional stacked discrete switch device embodiments shown in Figures 1 and 6 can be summarized as a normally-off transistor stacked with N normally-on transistors and with a voltage blocking device and an overvoltage protection device of each normally-on transistor, where N is a positive integer ≥ 1. The breakdown voltage X_Q of each transistor forming the stacked switch device is given by X_Q=X_SW / (N+1), where X_SW is the breakdown voltage of the entire stacked switch device. For a single normally-on transistor stacked with a normally-off transistor as shown in Figure 1, X_Q=1 / 2*X_SW. For Figure 6 As shown in FIG. , two normally-on transistors are stacked with a normally-off transistor, X_Q=1 / 3*X_SW, and so on.

[0044] Next, an embodiment of a bidirectional stacked switch device based on a symmetrical and / or asymmetrical bidirectional switch is described. The solid-state bidirectional switch has a first source terminal, a second source terminal, a compound semiconductor substrate (such as, for example, a GaN substrate), a common drift region located in the compound semiconductor substrate and connected in series between the two source terminals, a first gate, and a second gate. In the case of a symmetrical bidirectional switch, both gates are normally-on gates. In the case of an asymmetrical bidirectional switch, one gate is a normally-on gate (i.e., depletion mode) and the other gate is a normally-off gate (i.e., enhancement mode). For a normally-on gate, a current conduction channel exists near the gate in the absence of any voltage applied to the gate. For a normally-off gate, a current conduction channel does not exist near the gate in the absence of a suitable voltage applied to the gate.

[0045] Figure 8 The figure shows an embodiment of a bidirectional stacked switch device 200 based on asymmetric bidirectional switches BDSA and BDSB. The first asymmetric bidirectional switch BDSA includes a first source S1A, a second source S2A, a normally-off gate G1A, and a normally-on gate G2A. The second asymmetric bidirectional switch BDSB includes: a first source S1B, electrically connected to the second source S2A of the first asymmetric bidirectional switch BDSA to form a stacked device; a second source S2B; a normally-off gate G2B; and a normally-on gate G1B.

[0046] The asymmetric bidirectional switches BDSA, BDSB may be provided as discrete die 202, 204. For example, a first asymmetric bidirectional switch BDSA may be included in a first GaN die 202 and have at most half (1 / 2) of the maximum rated source-to-source (S2B to S1A) voltage of the bidirectional stacked switch device 200. A second asymmetric bidirectional switch BDSB may be included in a second GaN die 204 and have at most half (1 / 2) of the maximum rated source-to-source voltage of the bidirectional stacked switch device 200. For example, the maximum rated source-to-source voltage of the bidirectional stacked switch device 200 may be 1.2 kV or higher. The asymmetric bidirectional switches BDSA, BDSB may alternatively be monolithically integrated in the same die. In either case, the common drift regions / compound semiconductor substrates SUB1, SUB2 of the asymmetric bidirectional switches BDSA, BDSB are electrically isolated from each other to ensure that each asymmetric bidirectional switch BDSA, BDSB can safely block its own individual voltage.

[0047] The bidirectional stacked switch device 200 further includes: a first voltage blocking device 206 electrically connected between the first source S1A of the first asymmetric bidirectional switch BDSA and the normally-on gate G1B of the second asymmetric bidirectional switch BDSB. When the stacked device is disconnected, the first voltage blocking device 206 blocks a portion of the voltage across the bidirectional stacked switch device 200. When the normally-off gate G2B of the second asymmetric bidirectional switch BDSB is disconnected, the first overvoltage protection device DA disconnects the normally-on gate G2A of the first asymmetric bidirectional switch BDSA, so that the normally-on gate G2A of the first asymmetric bidirectional switch BDSA is passively controlled through the normally-off gate G2B of the second asymmetric bidirectional switch BDSB.

[0048] The bidirectional stacked switch device 200 further includes: a second voltage blocking device 208 electrically connected between the second source S2B of the second asymmetric bidirectional switch BDSB and the normally-on gate G2A of the first asymmetric bidirectional switch BDSA. When the stacked device is disconnected, the second voltage blocking device 208 blocks a portion of the voltage across the bidirectional stacked switch device 200. When the normally-off gate G1A of the first asymmetric bidirectional switch BDSA is disconnected, the second overvoltage protection device DB disconnects the normally-on gate G1B of the second asymmetric bidirectional switch BDSB, so that the normally-on gate G1B of the second asymmetric bidirectional switch BDSB is passively controlled by the normally-off gate G1A of the first asymmetric bidirectional switch BDSA. Therefore, only the normally-off gates G1A and G2B of the asymmetric bidirectional switches BDSA and BDSB are actively controlled (driven) to operate the bidirectional stacked switch device 200.

[0049] In an embodiment, the first voltage blocking device 206 is a first capacitor CA having: a first terminal 210 electrically connected to the first source S1A of the first asymmetric bidirectional switch BDSA; and a second terminal 212 electrically connected to the normally-on gate G1B of the second asymmetric bidirectional switch BDSB. Similarly, the second voltage blocking device 208 may be a second capacitor CB having: a first terminal 214 electrically connected to the second source S2B of the second asymmetric bidirectional switch BDSB; and a second terminal 216 electrically connected to the normally-on gate G2A of the first asymmetric bidirectional switch BDSA.

[0050] In an embodiment, the first overvoltage protection device DA includes one or more first diodes connected in series between the normally-on gate G2A of the first asymmetric bidirectional switch BDSA and the second source S2A of the first asymmetric bidirectional switch BDSA. The anode AN1_DA of the first diode of the first overvoltage protection device DA is electrically connected to the second source S2A of the first asymmetric bidirectional switch BDSA, and the cathode CTN_DA of the last diode of the first overvoltage protection device DA is electrically connected to the normally-on gate G2A of the first asymmetric bidirectional switch BDSA. Similarly, the second overvoltage protection device DB may include one or more second diodes connected in series between the normally-on gate G1B of the second asymmetric bidirectional switch BDSB and the first source S1B of the second asymmetric bidirectional switch BDSB. The anode AN2_DA of the first diode of the second overvoltage protection device DB is electrically connected to the first source S1B of the second asymmetric bidirectional switch BDSB, and the cathode of the last diode of the second overvoltage protection device DB is electrically connected to the normally-on gate G1B of the second asymmetric bidirectional switch BDSB. The number of diodes included in each overvoltage protection device DA, DB depends on the desired total forward voltage, as explained above.

[0051] Figure 8 The two stacked asymmetric bidirectional switches BDSA, BDSB in are used to block the entire (e.g., 1.2 kV) source-to-source voltage of the bidirectional stacked switch device 200, always using 100% of the two devices BDSA, BDSB. In addition, only two active gates G1A, G2B are required to fully operate the bidirectional stacked switch device 200. The bidirectional stacked switch device scheme can be further expanded to provide higher blocking voltage capabilities, as described in more detail below.

[0052] Fig. 9 An embodiment of a bidirectional stacked switch device 300 is shown, which is based on a pair of asymmetric bidirectional switches BDSA, BDSB and at least one symmetric bidirectional switch BDSC. Fig. 9 The asymmetric bidirectional switches BDSA and BDSB have the same Figure 8 The source and gate configurations described above are identical to the source and gate configurations described above. At least one symmetrical bidirectional switch BDSC is electrically connected between the pair of asymmetrical bidirectional switches BDSA, BDSB in a stacked configuration.

[0053] More specifically, the symmetrical bidirectional switch BDSC has: a first source S1C electrically connected to a second source S2A of a first asymmetrical bidirectional switch BDSA to form a first part of the stacked arrangement; and a second source S2C electrically connected to a first source S1B of a second asymmetrical bidirectional switch BDSB to form a second part of the stacked arrangement. The symmetrical bidirectional switch BDSC also has: a first normally-on gate G1C and a second normally-on gate G2C, neither of which is actively controlled (driven).

[0054] The first voltage blocking device 302 is electrically connected between the first source S1A of the first asymmetric bidirectional switch BDSA and the first normally-on gate G1C of the symmetric bidirectional switch BDSC. When the stacking device is disconnected, the first voltage blocking device 302 blocks a portion of the source-to-source (S2B to S1A) voltage across the switch device 300. When the normally-off gate G1A of the first asymmetric bidirectional switch BDSA is disconnected, the first overvoltage protection device DC1 disconnects the first normally-on gate G1C of the symmetric bidirectional switch BDSC, so that the first normally-on gate G1C of the symmetric bidirectional switch BDSC is passively controlled through the normally-off gate G1A of the first asymmetric bidirectional switch BDSA.

[0055] The second voltage blocking device 304 is electrically connected between the first source S1B of the second asymmetric bidirectional switch BDSB and the normally-on gate G2A of the first asymmetric bidirectional switch BDSA. When the stacking device is disconnected, the second voltage blocking device 304 blocks a portion of the source-to-source (S2B to S1A) voltage across the switch device 300. When the first normally-on gate G1C of the symmetric bidirectional switch BDSC is disconnected, the second overvoltage protection device DA disconnects the normally-on gate G2A of the first asymmetric bidirectional switch BDSA.

[0056] The third voltage blocking device 306 is electrically connected between the second source S2B of the second asymmetric bidirectional switch BDSB and the second normally-on gate G2C of the symmetric bidirectional switch BDSC. When the stacking device is disconnected, the third voltage blocking device 306 blocks a portion of the source-to-source (S2B to S1A) voltage across the switch device 300. When the normally-off gate G2B of the second asymmetric bidirectional switch BDSB is disconnected, the third overvoltage protection device DC2 disconnects the second normally-on gate G2C of the symmetric bidirectional switch BDSC, so that the second normally-on gate G2C of the symmetric bidirectional switch BDSC is passively controlled through the normally-off gate G2B of the second asymmetric bidirectional switch BDSB.

[0057] The fourth voltage blocking device 308 is electrically connected between the normally-on gate G1B of the second asymmetric bidirectional switch BDSB and the first source S1C of the symmetric bidirectional switch BDSC. When the stacking device is disconnected, the fourth voltage blocking device 308 blocks a portion of the source-to-source (S2B to S1A) voltage across the switch device 300. When the second normally-on gate G2C of the symmetric bidirectional switch BDSC is disconnected, the fourth overvoltage protection device DB disconnects the normally-on gate G1B of the second asymmetric bidirectional switch BDSB, so that the normally-on gate G1B of the second asymmetric bidirectional switch BDSB is passively controlled by the second normally-on gate G2C of the symmetric bidirectional switch BDSC.

[0058] According to an embodiment, each voltage blocking device 302, 304, 306, 308 is implemented as a capacitor. For example, the first voltage blocking device 302 may be a first capacitor CA having: a first terminal 310 electrically connected to a first source S1A of a first asymmetric bidirectional switch BDSA; and a second terminal 312 electrically connected to a first normally-on gate G1C of a symmetric bidirectional switch BDSC. The second voltage blocking device 304 may be a second capacitor CB having: a first terminal 314 electrically connected to a first source S1B of a second asymmetric bidirectional switch BDSB; and a second terminal 316 electrically connected to a normally-on gate G2A of the first asymmetric bidirectional switch BDSA. The third voltage blocking device 306 may be a third capacitor CC having: a first terminal 318 electrically connected to a second source S2B of a second asymmetric bidirectional switch BDSB; and a second terminal 320 electrically connected to a second normally-on gate G2C of a symmetric bidirectional switch BDSC. The fourth voltage blocking device 308 may be a fourth capacitor CD having a first terminal 322 electrically connected to the normally-on gate G1B of the second asymmetric bidirectional switch BDSB and a second terminal 324 electrically connected to the second source S2A of the first asymmetric bidirectional switch BDSA.

[0059] According to an embodiment, each overvoltage protection device DA, DB, DC1, DC2 is implemented as a diode chain. For example, the first overvoltage protection device DA may include a first diode connected in series between the normally-on gate G2A of the first asymmetric bidirectional switch BDSA and the second source S2A of the first asymmetric bidirectional switch BDSA. The anode AN1_DA of the first diode of the first overvoltage protection device DA is electrically connected to the second source S2A of the first asymmetric bidirectional switch BDSA, and the cathode CTN_DA of the last diode of the first overvoltage protection device DA is electrically connected to the normally-on gate G2A of the first asymmetric bidirectional switch BDSA.

[0060] The second overvoltage protection device DC1 may include a second diode connected in series between a first normally-on gate G1C of the symmetrical bidirectional switch BDSC and a first source S1C of the symmetrical bidirectional switch BDSC. An anode AN1_DC1 of the first diode of the second overvoltage protection device DC1 is electrically connected to the first source S1C of the symmetrical bidirectional switch BDSC, and a cathode CTN_DC1 of the last diode of the second overvoltage protection device DC1 is electrically connected to the first normally-on gate G1C of the symmetrical bidirectional switch BDSC.

[0061] The third overvoltage protection device DC2 may include a third diode connected in series between the second normally-on gate G2C of the symmetrical bidirectional switch BDSC and the second source S2C of the symmetrical bidirectional switch BDSC. An anode AN1_DC2 of the first diode of the third overvoltage protection device DC2 is electrically connected to the second source S2C of the symmetrical bidirectional switch BDSC, and a cathode CTN_DC2 of the last diode of the third overvoltage protection device DC2 is electrically connected to the second normally-on gate G2C of the symmetrical bidirectional switch BDSC.

[0062] The fourth overvoltage protection device DB may include a fourth diode connected in series between the normally-on gate G1B of the second asymmetric bidirectional switch BDSB and the first source S1B of the second asymmetric bidirectional switch BDSB. The anode AN1_DB of the first diode of the fourth overvoltage protection device DB is electrically connected to the first source S1B of the second asymmetric bidirectional switch BDSB, and the cathode CTN_DB of the last diode of the fourth overvoltage protection device DB is electrically connected to the normally-on gate G1B of the second asymmetric bidirectional switch BDSB. More generally, the number of diodes included in each overvoltage protection device DA, DB, DC1, DC2 depends on the desired total forward voltage, as explained above.

[0063] form Fig. 9 The bidirectional switches BDSA, BDSB, BDSC of the stacked switch device 300 shown in FIG. 3 may be provided as discrete dies 326, 328, 330. For example, each bidirectional switch BDSA, BDSB, BDSC may be included in a separate GaN die 326, 328, 330 and have at most one-third (1 / 3) of the maximum rated source-to-source (S2B to S1A) voltage of the switch device 300. The maximum rated source-to-source (S2B to S1A) voltage of the switch device 300 may be, for example, 1.8 kV or higher.

[0064] More generally, the bidirectional stacked switch arrangement scheme uses at least two bidirectional switches electrically connected in a stacked configuration, a first bidirectional switch (e.g., Figure 8 and 9 BDSA in) and a second bidirectional switch (e.g., Figure 8 and 9 The BDSB in each of the at least two bidirectional switches stacked between the first bidirectional switch and the second bidirectional switch each has a normally-on gate and a normally-off gate. Figure 8 and 9 The BDSC in the embodiment has a first normally-on gate and a second normally-on gate. The normally-off gate of the first bidirectional switch (e.g., Figure 8 and 9 G1A in) and the normally-off gate of the second bidirectional switch (e.g., Figure 8 and 9 The switching device is actively controlled by a voltage blocking device (e.g. Figure 8 and 9 CA, CB, CC and CD in the embodiment), each normally-on gate of the at least two bidirectional switches (e.g., Figure 8 and 9 G2A, G1B, G1C and G2C in the at least two bidirectional switches are electrically connected to the source of another bidirectional switch of the at least two bidirectional switches, and the voltage blocking device blocks the source-to-source voltage across the switching device when the switching device is turned off (for example, Figure 8 and 9 The voltage from S2B to S1A in the circuit is a portion of the voltage from S2B to S1A.

[0065] Next, an embodiment of a bidirectional stacked switch device based on a symmetric bidirectional switch and a low voltage (eg, 20V) MOS device is described.

[0066] Fig.10 An embodiment of a bidirectional stacked switch device 400 is shown, which is based on symmetrical bidirectional BDSX, BDSY stacked between low voltage MOS switch devices LV1, LV2 in a stacked configuration. The low voltage MOS switch devices LV1, LV2 are normally-off switches because both low voltage MOS switch devices LV1, LV2 are enhancement mode devices. Fig.10 The normally-off MOS switch devices LV1, LV2 in are referred to as "low voltage" because they have a lower breakdown voltage (e.g., 20V) compared to, for example, the symmetrical bidirectional switches BDSX, BDSY, which may be 650V rated GaN devices.

[0067] The at least two bidirectional switches BDSX, BDSY are electrically connected between a first normally-off MOS switch device LV1 and a second normally-off MOS switch device LV2 in a stacked configuration. Each bidirectional switch BDSX, BDSY has a first normally-on gate G1X, G1Y and a second normally-on gate G2X, G2Y. A first voltage blocking device 402 (such as a capacitor) is electrically connected to the second normally-on gate G2X of the first bidirectional switch BDSX and blocks a portion of the drain-to-source (DLV2 to SLV1) voltage across the switch device 400 when the switch device 400 is turned off. A second voltage blocking device 404 (such as a capacitor) is electrically connected to the first normally-on gate G1Y of the second bidirectional switch BDSY and blocks a portion of the drain-to-source (DLV2 to SLV1) voltage across the switch device 400 when the switch device 400 is turned off.

[0068] When the first (lower) normally-off MOS switch device LV1 is disconnected, the first overvoltage protection device DX1 (such as a single diode or a diode chain) disconnects the first normally-on gate G1X of the first bidirectional switch BDSX, so that the first normally-on gate G1X of the first bidirectional switch BDSX is passively controlled by the first normally-off MOS switch device LV1 being disconnected.

[0069] When the first (lower) normally-off MOS switch device LV1 is disconnected, the second overvoltage protection device DY1 (such as a single diode or a diode chain) disconnects the first normally-on gate G1Y of the second bidirectional switch BDSY so that the first normally-on gate G1Y of the second bidirectional switch BDSY is passively controlled by the first normally-off MOS switch device LV1.

[0070] When the second (upper) normally-off MOS switch device LV2 is disconnected, the third overvoltage protection device DX2 (such as a single diode or a diode chain) disconnects the second normally-on gate G2X of the first bidirectional switch BDSX, so that the second normally-on gate G2X of the first bidirectional switch BDSX is passively controlled by the second normally-off MOS switch device LV2.

[0071] When the second (upper) normally-off MOS switch device LV2 is disconnected, the fourth overvoltage protection device DY2 (such as a single diode or a diode chain) disconnects the second normally-on gate G2Y of the second bidirectional switch BDSY, so that the second normally-on gate G2Y of the second bidirectional switch BDSY is passively controlled by the second normally-off MOS switch device LV2.

[0072] By cascading one or more additional bidirectional switches between the first (lower) and second (upper) low voltage MOS switch devices LV1, LV2, Fig.10The bidirectional stacked switch device scheme illustrated in the figure can be extended to provide a higher blocking voltage capability for the switch device 400. An additional voltage blocking device (such as a capacitor) is provided for each additional bidirectional switch to block a portion of the switch device drain to source (DLV2 to SLV1) voltage when the switch device 400 is disconnected. A first additional overvoltage protection device (such as a single diode or a diode chain) is provided for disconnecting the lower normally-on gate of each additional bidirectional switch when the first (lower) normally-off MOS switch device LV1 is disconnected, so that the lower normally-on gate of each additional bidirectional switch is passively controlled by the first normally-off MOS switch device LV1. A second additional overvoltage protection device (such as a single diode or a diode chain) is provided for disconnecting the upper normally-on gate of each additional bidirectional switch when the second (upper) normally-off MOS switch device LV2 is disconnected, so that the upper normally-on gate of each additional bidirectional switch is passively controlled by the second normally-off MOS switch device LV2.

[0073] Although the present disclosure is not limited in this regard, the following numbered examples demonstrate one or more aspects of the present disclosure.

[0074] Example 1. A switching device, comprising: a first power transistor die, comprising a normally-on transistor, the normally-on transistor having at most half of a maximum rated drain-to-source voltage of the switching device; a second power transistor die, comprising a normally-off transistor, the normally-off transistor having at most half of the maximum rated drain-to-source voltage of the switching device, wherein the drain of the normally-off transistor is electrically connected to the source of the normally-on transistor to form a stacked device; a voltage blocking device, electrically connected between the gate of the normally-on transistor and the source of the normally-off transistor, and configured to block a portion of the voltage across the switching device when the stacked device is disconnected; and an overvoltage protection device, configured to disconnect the normally-on transistor when the normally-off transistor is disconnected, so that the stacked device is actively controlled only through the gate of the normally-off transistor.

[0075] Example 2. The switch device of Example 1, wherein the normally-on transistor is a normally-on GaN transistor, wherein the normally-off transistor is a normally-off GaN transistor, and wherein the maximum rated drain-to-source voltage of the switch device is 1.2 kV or higher.

[0076] Example 3. The switch device of Example 1 or 2, wherein the voltage blocking device is a capacitor having a first terminal electrically connected to the gate of the normally-on transistor and a second terminal electrically connected to the source of the normally-off transistor.

[0077] Example 4. A switch device as described in Example 1 or 2, wherein the voltage blocking device is a gate-controlled diode device having: a drain electrically connected to the gate of the normally-on transistor; and a gate and a source both electrically connected to the source of the normally-off transistor.

[0078] Example 5. A switching device as described in any one of Examples 1 to 4, wherein the overvoltage protection device includes one or more diodes connected in series between the gate of the normally-on transistor and the source of the normally-on transistor, wherein an anode of a first diode of the one or more diodes is electrically connected to the source of the normally-on transistor, and wherein a cathode of a last diode of the one or more diodes is electrically connected to the gate of the normally-on transistor.

[0079] Example 6. The switching device as described in Example 5 further includes: an additional diode electrically connected between the gate of the normally-on transistor and the source of the normally-on transistor, and anti-parallel to the one or more diodes, so that the cathode of the additional diode is electrically connected to the anode of the first diode of the one or more diodes, and the anode of the additional diode is electrically connected to the cathode of the last diode of the one or more diodes.

[0080] Example 7. A switching device as described in any one of Examples 1 to 6, further comprising: a third power transistor die including an additional normally-on transistor having at most one-third of the maximum rated drain-to-source voltage of the switching device, wherein the source of the additional normally-on transistor is electrically connected to the drain of the normally-on transistor; an additional voltage blocking device electrically connected between the gate of the additional normally-on transistor and the source of the normally-on transistor and configured to block a portion of the voltage across the switching device when the stacking device is disconnected; and an additional overvoltage protection device configured to disconnect the additional normally-on transistor when the normally-on transistor is disconnected so that the stacking device is actively controlled only through the gate of the normally-off transistor.

[0081] Example 8. A switch device as described in Example 7, wherein the voltage blocking device is a capacitor having: a first terminal electrically connected to the gate of the normally-on transistor; and a second terminal electrically connected to the source of the normally-off transistor, and wherein the additional voltage blocking device is a capacitor having: a first terminal electrically connected to the gate of the additional normally-on transistor; and a second terminal electrically connected to the source of the normally-on transistor.

[0082] Example 9. A switch device as described in Example 7, wherein the voltage blocking device is a gate-controlled diode device, the gate-controlled diode device having: a drain electrically connected to the gate of the normally-on transistor; and a gate and a source, both electrically connected to the source of the normally-off transistor, and wherein the additional voltage blocking device is a gate-controlled diode device, the gate-controlled diode device having: a drain electrically connected to the gate of the additional normally-on transistor; and a gate and a source, both electrically connected to the source of the normally-on transistor.

[0083] Example 10. A switching device as described in any one of Examples 7 to 9, wherein the overvoltage protection device includes a first one or more diodes connected in series between the gate of the normally-on transistor and the source of the normally-on transistor, wherein an anode of a first diode of the first one or more diodes is electrically connected to the source of the normally-on transistor, wherein a cathode of a last diode of the first one or more diodes is electrically connected to the gate of the normally-on transistor, wherein the additional overvoltage protection device includes a second one or more diodes connected in series between the gate of the additional normally-on transistor and the source of the additional normally-on transistor, wherein an anode of a first diode of the second one or more diodes is electrically connected to the source of the additional normally-on transistor, and wherein a cathode of a last diode of the second one or more diodes is electrically connected to the gate of the additional normally-on transistor.

[0084] Example 11. The switching device as described in Example 10 further includes: a first additional diode electrically connected between the gate of the normally-on transistor and the source of the normally-on transistor, and anti-parallel to the first one or more diodes, so that the cathode of the first additional diode is electrically connected to the anode of the first diode of the first one or more diodes, and the anode of the first additional diode is electrically connected to the cathode of the last diode of the first one or more diodes; and a second additional diode electrically connected between the gate of the additional normally-on transistor and the source of the additional normally-on transistor, and anti-parallel to the second one or more diodes, so that the cathode of the second additional diode is electrically connected to the anode of the first diode of the second one or more diodes, and the anode of the second additional diode is electrically connected to the cathode of the last diode of the second one or more diodes.

[0085] Example 12. A switch device, comprising: a first bidirectional switch, comprising a first source, a second source, a normally-off gate, and a normally-on gate; a second bidirectional switch, comprising a first source, a second source, a normally-off gate, and a normally-on gate electrically connected to the second source of the first bidirectional switch to form a stacked device; a first voltage blocking device electrically connected between the first source of the first bidirectional switch and the normally-on gate of the second bidirectional switch, and configured to block a portion of the voltage across the switch device when the stacked device is disconnected; a first overvoltage protection device, configured to disconnect the first bidirectional switch when the normally-off gate of the second bidirectional switch is disconnected the normally-on gate of the first bidirectional switch, so that the normally-on gate of the first bidirectional switch is passively controlled through the normally-off gate of the second bidirectional switch; a second voltage blocking device, electrically connected between the second source of the second bidirectional switch and the normally-on gate of the first bidirectional switch, and configured to block a portion of the voltage across the switching device when the stacking device is disconnected; and a second overvoltage protection device, configured to disconnect the normally-on gate of the second bidirectional switch when the normally-off gate of the first bidirectional switch is disconnected, so that the normally-on gate of the second bidirectional switch is passively controlled through the normally-off gate of the first bidirectional switch.

[0086] Example 13. The switch device of Example 12, wherein the first bidirectional switch is included in a first GaN die and has at most half of a maximum rated source-to-source voltage of the switch device, wherein the second bidirectional switch is included in a second GaN die and has at most half of the maximum rated source-to-source voltage of the switch device, and wherein the maximum rated source-to-source voltage of the switch device is 1.2 kV or higher.

[0087] Example 14. A switch device as described in Example 12 or 13, wherein: the first voltage blocking device is a first capacitor, the first capacitor having: a first terminal electrically connected to the first source of the first bidirectional switch; and a second terminal electrically connected to the normally-on gate of the second bidirectional switch; and the second voltage blocking device is a second capacitor, the second capacitor having: a first terminal electrically connected to the second source of the second bidirectional switch; and a second terminal electrically connected to the normally-on gate of the first bidirectional switch.

[0088] Example 15. A switch device as described in any one of Examples 12 to 14, wherein: the first overvoltage protection device includes a first one or more diodes connected in series between the normally-on gate of the first bidirectional switch and the second source of the first bidirectional switch, wherein an anode of a first diode of the first one or more diodes is electrically connected to the second source of the first bidirectional switch, and wherein a cathode of a last diode of the first one or more diodes is electrically connected to the normally-on gate of the first bidirectional switch; and the second overvoltage protection device includes a second one or more diodes connected in series between the normally-on gate of the second bidirectional switch and the first source of the second bidirectional switch, wherein an anode of a first diode of the second one or more diodes is electrically connected to the first source of the second bidirectional switch, and wherein a cathode of a last diode of the second one or more diodes is electrically connected to the normally-on gate of the second bidirectional switch.

[0089] Example 16. A switch device, comprising: a first bidirectional switch, comprising a first source, a second source, a normally-off gate, and a normally-on gate; a second bidirectional switch, comprising a first source, a second source, a first normally-on gate, and a second normally-on gate electrically connected to the second source of the first bidirectional switch to form a first part of a stacked device; a third bidirectional switch, comprising a first source, a second source, a first normally-on gate, and a normally-off gate electrically connected to the second source of the second bidirectional switch to form a second part of the stacked device; a first voltage blocking device electrically connected between the first source of the first bidirectional switch and the second bidirectional switch; a first overvoltage protection device, configured to disconnect the first normally-on gate of the second bidirectional switch when the normally-off gate of the first bidirectional switch is disconnected, so that the first normally-on gate of the second bidirectional switch is passively controlled by the normally-off gate of the first bidirectional switch; a second voltage blocking device, electrically connected between the first source of the third bidirectional switch and the normally-on gate of the first bidirectional switch, and configured to block a portion of the voltage across the switch device when the stacking device is disconnected; a first overvoltage protection device, configured to disconnect the first normally-on gate of the second bidirectional switch when the normally-off gate of the first bidirectional switch is disconnected, so that the first normally-on gate of the second bidirectional switch is passively controlled by the normally-off gate of the first bidirectional switch; and a second voltage blocking device, electrically connected between the first source of the third bidirectional switch and the normally-on gate of the first bidirectional switch, and configured to block a portion of the voltage across the switch device when the stacking device is disconnected. a portion of the voltage across the switching device; a second overvoltage protection device, configured to disconnect the normally-on gate of the first bidirectional switch when the first normally-on gate of the second bidirectional switch is disconnected; a third voltage blocking device, electrically connected between the second source of the third bidirectional switch and the second normally-on gate of the second bidirectional switch, and configured to block a portion of the voltage across the switching device when the stacking device is disconnected; a third overvoltage protection device, configured to disconnect the second normally-on gate of the second bidirectional switch when the normally-off gate of the third bidirectional switch is disconnected, so that the second normally-on gate of the second bidirectional switch is passively controlled through the normally-off gate of the third bidirectional switch; a fourth voltage blocking device, electrically connected between the normally-on gate of the third bidirectional switch and the first source of the second bidirectional switch, and configured to block a portion of the voltage across the switching device when the stacking device is disconnected; and a fourth overvoltage protection device, configured to disconnect the normally-on gate of the third bidirectional switch when the second normally-on gate of the second bidirectional switch is disconnected, so that the normally-on gate of the third bidirectional switch is passively controlled through the second normally-on gate of the second bidirectional switch.

[0090] Example 17. The switching device of Example 16, wherein the first bidirectional switch is included in a first GaN die and has at most one-third of a maximum rated source-to-source voltage of the switching device, wherein the second bidirectional switch is included in a second GaN die and has at most one-third of the maximum rated source-to-source voltage of the switching device, wherein the third bidirectional switch is included in a third GaN die and has at most one-third of the maximum rated source-to-source voltage of the switching device, and wherein the maximum rated source-to-source voltage of the switching device is 1.8 kV or higher.

[0091] Example 18. A switch device as described in Example 16 or 17, wherein: the first voltage blocking device is a first capacitor, the first capacitor having: a first terminal electrically connected to the first source of the first bidirectional switch; and a second terminal electrically connected to the first normally-on gate of the second bidirectional switch; the second voltage blocking device is a second capacitor, the second capacitor having: a first terminal electrically connected to the first source of the third bidirectional switch; and a second terminal electrically connected to the normally-on gate of the first bidirectional switch; the third voltage blocking device is a third capacitor, the third capacitor having: a first terminal electrically connected to the second source of the third bidirectional switch; and a second terminal electrically connected to the second normally-on gate of the second bidirectional switch; and the fourth voltage blocking device is a fourth capacitor, the fourth capacitor having: a first terminal electrically connected to the normally-on gate of the third bidirectional switch; and a second terminal electrically connected to the second source of the first bidirectional switch.

[0092] Example 19. A switch device as described in any one of Examples 16 to 18, wherein: the first overvoltage protection device includes a first one or more diodes connected in series between the normally-on gate of the first bidirectional switch and the second source of the first bidirectional switch, wherein the anode of a first diode of the first one or more diodes is electrically connected to the second source of the first bidirectional switch, and wherein the cathode of a last diode of the first one or more diodes is electrically connected to the normally-on gate of the first bidirectional switch; the second overvoltage protection device includes a second one or more diodes connected in series between the first normally-on gate of the second bidirectional switch and the first source of the second bidirectional switch, wherein the anode of a first diode of the second one or more diodes is electrically connected to the first source of the second bidirectional switch, and wherein the cathode of a last diode of the second one or more diodes is electrically connected to the second bidirectional switch. the first normally-on gate of the second bidirectional switch; the third overvoltage protection device includes a third one or more diodes connected in series between the second normally-on gate of the second bidirectional switch and the second source of the second bidirectional switch, wherein an anode of a first diode of the third one or more diodes is electrically connected to the second source of the second bidirectional switch, and wherein a cathode of a last diode of the third one or more diodes is electrically connected to the second normally-on gate of the second bidirectional switch; and the fourth overvoltage protection device includes a fourth one or more diodes connected in series between the normally-on gate of the third bidirectional switch and the first source of the third bidirectional switch, wherein an anode of a first diode of the fourth one or more diodes is electrically connected to the first source of the third bidirectional switch, and wherein a cathode of a last diode of the fourth one or more diodes is electrically connected to the normally-on gate of the third bidirectional switch.

[0093] Example 20. A switching device, comprising: a first normally-off switch; a second normally-off switch; at least two bidirectional switches electrically connected between the first normally-off switch and the second normally-off switch in a stacked configuration, each bidirectional switch comprising a first normally-on gate and a second normally-on gate; a voltage blocking device electrically connected to one of the normally-on gates of each bidirectional switch and configured to block a portion of the voltage across the switching device when the switching device is disconnected; a first overvoltage protection device configured to disconnect the first normally-on gate of each bidirectional switch when the first normally-off switch is disconnected, so that the first normally-on gate of each bidirectional switch is passively controlled by the first normally-off switch; and a second overvoltage protection device configured to disconnect the second normally-on gate of each bidirectional switch when the second normally-off switch is disconnected, so that the second normally-on gate of each bidirectional switch is passively controlled by the second normally-off switch.

[0094] Example 21. A switching device, comprising: at least two bidirectional switches electrically connected in a stacked configuration, wherein a first bidirectional switch and a second bidirectional switch of the at least two bidirectional switches each have a normally-on gate and a normally-off gate, wherein any remaining bidirectional switch of the at least two bidirectional switches stacked between the first bidirectional switch and the second bidirectional switch has a first normally-on gate and a second normally-on gate, wherein the switching device is actively controlled by the normally-off gate of the first bidirectional switch and the normally-off gate of the second bidirectional switch, wherein each normally-on gate of the at least two bidirectional switches is electrically connected to a source of another bidirectional switch of the at least two bidirectional switches by a voltage blocking device, the voltage blocking device being configured to block a portion of the voltage across the switching device when the switching device is open.

[0095] As used herein, the terms "having," "containing," "including," "comprising," and the like are open-ended terms that indicate the presence of stated elements or features but do not exclude additional elements or features. The articles "a," "an," and "the" are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

[0096] It should be understood that the features of the various embodiments described herein may be combined with each other, unless specifically noted otherwise.

[0097] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that various alternatives and / or equivalent implementations may replace the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptation or variation of the specific embodiments discussed herein. Therefore, it is intended that the present invention be limited only by the claims and their equivalents.

Claims

1. A switch device, comprising: a first power transistor die comprising a normally-on transistor having at most half the maximum rated drain-to-source voltage of the switching device; a second power transistor die including a normally-off transistor having at most half the maximum rated drain-to-source voltage of the switching device, wherein the drain of the normally-off transistor is electrically connected to the source of the normally-on transistor to form a cascaded device; a voltage blocking device electrically connected between the gate of the normally-on transistor and the source of the normally-off transistor and configured to block a portion of the voltage across the switching device when the stacking device is open; and An overvoltage protection device is configured to disconnect the normally-on transistor when the normally-off transistor is turned off, so that the stacking device is actively controlled only through the gate of the normally-off transistor.

2. The switching device of claim 1, wherein the normally-on transistor is a normally-on GaN transistor, wherein the normally-off transistor is a normally-off GaN transistor, and wherein the maximum rated drain-to-source voltage of the switching device is 1.2 kV or higher.

3. The switching device of claim 1, wherein the voltage blocking device is a capacitor having: a first terminal electrically connected to the gate of the normally-on transistor; and a second terminal electrically connected to the source of the normally-off transistor.

4. A switching device as described in claim 1, wherein the voltage blocking device is a gate-controlled diode device, and the gate-controlled diode device has: a drain, which is electrically connected to the gate of the normally-on transistor; and a gate and a source, both of which are electrically connected to the source of the normally-off transistor.

5. A switching device as described in claim 1, wherein the overvoltage protection device includes one or more diodes connected in series between the gate of the normally-on transistor and the source of the normally-on transistor, wherein an anode of a first diode of the one or more diodes is electrically connected to the source of the normally-on transistor, and wherein a cathode of a last diode of the one or more diodes is electrically connected to the gate of the normally-on transistor.

6. The switch device according to claim 5, further comprising: an additional diode electrically connected between the gate of the normally-on transistor and the source of the normally-on transistor and anti-parallel to the one or more diodes such that a cathode of the additional diode is electrically connected to the anode of the first diode of the one or more diodes and an anode of the additional diode is electrically connected to the cathode of the last diode of the one or more diodes.

7. The switch device according to claim 1, further comprising: a third power transistor die comprising an additional normally-on transistor having at most one-third of the maximum rated drain-to-source voltage of the switching device, wherein a source of the additional normally-on transistor is electrically connected to a drain of the normally-on transistor; an additional voltage blocking device electrically connected between a gate of the additional normally-on transistor and the source of the normally-on transistor and configured to block a portion of the voltage across the switching device when the stacking device is open; and An additional overvoltage protection device is configured to switch off the additional normally-on transistor when the normally-on transistor is switched off, so that the stacking device is actively controlled only through the gate of the normally-off transistor.

8. The switch device of claim 7, wherein the voltage blocking device is a capacitor, the capacitor having: a first terminal electrically connected to the gate of the normally-on transistor; and a second terminal electrically connected to the source of the normally-off transistor, and wherein the additional voltage blocking means is a capacitor having: a first terminal electrically connected to the gate of the additional normally-on transistor; and a second terminal electrically connected to the source of the normally-on transistor.

9. A switching device as described in claim 7, wherein the voltage blocking device is a gate-controlled diode device, the gate-controlled diode device having: a drain, electrically connected to the gate of the normally-on transistor; and a gate and a source, both of which are electrically connected to the source of the normally-off transistor, and wherein the additional voltage blocking device is a gate-controlled diode device, the gate-controlled diode device having: a drain, electrically connected to the gate of the additional normally-on transistor; and a gate and a source, both of which are electrically connected to the source of the normally-on transistor.

10. A switching device as described in claim 7, wherein the overvoltage protection device includes a first one or more diodes connected in series between the gate of the normally-on transistor and the source of the normally-on transistor, wherein the anode of a first diode of the first one or more diodes is electrically connected to the source of the normally-on transistor, wherein the cathode of a last diode of the first one or more diodes is electrically connected to the gate of the normally-on transistor, wherein the additional overvoltage protection device includes a second one or more diodes connected in series between the gate of the additional normally-on transistor and the source of the additional normally-on transistor, wherein the anode of a first diode of the second one or more diodes is electrically connected to the source of the additional normally-on transistor, and wherein the cathode of the last diode of the second one or more diodes is electrically connected to the gate of the additional normally-on transistor.

11. The switch device according to claim 10, further comprising: a first additional diode electrically connected between the gate of the normally-on transistor and the source of the normally-on transistor and anti-parallel to the first one or more diodes such that a cathode of the first additional diode is electrically connected to the anode of the first diode of the first one or more diodes and an anode of the first additional diode is electrically connected to the cathode of the last diode of the first one or more diodes; and a second additional diode electrically connected between the gate of the additional normally-on transistor and the source of the additional normally-on transistor and anti-parallel to the second one or more diodes, such that a cathode of the second additional diode is electrically connected to the anode of the first diode of the second one or more diodes and an anode of the second additional diode is electrically connected to the cathode of the last diode of the second one or more diodes.

12. A switch device, comprising: A first bidirectional switch, comprising a first source, a second source, a normally-off gate and a normally-on gate; a second bidirectional switch including a first source electrode, a second source electrode, a normally-off gate electrode and a normally-on gate electrode electrically connected to the second source electrode of the first bidirectional switch to form a stacked arrangement; a first voltage blocking device electrically connected between the first source of the first bidirectional switch and the normally-on gate of the second bidirectional switch and configured to block a portion of the voltage across the switch device when the stacking device is open; a first overvoltage protection device configured to disconnect the normally-on gate of the first bidirectional switch when the normally-off gate of the second bidirectional switch is disconnected, so that the normally-on gate of the first bidirectional switch is passively controlled by the normally-off gate of the second bidirectional switch; a second voltage blocking device electrically connected between the second source of the second bidirectional switch and the normally-on gate of the first bidirectional switch and configured to block a portion of the voltage across the switch device when the stacking device is open; and The second overvoltage protection device is configured to disconnect the normally-on gate of the second bidirectional switch when the normally-off gate of the first bidirectional switch is disconnected, so that the normally-on gate of the second bidirectional switch is passively controlled by the normally-off gate of the first bidirectional switch.

13. A switching device as described in claim 12, wherein the first bidirectional switch is included in a first GaN tube core and has at most half of the maximum rated source-to-source voltage of the switching device, wherein the second bidirectional switch is included in a second GaN tube core and has at most half of the maximum rated source-to-source voltage of the switching device, and wherein the maximum rated source-to-source voltage of the switching device is 1.2kV or higher.

14. The switch device of claim 12, wherein: The first voltage blocking device is a first capacitor having: a first terminal electrically connected to the first source of the first bidirectional switch; and a second terminal electrically connected to the normally-on gate of the second bidirectional switch; and The second voltage blocking device is a second capacitor, the second capacitor having: a first terminal electrically connected to the second source of the second bidirectional switch; and a second terminal electrically connected to the normally-on gate of the first bidirectional switch.

15. The switch device of claim 12, wherein: The first overvoltage protection device comprises a first one or more diodes connected in series between the normally-on gate of the first bidirectional switch and the second source of the first bidirectional switch, wherein an anode of a first diode of the first one or more diodes is electrically connected to the second source of the first bidirectional switch, and wherein a cathode of a last diode of the first one or more diodes is electrically connected to the normally-on gate of the first bidirectional switch; and The second overvoltage protection device includes a second one or more diodes connected in series between the normally-on gate of the second bidirectional switch and the first source of the second bidirectional switch, wherein an anode of a first diode of the second one or more diodes is electrically connected to the first source of the second bidirectional switch, and wherein a cathode of a last diode of the second one or more diodes is electrically connected to the normally-on gate of the second bidirectional switch.

16. A switch device comprising: A first bidirectional switch, comprising a first source, a second source, a normally-off gate and a normally-on gate; a second bidirectional switch including a first source electrode, a second source electrode, a first normally-on gate electrode, and a second normally-on gate electrode electrically connected to the second source electrode of the first bidirectional switch to form a first portion of a stacked arrangement; a third bidirectional switch including a first source electrode, a second source electrode, a normally-on gate electrode, and a normally-off gate electrode electrically connected to the second source electrode of the second bidirectional switch to form a second portion of the stacked device; a first voltage blocking device electrically connected between the first source of the first bidirectional switch and the first normally-on gate of the second bidirectional switch and configured to block a portion of the voltage across the switch device when the stacking device is open; a first overvoltage protection device configured to disconnect the first normally-on gate of the second bidirectional switch when the normally-off gate of the first bidirectional switch is disconnected, so that the first normally-on gate of the second bidirectional switch is passively controlled by the normally-off gate of the first bidirectional switch; a second voltage blocking device electrically connected between the first source of the third bidirectional switch and the normally-on gate of the first bidirectional switch and configured to block a portion of the voltage across the switch device when the stacking device is open; a second overvoltage protection device, configured to disconnect the normally-on gate of the first bidirectional switch when the first normally-on gate of the second bidirectional switch is disconnected; a third voltage blocking device electrically connected between the second source of the third bidirectional switch and the second normally-on gate of the second bidirectional switch and configured to block a portion of the voltage across the switch device when the stacking device is disconnected; a third overvoltage protection device, configured to disconnect the second normally-on gate of the second bidirectional switch when the normally-off gate of the third bidirectional switch is disconnected, so that the second normally-on gate of the second bidirectional switch is passively controlled by the normally-off gate of the third bidirectional switch; a fourth voltage blocking device electrically connected between the normally-on gate of the third bidirectional switch and the first source of the second bidirectional switch and configured to block a portion of the voltage across the switch device when the stacking device is open; and The fourth overvoltage protection device is configured to disconnect the normally-on gate of the third bidirectional switch when the second normally-on gate of the second bidirectional switch is disconnected, so that the normally-on gate of the third bidirectional switch is passively controlled by the second normally-on gate of the second bidirectional switch.

17. A switching device as described in claim 16, wherein the first bidirectional switch is included in a first GaN die and has at most one-third of the maximum rated source-to-source voltage of the switching device, wherein the second bidirectional switch is included in a second GaN die and has at most one-third of the maximum rated source-to-source voltage of the switching device, wherein the third bidirectional switch is included in a third GaN die and has at most one-third of the maximum rated source-to-source voltage of the switching device, and wherein the maximum rated source-to-source voltage of the switching device is 1.8 kV or higher.

18. The switch device of claim 16, wherein: The first voltage blocking device is a first capacitor having: a first terminal electrically connected to the first source of the first bidirectional switch; and a second terminal electrically connected to the first normally-on gate of the second bidirectional switch; The second voltage blocking device is a second capacitor, the second capacitor having: a first terminal electrically connected to the first source of the third bidirectional switch; and a second terminal electrically connected to the normally-on gate of the first bidirectional switch; The third voltage blocking device is a third capacitor, and the third capacitor has: a first terminal electrically connected to the second source of the third bidirectional switch; and a second terminal electrically connected to the second normally-on gate of the second bidirectional switch; and The fourth voltage blocking device is a fourth capacitor, and the fourth capacitor has: a first terminal electrically connected to the normally-on gate of the third bidirectional switch; and a second terminal electrically connected to the second source of the first bidirectional switch.

19. The switch device of claim 16, wherein: The first overvoltage protection device comprises a first one or more diodes connected in series between the normally-on gate of the first bidirectional switch and the second source of the first bidirectional switch, wherein an anode of a first diode of the first one or more diodes is electrically connected to the second source of the first bidirectional switch, and wherein a cathode of a last diode of the first one or more diodes is electrically connected to the normally-on gate of the first bidirectional switch; The second overvoltage protection device comprises a second one or more diodes connected in series between the first normally-on gate of the second bidirectional switch and the first source of the second bidirectional switch, wherein an anode of a first diode of the second one or more diodes is electrically connected to the first source of the second bidirectional switch, and wherein a cathode of a last diode of the second one or more diodes is electrically connected to the first normally-on gate of the second bidirectional switch; The third overvoltage protection device comprises a third one or more diodes connected in series between the second normally-on gate of the second bidirectional switch and the second source of the second bidirectional switch, wherein an anode of a first diode of the third one or more diodes is electrically connected to the second source of the second bidirectional switch, and wherein a cathode of a last diode of the third one or more diodes is electrically connected to the second normally-on gate of the second bidirectional switch; and The fourth overvoltage protection device includes a fourth one or more diodes connected in series between the normally-on gate of the third bidirectional switch and the first source of the third bidirectional switch, wherein an anode of a first diode of the fourth one or more diodes is electrically connected to the first source of the third bidirectional switch, and wherein a cathode of a last diode of the fourth one or more diodes is electrically connected to the normally-on gate of the third bidirectional switch.

20. A switch device comprising: First normally-off switch; The second normally-off switch; at least two bidirectional switches electrically connected between the first normally-off switch and the second normally-off switch in a stacked configuration, each bidirectional switch comprising a first normally-on gate and a second normally-on gate; a voltage blocking device electrically connected to one of the normally-on gates of each bidirectional switch and configured to block a portion of the voltage across the switching device when the switching device is open; a first overvoltage protection device configured to disconnect the first normally-on gate of each bidirectional switch when the first normally-off switch is disconnected, so that the first normally-on gate of each bidirectional switch is passively controlled by the first normally-off switch; and The second overvoltage protection device is configured to disconnect the second normally-on gate of each bidirectional switch when the second normally-off switch is disconnected, so that the second normally-on gate of each bidirectional switch is passively controlled by the second normally-off switch.

21. A switch device comprising: At least two bidirectional switches, electrically connected in a stacked configuration, wherein the first bidirectional switch and the second bidirectional switch of the at least two bidirectional switches each have a normally-on gate and a normally-off gate, Any remaining bidirectional switch of the at least two bidirectional switches stacked between the first bidirectional switch and the second bidirectional switch has a first normally-on gate and a second normally-on gate, wherein the switching device is actively controlled by the normally-off gate of the first bidirectional switch and the normally-off gate of the second bidirectional switch, Each normally-on gate of the at least two bidirectional switches is electrically connected to the source of another bidirectional switch of the at least two bidirectional switches through a voltage blocking device, and the voltage blocking device is configured to block a portion of the voltage across the switching device when the switching device is disconnected.

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