# Patent

## Title
Method and apparatus to improve power device reliability

## Abstract

Aspects of the disclosure provide a power device that includes an upper power module and a lower power module. The upper power module and the lower power module are coupled in series between two supply voltages, and are respectively controlled by a first control signal and a second control signal. Interconnections of the power device are inductively coupled to prevent reliability issues, such as crosstalk, self turn on, self sustained oscillation, and the like.

## Background
INCORPORATION BY REFERENCE
This application is a continuation-in-part (CIP) application of U.S. patent application Ser. No. 15/009,867, “METHOD AND APPARATUS FOR CURRENT/POWER BALANCING”, filed Jan. 29, 2016, which in turn is a continuation-in-part (CIP) application of U.S. patent application Ser. No. 14/724,408, “Method and Apparatus for Current/Power Balancing” filed on May 28, 2015. The entire disclosure of the above-identified applications is incorporated herein by reference in their entirety.


BACKGROUND
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A power module may use parallel power components to increase power capacity. For the parallel power components, equalizing current/power among the power components provides various benefits, such as improving component utilization, saving cost, improving system reliability. In an example, to equalize current/power among parallel power components, U.S. Patent Application Publication 2012/0235663 discloses a driver circuit to provide respective gate driver signals to drive the parallel power components.
SUMMARY
Aspects of the disclosure provide a power device that includes an upper power module and a lower power module. The upper power module is coupled to a first node, a second node and a first control node via first interconnections. The upper power module is controlled by a first driving signal at the first control node to turn on/off a first current path between the first node that receives a first supply voltage and the second node. The lower power module is coupled to the second node, a third node and a second control node via second interconnections. The lower power module is controlled by a second driving signal at the second control node to turn on/off a second path between the second node and the third node that receives a second supply voltage that is lower than the first voltage. A first interconnection and a second interconnection of the first interconnections are inductively coupled to prevent a turn-on of the upper power module when the first driving signal is at a first voltage level to turn off the upper power module and the second control signal is at a second voltage level to turn on the lower power module. In an example, the first driving signal transits to the first voltage level to turn off the upper power module before the second driving signal transits to the second voltage level to turn on the lower power module.
According to an aspect of the disclosure, the upper power module includes a first switch circuit in parallel with a second switch circuit. The first switch circuit and the second switch circuit are coupled to the first node, the second node and the first control node via the first interconnections. The lower power module includes a third switch circuit in parallel with a fourth switch circuit. The third switch circuit and the fourth switch circuit are coupled to the second node, the third node and the second control node via the second interconnections.
In an example, the first switch circuit includes a first SiC metal-oxide-semiconductor field effect transistor, the second switch circuit includes a second SiC metal-oxide-semiconductor field effect transistor, the third switch circuit includes a third SiC metal-oxide-semiconductor field effect transistor, and the fourth switch circuit includes a fourth SiC metal-oxide-semiconductor field effect transistor.
In an embodiment, the first interconnection and the second interconnection are among interconnections that interconnect the first switch circuit to the first node, the second node, and the first control node. In an example, parasitic inductances introduced by the first interconnection and the second interconnection are in an inversely coupled state. Further, the first interconnection interconnects a gate terminal of the first switch circuit to the first control node, and the second interconnection interconnects a drain terminal of the first switch circuit to the first node.
Aspects of the disclosure provide a power device that includes an upper power module and a lower power module. The upper power module is coupled to a first node, a second node and a first control node via first interconnections. The upper power module is controlled by a first driving signal at the first control node to turn on/off a first current path between the first node that receives a first supply voltage and the second node. The lower power module is coupled to the second node, a third node and a second control node via second interconnections. The lower power module is controlled by a second driving signal at the second control node to turn on/off a second path between the second node and the third node that receives a second supply voltage that is lower than the first voltage. In an example, the second supply voltage is ground. In an embodiment, a first interconnection and a second interconnection of the second interconnections are inductively coupled to prevent self turn-on of the lower power module when the second driving signal is at a voltage level to turn off the lower power module. In another embodiment, a first interconnection and a second interconnection of the second interconnections are inductively coupled to prevent self sustained oscillation of the lower power module when the second driving signal is at a voltage level to turn on the lower power module.
According to an aspect of the disclosure, the upper power module includes a first switch circuit in parallel with a second switch circuit, the first switch circuit and the second switch circuit being coupled to the first node, the second node and the first control node via the first interconnections, and the lower power module includes a third switch circuit in parallel with a fourth switch circuit, the third switch circuit and the fourth switch circuit being coupled to the second node, the third node and the second control node via the second interconnections.
In an embodiment, the first switch circuit includes a first SiC metal-oxide-semiconductor field effect transistor, the second switch circuit includes a second SiC metal-oxide-semiconductor field effect transistor, the third switch circuit includes a third SiC metal-oxide-semiconductor field effect transistor, and the fourth switch circuit includes a fourth SiC metal-oxide-semiconductor field effect transistor.
In an example, the first interconnection and the second interconnection are among interconnections that interconnect the third switch circuit and the fourth switch to the second node, the third node, and the second control node. For example, parasitic inductances introduced by the first interconnection and the second interconnection are in a directly coupled state. Further, the first interconnection interconnects a gate terminal of the third switch circuit to the second control node, and the second interconnection interconnects a drain terminal of the fourth switch circuit to the second node.



BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments of this disclosure that are proposed as examples will be described in detail with reference to the following figures, wherein like numerals reference like elements, and wherein:
FIG. 1 shows a diagram of a system 100 according to an embodiment of the disclosure;
FIG. 2 shows an exploded view in a power module 210 according to an embodiment of the disclosure;
FIG. 3 shows a flow chart outlining a process example according to an embodiment of the disclosure;
FIGS. 4 and 5 show plots of simulation results according to an embodiment of the disclosure;
FIG. 6 shows a diagram of a power module 610 according to an embodiment of the disclosure;
FIG. 7 shows a diagram of a power module 710 according to an embodiment of the disclosure;
FIG. 8A shows a diagram of the power module 610 for a simulation;
FIG. 8B shows a plot of simulation results for the power module 610 in FIG. 8A;
FIG. 9A shows a diagram of the power module 710 for a simulation;
FIG. 9B shows a plot of simulation results for the power module 710 in FIG. 9A;
FIG. 10 shows a diagram of a power module 1010 according to an embodiment of the disclosure;
FIGS. 11A-11B show plots of simulation results according to an embodiment of the disclosure;
FIG. 12 shows a diagram of a power device 1201 according to an embodiment of the disclosure;
FIGS. 13A-13B show plots of simulation results according to an embodiment of the disclosure;
FIG. 14 shows a diagram of a power device 1401 according to an embodiment of the disclosure;
FIGS. 15A-15B show plots of simulation results according to an embodiment of the disclosure;
FIGS. 16A-16B show plots of simulation results according to an embodiment of the disclosure; and
FIG. 17 shows a flow chart outlining a process example according to an embodiment of the disclosure.



DETAILED DESCRIPTION OF EMBODIMENTS
FIG. 1 shows a diagram of a system 100 according to an embodiment of the disclosure. The system 100 includes a power module 110 that uses mutual inductance coupling to balance current and/or power in parallel components.
The system 100 can be any suitable system that requires a relatively large power, such as a hybrid vehicle, an electric vehicle, a wind energy system, a printing system, and the like. During operation, in an example, the power module 110 needs to provide a relatively large current, such as in the order of Ampere, in the order of tens of Amperes, in the order of hundreds of Amperes, more than hundreds of Amperes, and the like. In an embodiment, the power module 110 is configured to use parallel components to share the relatively large current load.
In an embodiment, the power module 110 includes a power converter circuit, such as a DC-to-AC inverter, an AC-to-DC rectifier, and the like, and is implemented using semiconductor switching devices. The semiconductor switching devices form a plurality of switchable current paths to share the current load. According to an aspect of the disclosure, the semiconductor switching devices may have wide parameter variations, such as threshold voltage (Vth) variations, on-resistance Rds(on) variations, and the like due to manufacturing process. The parameter variations can cause unbalanced current/power on the plurality of switchable current paths. According to an aspect of the disclosure, mutual inductance coupling is used to improve current/power balance among the plurality of switchable current paths.
In the FIG. 1 example, the power module 110 has one or more control nodes NODE_C1-NODE_C2, a first power node NODE_P and a second power node NODE_P. Further, the power module 110 includes a plurality of switch modules, such as a first switch module 120, a second switch module 130 and the like that. The switch modules are coupled in parallel to the control nodes and the power nodes using interconnection components, such as wirebonds, busbars and the like. The switch modules are configured to switch on/off current paths between the first power node NODE_P and the second power node NODE_G based on control signals received at the control nodes NODE_C1-NODE_C2. In an example, the control nodes NODE_C1-NODE_C2 are coupled, fbr example directly connected, together to receive a same control signal. In another example, the control nodes NODE_C1-NODE_C2 are separate nodes to receive different control signals.
Each switch module can include one or more transistors. When multiple transistors are used in a switch module, the multiple transistors can be arranged in various topologies to act as a switch.
Specifically, in the FIG. 1 example, the first switch module 120 includes a first transistor Q1, and the second switch module 130 includes a second transistor Q2. The first transistor Q1 and the second transistor Q2 can be any suitable transistors, such as metal-oxide-semiconductor field effect transistors (MOSFET) and the like. In an example, the first transistor Q1 and the second transistor Q2 are SiC MOSFET transistors that may have relatively wide parameter variations due to manufacturing process.
Further, in the FIG. 1 example, the first transistor Q1 has a gate terminal G1, a source terminal S1 and a drain terminal D1. The gate terminal G1 is coupled to the first control node NODE_C1 via an interconnection component 121, the drain terminal D1 is coupled to the first power node NODE_P via an interconnection component 123, and the source terminal S1 is coupled to the second power node NODE_G via an interconnection component 122. Similarly, the second transistor Q2 has a gate terminal G2, a source terminal S2 and a drain terminal D2. The gate terminal G2 is coupled to the first control node NODE_C2 via an interconnection component 131, the drain terminal D2 is coupled to the first power node NODE_P via an interconnection component 133, and the source terminal S2 is coupled to the second power node NODE_G via an interconnection component 132.
According to an aspect of the disclosure, the interconnection components introduce parasitic inductances that influence the switching operation of the power module 110. For example, the interconnection component 121 introduces an inductance Lgs1, the interconnection component 122 introduces an inductance Lss1, the interconnection components 123 introduces an inductance Lds1, the interconnection component 131 introduces an inductance Lgs2, the interconnection component 132 introduces an inductance Lss2 and the interconnection component 133 introduces an inductance Lds2.
In addition, according to an aspect of the disclosure, the interconnection components are purposely mutual coupled to introduce mutual coupling parasitic inductances to balance current/power among the switch modules in the power module 110. Specifically, in the FIG. 1 example, the interconnection component 121 and the interconnection component 133 are purposely mutually coupled to introduce a mutual coupling parasitic inductance having a mutual coupling coefficient K1; and the interconnection component 123 and the interconnection component 131 are purposely mutually coupled to introduce a mutual coupling parasitic inductance having a mutual coupling coefficient K2.
According to an aspect of the disclosure, the mutual coupling is suitably designed such as the mutual coupling parasitic inductance improves current/power balance among the switch modules. In the FIG. 1 example, when the mutual coupling coefficients K1 and K2 are negative values, the mutual coupling parasitic inductances can improve current/power balance among the switch modules in the power module 110. In an example, at a time to switch on the first transistor Q1 and the second transistor Q2, a first current flowing through the first transistor Q1 (also flowing through the interconnection module 123) increases faster and is larger than a second current flowing through the second transistor Q2. The mutual coupling inductance between the interconnection component 123 and the interconnection component 131 then causes a voltage increase at the gate terminal G2 of the second transistor Q2, and thus turns on the second transistor Q2 more, and increases the second current flowing through the second transistor Q2. When the second current flowing through the second transistor Q2 (also flowing through the interconnection module 133) increases faster and is larger than the first current flowing through the first transistor Q1, the mutual coupling inductance between the interconnection component 133 and the interconnection component 121 causes a voltage increase at the gate terminal G1, and thus turns on the first transistor Q1 more, and increases the first current flowing through the first transistor Q1.
Similarly, at a time to switch off the first transistor Q1 and the second transistor Q2, the transient current flowing through the first transistor Q1 and the second transistor Q2 is balanced due to the mutual inductance coupling.
According to an aspect of the disclosure, when the first transistor Q1 and the second transistor Q2 are SiC MOSFET transistors, the on-resistance Rds(on) of the SiC MOSFET transistor has positive temperature coefficient, and thus the SiC MOSFET transistors intrinsically have negative feedback. Variations of the on-resistance Rds(on) may cause unbalance in the steady-state current, and the negative feedback of the on-resistance Rds(on) self-balances the steady-state current in the first transistor Q1 and the second transistor Q2.
Further, variations in the threshold voltage Vth may cause unbalance in the transient current. The threshold voltage Vth has negative temperature coefficient, and thus can cause a positive feedback and the unbalance in the transient current. The mutual inductance coupling technique can be used to balance the transient current at switching on/off time.
It is noted that the power module 110 can be implemented by various technology. In an example, switch modules, such as the first switch module 120, the second switch module 130, and the like, are implemented as bare dies, and the interconnection modules are implemented as wirebonds and/or busbars. The switch modules, the interconnection modules and other suitable components are assembled in a package to form the power module 110. In another example, the switch modules are discrete devices that are assembled in separate packages, and the switch modules are interconnected by wirebonds and busbars. In another example, the switch modules are integrated on an integrated circuit (IC) chip, and the interconnection modules are implemented as wirebonds on the IC chip using IC manufacturing technology.
FIG. 2 shows a plot for an exploded view in a power module 210 according to an embodiment of the disclosure. In an embodiment, the power module 110 in FIG. 1 is implemented as the power module 210 in FIG. 2. The power module 210 includes switch modules, such as a first switch module 220, a second switch module 230, and the like that are implemented using bare dies. Further, the power module 210 includes interconnection modules, such as interconnection modules 221, 223, 231, 233 and the like, that are implemented using busbars. The power module 210 is implemented in the form of a package in an example.
For example, the first switch module 220 is a first bare die having a first transistor implemented using a SiC MOSFET technology. Thus, the drain terminal D1 of the first transistor is formed, for example as a bond pad, on the substrate of the first bare die, and the gate terminal G1 and the source terminal S1 of the first transistor are formed, for example as bond pads on the face side (opposite side of the substrate) of the first bare die.
Similarly, the second switch module 230 is a second bare die having a second transistor implemented using the SiC MOSFET technology. Thus, the drain terminal D2 of the second transistor is formed, for example as a bond pad, on the substrate of the second bare die, and the gate terminal G2 and the source terminal S2 of the second transistor are formed, for example as bond pads, on the face side (opposite side of the substrate) of the second bare die.
In an embodiment, the first bare die and the second bare die are disposed face to face. The interconnection module 221 is connected to the gate terminal G1 of the first transistor, the interconnection module 231 is connected to the gate terminal G2 of the second transistor, the interconnection module 223 is connected to the drain terminal D1 of the first transistor, and the interconnection module 231 is connected to the drain terminal D2 of the second transistor.
Further, in the embodiment, the interconnection module 221 and the interconnection module 233 are disposed to have a mutual coupling parasitic inductance having a mutual coupling coefficient K1. For example, the interconnection module 221 and the interconnection module 233 are disposed nearby, such that a current change in one of the interconnection modules can induce a voltage on the other interconnection module. In addition, the interconnection module 231 and the interconnection module 223 are disposed to have a mutual coupling parasitic inductance having a mutual coupling coefficient K2. For example, the interconnection module 223 and the interconnection module 231 are disposed nearby, such that a current change in one of the interconnection modules can induce a voltage in the other interconnection module. In an example, the mutual coupling parasitic inductance is suitably designed to improve transient current/power balance at the time of switching on/off the first and second transistors.
It is noted that, for ease and simplicity, the power module 210 includes other suitable components that are not shown in FIG. 2. For example, the source terminals S1 and S2 are connected by a suitable interconnection module not shown, such as a wirebond, a busbar and the like. It is also noted that, the configuration of the dies and the busbars in FIG. 2 can be suitably modified. For example, the two dies can be disposed in a back to back manner in an example, or can be disposed side by side in an example.
FIG. 3 shows a flow chart outlining a process 300 according to an embodiment of the disclosure. In an example, the process 300 is executed to implement the power module 210. The process starts at S301, and proceeds to S310.
At S310, a first transistor is disposed. For example, the first transistor is implemented on a first bare die using the SiC MOSFET technology.
At S320, a second transistor is disposed. For example, the second transistor is implemented on a second bare die using the SiC MOSFET technology.
At S330, interconnections are disposed to inductively couple the drain terminal of the first transistor to the gate terminal of the second transistor. In the FIG. 2 example, the interconnection module 223 connects with the drain terminal of the first transistor, and the interconnection module 231 connects with the gate terminal of the second transistor. The interconnection module 223 and the interconnection module 231 are disposed, for example nearby, to be inductively coupled.
At S340, interconnections are disposed to inductively couple the drain terminal of the second transistor to the gate terminal of the first transistor. In the FIG. 2 example, the interconnection 233 module connects with the drain terminal of the second transistor, and the interconnection module 221 connects with the gate terminal of the first transistor. The interconnection module 233 and the interconnection module 221 are disposed, for example nearby, to be inductively coupled. Then the process proceeds to S399 and terminates.
It is noted that the process 300 can include other suitable steps to implement a power module. Further, the steps in the process 300 can be executed at the same time or in a different order.
FIG. 4 shows a plot 400 of simulation result according to an embodiment of the disclosure. For example, the plot 400 shows voltage and current changes with or without mutual coupling parasitic inductance when a power module with parallel transistors is switched on. The X-axis shows time, and the Y-axis shows voltage and current values.
The plot 400 includes five waveforms 410-450. The waveform 410 (in medium dashed line) shows drain current of the first transistor without mutual coupling parasitic inductance, the waveform 420 (in long-short dashed line) shows drain current of the second transistor without mutual coupling parasitic inductance, the waveform 430 (in solid line) shows drain current of the first transistor with mutual coupling parasitic inductance, the waveform 440 (in short dashed line) shows drain current of the second transistor with mutual coupling parasitic inductance, and the waveform 450 (in long dashed line) shows the drain-source voltage Vds.
As shown in FIG. 4, at time ton, the first transistor and the second transistor are switched on. Without mutual coupling parasitic inductance, the transient current in the first transistor and the transient current in the second transistor have relatively large difference. With mutual coupling parasitic inductance, the transient current difference in the first transistor and the second transistor is reduced.
FIG. 5 shows a plot 500 of simulation result according to an embodiment of the disclosure. For example, the plot 500 shows voltage and current changes with or without mutual coupling parasitic inductance when a power module with parallel transistors is switched off. The X-axis shows time, and the Y-axis shows voltage and current values.
The plot 500 includes five waveforms 510-550. The waveform 510 (in medium dashed line) shows drain current of the first transistor without mutual coupling parasitic inductance, the waveform 520 (in long-short dashed line) shows drain current of the second transistor without mutual coupling parasitic inductance, the waveform 530 (in solid line) shows drain current of the first transistor with mutual coupling parasitic inductance, the waveform 540 (in short dashed line) shows drain current of the second transistor with mutual coupling parasitic inductance, and the waveform 550 (in long dashed line) shows the drain-source voltage Vds.
As shown in FIG. 5, at time toff, the first transistor and the second transistor are switched off. Without mutual coupling parasitic inductance, the transient current in the first transistor and the transient current in the second transistor have relatively large difference as shown by the waveforms 510 and 520. With mutual coupling parasitic inductance, the transient current difference in the first transistor and the second transistor is reduced as shown by the waveforms 530 and 540.
FIG. 6 shows a circuit diagram of a power module 610 for simulation according to an embodiment of the disclosure. The power module 610 operates similarly to the power module 110 described above, and also utilizes certain components that are identical or equivalent to those used in the power module 110; the description of these components has been provided above and will be omitted here for clarity purposes.
In the FIG. 6 example, the power module 610 includes two driving nodes PC1 and PC2 to receive a control signal VDRV. Further, the power module 610 includes a drain node D and a source node S. In an example, the drain node D and the source node S are connected to a power source. The power module 610 conducts a current flowing from the drain node D to the source node S in response to the control signal VDRV.
According to an aspect of the disclosure, the power module 610 includes a plurality of switch modules, such as a first switch module 620, a second switch module 630 and the like. The switch modules are in parallel coupled to the driving nodes PC1 and PC2, the drain node D and the source node S using interconnection components, such as wirebonds, busbars and the like. The switch modules are configured to switch on/off current paths between the drain node D and the source node S based on the control signal Vrmv received at the driving nodes PC1 and PC2.
Each switch module can include one or more transistors. When multiple transistors are used in a switch module, the multiple transistors can be arranged in various topologies to act as a switch.
Specifically, in the FIG. 6 example, the first switch module 620 includes a first transistor, and the second switch module 630 includes a second transistor. The first transistor and the second transistor can be any suitable transistors, such as metal-oxide-semiconductor field effect transistors (MOSFET) and the like. In an example, the first transistor and the second transistor are SiC MOSFET transistors that may have relatively wide parameter variations due to manufacturing process.
It is noted that real transistors can possess various parasitic elements, and are generally modeled using equivalent circuits in simulation. In the FIG. 6 example, the first transistor has a gate terminal G1, a source terminal S1 and a drain terminal D1, and is modeled using a transistor model M1, capacitors C1-C3, and a diode DD1 coupled together as shown in FIG. 6. Similarly, the second transistor has a gate terminal G2, a source terminal S2 and a drain terminal D2, and is modeled using a transistor model M2, capacitors C4-C6 and a diode DD2 coupled together as shown in FIG. 6.
According to an aspect of the disclosure, the terminals of the first transistor and the second transistors are coupled to the driving nodes PC1-PC2, the drain node D, and the source node S by interconnection components, and the interconnection components introduce parasitic inductances that influence the switching operation of the power module 610. The interconnection components can be modeled using inductances. For example, in the FIG. 6 example, the interconnection components between the driving node PC1 and the gate terminals G1 and G2 are modeled using inductances Lggc, Lgg1, and Lgg2 coupled together as shown in FIG. 6; the interconnection components between the driving node PC2 and the source terminals S1 and S2 are modeled using inductances Lgsc, Lgs1, and Lgs2 coupled together as shown in FIG. 6; the interconnection components between the source node S and the source terminals S1 and S2 are modeled using inductances Lsc, Ls1 and Ls2 coupled together as shown in FIG. 6; the interconnection components between the drain node D and the drain terminals D1 and D2 are modeled using inductances Ldc, Ld1, and Ld2 coupled together as shown in FIG. 6.
According to an aspect of the disclosure, the interconnection components can be purposely mutual coupled to introduce mutual coupling parasitic inductances to balance current/power among the switch modules in a power module. According to an aspect of the disclosure, parasitic inductances can be in a directly coupled state or an inverse coupled state. When the parasitic inductances are in the directly coupled state, cross coupling techniques can be used to reduce current/power unbalance, and when the parasitic inductances are in the inversely coupled state, self-coupling techniques can be used to reduce current/power unbalance.
In the FIG. 6 example, the direction of the drain inductance (e.g., the direction of Ld1 and Ld2) and the direction of the gate inductance (e.g., the direction of Lgg1 and Lgg2) of transistors make the drain inductance and the gate inductance in the directly coupled state (assuming positive mutual coupling coefficient). In the directly coupled state, when the drain current increases, the coupling of the drain inductance and the gate inductance can cause an increase in the gate voltage. In order to have a negative feedback to reduce the current/power unbalance for the directly coupled state, the drain inductance Ld1 of the first switch module 620 is cross coupled to the gate inductance Lgg2 of the second switch module 630 with a first mutual coupling coefficient, and the drain inductance Ld2 of the second switch module 630 is cross coupled to the gate inductance Lgg1 of the first switch module 620 with a second mutual coupling coefficient. In the example, positive mutual coupling coefficients are used. Further, in an example, with higher mutual coupling coefficients (e.g., 0.9), the difference between the different current paths is smaller, the switching speed is faster, but the transistors may have higher current overshoot peak.
According to an aspect of the disclosure, four cross coupling techniques (drain-gate cross coupling, drain-Kelvin gate cross coupling, source-gate cross coupling, and source-Kelvin gate cross coupling) can be used to introduce mutual coupling parasitic inductances between parallel switch modules.
For example, for the drain-gate cross coupling, the interconnection component modeled by the drain inductance Ld1 of the first switch module 620 and the interconnection component modeled by the gate inductance Lgg2 of the second switch module 630 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 611, and the interconnection component modeled by the drain inductance Ld2 of the second switch module 630 and the interconnection component modeled by the gate inductance Lgg1, of the first switch module 620 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 612.
For the drain-Kelvin gate cross coupling, the interconnection component modeled by the drain inductance Ld1 of the first switch module 620 and the interconnection component modeled by the Kelvin gate inductance Lgs2 of the second switch module 630 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 613, and the interconnection component modeled by the drain inductance Ld2 of the second switch module 630 and the interconnection component modeled by the Kelvin gate inductance Lgs1 of the first switch module 620 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 614.
For the source-gate cross coupling, the interconnection component modeled by the source inductance Ls1 of the first switch module 620 and the interconnection component modeled by the gate inductance Lgg2 of the second switch module 630 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 615, and the interconnection component modeled by the source inductance Ls2 of the second switch module 630 and the interconnection component modeled by the gate inductance Lgg1 of the first switch module 620 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 616.
For the source-Kelvin gate cross coupling, the interconnection component modeled by the drain inductance Ls1 of the first switch module 620 and the interconnection component modeled by the Kelvin gate inductance Lgs2 of the second switch module 630 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 617, and the interconnection component modeled by the source inductance Ls2 of the second switch module 630 and the interconnection component modeled by the Kelvin gate inductance Lgs1 of the first switch module 620 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 618.
FIG. 7 shows a diagram of a power module 710 for circuit simulation according to an embodiment of the disclosure. The power module 710 operates similarly to the power module 610 described above, and also utilizes certain components that are identical or equivalent to those used in the power module 610; the description of these components has been provided above and will be omitted here for clarity purposes.
In the FIG. 7 example, the direction of the drain inductance (e.g., the direction of Ld1 and Ld2) and the direction of the gate inductance (e.g., the direction of Lgg1 and Lgg2) are configured in the inversely coupled state (assuming positive mutual coupling coefficient). In the inversely coupled state, when the drain current increases, the coupling of the drain inductance and the gate inductance can cause a decrease in the gate voltage. In order to have a negative feedback to reduce the current unbalance for the inversely coupled state, self-coupling techniques can be used. For example, the drain inductance Ld1 of the first switch module 720 is self-coupled to the gate inductance Lgg1 of the first switch module 720, and the drain inductance Ld2 of the second switch module 730 is self-coupled to the gate inductance Lgg2 of the second switch module 730 with positive mutual coupling coefficients to reduce power/current unbalance.
According to an aspect of the disclosure, four self-coupling techniques (drain-gate self-coupling, drain-Kelvin gate self-coupling, source-gate self-coupling, and source-Kelvin gate self-coupling) can be used to introduce mutual coupling parasitic inductances within each switch module.
For example, for the drain-gate self-coupling, the interconnection component modeled by the drain inductance Ld1 of the first switch module 720 and the interconnection component modeled by the gate inductance Lgg1 of the first switch module 720 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 711, and the interconnection component modeled by the drain inductance Ld2 of the second switch module 730 and the interconnection component modeled by the gate inductance Lgg2 of the second switch module 730 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 712.
For the drain-Kelvin gate self-coupling, the interconnection component modeled by the drain inductance Ld1 of the first switch module 720 and the interconnection component modeled by the Kelvin gate inductance Lgs1 of the first switch module 720 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 713, and the interconnection component modeled by the drain inductance Ld2 of the second switch module 730 and the interconnection component modeled by the Kelvin gate inductance Lgs2 of the second switch module 730 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 714.
For the source-gate self-coupling, the interconnection component modeled by the source inductance Ls1 of the first switch module 720 and the interconnection component modeled by the gate inductance Lgg1 of the first switch module 720 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 715, and the interconnection component modeled by the source inductance Ls1 of the second switch module 730 and the interconnection component modeled by the gate inductance Lgg2 of the second switch module 730 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 716.
For the source-Kelvin gate self-coupling, the interconnection component modeled by the drain inductance Ls1 of the first switch module 720 and the interconnection component modeled by the Kelvin gate inductance Lgs1 of the first switch module 730 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 717, and the interconnection component modeled by the source inductance Ls2 of the second switch module 730 and the interconnection component modeled by the Kelvin gate inductance Lgs2 of the second switch module 720 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 718.
FIG. 8A shows a diagram of the power module 610 for a simulation. In the FIG. 8A example, the power module 610 is in a directly coupled state that uses a cross coupling technique to improve current balance according to an embodiment of the disclosure.
FIG. 8B shows a plot of simulation result for the power module 610 in FIG. 8A. In the power module 610 of FIG. 8A, the direction of the drain inductance (e.g., the direction of Ld2 and Ld2) and the direction of the gate inductance (e.g., the direction of Lgg1 and Lgg2) are configured in the directly coupled state. With the directly coupled state, cross-coupling techniques, such as the drain-gate cross coupling technique as shown by 611 and 612, are used to reduce current unbalance.
In FIG. 8B, the X-axis shows time and the Y-axis shows drain current for switch modules. The plot 800 compares the drain current during switching for a first simulation using a first mutual coupling coefficient of zero (without using cross coupling technique) and a second simulation using a second mutual coupling coefficient of 0.9 (using a cross coupling technique). The plot 800 includes a first curve 810 and a second current 820 of drain current for the first simulation without using cross-coupling technique, and a third curve 830 and a fourth curve 840 of drain current for the second simulation that uses cross coupling technique.
As seen in FIG. 8B, the drain current difference between the third curve 830 and the fourth curve 840 is relatively smaller than the drain current difference between the first curve 810 and the second curve 820. Thus, the cross-coupling technique for the directly coupled state reduces current unbalance. Also seen in FIG. 8B, with the cross coupling technique, the switching current is larger, the switching speed is faster, and the current overshoot peak is higher.
FIG. 9A shows a diagram of the power module 710 for a simulation. In the FIG. 9A example, the power module 710 is in an inversely coupled state that uses a self-coupling technique to improve current balance according to an embodiment of the disclosure.
FIG. 9B shows a plot of simulation result for the power module 710 in FIG. 9A. In the FIG. 9A example, the direction of the drain inductance (e.g., the direction of Ld2 and Ld2) and the direction of the gate inductance (e.g., the direction of Lgg1 and Lgg2) are configured in the inversely coupled state. With the inversely coupled state, self-coupling techniques, such as the drain-gate self-coupling technique as shown by 711 and 712, are used to reduce current unbalance.
In FIG. 9B, the X-axis shows time and the Y-axis shows drain current for switch modules. The plot 900 compares the drain current during switching for a first simulation using a first mutual coupling coefficient of zero (without using self-coupling technique) and a second simulation using a second mutual coupling coefficient of 0.9 (using a self-coupling technique). The plot 900 includes a first curve 910 and a second current 920 of drain current for the first simulation without using self-coupling technique, and a third curve 930 and a fourth curve 940 of drain current for the second simulation that uses self-coupling technique.
As seen in FIG. 9B, the drain current difference between the third curve 930 and the fourth curve 940 is relatively smaller than the drain current difference between the first curve 910 and the second curve 920. Thus, the self-coupling techniques for the inversely coupled state can reduce current unbalance. Also seen in FIG. 9B, with the self-coupling technique, the switching current is smaller, the switching speed is slower, and the current overshoot peak is lower.
According to an aspect of the disclosure, the cross-coupling techniques for the directly coupled state and the self-coupling techniques for the inversely coupled state can be suitably combined to improve current balance.
FIG. 10 shows a diagram of a power module 1010 for circuit simulation according to an embodiment of the disclosure. The power module 1010 operates similarly to the power module 610 and the power module 710 described above, and also utilizes certain components that are identical or equivalent to those used in the power module 610 and the power module 710; the description of these components has been provided above and will be omitted here for clarity purposes. In the power module 1010, the drain inductance and the gate inductance are in the directly coupled state while the source inductance and the Kelvin gate inductance are in the inversely coupled state.
In the FIG. 10 example, the interconnection component modeled by the drain inductance Ld1 of the first switch module 1020 and the interconnection component modeled by the gate inductance Lgg2 of the second switch module 1030 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 1011, and the interconnection component modeled by the drain inductance Ld2 of the second switch module 1030 and the interconnection component modeled by the gate inductance Lgg1 of the first switch module 1020 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 1012.
Further, in the FIG. 10 example, the interconnection component modeled by the drain inductance Ls1 of the first switch module 1020 and the interconnection component modeled by the Kelvin gate inductance Lgs1 of the first switch module 1030 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 1017, and the interconnection component modeled by the source inductance Ls2 of the second switch module 1030 and the interconnection component modeled by the Kelvin gate inductance Lgs2 of the second switch module 1020 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 1018.
FIGS. 11A-11B show simulation result for the power module 1010 according to an embodiment of the disclosure. FIG. 11A shows drain current during switching for a first simulation using a first mutual coupling coefficient of zero (without using any of the cross coupling technique and self-coupling technique) and FIG. 11B shows the drain current during switching for a second simulation using a second mutual coupling coefficient of 0.9 (for both cross coupling and self-coupling techniques).
As seen in FIGS. 11A and 11B, the switching speed and peak current are about the same for the first simulation and the second simulation; however, the current unbalance is significantly reduced, specifically in the first few oscillation cycles.
Further, according to an aspect of the disclosure, the parasitic inductance coupling can be used to eliminate reliability issues, such as crosstalk, self turn on, self sustained oscillation and the like, for switching operations of power devices, and to improve reliability without sacrificing switching speed or increasing complexity.
FIG. 12 shows a diagram of a power device 1201 according to an embodiment of the disclosure. The power device 1201 is configured to use a half-bridge topology that includes an upper power module 1210 and a lower power module 1260 coupled in series between a first power supply voltage VDD (high voltage of a power supply) and a second power supply voltage VSS (low voltage of the power supply). In the FIG. 12 example, the upper power module 1210 is configured to use parasitic inductance couplings to eliminate cross-talk and improve switching reliability.
The upper power module 1210 includes one switch module or multiple switch modules (e.g., a first switch module 1220 and a second switch module 1230) coupled in parallel. The one or more switch modules are coupled to a first node (N1), a second node (N2), and control nodes (NC1 and NC2) via interconnections. The control nodes NC1 and NC2 receive a first driving signal VDRV-HS to control the upper power module 1210. The first driving signal VDRV-HS is generated to turn on/off a first current path between the first node (N1) and the second node (N2). The lower power module 1260 includes one switch module or multiple switch modules (e.g., a third switch module 1270 and a fourth switch module 1280) coupled in parallel. The one or more switch circuits are coupled to the second node (N2), a third node (N3), and control nodes (NC3 and NC4) via interconnections. The control nodes NC3 and NC4 receive a second driving signal VDRV-LS. The second driving signal VDRV-LS is generated to turn on/off a second current path between the second node (N2) and the third node (N3).
Specifically, in the FIG. 12 example, the upper power module 1210 operates similarly to the power modules described above, such as the power module 110, the power module 610, the power module 710 and the like. The upper power module 1210 also utilizes certain components that are identical or equivalent to those used in the power modules described above; the description of these components has been provided above and will be omitted here for clarity purposes.
Similarly, in the FIG. 12 example, the lower power module 1260 operates similarly to the power modules described above, such as the power module 110, the power module 610, the power module 710 and the like. The lower power module 1260 also utilizes certain components that are identical or equivalent to those used in the power modules described above; the description of these components has been provided above and will be omitted here for clarity purposes.
It is noted that, in an example, the power device 1201 includes a control circuit (not shown) suitably configured to generate the first driving signal VDRV-HS and the second driving signal VDRV-LS. In an embodiment, the first driving signal VDRV-HS and the second driving signal VDRV-LS are generated to be complementary to each other with a positive non-overlapping dead-time.
In the FIG. 12 example, the upper power module 1210 is configured similarly to the power module 710 in the inversely coupled state. Specifically, the direction of the drain inductance (e.g., the direction of Ld1-HS and Ld2-HS) and the direction of the gate inductance (e.g., the direction of Lgg1-HS and Lgg2-HS) are configured in the inversely coupled state (assuming positive mutual coupling coefficient). In the inversely coupled state, when the drain current increases, the coupling of the drain inductance and the gate inductance can cause a decrease in the gate voltage. Further, self-coupling techniques can be used to improve switching reliability. For example, in the upper power module 1210, the interconnection component modeled by the drain inductance Ld1-HS of the first switch module 1220 and the interconnection component modeled by the gate inductance Lgg1-HS of the first switch module 1220 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 1211, and the interconnection component modeled by the drain inductance Ld2-HS of the second switch module 1230 and the interconnection component modeled by the gate inductance Lgg2-HS of the second switch module 1230 are purposely mutually coupled to introduce a mutual coupling parasitic inductance as shown by 1212.
According to an aspect of the disclosure, the parasitic inductance introduced by the mutual coupling of interconnection components (e.g., 1211 and 1212) can be used to eliminate cross-talk and improve switching reliability.
During operation, in an example, before a switching off of the upper power module 1210, the first driving signal VDRV-HS is of a relatively high voltage to maintain the upper power module 1210 to be turned on, and the second driving signal VDRV-LS is of a relatively low voltage to turn off the lower power module 1260. Specifically, before the switching off of the upper power module 1210, the first switch module 1220 and the second switch module 1230 are turned on and the third switch module 1270 and the fourth switch module 1280 are turned off. Thus, the first switch module 1220 and the second switch module 1230 form a current path between the first node N1 and the second node N2, and the second node N2 has a relatively high voltage, for example about the level of VDD.
At the switching off time of the upper power module 1210, the first driving signal VDRV-HS is controlled to switch from the relatively high voltage to the relatively low voltage to turn off the upper power module 1210, e.g., turn off the first switch module 1220 and the second switch module 1230.
Then, the first driving signal VDRV-HS and the second driving signal VDRV-LS are of the relatively low voltage for the positive non-overlapping dead-time after the switching off time of the upper power module 1210 and before a switching on time of the lower power module 1260.
At the switching on time of the lower power module 1260, the first driving signal VDRV-HS is maintained at the relatively low voltage to keep the upper power module 1210 to be turned off, and the second driving signal VDRV-LS is controlled to switch from the relatively low voltage to the relatively high voltage to turn on the lower power module 1260.
After the switching on of the lower power module 1260, the first driving signal VDRV-HS is of the relatively low voltage to maintain the upper power module 1210 to be turned off, and the second driving signal VDRV-LS is of the relatively high voltage to turn on the lower power module 1260. Specifically, after the switching on of the lower power module 1260, the first switch module 1220 and the second switch module 1230 are turned off and the third switch module 1270 and the fourth switch module 1280 are turned on. Thus, the third switch module 1270 and the fourth switch module 1280 form a current path between the second node N2 and the third node N3, and the second node N2 has a relatively low voltage, for example about the level of VSS.
According to an aspect of the disclosure, at the time to switch on the lower power module 1260, the voltage at the second node N2 drops from the relatively high voltage (e.g., VDD) to the relatively low voltage (e.g., VSS) in a relatively short time, the change of the voltage in the short time (a relatively large dv/dt) can cause a relatively large gate current to the switch modules 1220 and 1230 to cause an increase of the gate voltages of the switch module 1220 and the switch module 1230. The gate voltage increase can turn on the switch module 1220 and the switch module 1230 for a short time, and the unintentional turn-on of the upper power module 1210 is referred to as crosstalk and can cause reliability issue, for example, large leakage current I1 and I2 during the short time. However, due to the inversely coupled state and the self-coupling techniques (e.g., 1211 and 1212) used in the upper power module 1210, when the drain current I1/I2 increases, the coupling of the drain inductance and the gate inductance can cause a decrease in the gate voltage, and thus to turn off the switch modules 1220 and 1230 to prevent the crosstalk.
It is noted that while the power device 1201 uses a self-coupling technique in the inversely coupled state to eliminate the crosstalk, the power device 1201 can be suitably modified to use other suitable parasitic inductance coupling techniques to eliminate crosstalk type of reliability issues.
FIGS. 13A and 13B show plots of waveforms of simulation for the power device 1201 according to an embodiment of the disclosure. FIG. 13A shows results from a first simulation using non-zero mutual coupling coefficient for 1211 and 1212. FIG. 13A includes a first waveform 1310 for the second driving signal VDRV-LS and a second waveform 1320 for the drain current I1 of the first switch module 1220. FIG. 13B shows results from a second simulation using zero mutual coupling coefficient for 1211 and 1212. FIG. 13B includes a third waveform 1330 for the second driving signal VDRV-LS and a fourth waveform 1340 for the drain current I1 of the first switch module 1220.
As seen in FIG. 13B, without the mutual coupling (zero mutual coupling coefficient), when the second driving signal VDRV-LS switches from the relatively low voltage to the relatively high voltage to switch on the lower power module 1260, a relatively large current (shown by 1345) flows through the first switch module 1220. The relatively large current is caused by the voltage change at the second node N2 at the time of switching on the lower power module 1260.
As seen in FIG. 13A, with the mutual coupling (non-zero mutual coupling coefficient), when the second driving signal VDRV-LS switches from the relatively low voltage to the relatively high voltage to switch on the lower power module 1260, the current flows through the first switch module 1220 can be kept low.
FIG. 14 shows a diagram of a power device 1401 according to an embodiment of the disclosure. The power device 1401 operates similarly to the power device 1201 described above. The power device 1401 also utilizes certain components that are identical or equivalent to those used in the power device 1201; the description of these components has been provided above and will be omitted here for clarity purposes. In the FIG. 14 example, the lower power module 1460 is configured to use parasitic inductance couplings to prevent self turn-on and/or self-sustained oscillation and improve switching reliability.
In the FIG. 14 example, the lower power module 1460 is configured similarly to the power module 610 in the directly coupled state. Specifically, the direction of the drain inductance (e.g., the direction of LDRV-LS and Ld2-LS) and the direction of the gate inductance (e.g., the direction of Lgg1-LS and Lgg2-LS) of transistors make the drain inductance and the gate inductance in the directly coupled state (assuming positive mutual coupling coefficient). In the directly coupled state, when the drain current increases, the coupling of the drain inductance and the gate inductance can cause an increase in the gate voltage.
In the FIG. 14 example, to prevent self turn-on and/or self sustained oscillation, a cross-coupling technique can be used. In the example, the drain inductance Ld1-LS of the third switch module 1470 is cross-coupled to the gate inductance Lgg2-LS of the fourth switch module 1480 with a first mutual coupling coefficient as shown by 1461, and the drain inductance Ld2-LS of the fourth switch module 1480 is cross coupled to the gate inductance Lgg1-LS of the third switch module 1470 with a second mutual coupling coefficient as shown by 1462. In the example, positive mutual coupling coefficients are used.
According to an aspect of the disclosure, the parasitic induced introduced by the mutual coupling of interconnection components (e.g., 1461 and 1462) can be used to prevent self turn-on and improve switching reliability.
During operation, in an example, before a switching off of the lower power module 1460, the second driving signal VDRV-LS is of a relatively high voltage to maintain the lower power module 1460 to be turned on, and the first driving signal VDRV-HS is of a relatively low voltage to turn off the upper power module 1410. Specifically, before the switching off of the lower power module 1460, the third switch module 1470 and the fourth switch module 1480 are turned on and the first switch module 1420 and the second switch module 1430 are turned off. Thus, the third switch module 1470 and the fourth switch module 1480 form a current path between the second node N2 and the third node N3, and the second node N2 has a relatively low voltage, for example about the level of VSS.
At the switching off time of the lower power module 1460, the second driving signal VDRV-LS is controlled to switch from the relatively high voltage to the relatively low voltage to turn off the lower power module 1460, e.g., turn off the third switch module 1470 and the fourth switch module 1480.
Then, the first driving signal VDRV-HS and the second driving signal VDRV-LS are of the relatively low voltage for the positive non-overlapping dead-time after the switching off time of the upper power module 1410 and before a switching on time of the lower power module 1460. However, the lower power module 1460 may turn on itself with very large currents due to the existence of common source inductance induced positive gate voltage. This induced positive gate voltage can subsequently turn on the lower power module 1460 again even though the second driving signal VDRV-LS is low.
According to an aspect of the disclosure, due to the directly coupled state and the cross-coupling techniques used in the lower power module 1460, when the drain current I3/I4 increases, the cross coupling of the drain inductance and the gate inductance can cause a decrease in the gate voltage, and thus to turn off the switch modules 1470 and 1480, and prevent the self turn-on.
According to an aspect of the disclosure, the parasitic induced introduced by the mutual coupling of interconnection components (e.g., 1461 and 1462) can be used to prevent self sustained oscillation and improve switching reliability.
During operation, in an example, when the second driving signal VDRV-LS is of a relatively high voltage to turn on the lower power module 1460, due to high drain current of the third switch module 1470 and the fourth switch module 1480 and relatively large gate inductance of the third switch module 1470 and the fourth switch module 1480, the third switch module 1470 and the fourth switch module 1480 can enter a self-sustained oscillation to repetitively turn on and off.
According to an aspect of the disclosure, due to the directly coupled state and the cross-coupling techniques used in the lower power module 1460, when the drain current I3/I4 changes fast, the cross coupling of the drain inductance and the gate inductance can cause the gate voltage to change in a direction to counteract the drain current change, and thus to prevent the self-sustained oscillation.
It is noted that while the power device 1401 uses a cross-coupling technique in the directly coupled state to prevent the self turn on and/or self sustained oscillation, the power device 1401 can be suitably modified to use other suitable parasitic inductance coupling techniques to prevent the self turn on and/or self sustained oscillation types of reliability issues.
FIGS. 15A-15B show plots of simulation results for the power device 1401 according to an embodiment of the disclosure. FIG. 15A shows results of a first simulation using non-zero mutual coupling coefficient for 1461 and 1462. FIG. 15A includes a first waveform 1510 for the second driving signal VDRV-LS, a second waveform 1520 for the drain current I3 of the third switch module 1470 and a third waveform 1525 for the drain current I4 of the fourth switch module 1480. FIG. 15B shows results of a second simulation using zero mutual coupling coefficient for 1461 and 1462. FIG. 15B includes a fourth waveform 1530 for the second driving signal, a fifth waveform 1540 for the drain current I3 of the third switch module 1470 and a sixth waveform 1545 for the drain current I4 of the fourth switch module 1480.
As seen in FIG. 15B, without the mutual coupling (coupling coefficients are zero), when the second driving signal VDRV-LS switches from the relatively high voltage to the relatively low voltage to turn off the lower power module 1460, the third switch module 1470 and the fourth switch module 1480 can turn off and then self turn on with a relatively large current flowing through the third switch module 1470 and the fourth switch module 1480 as shown by the fifth waveform 1540 and the six waveform 1545 at about 200 ns.
As seen in FIG. 15A, with the mutual coupling (non-zero coupling coefficients), when the second driving signal VDRV-LS switches from the relatively high voltage to the relatively low voltage to switch off the lower power module 1460, the third switch module 1470 and the fourth switch module 1480 can be turned off and can be kept in the turn-off state.
FIGS. 16A-16B show plots of simulation results for the power device 1401 according to an embodiment of the disclosure. FIG. 16A shows results of a first simulation using non-zero mutual coupling coefficient for 1461 and 1462. FIG. 16A includes a first waveform 1610 for the second driving signal VDRV-LS, a second waveform 1620 for the drain current I3 of the third switch module 1470 and a third waveform 1625 for the drain current I4 of the fourth switch module 1480. FIG. 16B shows results of a second simulation using zero mutual coupling coefficient for 1461 and 1462. FIG. 16B includes a fourth waveform 1630 for the second driving signal VDRV-LS, a fifth waveform 1640 for the drain current I3 of the third switch module 1470 and a sixth waveform 1645 for the drain current I4 of the fourth switch module 1480.
As seen in FIG. 16B, without the mutual coupling (coupling coefficients are zero), when the second driving signal VDRV-LS switches from the relatively low voltage to the relatively high voltage and stays at the relatively high voltage, the third switch module 1470 and the fourth switch module 1480 can repetitively turn on and off in a self sustained oscillation with a relatively large current flowing through the third switch module 1470 and the fourth switch module 1480 as shown by the fifth waveform 1640 and the six waveform 1645 from 20 ns to 70 ns in FIG. 16B.
As seen in FIG. 16A, with the mutual coupling (non-zero coupling coefficients), when the second driving signal VDRV-LS switches from the relatively low voltage to the relatively high voltage and stays at the relatively high voltage to switch on the lower power module 1460, the third switch module 1470 and the fourth switch module 1480 can be turned on and can be kept in the turn-on state.
FIG. 17 shows a flow chart outlining a process example 1700 according to an embodiment of the disclosure. In an example, the process 1700 is executed to implement a power device, such as the power device 1201, the power device 1401, and the like. The process starts at S1701, and proceeds to S1710.
At S1710, reliability issues in the switching operations of a power device are determined. For example, the reliability issues can be identified during a design of the power device based on various information sources, such as feedback from clients of previous implementation, power device simulations, and the like.
At S1720, parasitic inductance coupling techniques to eliminate the reliability issues are determined. In an example, when crosstalk is identified as a reliability issue for the power device, the parasitic inductance coupling technique used in the power device 1201 can be determined to eliminate the crosstalk; and when the self turn on or self sustained oscillation is identified as reliability issue for the power device, the parasitic inductance coupling technique used in the power device 1401 can be determined to prevent self turn on or the self sustained oscillation.
At S1730, transistors and interconnections are disposed according to the determined parasitic inductance coupling techniques. During manufacturing of the power device, the transistors and the interconnections can be disposed according to the determined parasitic inductance coupling techniques. Then the process proceeds to S1730 and terminates.
When implemented in hardware, the hardware may comprise one or more of discrete components, an integrated circuit, an application-specific integrated circuit (ASIC), etc.
While aspects of the present disclosure have been described in conjunction with the specific embodiments thereof that are proposed as examples, alternatives, modifications, and variations to the examples may be made. Accordingly, embodiments as set forth herein are intended to be illustrative and not limiting. There are changes that may be made without departing from the scope of the claims set forth below.

## Claims

1. A power device, comprising:
an upper power module coupled to a first node, a second node and a first control node via first interconnections, the upper power module being controlled by a first driving signal at the first control node to turn on/off a first current path between the first node that receives a first supply voltage and the second node;
a lower power module coupled to the second node, a third node and a second control node via second interconnections, the lower power module being controlled by a second driving signal at the second control node to turn on/off a second current path between the second node and the third node that receives a second supply voltage that is lower than the first supply voltage, wherein the first interconnections are inductively coupled to prevent a turn-on of the upper power module when the first driving signal is at a first voltage level to turn off the upper power module and the second driving signal is at a second voltage level to turn on the lower power module.

2. The power device of claim 1, wherein the upper power module comprises:
a first switch circuit in parallel with a second switch circuit, the first switch circuit and the second switch circuit being coupled to the first node, the second node and the first control node via the first interconnections.

3. The power device of claim 2, wherein the lower power module comprises:
a third switch circuit in parallel with a fourth switch circuit, the third switch circuit and the fourth switch circuit being coupled to the second node, the third node and the second control node via the second interconnections.

4. The power device of claim 3, wherein the first switch circuit includes a first SiC metal-oxide-semiconductor field effect transistor, the second switch circuit includes a second SiC metal-oxide-semiconductor field effect transistor, the third switch circuit includes a third SiC metal-oxide-semiconductor field effect transistor, and the fourth switch circuit includes a fourth SiC metal-oxide-semiconductor field effect transistor.

5. The power device of claim 2, wherein the first interconnection and the second interconnection are among interconnections that interconnect the first switch circuit to the first node, the second node, and the first control node.

6. The power device of claim 5, wherein parasitic inductances introduced by the first interconnection and the second interconnection are in an inversely coupled state.

7. The power device of claim 5, wherein the first interconnection interconnects a gate terminal of the first switch circuit to the first control node, and the second interconnection interconnects a drain terminal of the first switch circuit to the first node.

8. A power device, comprising:
an upper power module coupled to a first node, a second node and a first control node via first interconnections, the upper power module being controlled by a first driving signal at the first control node to turn on/off a first current path between the first node that receives a first supply voltage and the second node;
a lower power module coupled to the second node, a third node and a second control node via second interconnections, the lower power module being controlled by a second driving signal at the second control node to turn on/off a second current path between the second node and the third node that receives a second supply voltage that is lower than the first supply voltage, wherein the second interconnections are inductively coupled to prevent self turn-on of the lower power module when the second driving signal is at a voltage level to turn off the lower power module.

9. The power device of claim 8, wherein
the upper power module comprises:
a first switch circuit in parallel with a second switch circuit, the first switch circuit and the second switch circuit being coupled to the first node, the second node and the first control node via the first interconnections; and

the lower power module comprises:
a third switch circuit in parallel with a fourth switch circuit, the third switch circuit and le fourth switch circuit being coupled to the second node, the third node and the second control node via the second interconnections.

10. The power device of claim 9, wherein the first switch circuit includes a first SiC metal-oxide-semiconductor field effect transistor, the second switch circuit includes a second SiC metal-oxide-semiconductor field effect transistor, the third switch circuit includes a third SiC metal-oxide-semiconductor field effect transistor, and the fourth switch circuit includes a fourth SiC metal-oxide-semiconductor field effect transistor.

11. The power device of claim 9, wherein the first interconnection and the second interconnection are among interconnections that interconnect the third switch circuit and the fourth switch circuit to the second node, the third node, and the second control node.

12. The power device of claim 11, wherein parasitic inductances introduced by the first interconnection and the second interconnection are in a directly coupled state.

13. The power device of claim 12, wherein the first interconnection interconnects a gate terminal of the third switch circuit to the second control node, and the second interconnection interconnects a drain terminal of the fourth switch circuit to the second node.

14. A power device, comprising:
an upper power module coupled to a first node, a second node and a first control node via first interconnections, the upper power module being controlled by a first driving signal at the first control node to turn on/off a first current path between the first node that receives a first supply voltage and the second node;
a lower power module coupled to the second node, a third node and a second control node via second interconnections, the lower power module being controlled by a second driving signal at the second control node to turn on/off a second current path between the second node and the third node that receives a second supply voltage that is lower than the first supply voltage, wherein the second interconnections are inductively coupled to prevent self sustained oscillation of the lower power module when the second driving signal is at a voltage level to turn on the lower power module.

15. The power device of claim 14, wherein
the upper power module comprises:
a first switch circuit in parallel with a second switch circuit, the first switch circuit and the second switch circuit being coupled to the first node, the second node and the first control node via the first interconnections; and

the lower power module comprises:
a third switch circuit in parallel with a fourth switch circuit, the third. switch circuit and the fourth switch circuit being coupled to the second node, the third node and the second control node via the second interconnections.

16. The power device of claim 15, wherein the first switch circuit includes a first SiC metal-oxide-semiconductor field effect transistor, the second switch circuit includes a second SiC metal-oxide-semiconductor field effect transistor, the third switch circuit includes a third SiC metal-oxide-semiconductor field effect transistor, and the fourth switch circuit includes a fourth SiC metal-oxide-semiconductor field effect transistor.

17. The power device of claim 15, wherein the first interconnection and the second interconnection are among interconnections that interconnect the third switch circuit and the fourth switch circuit to the second node, the third node, and the second control node.

18. The power device of claim 17, wherein parasitic inductances introduced by the first interconnection and the second interconnection are in a directly coupled state.

19. The power device of claim 18, wherein the first interconnection interconnects a gate terminal of the third switch circuit to the second control node, and the second interconnection interconnects a drain terminal of the fourth switch circuit to the second node.