阅读说明：本技术 基于错误状况而改变晶体管的背面电极的电压的电路
(Circuit for changing voltage of back electrode of transistor based on error condition
) 是由 J·罗伊格-吉塔特
J·C·J·杰森斯 于 2019-08-29 设计创作，主要内容包括：本发明题为“基于错误状况而改变晶体管的背面电极的电压的电路”。本发明提供了一种电路,该电路可以包括晶体管、传感器和开关。晶体管可以包括漏极电极、栅极电极、源极电极和背面电极。传感器可以被配置为检测晶体管中的错误状况。开关可以被配置为响应于传感器检测到晶体管中的错误状况而改变在背面电极处的电压,在背面电极处的电压的改变减小漏极电极与源极电极之间的电流。(The invention provides a circuit for changing the voltage of the back electrode of a transistor based on an error condition. A circuit may include a transistor, a sensor, and a switch. The transistor may include a drain electrode, a gate electrode, a source electrode, and a back surface electrode. The sensor may be configured to detect an error condition in the transistor. The switch may be configured to change a voltage at the back electrode in response to the sensor detecting an error condition in the transistor, the change in voltage at the back electrode reducing a current between the drain electrode and the source electrode.)
1. A circuit, comprising:
a transistor including a drain electrode, a gate electrode, a source electrode, and a back electrode;
a sensor configured to detect an error condition in the transistor; and
a switch configured to change a voltage at the back side electrode in response to the sensor detecting the error condition in the transistor, the change in voltage at the back side electrode reducing current between the drain electrode and the source electrode.
2. The circuit of claim 1, wherein the transistor comprises a high electron mobility transistor.
3. The circuit of claim 1, wherein the change in the voltage at the back electrode increases a magnitude of a threshold voltage of the gate electrode.
4. The circuit of claim 1, wherein:
the transistor comprises an n-channel device; and is
The change in the voltage at the back electrode causes the voltage at the back electrode to become negative relative to the source electrode.
5. The circuit of claim 1, wherein the error condition comprises a temperature of at least one of the drain electrode, the gate electrode, or the source electrode measured by the sensor exceeding a temperature threshold.
6. The circuit of claim 1, wherein the error condition comprises a current measured by the sensor between the drain electrode and the source electrode exceeding a current threshold.
7. The circuit of claim 1, wherein the error condition comprises a voltage measured by the sensor at the transistor exceeding a voltage threshold.
8. A circuit, comprising:
a common node;
a transistor comprising a drain electrode, a gate electrode, a source electrode, and a back electrode, the source electrode electrically coupled to the common node;
a current source;
a switch coupled to the current source and to the common node;
a capacitor coupled to the current source and to the back electrode;
a diode comprising an anode electrically coupled to the capacitor and the back electrode and a cathode electrically coupled to the common node;
a sensor configured to detect an error condition at the transistor; and
a switch controller configured to cause the switch to conduct current between the current source and the common node in response to the sensor detecting the error condition.
9. The circuit of claim 8, wherein:
the transistor comprises an n-channel device; and is
The change in the voltage at the back electrode causes the voltage at the back electrode to become negative with respect to the source electrode.
10. A circuit, comprising:
a common node;
a transistor comprising a drain electrode, a gate electrode, a source electrode, and a back electrode, the source electrode electrically coupled to the common node;
a current source;
a capacitor coupled to the current source and to the back electrode;
a first switch comprising a first node and a second node, the first node electrically coupled to the capacitor, the back electrode, and the second node electrically coupled to the common node;
a second switch coupled to the current source and to the common node;
a diode comprising an anode electrically coupled to the capacitor, the back electrode, and the first node of the first switch and a cathode electrically coupled to the common node;
a sensor configured to detect an error condition at the transistor; and
a switch controller configured to cause the first switch not to conduct current between the current source and the common node in response to the sensor detecting the error condition.
11. The circuit of claim 10, wherein the diode comprises a High Electron Mobility Transistor (HEMT) including a drain node coupled to the capacitor and the backside electrode, a gate electrode coupled to the capacitor, the backside electrode and the drain node, and a source node coupled to the common node.
12. A circuit, comprising:
a common node;
a transistor comprising a drain electrode, a gate electrode, a source electrode, and a back electrode, the source electrode electrically coupled to the common node;
a current source;
a switch coupled to the current source and to the common node;
a capacitor coupled to the current source;
a first diode comprising a first anode and a first cathode, the first anode electrically coupled to the capacitor and the first cathode electrically coupled to the common node;
a second diode comprising a second anode electrically coupled to the back electrode and a second cathode electrically coupled to the first anode and to the capacitor;
a sensor configured to detect an error condition at the transistor; and
a switch controller configured to cause the switch to conduct current between the current source and the common node in response to the sensor detecting the error condition.
13. The circuit of claim 12, wherein the diode comprises a High Electron Mobility Transistor (HEMT) including a drain node coupled to the capacitor and the backside electrode, a gate electrode coupled to the capacitor, the backside electrode and the drain node, and a source node coupled to the common node.
Technical Field
This description relates to electronic circuits, including protection against damage due to overstressing of electronic circuits.
Background
Switches, such as gallium nitride (GaN) transistors, can be quickly damaged by power or current surges. The conducting transistor may become damaged during a short circuit event.
Disclosure of Invention
According to one example, a circuit may include a transistor, a sensor, and a switch. The transistor may include a drain electrode, a gate electrode, a source electrode, and a back surface electrode. The sensor may be configured to detect an error condition in the transistor. The switch may be configured to change a voltage at the back electrode in response to the sensor detecting an error condition in the transistor, the change in voltage at the back electrode reducing a current between the drain electrode and the source electrode.
A circuit may include: a common node; a transistor; a current source; a switch coupled to the current source and to the common node; a capacitor coupled to a current source and to a back electrode of the transistor; a diode; a sensor configured to detect an error condition at the transistor; and a switch controller. The transistor may include a drain electrode, a gate electrode, a source electrode, and a back electrode, the source electrode being electrically coupled to the common node. The diode may include an anode and a cathode. The anode may be electrically coupled to the capacitor and the back electrode. The cathode may be electrically coupled to a common node. The switch controller may be configured to cause the switch to conduct current between the current source and the common node in response to the sensor detecting the error condition.
A circuit may include: a common node; a transistor; a current source; a capacitor; a first switch; a second switch; a diode; a sensor configured to detect an error condition at the transistor; and a switch controller configured to cause the first switch not to conduct current between the current source and the common node in response to the sensor detecting the error condition. The transistor may include a drain electrode, a gate electrode, a source electrode, and a back electrode, the source electrode being electrically coupled to the common node. The capacitor may be coupled to a current source and to the back electrode. The first switch may include a first node and a second node, the first node being electrically coupled to the capacitor, the back electrode, and the second node being electrically coupled to the common node. The second switch may be coupled to the current source and to the common node. The diode may include an anode and a cathode. The anode may be electrically coupled to the capacitor, the back electrode, and a first node of the first switch. The cathode may be electrically coupled to a common node.
A circuit may include: a common node; a transistor; a current source; a switch coupled to the current source and to the common node; a capacitor coupled to a current source; a first diode; a second diode; a sensor configured to detect an error condition at the transistor; and a switch controller configured to cause the switch to conduct current between the current source and the common node in response to the sensor detecting the error condition. The transistor may include a drain electrode, a gate electrode, a source electrode, and a back electrode, the source electrode being electrically coupled to the common node. The first diode may include a first anode and a first cathode. The first anode may be electrically coupled to the capacitor. The first cathode may be electrically coupled to a common node. The second diode may include a second anode and a second cathode. The second anode may be electrically coupled to the back electrode. The second cathode may be electrically coupled to the first anode and to the capacitor.
The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.
Drawings
FIG. 1 is a diagram of a circuit for varying a voltage of a back electrode of a transistor in response to detecting an error condition, according to one example.
Fig. 2A is a diagram of the sensor and transistor of fig. 1 according to one example.
Fig. 2B is a diagram of the sensor and transistor of fig. 1 according to one example.
Fig. 2C is a diagram of the sensor and transistor of fig. 1 according to one example.
Fig. 3 is a graph showing voltage and current in the circuit of fig. 1 according to one example.
FIG. 4 is a diagram of a circuit for varying a voltage of a back electrode of a transistor in response to detecting an error condition, according to one example.
FIG. 5 is a diagram of a circuit for varying a voltage of a back electrode of a transistor in response to detecting an error condition, according to one example.
FIG. 6 is a diagram of a circuit for varying a voltage of a back electrode of a transistor in response to detecting an error condition, according to one example.
FIG. 7 is a diagram of a circuit for varying a voltage of a back electrode of a transistor in response to detecting an error condition, according to one example.
Fig. 8A is a diagram of a circuit that may be included in any of the circuits shown in fig. 1, 4, 5, 6, or 7, according to one example.
Fig. 8B is a diagram of a circuit that may be included in any of the circuits shown in fig. 1, 4, 5, 6, or 7, according to one example.
FIG. 9 is a diagram of a circuit for varying a voltage of a back electrode of a transistor in response to detecting an error condition, according to one example.
Detailed Description
To prevent damage to the transistor, the circuit may detect an error condition in the transistor and change the voltage at the body or back electrode of the transistor. The change in voltage at the body or back side electrode can reduce the current through the transistor, such as by increasing the threshold voltage of the gate of the transistor, to take advantage of the body effect that enables the body or back side electrode to act as the other gate of the transistor. The reduction in current may prevent damage to the transistor and/or other components.
Fig. 1 is a diagram of a circuit for varying the voltage of the back electrode 110 of the transistor 102 in response to detecting an error condition, according to one example. In some examples, transistor 102 may be implemented on a gallium nitride (GaN) substrate, a GaN-on-silicon carbide (SiC) substrate, a GaN-on-sapphire substrate, and/or as a GaN transistor. In some examples, GaN transistors may be selected for high power and/or high temperature applications. As non-limiting examples, the transistor 102 may include a positively doped GaN transistor, a High Electron Mobility Transistor (HEMT), a depletion mode HEMT (dhemt), a GaN metal-insulator-semiconductor (MIS) HEMT, or a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). In the example of a GaN transistor, the response of the circuit to the error condition may compensate for the GaN transistor's susceptibility to a short circuit due to the GaN transistor's large thermal impedance over a short period of time. Transistor 102 may include a drain electrode 104, a gate electrode 106, a source electrode 108, and a back electrode 110. In some embodiments, transistor 102 may include one or more semiconductor materials other than or different from GaN, such as a lateral transistor integrated on top of a semiconductor substrate and isolated from the substrate bulk by a capacitor (which may be a dielectric or junction capacitor) and/or a power transistor integrated in silicon-on-insulator.
The circuit may include a sensor 112 configured to detect an error condition in the transistor 102. Sensor 112 may perform measurements on transistor 102 and determine whether the measurements meet and/or exceed a threshold that satisfies an error condition. As non-limiting examples, the error condition may include the measured temperature at the measured electrode reaching or exceeding a temperature threshold, the measured current at the measured electrode reaching or exceeding a current threshold, or the measured voltage at the measured electrode or at both measured electrodes reaching or exceeding a voltage threshold. In some examples, the measured electrodes may include a drain electrode 104 as shown in fig. 2A, a source electrode 108 as shown in fig. 2B, or a gate electrode 106 as shown in fig. 2C.
In some implementations, the sensor 112 can measure two or all three of the drain electrode 104, the source electrode 108, and/or the gate electrode 106. In some examples, the sensor 112 may measure two or three of temperature, current, and/or voltage at one, two, or three of the drain electrode 104, the source electrode 108, and/or the gate electrode 106, and determine whether a temperature threshold, a current threshold, and/or a voltage threshold are all met or exceeded.
In some embodiments, transistor 102 may be implemented in a GaN substrate (and/or GaN epitaxial layers associated with the substrate) and may be co-packaged (e.g., included in a separate semiconductor die and molded within a single package or module) and/or co-integrated with the remaining components (such as sensor 112, power supply 116, capacitor 120, switching network 114, and/or common node 118) implemented in a silicon substrate. In some embodiments, transistor 102 and capacitor 120 may be implemented in a GaN substrate, and the remaining components co-packaged and/or co-integrated with transistor 102 and capacitor 120 may be implemented in silicon. In some embodiments, all of the components may be implemented in, encapsulated in, and/or integrated in a GaN substrate. The wide bandgap of GaN is beneficial for high power and/or high frequency applications.
Fig. 2A is a diagram of sensor 112 and transistor 102 of fig. 1 according to one example. In this example, the sensor 112 measures a property at the drain electrode 104, such as temperature, current, and/or voltage.
Fig. 2B is a diagram of the sensor and transistor of fig. 1 according to one example. In this example, the sensor 112 measures a property at the source electrode 108, such as temperature, current, and/or voltage.
Fig. 2C is a diagram of the sensor and transistor of fig. 1 according to one example. In this example, the sensor 112 measures a property at the gate electrode 106, such as temperature, current, and/or voltage.
Returning to fig. 1, the sensor 112 and/or a controller (shown in fig. 4, 5, 6, 7, and 9) coupled to and/or receiving signals from the sensor 112 may control and/or vary the voltage at the back electrode 110 by opening or closing a switch network 114 coupled to the back electrode 110. The switching network 114 may include one or more switches 114X, 114Y. Either or both of the switches 114X, 114Y may include a transistor, such as a High Electron Mobility Transistor (HEMT). Either or both of the switches 114X, 114Y in the switching network 114 may include a transistor, such as a metal-insulator-semiconductor hemt (mishemt).
Opening (e.g., turning off) or closing (e.g., turning on) of the switching network 114 may control and/or vary the voltage at the back electrode 110. After switch 114Y is closed and/or turned on, capacitor 120 may cause the voltage at back electrode 110 to be capacitively pushed negative with respect to source electrode 108. In some examples where transistor 102 is an n-channel device, sensor 112 and/or switching network 114 may reduce the voltage at back electrode 110 to increase the threshold voltage at gate 106, which may turn off transistor 102 and cause transistor 102 to stop conducting current, thereby preventing damage to transistor 102. In some examples, the switching network 114 may reduce the voltage at the back electrode 110 by: closing switch 114X to couple back electrode 110 to common node 118 brings the voltage at back electrode 110 to a lower voltage than when switch 114X is open and back electrode 110 is coupled to supply voltage 116 via capacitor 120. In some examples, the switching network 114 may reduce the voltage at the back electrode by: closing switch 114Y couples capacitor 120 to common node 118, which reduces the voltage at back electrode 110. According to an exemplary embodiment, the power source 116 may include a current source or a voltage source. In some examples, the power supply 116 can be a power supply having a non-zero and/or non-infinite impedance characterized by an output impedance greater than the on-resistance of the switch 114X coupled to the power supply 116. The output impedance of the power supply 116 may cause the power supply 116 to act as a current source as compared to the switch 114X.
In an n-channel example, the switch network 114 can increase the absolute magnitude of the voltage, such as by causing the voltage at the back electrode 110 to be negative due to the closing of the switch 114Y coupled to the capacitor 120, coupling the back electrode 110 to the supply voltage 116 via the capacitor 120, which causes the voltage at the back electrode 110 to reach a negative voltage. During normal operation, the voltage between the back electrode 110 and the source electrode 108 may be near zero, but during a surge event when the switch 114Y is closed, the voltage between the back electrode 110 and the source electrode 108 may be inversely proportional (equal in magnitude but opposite in sign or polarity) to the voltage between the drain electrode 104 and the source electrode 108.
In some examples where transistor 102 is a p-channel device, sensor 112 and/or switching network 114 may increase the voltage at back electrode 110 to reduce the threshold voltage at gate 106 (and/or make it more negative or increase its absolute value), which may turn off transistor 102 and cause transistor 102 to stop conducting current, thereby preventing damage to transistor 102. The change in voltage at the back electrode 110 may reduce the current flowing through the transistor 102 when an increase in voltage at the gate electrode 106 would otherwise increase the current flowing through the transistor 102. The reduction in current flowing through transistor 102 may prevent damage to transistor 102.
FIG. 3 is a diagram showing voltages 302A, 302B, 306A, 306B and currents 304A, 304B in the circuit of FIG. 1 according to an example based on DHEMT. In this example, the Vbus voltage is 400 volts, the resistances in series with the gate and substrate are all 9 ohms, the voltage provided by the driver decreases from 1 volt to negative 18 volts, the ramp time is 1 nanosecond, and the voltage across the capacitor ranges from zero to negative four hundred volts.
Without changing the voltage at the back electrode 110 (denoted as substrate voltage V)SUB302A) In the case of (2), voltage V SUB302A will remain constant, such as at zero or ground. In case of changing the voltage of the back electrode 110, the absolute value of the voltage at the back electrode 110 (expressed as the substrate voltage V)SUB302B) Increases over a short period of time 312, such as 5 nanoseconds, such as from zero to minus four hundred volts. The voltage at the gate electrode 106 (denoted as V) with or without changing the voltage of the back electrode 110gs(306A indicates the voltage at the gate electrode 106 when the voltage at the back electrode 110 does not change, and 306B indicates the voltage at the gate electrode 106 when the voltage at the back electrode 110 does change)) increases over a longer period of time 310 than the increase in voltage at the back electrode 110, such as from a negative value of negative fifteen volts to a small positive value, such as one volt. Current 304B through transistor 102 from drain electrode 104 to source electrode 108 is responsive to voltage V at back electrode 110SUB302B is increased by an increase in the gate voltages 306A, 306B as compared to the voltage V at the back electrode 110SUB302A remains constant (as the current 304A increases from zero to one hundred amps) by a smaller amount (such as from zero to fifty amps). These voltage values and current values are merely examples. The reduced increase in current may reduce damage to transistor 102.
Fig. 4 is a diagram of a circuit for varying the voltage of the back electrode 110 of the transistor 102 in response to detecting an error condition, according to one example. In this example, the sensor 112 described with reference to fig. 1, 2A, 2B, and 2C may include a sensor 112A that senses and/or determines a property at one or more nodes on the transistor 102, and a switch controller 112B in communication with the sensor 112A that causes the switch 114A to conduct current between the power supply 116 and the common node 118 in response to the sensor 112A detecting an error condition. The sensor 112A may include any of the features of the sensor 112 described above. The power source 116 may include a voltage source or a current source.
The switch 114A may be an example of the switching network 114 described with respect to fig. 1. The switch 114A may be coupled to a power source 116. The switch 114A may include a transistor, such as a High Electron Mobility Transistor (HEMT). In examples where the switch 114A includes a HEMT, the high switching speed of the HEMT may enable the switch 114A to quickly respond to an error condition in the transistor 102 to reduce the likelihood of damage to the transistor 102. The drain electrode of switch 114A may be coupled to power source 116 and the source electrode of switch 114A may be coupled to the drain electrode of another switch 408, and/or to common node 118.
The controller 112B may be coupled to the gate electrode 404 of the switch 114A to enable the controller 112B to control whether the switch 114A is on, acts as a closed switch and conducts current, or whether the switch 114A is off, acts as an open switch and prevents current from flowing through the switch 114A. When switch 114A is closed and conducting current, power source 116 may be coupled to common node 118 and to source electrode 108 of transistor 102.
The circuit may include a capacitor 402. Capacitor 402 may include a first terminal 402A coupled to power source 116 and to switch 114A, and a second terminal 402B coupled to back electrode 110 of transistor 102 and to anode 406A of diode 406. After switch 114A closes and/or turns on, capacitor 402 may cause the voltage at back electrode 110 to be capacitively pushed negative with respect to source electrode 108. When the switch 114A is turned off and/or open, the first end 402A of the capacitor 402 may accumulate charge. When the switch 114A is turned on and/or becomes closed, the coupling of the first end 402A of the capacitor 402 to the common node 118 and/or the source electrode 108 of the transistor may cause the second end 402B of the capacitor to quickly become negative to quickly reduce the voltage of the back electrode 110 of the transistor 102, reduce the current flowing through the transistor 102 from the drain 104 to the source 108, and prevent damage to the transistor 102. Capacitor 402 may increase the speed at which the voltage at back electrode 110 of transistor 102 decreases in response to switch 114A turning on and/or closing to reduce the likelihood of damage to transistor 102.
The circuit may include a gate 410 of the second switch 408 (switch 114A may be considered a first switch) and a predriver 412 that controls the gate electrode 106 of transistor 102. The second switch 408 may include a transistor, such as a HEMT. The pre-driver 412 may provide a voltage to the gate electrode 106 of the transistor 102 to activate and/or turn on the transistor 102 and a voltage to the gate 410 of the second switch 408. The second switch 408 may be coupled to and/or disposed between the switch 114A and the common node 118, and may complete a path between the power supply 116 and the common node. When the pre-driver 412 provides a sufficient voltage (such as a threshold voltage) to both the gate 410 of the second switch 408 and the gate electrode 106 of the transistor 102, the transistor 102 may be activated and the second switch 408 may conduct current when the switch 114A is turned on and/or closed. Both the transistor 102 and the second switch 408 may be turned off and/or disconnected when the pre-driver 412 does not provide sufficient voltage.
In some embodiments, transistor 102 may be implemented in a GaN substrate (and/or GaN epitaxial layers associated with the substrate) and may be co-packaged and/or co-integrated with the remaining components (such as sensor 112A, controller 112B, power supply 116, pre-driver 412, switch 408, capacitor 402, and/or diode 406), where the remaining components are implemented in a silicon substrate. In some embodiments, transistor 102 and capacitor 402 may be implemented in a GaN substrate, and the remaining components co-packaged and/or co-integrated with transistor 102 and capacitor 402 may be implemented in silicon. In some embodiments, all of the components may be implemented in, encapsulated in, and/or integrated in a GaN substrate.
Fig. 5 is a diagram of a circuit for varying the voltage of the back electrode 110 of the transistor 102 in response to detecting an error condition, according to one example. In this example, a first terminal of the second switch 508, which may include the features of the second switch 408 described above with respect to fig. 4, may be coupled to the power source 116 and to the first terminal 402A of the capacitor, and a second terminal of the second switch 508 may be coupled to the switch 114B. The switch 114B may include features of either of the switches 114, 114A described above, and may be coupled between the second switch 508 and the common node 118. The drain electrode of switch 114B may be coupled to second switch 508 and/or to power source 116, and the source electrode of switch 114B may be coupled to common node 118.
Fig. 6 is a diagram of a circuit for varying the voltage of the back electrode 110 of the transistor 102 in response to detecting an error condition, according to one example. In this example, the switch 114C, which may include the features of any of the switches 114, 114A, 114B described above, may include a first terminal and a second terminal. The drain node and/or first terminal of switch 114C may be coupled to the back electrode 110 of transistor 102, to the second terminal 402B of capacitor 402, and to the anode 406A of diode 406. A source node and/or a second terminal of switch 114C may be coupled to common node 118 and to source 108 of transistor 102. A first terminal of a second switch 608, which may include the features of the second switch 408 described above with respect to fig. 4, may be coupled to the power source 116 and to the first terminal 402A of the capacitor, and a second terminal of the second switch 608 may be coupled to the common node 118. Regardless of the state of the switch 114C, the first terminal 402A of the capacitor 402 may accumulate charge. When the switch 114C is turned off and/or becomes open, the coupling of the first end 402A of the capacitor 402 to the common node 118 and/or the source electrode 108 of the transistor (which is done by the switch 508 in this example) may cause the second end 402B of the capacitor 402 to quickly become negative to quickly reduce the voltage of the back electrode 110 of the transistor 102, reduce the current flowing through the transistor 102 from the drain 104 to the source 108, and prevent damage to the transistor 102.
Fig. 7 is a diagram of a circuit for varying the voltage of the back electrode 110 of the transistor 102 in response to detecting an error condition, according to one example. The circuit of fig. 7 includes the features of the circuit of fig. 4 with the addition of a second diode 706 coupled between the anode 406B of the diode 406 (which may be considered a first diode) and the back electrode 110 of the transistor 102. In this example, an anode 706A of the second diode 706 is coupled to the back electrode 110 of the transistor 102. In this example, the cathode 706B of the second diode 706 is coupled to the second terminal 402B of the capacitor 402 and to the anode 406A of the first diode 406. The second diode 706 may act as a charge pump to prevent reverse charge flow and reduce and/or push down the voltage at the back electrode 110 of the transistor 102 to gradually reduce the current through the transistor 102 whenever the sensor 112A detects an error condition and the controller 112B turns on and/or closes the switch 114A.
Fig. 8A is a diagram of a circuit that may be included in any of the circuits shown in fig. 1, 4, 5, 6, or 7, according to one example. In this example, transistor 102 may be implemented as an operational amplifier 815, a resistor 820, and a variable resistor 822. In this example, a drain electrode 804 corresponding to the drain electrode 104 described above is coupled to a first end of a resistor 820. In some examples, a gate electrode, rather than a drain electrode, may be coupled to a first end of resistor 820. In some examples, a driver power supply, rather than a drain electrode or a gate electrode, may be coupled to a first end of resistor 820.
A second end of the resistor 820 is coupled to a first input node of the operational amplifier 815 and to a first end of a variable resistor 822. A second terminal of the variable resistor 822 is coupled to the output node of the operational amplifier 815 and to the back electrode 810. The rear electrode 810 corresponds to the rear electrode 110 described above. A second input node of the operational amplifier 815 may be coupled to a source electrode 808, which may correspond to the source electrode 108 described above. The variable resistor 822 may be a transistor, such as a GaN transistor, and the sensor 112 may be coupled between gate and source terminals and/or gate and source electrodes of the transistor. The resistance of the variable resistor 822 may be near zero such that the variable resistor 822 is a conductor when no error condition is detected, and the resistance of the variable resistor 822 may be an order of magnitude higher (such as ten or one hundred times higher) than the resistance of the resistor 802 when an error condition is detected.
Fig. 8B is a diagram of a circuit that may be included in any of the circuits shown in fig. 1, 4, 5, 6, or 7, according to one example. In this example, the transistor 102 can be implemented as an operational amplifier 865, a variable resistor 870, and a resistor 872. In this example, a drain electrode 804 corresponding to the above-described drain electrode 104 is coupled to a first end of the variable resistor 870. In some examples, a gate electrode, rather than a drain electrode, may be coupled to a first end of the variable resistor 870. In some examples, a driver power supply, rather than a drain electrode or a gate electrode, may be coupled to a first end of resistor 820.
A second terminal of the variable resistor 870 is coupled to a first input node of the operational amplifier 865 and to a first terminal of the resistor 872. A second terminal of resistor 872 is coupled to the output node of operational amplifier 815 and to the back electrode 860. The rear electrode 860 corresponds to the rear electrode 110. The second input node of operational amplifier 815 may be coupled to a source electrode 868, which corresponds to source electrode 108 described above. Variable resistor 870 may be a transistor, such as a GaN transistor, and sensor 112 may be coupled between a gate terminal and a source terminal and/or a gate electrode and a source electrode of transistor 102. The resistance of variable resistor 870 may be very high such that variable resistor 870 acts as an open circuit when no error condition is detected, and the resistance of variable resistor 870 may be an order of magnitude lower (such as one-tenth or one-hundredth) than the resistance of resistor 802 when an error condition is detected.
Fig. 9 is a diagram of a circuit for varying the voltage of the back electrode 110 of the transistor 102 in response to detecting an error condition, according to one example. In this example, the gate driver 950 may control the gate electrode 106 of the transistor 102. The switch 908 may be coupled between a first input of the operational amplifier 952 and the drain electrode 104 of the transistor 102. The switch 908 may include a transistor, such as a GaN transistor, and/or may be a positively doped GaN transistor. The switch controller 112B may be coupled to a gate electrode 904 of a switch 908. The back electrode 110 of the transistor 102 may be coupled to the back electrode of the switch 908.
A second input of operational amplifier 952 may be coupled to source electrode 108 of transistor 102. A first input of the operational amplifier 952 may be coupled to a first end of a resistor 954. A second terminal of the resistor 954 may be coupled to an output of the operational amplifier 952 and to the back electrode 110.
Various exemplary embodiments are described.
