U.S. patent application number 16/052479 was filed with the patent office on 2020-02-06 for driver for switching gallium nitride (gan) devices.
The applicant listed for this patent is Infineon Technologies AG. Invention is credited to Maurizio Galvano, Roberto Penzo.
Application Number | 20200044554 16/052479 |
Document ID | / |
Family ID | 69141269 |
Filed Date | 2020-02-06 |
United States Patent
Application |
20200044554 |
Kind Code |
A1 |
Penzo; Roberto ; et
al. |
February 6, 2020 |
DRIVER FOR SWITCHING GALLIUM NITRIDE (GAN) DEVICES
Abstract
A device for switching Gallium Nitride (GaN) devices includes a
high side driver, low side driver, and high side charge circuitry.
The high side driver is adapted to control a high side GaN device
using a high side supply. The low side driver is adapted to control
a low side GaN device using a low side supply. The high side charge
circuitry is adapted to charge the high side supply with the low
side supply when the low side driver activates the low side GaN
device.
Inventors: |
Penzo; Roberto; (Vigonza
(PD), IT) ; Galvano; Maurizio; (Padova, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineon Technologies AG |
Neubiberg |
|
DE |
|
|
Family ID: |
69141269 |
Appl. No.: |
16/052479 |
Filed: |
August 1, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02M 3/158 20130101;
H03K 17/687 20130101; H02M 1/08 20130101; H03K 17/063 20130101;
H03K 2217/0063 20130101; H01L 29/778 20130101; H03K 2217/0072
20130101; H01L 29/2003 20130101; Y02B 70/1483 20130101; H03K
2217/0081 20130101 |
International
Class: |
H02M 1/08 20060101
H02M001/08; H01L 29/20 20060101 H01L029/20; H01L 29/778 20060101
H01L029/778; H03K 17/687 20060101 H03K017/687 |
Claims
1. A device for switching Gallium Nitride (GaN) devices, the device
comprising: a high side driver adapted to control a high side GaN
device using a high side supply, wherein the high side supply
comprises a capacitor; a low side driver adapted to control a low
side GaN device using a low side supply; and high side charge
circuitry adapted to charge the high side supply with the low side
supply when the low side driver activates the low side GaN device,
wherein, to charge the high side supply, the high side charge
circuitry is adapted to couple a gate of the low side GaN device to
the capacitor of the high side supply such that the low side supply
charges the capacitor of the high side supply when the low side
driver activates the low side GaN device.
2. The device of claim 1, wherein the high side charge circuitry is
adapted to prevent current from flowing from the high side supply
to the low side driver and to permit current to flow from the low
side driver to the high side supply.
3. The device of claim 2, wherein the high side charge circuitry
comprises a diode comprising an anode coupled the low side driver
and a cathode coupled to the high side supply to prevent current
from flowing from the high side supply to the low side driver and
to permit current to flow from the low side driver to the high side
supply.
4. The device of claim 2, wherein the high side charge circuitry
comprises: a switching element comprising a first node coupled the
high side supply and a second node coupled to the low side driver;
and active switching circuitry adapted to selectively activate the
switching element to prevent current from flowing from the high
side supply to the low side driver and to permit current to flow
from the low side driver to the high side supply.
5. The device of claim 1, wherein the capacitor is a first
capacitor and wherein the low side supply comprises a second
capacitor coupled in parallel with a voltage source.
6. The device of claim 1, comprising one or more of: low side
discharge circuitry adapted to reduce current flow from the low
side driver to the low side GaN device and to refrain from reducing
current flow from the low side GaN device to the low side driver;
or high side discharge circuitry adapted to reduce current flow
from the high side driver to the high side GaN device and to
refrain from reducing current flow from the high side GaN device to
the high side driver.
7. The device of claim 1, wherein the low side driver is adapted to
establish a first low side channel between a positive terminal of
the low side supply and the low side GaN device to activate the low
side GaN device and to establish a second low side channel between
a negative terminal of the low side supply and the low side GaN
device to deactivate the low side GaN device; and wherein the high
side driver is adapted to establish a first high side channel
between a positive terminal of the high side supply and the high
side GaN device to activate the high side GaN device and to
establish a second high side channel between a negative terminal of
the high side supply and the low side GaN device to deactivate the
high side GaN device.
8. The device of claim 7, wherein the low side driver comprises: a
first low side switching element comprising a first node coupled to
the positive terminal of the low side supply, a second node coupled
to the low side GaN device, and a control node; a second low side
switching element comprising a first node coupled to the low side
GaN device, a second node coupled to the negative terminal of the
low side supply, and a control node; and low side driving circuitry
adapted to generate a first control signal at the control node of
the first low side switching element to cause the first low side
switching element to establish the first low side channel between
the positive terminal of the low side supply and the low side GaN
device to activate the low side GaN device and to generate a second
control signal at the control node of the second low side switching
element to cause the second low side switching element to establish
the second low side channel between the negative terminal of the
low side supply and the low side GaN device to deactivate the low
side GaN device.
9. The device of claim 7, wherein the high side driver comprises: a
first high side switching element comprising a first node coupled
to the positive terminal of the high side supply, a second node
coupled to the high side GaN device, and a control node; a second
high side switching element comprising a first node coupled to the
high side GaN device, a second node coupled to the negative
terminal of the high side supply, and a control node; and high side
driving circuitry adapted to generate a first control signal at the
control node of the first high side switching element to cause the
first high side switching element to establish the first high side
channel between the positive terminal of the high side supply and
the high side GaN device to activate the high side GaN device and
to generate a second control signal at the control node of the
second high side switching element to cause the second high side
switching element to establish the second high side channel between
the negative terminal of the high side supply and the high side GaN
device to deactivate the high side GaN device.
10. The device of claim 1, wherein the high side GaN device
comprises a control node coupled to the high side driver, a first
node coupled to a positive terminal of a power converter supply,
and a second node coupled to one or more converter elements for a
power converter adapted to receive power from the power converter
supply and output a regulated voltage or regulated current; and
wherein the low side GaN device comprises a control node coupled to
the low side driver, a first node coupled to the one or more
converter elements, and a second node coupled to a negative
terminal of the power converter supply.
11. A method for driving a Gallium Nitride (GaN) devices, the
method comprising: controlling a high side GaN device using a high
side supply, wherein the high side supply comprises a capacitor;
controlling a low side GaN device using a low side supply; and
charging the high side supply with the low side supply when the low
side driver activates the low side GaN device, wherein charging the
high side supply comprises coupling a gate of the low side GaN
device to the capacitor of the high side supply such that the low
side supply charges the capacitor of the high side supply when the
low side driver activates the low side GaN device.
12. The method of claim 11, wherein charging the high side supply
comprises: preventing current from flowing from the high side
supply to the low side driver; and permitting current to flow from
the low side driver to the high side supply.
13. The method of claim 12, wherein charging the high side voltage
comprises: selectively activating a switching element to prevent
current from flowing from the high side supply to the low side
driver and to permit current to flow from the low side driver to
the high side supply.
14. The method of claim 11, wherein the capacitor is a first
capacitor and wherein the low side supply comprises a second
capacitor coupled in parallel with a voltage source.
15. The method of claim 11, wherein controlling the high side GaN
device comprises reducing current flow from the high side driver to
the high side GaN device and refraining from reducing current flow
from the high side GaN device to the high side driver; and wherein
controlling the low side GaN device comprises reducing current flow
from the low side driver to the low side GaN device and refraining
from reducing current flow from the low side GaN device to the low
side driver.
16. The method of claim 11, wherein controlling the low side GaN
device comprises establishing a first low side channel between a
positive terminal of the low side supply and the low side GaN
device to activate the low side GaN device and establishing a
second low side channel between a negative terminal of the low side
supply and the low side GaN device to deactivate the low side GaN
device; and wherein controlling the high side GaN device comprises
establishing a first high side channel between a positive terminal
of the high side supply and the high side GaN device to activate
the high side GaN device and establishing a second high side
channel between a negative terminal of the high side supply and the
high side GaN device to deactivate the high side GaN device.
17. The method of claim 16, wherein controlling the low side GaN
device comprises: generating a control signal at a control node of
a first low side switching element to cause the first low side
switching element to establish the first low side channel between
the positive terminal of the low side supply and the low side GaN
device to activate the low side GaN device; and generating a second
control signal at a control node of a second low side switching
element to cause the second low side switching element to establish
the second low side channel between the negative terminal of the
low side supply and the low side GaN device to deactivate the low
side GaN device.
18. The method of claim 16, wherein controlling the high side GaN
device comprises: generating a first control signal at a control
node of a first high side switching element to cause the first high
side switching element to establish the first high side channel
between the positive terminal of the high side supply and the high
side GaN device to activate the high side GaN device; and
generating a second control signal at a control node of a second
high side switching element to cause the second high side switching
element to establish the second high side channel between the
negative terminal of the high side supply and the high side GaN
device to deactivate the high side GaN device.
19. The method of claim 11, wherein the high side GaN device
comprises a control node coupled to the high side driver, a first
node coupled to a positive terminal of a power converter supply,
and a second node coupled to one or more converter elements for a
power converter adapted to receive power from the power converter
supply and output a regulated voltage or regulated current; and
wherein the low side GaN device comprises a control node coupled to
the low side driver, a first node coupled to the one or more
converter elements, and a second node coupled to a negative
terminal of the power converter supply.
20. A system for controlling a power converter, the system
comprising: a high side GaN device; a low side GaN device; a high
side driver adapted to control the high side GaN device using a
high side supply, wherein the high side supply comprises a
capacitor; a low side driver adapted to control the low side GaN
device using a low side supply; and high side charge circuitry
adapted to charge the high side supply with the low side supply
when the low side driver activates the low side GaN device,
wherein, to charge the high side supply, the high side charge
circuitry is adapted to couple a gate of the low side GaN device to
the capacitor of the high side supply such that the low side supply
charges the capacitor of the high side supply when the low side
driver activates the low side GaN device.
Description
TECHNICAL FIELD
[0001] This disclosure relates to circuitry for driving Gallium
Nitride (GaN) devices, particularly, GaN devices in half bridge
switching applications.
BACKGROUND
[0002] Gallium Nitride (GaN) devices have desirable
characteristics, which can make them more suitable compared to
metal-oxide-semiconductor field-effect transistors (MOSFETs) in
half bridge switching applications, especially when high
frequencies and high efficiencies are needed. For example GaN
devices can have a faster switching speed and/or a smaller package
compared to MOSFETs. Moreover, GaN devices can omit a parasitic
body diode, which can result in no reverse recovery losses.
Further, GaN devices are capable of reverse conduction. As such,
GaN devices may omit an external anti-parallel diode.
SUMMARY
[0003] In general, this disclosure is directed to a driver for
Gallium Nitride (GaN) devices with a high side supply that is
charged with a low side supply. For example, the driver may be
adapted to charge the high side supply with the low side supply
when the low side driver activates the low side GaN device. In this
way, the driver may charge the high side supply to a desired
floating voltage without necessarily relying on additional
components for post-regulation of the voltage output by the high
side supply or clamping the voltage output by the high side
supply.
[0004] In an example, a device for switching GaN devices includes a
high side driver adapted to control a high side GaN device using a
high side supply, a low side driver adapted to control a low side
GaN device using a low side supply, and high side charge circuitry
adapted to charge the high side supply with the low side supply
when the low side driver activates the low side GaN device.
[0005] In another example, a method for driving GaN devices
includes controlling a high side GaN device using a high side
supply, controlling a low side GaN device using a low side supply,
and charging the high side supply with the low side supply when the
low side driver activates the low side GaN device.
[0006] In another example, a system for controlling a power
converter includes a high side GaN device, a low side GaN device, a
high side driver adapted to control the high side GaN device using
a high side supply, a low side driver adapted to control the low
side GaN device using a low side supply, and high side charge
circuitry adapted to charge the high side supply with the low side
supply when the low side driver activates the low side GaN
device.
[0007] Details of these and other examples are set forth in the
accompanying drawings and the description below. Other features,
objects, and advantages will be apparent from the description and
drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is a block diagram illustrating a driver for Gallium
Nitride (GaN) devices with a high side supply that is charged with
a low side supply in accordance with one or more techniques of this
disclosure.
[0009] FIG. 2 is a circuit diagram illustrating a first example of
the driver of FIG. 1 in accordance with one or more techniques of
this disclosure.
[0010] FIG. 3 is a circuit diagram illustrating a second example of
the driver of FIG. 1 in accordance with one or more techniques of
this disclosure.
[0011] FIG. 4 is a circuit diagram illustrating a third example of
the driver of FIG. 1 in accordance with one or more techniques of
this disclosure.
[0012] FIG. 5 is a circuit diagram illustrating a fourth example of
the driver of FIG. 1 in accordance with one or more techniques of
this disclosure.
[0013] FIG. 6 is a first illustration of a performance of the
driver of FIG. 1 in accordance with one or more techniques of this
disclosure.
[0014] FIG. 7 is a second illustration of a performance of the
driver of FIG. 1 in accordance with one or more techniques of this
disclosure.
[0015] FIG. 8 is a third illustration of a performance of the
driver of FIG. 1 in accordance with one or more techniques of this
disclosure.
[0016] FIG. 9 is a flow diagram for a method for driving GaN
devices in accordance with one or more techniques of this
disclosure.
DETAILED DESCRIPTION
[0017] A difficulty when driving Gallium Nitride (GaN) Enhancement
High-electron-mobility transistor (e-HEMTs) is the narrow gate
voltage range (-4V/+6V typical) of GaN e-HEMTs compared to
metal-oxide-semiconductor field-effect transistors (MOSFETs).
Another characteristic of a GaN e-HEMT is that reverse current flow
with the Voltage Gate to Source "V.sub.GS" less than zero (e.g.,
V.sub.GS.ltoreq.0 V) is "diode-like" and establishes when the gate
voltage with respect to the drain exceeds a voltage threshold
"V.sub.th" of the GaN e-HEMT. An example of the Voltage Source to
Drain "V.sub.SD" follows.
V.sub.SD=V.sub.SG+V.sub.GD=-V.sub.GS+V.sub.th+I*R.sub.rev_ON
(equation 1)
[0018] where "V.sub.SG" is the Voltage Source to Gate, "V.sub.GD"
is the Voltage Gate to Drain, "I" is the current at the GaN e-HEMT,
and "Rrev_ON" is the resistance of the GaN e-HEMT.
[0019] Given that the voltage threshold "V.sub.th" is in the range
1.5 V-2 V, the Voltage Source to Drain "V.sub.SD" is typically
higher than the voltage threshold of a silicon power MOSFET. For
high voltage and high dV/dt kW applications, GaN e-HEMTs may be
turned off with a negative Voltage Gate to Source "V.sub.GS",
further increasing the Voltage Source to Drain "V.sub.SD" needed by
the GaN e-HEMT device to operate in reverse.
[0020] Such GaN e-HEMT characteristics may be undesirable in
applications in which low side free-wheeling is used, such as, but
not limited to, half bridge switching applications using a high
side GaN e-HEMT device and a low side GaN e-HEMT device. For
example, when the high side GaN e-HEMT "T.sub.H" is turned off, a
positive inductor current is forced to flow on the low side, which
goes into reverse conduction, which results in the switching node
voltage being equal to Voltage Drain to Source "V.sub.DS" voltage
of the low side GaN e-HEMT "T.sub.L" during dead switching. In
bootstrap capacitor based high side drivers, the negative voltage
at the switching node (e.g. the high side driver floating ground)
may overcharge the bootstrap capacitor above the maximum rating of
GaN Voltage Source to Gate "V.sub.GS," which may result in damage
to the high side GaN e-HEMT device.
[0021] In some systems, additional post-regulation circuitry is
used to regulate a bootstrap voltage to avoid damaging the GaN
e-HEMT while preserving driving capabilities. In other systems,
additional external (or internal) Zener diodes (plus a resistor) is
used to clamp bootstrap voltage to avoid damaging the GaN e-HEMT
while preserving driving capabilities. In yet further systems, an
additional series switch with its body diode back-to-back connected
to the bootstrap diode is used to cut out the recharge path when
the low side GaN e-HEMT device is OFF (e.g., operating in an open
state).
[0022] In accordance with one or more techniques described herein,
a driver may include high side charge circuitry adapted to charge
the high side supply with the low side supply when the low side
driver activates the low side GaN device. For example, a driver may
be adapted to connect a bootstrap diode to the low side GaN e-HEMT
gate re-using the already existing gate pull-up pMOS as a blocking
switch, optimizing the synchronization between low side GaN e-HEMT
turn-on and bootstrap capacitor recharge path activation, thus
protecting the application against bootstrap overcharge with no
extra pin and silicon cost. Some advantages of including such high
side charge circuitry may include, but are not limited to, for
example, an optimal timing between low side turn-on and bootstrap
capacitor recharge path activation, no additional external or
internal components, and no additional driver pins.
[0023] FIG. 1 is a block diagram illustrating a driver for GaN
devices with a high side supply that is charged with a low side
supply in accordance with one or more techniques of this
disclosure. FIG. 1 shows system 100 which includes low side supply
102, low side driver 104, low side GaN device 106, high side charge
circuitry 110, high side supply 112, high side driver 114, high
side GaN device 116, and converter elements 124. System 100 may
include additional components than those shown. In some examples,
system 100 may be implemented as a single or multiple integrated
circuit (IC) packages.
[0024] Low side supply 102 may be configured to provide electrical
power to one or more other components of system 100. For instance,
low side supply 102 may be configured to supply a charge at a gate
of low side GaN device 106. In some examples, low side supply 102
may be an output of a power converter, power inverter, regulator,
or other power conversion circuitry. For instance, low side supply
102 may be an output of a direct current (DC) to DC power
converter, an alternating current (AC) to DC power converter, a DC
to AC power inverter, a linear regulator, or other power conversion
circuitry.
[0025] Low side driver 104 may be adapted to control low side GaN
device 106 using low side supply 102. For example, low side driver
104 may include switching elements that couple a gate of low side
GaN device 106 to a positive terminal of low side supply 102 or a
negative terminal (e.g., ground) of low side supply 102. Examples
of switching elements may include, but are not limited to, junction
field-effect transistor (JFET), metal-oxide-semiconductor
Field-Effect-Transistor (MOSFET), dual-gate MOSFET, insulated-gate
bipolar transistor (IGBT), any other type of FET, or any
combination of the switching elements. Examples of MOSFETS may
include, but are not limited to, p-channel MOSFET (pMOS), n-channel
MOSFET (nMOS), double diffused MOSFET (DMOS), or any other type of
MOSFET, or any combination of the same. In some examples, a
switching element may comprise a high-electron mobility transistor,
a GaN based transistor, or another switching element. Other
materials may also be used to realize a switching element.
[0026] Low side driver 104 may include low side driving circuitry
adapted to selectively drive switching elements to couple a gate of
low side GaN device 106 to a positive terminal of low side supply
102 or a negative terminal (e.g., ground) of low side supply 102.
Low side driving circuitry may comprise a modulation (e.g.,
pulse-width modulation) controller. For example, low side driving
circuitry may output, to the switching elements, a high signal
(e.g., logical `1`) during a first portion of a pulse-width
modulation cycle to cause switching elements to couple a gate of
low side GaN device 106 to a positive terminal of low side supply
102. In the example, low side driving circuitry may output, to
switching elements, a low signal (e.g., logical `0`) during a
second portion of a pulse-width modulation cycle to cause switching
elements to couple a gate of low side GaN device 106 to a negative
terminal of low side supply 102. In some examples, low side driving
circuitry may output, to switching elements, one or more dead-time
signal during a third portion of a pulse-width modulation cycle to
cause switching elements to decouple a gate of low side GaN device
106 from the low side supply 102.
[0027] Low side driving circuitry may comprise any suitable
arrangement of hardware, software, firmware, or any combination
thereof. Low side driving circuitry may include any one or more
microprocessors, digital signal processors (DSPs), application
specific integrated circuits (ASICs), field programmable gate
arrays (FPGAs), or any other equivalent integrated or discrete
logic circuitry, as well as any combinations of such components.
When low side driving circuitry includes software or firmware, low
side driving circuitry may further include any necessary hardware
for storing and executing the software or firmware, such as one or
more memories and one or more processors or processing units. In
general, a processing unit may include one or more microprocessors,
DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete
logic circuitry, as well as any combinations of such
components.
[0028] High side supply 112 may be adapted to provide electrical
power to one or more other components of system 100. For instance,
high side supply 112 may be adapted to supply a charge at a gate of
high side GaN device 116. In some examples, high side supply 112
may be floating. For example, high side supply 112 may have a
negative terminal that has a voltage different from a ground of
system 100 (e.g., a negative terminal of low side supply 102). In
some examples, high side supply 112 includes a capacitor. A
capacitor may include, an electrical component adapted to store
electrical energy in an electric field. Examples of an electrical
component configured to store electrical energy in an electric
field may include, but are not limited to, ceramic capacitors, film
capacitors, electrolytic capacitors (e.g., aluminum, tantalum,
niobium, or the like), super capacitors (e.g., double layer,
pseudocapacitors, hybrid capacitors), mica capacitors, or another
capacitor. Although examples of this disclosure may refer to a
capacitor as a single capacitor, in some examples, a capacitor may
be an array of capacitive elements. For instance, high side supply
112 may include a capacitor formed of an array of capacitive
elements coupled in parallel and/or series. In some instances, each
capacitive element may be a discrete component, while in other
instances, each one of the capacitive elements may be contained
within a single package (e.g., capacitor array).
[0029] High side driver 114 may include high side driving circuitry
adapted to selectively drive switching elements to couple a gate of
high side GaN device 116 to a positive terminal of high side supply
112 or a negative terminal of high side supply 112. High side
driving circuitry may comprise a modulation (e.g., pulse-width
modulation) controller. For example, high side driving circuitry
may output, to the switching elements, a high signal (e.g., logical
`1`) during a first portion of a pulse-width modulation cycle to
cause switching elements to couple a gate of high side GaN device
116 to a positive terminal of high side supply 112. In the example,
high side driving circuitry may output, to switching elements, a
low signal (e.g., logical `0`) during a second portion of a
pulse-width modulation cycle to cause switching elements to couple
a gate of high side GaN device 116 to a negative terminal of high
side supply 112. In some examples, high side driving circuitry may
output, to switching elements, one or more dead-time signal during
a third portion of a pulse-width modulation cycle to cause
switching elements to decouple a gate of high side GaN device 116
from the high side supply 112.
[0030] High side driving circuitry may comprise any suitable
arrangement of hardware, software, firmware, or any combination
thereof. High side driving circuitry may include any one or more
microprocessors, digital signal processors (DSPs), application
specific integrated circuits (ASICs), field programmable gate
arrays (FPGAs), or any other equivalent integrated or discrete
logic circuitry, as well as any combinations of such components.
When high side driving circuitry includes software or firmware, low
side driving circuitry may further include any necessary hardware
for storing and executing the software or firmware, such as one or
more memories and one or more processors or processing units.
[0031] High side charge circuitry 110 may be adapted to charge high
side supply 112 with low side supply 102 when low side driver 104
activates low side GaN device 106. In some examples, high side
charge circuitry 110 may be adapted to prevent current from flowing
from high side supply 112 to low side driver 104 and to permit
current to flow from low side driver 104 to high side supply 112.
For example, high side charge circuitry 110 may be configured to
generate a channel that electronically couples low side supply 102
to high side supply 112 when low side driver 104 activates low side
GaN device 106. For instance, high side charge circuitry may be
coupled to an output of low side driver 104 and/or a gate of low
side GaN device 106. In some examples, high side charge circuitry
110 may include a diode that prevents current from flowing from
high side supply 112 to low side supply 102 and permits current to
flow from low side supply 102 to high side supply 112. In some
examples, high side charge circuitry 110 may include a switch that
is selectively activated to prevent current from flowing from high
side supply 112 to low side supply 102 and to permit current to
flow from low side supply 102 to high side supply 112.
[0032] Converter elements 124 may be adapted to provide a target
voltage, current, or power at a load. Converter elements 124 may
include, for example, one or more of a capacitor, an inductor, a
resistor, a transformer, a sensor, or another converter element. In
some examples, a load is coupled to converter elements 124 that is
configured to receive the target voltage, current, or power output
by converter elements 124.
[0033] Rather than relying on specialized circuitry for regulating
a voltage at high side supply 112, high side charge circuitry 110
is adapted to charge high side supply 112 with low side supply 102
when low side driver 104 activates low side GaN device 106. For
example, when low side driver 104 couples a gate of low side GaN
device 106 to a positive terminal of low side driver 104, high side
charge circuitry 110 may couple a positive terminal of high side
supply 112 to the positive terminal of low side driver 104. In this
example, low side GaN device 106 forms a channel that couples the
negative terminal of low side supply 102 and high side supply 112
such that low side supply 102 charges high side supply 112. For
instance, low side GaN device 106 forms a channel that couples the
negative terminal of low side supply 102 and high side supply 112
such that high side supply 112 charges a capacitor of high side
supply 112.
[0034] FIG. 2 is a circuit diagram illustrating a first example of
the driver of FIG. 1 in accordance with one or more techniques of
this disclosure. As shown, system 200 includes low side supply 202,
low side driver 204, low side GaN device 206, high side charge
circuitry 210, high side supply 212, high side driver 214, high
side GaN device 216, and converter elements 224. System 200 may
include additional components than those shown. In some examples,
system 200 may be implemented as a single or multiple IC packages.
Low side supply 202, low side driver 204, and low side GaN device
206 may be examples of low side supply 102, low side driver 104,
low side GaN device 106, respectively. High side supply 212, high
side driver 214, and high side GaN device 216 are examples of high
side supply 112, high side driver 114, and high side GaN device
116, respectively. As shown, high side supply 212 may include a
capacitive element (e.g., capacitor). High side charge circuitry
210 is an example of high side charge circuitry 110 and converter
elements 224 is an example of converter elements 124. For example,
converter elements 224 may include an inductor. FIG. 2 is described
in the context of FIG. 1 for exemplary purposes only.
[0035] As shown, high side GaN device 216 includes a control node
coupled to high side driver 214, a first node coupled to positive
terminal 215 of a power converter supply, and a second node coupled
to one or more converter elements 224 for a power converter adapted
to receive power from the power converter supply and output a
regulated voltage or regulated current. In this example, low side
GaN device 206 includes a control node coupled to low side driver
204, a first node coupled to one or more converter elements 224,
and a second node coupled to negative terminal 217 of the power
converter supply. The power converter supply may be an output of a
linear regulator, power converter, power inverter, or another
regulated voltage supply. For example, the power converter supply
may be an output of a direct current (DC) to DC power converter, an
alternating current (AC) to DC power converter, a DC to AC power
inverter, or another regulated voltage supply. The power converter
supply may include a battery which may be configured to store
electrical energy. Examples of batteries may include, but are not
limited to, nickel-cadmium, lead-acid, nickel-metal hydride,
nickel-zinc, silver-oxide, lithium-ion, lithium polymer, any other
type of rechargeable battery, or any combination of batteries.
[0036] Low side supply 202 includes regulated voltage supply 230
coupled in parallel with capacitor 232. Regulated voltage supply
230 may be an output of a linear regulator, power converter, power
inverter, or another regulated voltage supply. For example,
regulated voltage supply 230 may be an output of a direct current
(DC) to DC power converter, an alternating current (AC) to DC power
converter, a DC to AC power inverter, or another regulated voltage
supply. Regulated voltage supply 230 may include a battery which
may be configured to store electrical energy.
[0037] Low side driver 204 includes first low side switching
element 234, second low side switching element 236, and low side
driving circuitry 238. First low side switching element 234
includes a first node coupled to a positive terminal of low side
supply 202, a second node coupled to a control node of low side GaN
device 206, and a control node. Second low side switching element
236 includes a first node coupled to the control node of low side
GaN device 206, a second node coupled to the negative terminal of
low side supply 202, and a control node. The control node of first
low side switching element 234 and/or the control node of second
low side switching element 236 may be coupled to low side driving
circuitry 238.
[0038] Low side driving circuitry 238 may be adapted to generate a
first control signal at the control node of first low side
switching element 234 to cause first low side switching element 234
to establish the first low side channel between the positive
terminal of low side supply 202 and the control node of low side
GaN device 206 to activate low side GaN device 206. In some
example, low side driving circuitry 238 may be adapted to generate
a second control signal at the control node of second low side
switching element 236 to cause second low side switching element
236 to establish the second low side channel between the negative
terminal of low side supply 202 and the control node of low side
GaN device 206 to deactivate low side GaN device 206.
[0039] High side driver 214 includes first high side switching
element 244, second high side switching element 246, and high side
driving circuitry 248. First high side switching element 244
includes a first node coupled to a positive terminal of high side
supply 212, a second node coupled to a control node of high side
GaN device 216, and a control node. Second high side switching
element 246 includes a first node coupled to the control node of
high side GaN device 216, a second node coupled to the negative
terminal of high side supply 212, and a control node. The control
node of first high side switching element 244 and/or the control
node of second high side switching element 246 may be coupled to
high side driving circuitry 248.
[0040] High side driving circuitry 248 may be adapted to generate a
first control signal at the control node of first high side
switching element 244 to cause first high side switching element
244 to establish the first high side channel between the positive
terminal of high side supply 212 and the control node of high side
GaN device 216 to activate high side GaN device 216. In some
example, high side driving circuitry 248 may be adapted to generate
a second control signal at the control node of second high side
switching element 246 to cause second high side switching element
246 to establish the second high side channel between the negative
terminal of high side supply 212 and the control node of high side
GaN device 216 to deactivate high side GaN device 216.
[0041] High side charge circuitry 210 includes diode 250. As shown,
diode 250 includes an anode coupled low side driver 204 and a
cathode coupled to high side supply 212 to prevent current from
flowing from high side supply 212 to low side driver 204 and to
permit current to flow from low side driver 204 to high side supply
212.
[0042] Rather than relying on specialized circuitry for regulating
a voltage at high side supply 212, high side charge circuitry 210
is adapted to charge high side supply 212 with low side supply 202
when low side driver 204 activates low side GaN device 206. For
example, when low side driver 204 couples a gate of low side GaN
device 206 to a positive terminal of low side supply 202, diode 250
may couple low side driver 204 to the positive terminal of high
side supply 212. In this example, low side GaN device 206 forms a
channel that couples the negative terminal of low side supply 202
and the negative terminal of high side supply 212 such that low
side supply 202 charges high side supply 212. For instance, low
side GaN device 206 forms a channel that couples the negative
terminal of low side supply 202 and the negative terminal of high
side supply 212 such that low side supply 202 charges a capacitor
of high side supply 212.
[0043] FIG. 3 is a circuit diagram illustrating a second example of
the driver of FIG. 1 in accordance with one or more techniques of
this disclosure. As shown, system 300 includes low side supply 302,
low side driver 304, low side GaN device 306, high side charge
circuitry 310, high side supply 312, high side driver 314, high
side GaN device 316, and converter elements 324, which may be
substantially similar to low side supply 202, low side driver 204,
low side GaN device 206, high side charge circuitry 210, high side
supply 212, high side driver 214, high side GaN device 216, and
converter elements 224, respectively. Moreover, system 300 further
includes low side discharge circuitry 308 and high side discharge
circuitry 318. System 300 may include additional components than
those shown. In some examples, system 300 may be implemented as a
single or multiple IC packages. FIG. 3 is described in the context
of FIG. 1 for exemplary purposes only.
[0044] Low side discharge circuitry 308 is adapted to reduce
current flow from low side driver 304 to low side GaN device 306
and to refrain from reducing current flow from low side GaN device
306 to low side driver 304. Low side discharge circuitry 308 may
include resistor 352, diode 354, and resistor 356. As shown, a
first side of low side discharge circuitry 308 is coupled to low
side driver 304 and a second side of low side discharge circuitry
308 is coupled to low side GaN device 306. The first side of low
side discharge circuitry 308 is coupled to a cathode of diode 354
and a first node of resistor 352. The anode of diode 354 is coupled
to a first node of resistor 356. The second side of low side
discharge circuitry 308 is coupled to a second node of resistor 356
and a second side of resistor 352.
[0045] High side discharge circuitry 318 may be adapted to reduce
current flow from high side driver 314 to high side GaN device 316
and to refrain from reducing current flow from high side GaN device
316 to high side driver 314. High side discharge circuitry 318 may
include a first resistor, a diode, and a second resistor arranged
similarly to low side discharge circuitry 308.
[0046] In the example of FIG. 3, high side charge circuitry 310 is
adapted to charge high side supply 312 with low side supply 302
when low side driver 304 activates low side GaN device 306. For
example, when low side driver 304 couples a gate of low side GaN
device 306 to a positive terminal of low side supply 302, high side
charge circuitry 310 may couple the gate of low side GaN device 306
to the positive terminal of high side supply 312. In this example,
low side GaN device 306 forms a channel that couples the negative
terminal of low side supply 302 and the negative terminal of high
side supply 312 such that low side supply 302 charges high side
supply 312.
[0047] FIG. 4 is a circuit diagram illustrating a third example of
the driver of FIG. 1 in accordance with one or more techniques of
this disclosure. As shown, system 400 includes low side supply 402,
low side driver 404, low side GaN device 406, high side supply 412,
high side driver 414, high side GaN device 416, and converter
elements 424, which may be substantially similar to low side supply
202, low side driver 204, low side GaN device 206, high side supply
212, high side driver 214, high side GaN device 216, and converter
elements 224, respectively. System 400 further includes high side
charge circuitry 410. System 400 may include additional components
than those shown. In some examples, system 400 may be implemented
as a single or multiple IC packages. FIG. 4 is described in the
context of FIG. 1 for exemplary purposes only.
[0048] High side charge circuitry 410 includes switching element
460 and active switching circuitry 462. Switching element 460
includes a first node coupled high side supply 412 and a second
node coupled to low side driver 404 and/or low side GaN device 406.
Active switching circuitry 462 may be adapted to selectively
activate switching element 460 to prevent current from flowing from
high side supply 412 to low side driver 404 and to permit current
to flow from low side driver 404 to high side supply 412.
[0049] In the example of FIG. 4, high side charge circuitry 410 is
adapted to charge high side supply 412 with low side supply 402
when low side driver 404 activates low side GaN device 406. For
example, when low side driver 404 couples a gate of low side GaN
device 406 to a positive terminal of low side supply 402, active
switching circuitry 462 drives switching element 460 to couple the
gate of low side GaN device 406 to the positive terminal of high
side supply 412. In this example, low side GaN device 406 forms a
channel that couples the negative terminal of low side supply 402
and the negative terminal of high side supply 412 such that low
side supply 402 charges high side supply 412.
[0050] FIG. 5 is a circuit diagram illustrating a fourth example of
the driver of FIG. 1 in accordance with one or more techniques of
this disclosure. As shown, system 500 includes low side supply 502,
low side driver 504, low side GaN device 506, high side charge
circuitry 510, high side supply 512, high side driver 514, high
side GaN device 516, and converter elements 524, which may be
substantially similar to low side supply 402, low side driver 404,
low side GaN device 406, high side charge circuitry 410, high side
supply 412, high side driver 414, high side GaN device 416, and
converter elements 424, respectively. Moreover, system 500 further
includes low side discharge circuitry 508 and high side discharge
circuitry 518. System 500 may include additional components than
those shown. In some examples, system 500 may be implemented as a
single or multiple IC packages. FIG. 5 is described in the context
of FIGS. 1 and 4 for exemplary purposes only.
[0051] Low side discharge circuitry 508 is adapted to reduce
current flow from low side driver 504 to low side GaN device 506
and to refrain from reducing current flow from low side GaN device
506 to low side driver 504. Low side discharge circuitry 508 may
include resistor 552, diode 554, and resistor 556. As shown, a
first side of low side discharge circuitry 508 is coupled to low
side driver 504 and a second side of low side discharge circuitry
508 is coupled to low side GaN device 506. The first side of low
side discharge circuitry 508 is coupled to a cathode of diode 554
and a first node of resistor 552. The anode of diode 554 is coupled
to a first node of resistor 556. The second side of low side
discharge circuitry 508 is coupled to a second node of resistor 556
and a second side of resistor 552.
[0052] High side discharge circuitry 518 may be adapted to reduce
current flow from high side driver 514 to high side GaN device 516
and to refrain from reducing current flow from high side GaN device
516 to high side driver 514. High side discharge circuitry 518 may
include a first resistor, a diode, and a second resistor arranged
similarly to low side discharge circuitry 508.
[0053] In the example of FIG. 5, high side charge circuitry 510 is
adapted to charge high side supply 512 with low side supply 502
when low side driver 504 activates low side GaN device 506. For
example, when low side driver 504 couples a gate of low side GaN
device 506 to a positive terminal of low side supply 502, high side
charge circuitry 510 may couple the gate of low side GaN device 506
to the positive terminal of high side supply 512. In this example,
low side GaN device 506 forms a channel that couples the negative
terminal of low side supply 502 and the negative terminal of high
side supply 512 such that low side supply 502 charges high side
supply 512.
[0054] FIG. 6 is a first illustration of a performance of the
driver of FIG. 1 in accordance with one or more techniques of this
disclosure. The abscissa axis (e.g., horizontal) of FIG. 6
represents time and the ordinate axis (e.g., vertical) of FIG. 6
represents a converter voltage (SWN) 602 at an input to converter
elements 124, a high side switching voltage (HX-SWN) 604 at a gate
of high side GaN device 116, a low side switching voltage (LX) 606
at a gate of low side GaN device 106, and a bootstrap voltage 608
(Bootstrap_Diode) at high side charge circuitry 110.
[0055] As shown, converter voltage 602 is negative during
dead-times 610, for example, due to free-wheeling inductor current
flow. However, bootstrap voltage 608 illustrates that high side
charge circuitry 110 blocks a charging of high side supply 112
during dead-times 610. In this way, high side charge circuitry 110
may avoid overcharging of high side supply 112 in a presence of low
side free-wheeling inductor current flow.
[0056] FIG. 7 is a second illustration of a performance of the
driver of FIG. 1 in accordance with one or more techniques of this
disclosure. The abscissa axis (e.g., horizontal) of FIG. 7
represents time and the ordinate axis (e.g., vertical) of FIG. 7
represents an inductor current 702 at converter elements 124,
converter voltage 704 at an input to converter elements 124, a high
side supply voltage 706 at high side supply 112, a bootstrap
voltage 708 at high side charge circuitry 110, and gate-to-source
voltage 710 at high side GaN device 116. As shown, high side supply
voltage 706 remains less than a maximum GaN voltage rating of 5
volts, thereby resulting in gate-to-source voltage 710 being less
than the maximum GaN voltage rating. As such, techniques described
here may prevent an overcharge of high side supply 112 above the
maximum rating of GaN Voltage Source to Gate "V.sub.GS".
[0057] FIG. 8 is a third illustration of a performance of the
driver of FIG. 1 in accordance with one or more techniques of this
disclosure. The abscissa axis (e.g., horizontal) of FIG. 8
represents time and the ordinate axis (e.g., vertical) of FIG. 8
represents converter voltage 802 at an input to converter elements
124, a bootstrap voltage 804 at high side charge circuitry 110, a
low side switching voltage 806 at a gate of low side GaN device
106, and a low side driving voltage 808 output by low side driver
104. As shown, when first low side switching element 234 (e.g., a
pull-up pMOS) is OFF (e.g., deactivated) the body diode of first
low side switching element 234 blocks the charge path from low side
supply 102 (e.g., VCC). When first low side switching element 234
(e.g., a pull-up pMOS) ON (e.g., activated) the charge path is
active, but converter voltage 802 is not dangerous because low side
GaN device 106 is turned ON (e.g., activated). In this way, system
100 may help to achieve a desired timing between low side turn-on
of low side GaN device 106 and the bootstrap cap recharge path
activation, even in a presence of additional external components on
the gate driving path.
[0058] FIG. 9 is a flow diagram for a method for driving GaN
devices in accordance with one or more techniques of this
disclosure. FIG. 9 is described in the context of FIGS. 1-8 for
exemplary purposes only. In operation, low side driver 104 controls
low side GaN device 106 using low side supply 102 (902). High side
driver 114 control high side GaN device 116 using high side supply
112 (904). High side charge circuitry 110 charges high side supply
112 with low side supply 102 when low side driver 104 activates low
side GaN device 106 (906).
[0059] While a device has been described with reference to
illustrative embodiments, this description is not intended to be
construed in a limiting sense. Various modifications and
combinations of the illustrative embodiments, as well as other
embodiments of the invention, will be apparent to persons skilled
in the art upon reference to the description. It is therefore
intended that the appended claims encompass any such modifications
or embodiments.
[0060] The following examples may illustrate one or more aspects of
the disclosure.
EXAMPLE 1
[0061] A device for switching Gallium Nitride (GaN) devices, the
device comprising: a high side driver adapted to control a high
side GaN device using a high side supply; a low side driver adapted
to control a low side GaN device using a low side supply; and high
side charge circuitry adapted to charge the high side supply with
the low side supply when the low side driver activates the low side
GaN device.
EXAMPLE 2
[0062] The device of example 1, wherein the high side charge
circuitry is adapted to prevent current from flowing from the high
side supply to the low side driver and to permit current to flow
from the low side driver to the high side supply.
EXAMPLE 3
[0063] The device of any combination of examples 1-2, wherein the
high side charge circuitry comprises a diode comprising an anode
coupled the low side driver and a cathode coupled to the high side
supply to prevent current from flowing from the high side supply to
the low side driver and to permit current to flow from the low side
driver to the high side supply.
EXAMPLE 4
[0064] The device of any combination of examples 1-3, wherein the
high side charge circuitry comprises: a switching element
comprising a first node coupled the high side supply and a second
node coupled to the low side driver; and active switching circuitry
adapted to selectively activate the switching element to prevent
current from flowing from the high side supply to the low side
driver and to permit current to flow from the low side driver to
the high side supply.
EXAMPLE 5
[0065] The device of any combination of examples 1-4, wherein the
low side supply comprises a capacitor coupled in parallel with a
voltage source; and wherein the high side supply comprises a
capacitor.
EXAMPLE 6
[0066] The device of any combination of examples 1-5, comprising
one or more of: low side discharge circuitry adapted to reduce
current flow from the low side driver to the low side GaN device
and to refrain from reducing current flow from the low side GaN
device to the low side driver; or high side discharge circuitry
adapted to reduce current flow from the high side driver to the
high side GaN device and to refrain from reducing current flow from
the high side GaN device to the high side driver.
EXAMPLE 7
[0067] The device of any combination of examples 1-6, wherein the
low side driver is adapted to establish a first low side channel
between a positive terminal of the low side supply and the low side
GaN device to activate the low side GaN device and to establish a
second low side channel between a negative terminal of the low side
supply and the low side GaN device to deactivate the low side GaN
device; and wherein the high side driver is adapted to establish a
first high side channel between a positive terminal of the high
side supply and the high side GaN device to activate the high side
GaN device and to establish a second high side channel between a
negative terminal of the high side supply and the low side GaN
device to deactivate the high side GaN device.
EXAMPLE 8
[0068] The device of any combination of examples 1-7, wherein the
low side driver comprises: a first low side switching element
comprising a first node coupled to the positive terminal of the low
side supply, a second node coupled to the low side GaN device, and
a control node; a second low side switching element comprising a
first node coupled to the low side GaN device, a second node
coupled to the negative terminal of the low side supply, and a
control node; and low side driving circuitry adapted to generate a
first control signal at the control node of the first low side
switching element to cause the first low side switching element to
establish the first low side channel between the positive terminal
of the low side supply and the low side GaN device to activate the
low side GaN device and to generate a second control signal at the
control node of the second low side switching element to cause the
second low side switching element to establish the second low side
channel between the negative terminal of the low side supply and
the low side GaN device to deactivate the low side GaN device.
EXAMPLE 9
[0069] The device of any combination of examples 1-8, wherein the
high side driver comprises: a first high side switching element
comprising a first node coupled to the positive terminal of the
high side supply, a second node coupled to the high side GaN
device, and a control node; a second high side switching element
comprising a first node coupled to the high side GaN device, a
second node coupled to the negative terminal of the high side
supply, and a control node; and high side driving circuitry adapted
to generate a first control signal at the control node of the first
high side switching element to cause the first high side switching
element to establish the first high side channel between the
positive terminal of the high side supply and the high side GaN
device to activate the high side GaN device and to generate a
second control signal at the control node of the second high side
switching element to cause the second high side switching element
to establish the second high side channel between the negative
terminal of the high side supply and the high side GaN device to
deactivate the high side GaN device.
EXAMPLE 10
[0070] The device of any combination of examples 1-9, wherein the
high side GaN device comprises a control node coupled to the high
side driver, a first node coupled to a positive terminal of a power
converter supply, and a second node coupled to one or more
converter elements for a power converter adapted to receive power
from the power converter supply and output a regulated voltage or
regulated current; and wherein the low side GaN device comprises a
control node coupled to the low side driver, a first node coupled
to the one or more converter elements, and a second node coupled to
a negative terminal of the power converter supply.
EXAMPLE 11
[0071] A method for driving a Gallium Nitride (GaN) devices, the
method comprising: controlling a high side GaN device using a high
side supply; controlling a low side GaN device using a low side
supply; and charging the high side supply with the low side supply
when the low side driver activates the low side GaN device.
EXAMPLE 12
[0072] The method of example 11, wherein charging the high side
supply comprises: preventing current from flowing from the high
side supply to the low side driver; and permitting current to flow
from the low side driver to the high side supply.
EXAMPLE 13
[0073] The method of any combination of examples 11-12, wherein
charging the high side voltage comprises: selectively activating a
switching element to prevent current from flowing from the high
side supply to the low side driver and to permit current to flow
from the low side driver to the high side supply.
EXAMPLE 14
[0074] The device of any combination of examples 11-13, wherein the
low side supply comprises a capacitor coupled in parallel with a
voltage source; and wherein the high side supply comprises a
capacitor.
EXAMPLE 15
[0075] The method of any combination of examples 11-14, wherein
controlling the high side GaN device comprises reducing current
flow from the high side driver to the high side GaN device and
refraining from reducing current flow from the high side GaN device
to the high side driver; and wherein controlling the low side GaN
device comprises reducing current flow from the low side driver to
the low side GaN device and refraining from reducing current flow
from the low side GaN device to the low side driver.
EXAMPLE 16
[0076] The method of any combination of examples 11-15, wherein
controlling the low side GaN device comprises establishing a first
low side channel between a positive terminal of the low side supply
and the low side GaN device to activate the low side GaN device and
establishing a second low side channel between a negative terminal
of the low side supply and the low side GaN device to deactivate
the low side GaN device; and wherein controlling the high side GaN
device comprises establishing a first high side channel between a
positive terminal of the high side supply and the high side GaN
device to activate the high side GaN device and establishing a
second high side channel between a negative terminal of the high
side supply and the high side GaN device to deactivate the high
side GaN device.
EXAMPLE 17
[0077] The method of any combination of examples 11-16, wherein
controlling the low side GaN device comprises: generating a control
signal at a control node of a first low side switching element to
cause the first low side switching element to establish the first
low side channel between the positive terminal of the low side
supply and the low side GaN device to activate the low side GaN
device; and generating a second control signal at a control node of
a second low side switching element to cause the second low side
switching element to establish the second low side channel between
the negative terminal of the low side supply and the low side GaN
device to deactivate the low side GaN device.
EXAMPLE 18
[0078] The method of any combination of examples 11-17, wherein
controlling the high side GaN device comprises: generating a first
control signal at a control node of a first high side switching
element to cause the first high side switching element to establish
the first high side channel between the positive terminal of the
high side supply and the high side GaN device to activate the high
side GaN device; and generating a second control signal at a
control node of a second high side switching element to cause the
second high side switching element to establish the second high
side channel between the negative terminal of the high side supply
and the high side GaN device to deactivate the high side GaN
device.
EXAMPLE 19
[0079] The method of any combination of examples 11-18, wherein the
high side GaN device comprises a control node coupled to the high
side driver, a first node coupled to a positive terminal of a power
converter supply, and a second node coupled to one or more
converter elements for a power converter adapted to receive power
from the power converter supply and output a regulated voltage or
regulated current; and wherein the low side GaN device comprises a
control node coupled to the low side driver, a first node coupled
to the one or more converter elements, and a second node coupled to
a negative terminal of the power converter supply.
EXAMPLE 20
[0080] A system for controlling a power converter, the system
comprising: a high side GaN device; a low side GaN device; a high
side driver adapted to control the high side GaN device using a
high side supply; a low side driver adapted to control the low side
GaN device using a low side supply; and high side charge circuitry
adapted to charge the high side supply with the low side supply
when the low side driver activates the low side GaN device.
[0081] Various aspects have been described in this disclosure.
These and other aspects are within the scope of the following
claims.
* * * * *