Common-source cascaded power devices, switching circuits, and driving methods for power devices.

Abstract

This application relates to a common-source cascaded power device, a switching circuit, and a driving method for the power device. The common-source cascaded power device includes: a low-voltage switching device, a depletion-mode switching device, a drive level conversion unit, a turn-off current detection unit, a drive current control unit, a current source, and a power supply unit. The source of the low-voltage switching device is electrically connected to the gate of the depletion-mode switching device, and the drain of the low-voltage switching device is electrically connected to the source of the depletion-mode switching device. The control terminal of the common-source cascaded power device is electrically connected to a drive resistor and is used to receive a pulse signal transmitted by the drive resistor. The turn-off current detection unit is electrically connected to the control terminal and is used to detect the turn-off current value of the control terminal during the turn-off phase when the pulse signal is low. Using the embodiments of this application, the turn-on speed of the depletion-mode switching device in the common-source cascaded power device can be adjusted.

Description

Technical Field

[0001] This application relates to the field of semiconductor device technology, and in particular to a common-source cascaded power device, a switching circuit, and a driving method for the power device. Background Technology

[0002] In the field of power devices, cascode power devices are typically composed of a low-voltage switching device and a depletion-mode switching device connected in series. For example... Figure 1 As shown, the drain D1 of the low-voltage switching device Q1 is connected to the source S2 of the depletion-mode switching device, while the gate G2 of the depletion-mode switching device Q2 is connected to the source S1 of the low-voltage switching device Q1. When the low-voltage switching device Q1 is turned off, the depletion-mode switching device Q2 is simultaneously turned off because its gate voltage is pulled low, thus making the Cascode power device exhibit enhancement-mode switching characteristics overall.

[0003] However, existing Cascode power devices cannot directly control the switching speed of the depletion-type switching device Q2, making it difficult to precisely adjust its drain-source voltage change rate (dv / dt), which in turn limits the flexible control of the switching frequency or speed. This defect can cause voltage / current oscillations during the switching process, leading to a decrease in the system's electromagnetic compatibility (EMC) performance, manifested as increased high-frequency noise interference, excessive conducted emissions, or enhanced electromagnetic radiation, while also increasing the switching stress on the rectifier diodes. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this application proposes a common-source cascaded power device, a switching circuit, and a driving method for the power device, which can achieve precise control of the conduction speed of the depletion-type switching device.

[0005] This application provides a common-source cascaded power device, comprising: a low-voltage switching device, a depletion-mode switching device, a drive level conversion unit, a turn-off current detection unit, a drive current control unit, a current source, and a power supply unit; the source of the low-voltage switching device is electrically connected to the gate of the depletion-mode switching device, and the drain of the low-voltage switching device is electrically connected to the source of the depletion-mode switching device; the control terminal of the common-source cascaded power device is electrically connected to a drive resistor for receiving pulse signals transmitted by the drive resistor; the turn-off current detection unit is electrically connected to the control terminal for detecting the turn-off current value of the control terminal during the turn-off phase when the pulse signal is low; the drive level conversion unit is electrically connected to the control terminal, the gate of the low-voltage switching device, the positive voltage terminal, and the ground terminal, respectively. During the conduction phase when the pulse signal is high, a first path is established between the positive voltage terminal and the gate of the low-voltage switching device, so that the positive voltage terminal provides a drive voltage to the gate of the low-voltage switching device. The drive current control unit is electrically connected to the turn-off current detection unit and the current source, which is located on the first path. During the conduction phase, based on a pre-set correspondence between the turn-off current and the drive current, and the turn-off current value during the turn-off phase, the current source is controlled to provide a drive current of a first target current value to the gate of the low-voltage switching device, wherein the first target current value is positively correlated with the turn-off current value. The power supply unit is electrically connected to the turn-off current detection unit and the positive voltage terminal, and is used to supply power to the turn-off current detection unit and the positive voltage terminal.

[0006] Optionally, the cascaded power device further includes a midpoint voltage detection unit, which is electrically connected between the intermediate node and the drive current control unit. The intermediate node is the connection point between the drain of the low-voltage switching device and the source of the depletion-type switching device. The midpoint voltage detection unit is used to output a first level to the drive current control unit when the voltage value detected at the intermediate node is less than or equal to the target voltage value. When the intermediate node is at the target voltage value, the depletion-type switching device is fully turned on. The drive current control unit is used to respond to the first level by controlling the current source to provide a drive current of a second target current value to the gate of the low-voltage switching device. The second target current value is greater than the first target current value.

[0007] Optionally, the common-source cascaded power device further includes a drive voltage detection unit, which is electrically connected between the gate of the low-voltage switching device and the drive current control unit. The drive voltage detection unit is used to detect the gate voltage of the low-voltage switching device and transmit the gate voltage to the drive current control unit. The drive current control unit is used to control the current source to provide a drive current of a second target current value to the gate of the low-voltage switching device when the gate voltage of the low-voltage switching device reaches the Miller plateau voltage of the low-voltage switching device. The second target current value is greater than the first target current value.

[0008] Optionally, the cascaded power device further includes a midpoint voltage detection unit and a drive voltage detection unit. The midpoint voltage detection unit is electrically connected between the intermediate node and the drive current control unit. The intermediate node is the connection point between the drain of the low-voltage switching device and the source of the depletion-mode switching device. The midpoint voltage detection unit outputs a first level to the drive current control unit when the voltage value detected at the intermediate node is less than or equal to the target voltage value. The drive voltage detection unit is electrically connected between the gate of the low-voltage switching device and the drive current control unit. The drive voltage detection unit detects the gate voltage of the low-voltage switching device and transmits the gate voltage to the drive current control unit. When the drive current control unit receives the first level transmitted by the midpoint voltage detection unit and the gate voltage of the low-voltage switching device reaches the Miller plateau voltage of the low-voltage switching device, it controls the current source to provide a drive current of a second target current value to the gate of the low-voltage switching device. The second target current value is greater than the first target current value.

[0009] Optionally, the turn-off current detection unit includes a current mirror, which is powered by a first reference voltage provided by a first reference voltage terminal. The input branch of the current mirror is electrically connected to the control terminal of the cascaded power device, and the output branch of the current mirror is electrically connected to the ground terminal through a first resistor. The drive current control unit is electrically connected to the connection node between the output branch and the first resistor. The drive current control unit is used to detect the voltage value of the first resistor during the turn-off phase and calculate the turn-off current value based on the voltage value and the resistance value of the first resistor.

[0010] Optionally, the midpoint voltage detection unit includes a comparator, the non-inverting input of which is electrically connected to the second reference voltage terminal, and the inverting input of which is electrically connected to the intermediate node; wherein the second reference voltage value is equal to the target voltage value.

[0011] Optionally, the midpoint voltage detection unit includes a comparator and a first diode. The non-inverting input terminal of the comparator is electrically connected to the second reference voltage terminal, the anode of the first diode is electrically connected to the inverting input terminal of the comparator, and the cathode of the first diode is electrically connected to the midpoint. The second reference voltage value is equal to the difference between the target voltage value and the breakdown voltage value of the first diode.

[0012] Optionally, the drive voltage detection unit includes a first buffer, the input terminal of which is electrically connected to the gate of the low-voltage switching device, and the output terminal of which is electrically connected to the drive current control unit.

[0013] Optionally, the first buffer is a linear operational amplifier, with its non-inverting input terminal electrically connected to the gate of the low-voltage switching device, and its inverting input terminal electrically connected to the output terminal of the linear operational amplifier and the drive current control unit.

[0014] Optionally, the output terminal of the power supply unit is electrically connected to the first reference voltage terminal, the second reference voltage terminal, and the positive voltage terminal, and is used to provide the first reference voltage terminal, the second reference voltage terminal, and the positive voltage terminal with their respective voltage values.

[0015] Optionally, the input terminal of the power supply unit is electrically connected to the control terminal and / or intermediate node of the cascaded power device. The intermediate node is the connection node between the drain of the low-voltage switching device and the source of the depletion-mode switching device, used to receive the voltage signal from the control terminal and / or the intermediate node, and to perform voltage conversion on the voltage signal.

[0016] Optionally, the common source cascaded power device also includes a power supply pin, the input terminal of the power supply unit is electrically connected to the power supply pin, and the power supply unit is used to receive the voltage signal from the power supply pin and perform voltage conversion on the voltage signal.

[0017] Optionally, the conduction phase includes a first conduction sub-phase, a second conduction sub-phase, and a third conduction sub-phase; the drive current control unit is used to control the current source to provide a drive current of a preset current value to the gate of the low-voltage switching device in the first conduction sub-phase; to control the current source to provide a drive current of a first target current value to the gate of the low-voltage switching device in the second conduction sub-phase; and to control the current source to provide a drive current of a second target current value to the gate of the low-voltage switching device in the third conduction sub-phase.

[0018] Optionally, the preset current value is less than the second target current value.

[0019] Optionally, the drive current control unit is specifically configured to, during the conduction phase of the current cycle, control the current source to provide a drive current of the first target current value to the gate of the low-voltage switching device based on a pre-set correspondence between the turn-off current and the drive current and the average value of the turn-off current during the turn-off phase of the previous multiple cycles; or, the drive current control unit is specifically configured to, during the conduction phase of each cycle, control the current source to provide a drive current of the first target current value to the gate of the low-voltage switching device based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase of the previous cycle; or, the drive current control unit is specifically configured to, during the conduction phase of all cycles, control the current source to provide a drive current of the first target current value to the gate of the low-voltage switching device based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase of the first cycle.

[0020] This application also proposes a switching circuit, including a common source cascaded power device and a start-up adjustment unit. The start-up adjustment unit includes a driving resistor. The first end of the driving resistor is used to receive a pulse signal, and the second end of the driving resistor is electrically connected to the control terminal of the common source cascaded power device for transmitting a pulse signal to the control terminal.

[0021] Optionally, the start-up adjustment unit further includes a first turn-off resistor, which is electrically connected between the control terminal of the cascaded power device and the source terminal of the cascaded power device.

[0022] Optionally, the start-up adjustment unit also includes a second diode, the anode of which is used to receive pulse signals, and the cathode of which is electrically connected to the first end of the drive resistor. The second diode is used to transmit the pulse signals through the drive resistor to the control terminal of the common source cascaded power device.

[0023] Optionally, the start-up adjustment unit also includes a second turn-off resistor, and the branch containing the second diode and the drive resistor is connected in parallel with the second turn-off resistor at the control terminal of the cascaded power device.

[0024] This application also proposes a driving method for a common-source cascaded power device, the common-source cascaded power device including any of the common-source cascaded power devices provided in the above embodiments, comprising: receiving a pulse signal transmitted by a driving resistor; during the turn-off phase when the pulse signal is low, detecting the turn-off current value of the control terminal of the common-source cascaded power device; during the turn-on phase when the pulse signal is high, connecting a first path between the positive voltage terminal and the gate of a low-voltage switching device, so that the positive voltage terminal provides a driving voltage to the gate of the low-voltage switching device; during the turn-on phase, based on a preset correspondence between the turn-off current and the driving current and the turn-off current value during the turn-off phase, controlling a current source to provide a driving current of a first target current value to the gate of the low-voltage switching device, wherein the first target current value is positively correlated with the turn-off current value.

[0025] Optionally, the driving method further includes: when the voltage value of the intermediate node is detected to be less than or equal to the target voltage value, and / or when the gate voltage of the low-voltage switching device reaches the Miller plateau voltage of the low-voltage switching device, controlling the current source to provide a driving current of a second target current value to the gate of the low-voltage switching device, the second target current value being greater than the first target current value, wherein the intermediate node is the connection node between the drain of the low-voltage switching device and the source of the depletion-type switching device.

[0026] Optionally, the conduction phase includes a first conduction sub-phase, a second conduction sub-phase, and a third conduction sub-phase; in the first conduction sub-phase, a control current source provides a drive current of a preset current value to the gate of the low-voltage switching device; in the second conduction sub-phase, a control current source provides a drive current of a first target current value to the gate of the low-voltage switching device; and in the third conduction sub-phase, a control current source provides a drive current of a second target current value to the gate of the low-voltage switching device.

[0027] Optionally, during the turn-on phase, based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device. This includes: during the turn-on phase of the current cycle, based on a pre-set correspondence between the turn-off current and the drive current and the average value of the turn-off current during the turn-off phase in previous cycles, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device; or, during the turn-on phase of each cycle, based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase in the previous cycle, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device; or, during the turn-on phase of all cycles, based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase in the first cycle, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device.

[0028] The common-source cascaded power device, switching circuit, and driving method provided in this application detect the turn-off current at the control terminal of the common-source cascaded power device during the turn-off phase using a turn-off current detection unit. The drive current control unit dynamically adjusts the drive current during the conduction phase based on the magnitude of the turn-off current. If a large turn-off current is detected, the drive current is increased; if a small turn-off current is detected, the drive current is decreased. This achieves regulation of the conduction speed of the depletion-type switching device, smoothing voltage / current changes during the switching process, reducing voltage / current spikes, and helping to suppress high-frequency oscillations and reduce voltage stress on the rectifier diode. Attached Figure Description

[0029] The preferred embodiments of this application will now be described in further detail with reference to the accompanying drawings, wherein:

[0030] Figure 1 This is a circuit diagram of a cascaded power device based on the existing common source and common gate technology;

[0031] Figure 2 This is a schematic diagram of the connection structure between the driving resistor and the low-voltage switching device in the prior art;

[0032] Figure 3 This is a schematic diagram showing the location of the Miller capacitor in a common-source, common-gate cascaded power device in the prior art;

[0033] Figure 4 This is a schematic diagram of the circuit connection between a common source cascaded power device and a start-up regulation unit according to an embodiment of this application;

[0034] Figure 5 This is a circuit diagram of another common-source cascaded power device in an embodiment of this application;

[0035] Figure 6 This is a circuit diagram of another common-source cascaded power device in the embodiments of this application;

[0036] Figure 7 This is a circuit diagram of another common-source cascaded power device according to an embodiment of this application;

[0037] Figure 8 This is a circuit diagram of another common-source cascaded power device according to an embodiment of this application;

[0038] Figure 9 This is a schematic diagram illustrating the voltage and current changes of the cascaded power device with common source and common gate in this application during the driving process;

[0039] Figure 10 This is a circuit diagram of a switching circuit according to an embodiment of this application;

[0040] Figure 11 This is a circuit diagram of another switching circuit according to an embodiment of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] In the following detailed description, reference can be made to the accompanying drawings, which form part of this application and illustrate specific embodiments of the present application. In the drawings, similar reference numerals describe substantially similar components in different figures. Specific embodiments of the present application are described in sufficient detail below to enable those skilled in the art to implement the technical solutions of the present application. It should be understood that other embodiments may also be utilized, or structural, logical, or electrical changes may be made to the embodiments of the present application.

[0043] In this document, the terms "first," "second," "third," etc., are used only to distinguish one entity (or operation) from another in textual description, and do not require or imply any sequential order between these entities (or operations).

[0044] The following is a brief introduction to the concepts and technical terms that may be involved in the embodiments of this application.

[0045] Miller capacitance: Inside a transistor, there is a tiny, actual parasitic capacitance Cgd between the control electrode (gate G) and the output electrode (drain D). When the transistor turns from off to on, the voltage change will have a "drawing away" or "injecting" effect on the control current through the parasitic capacitance Cgd. This parasitic capacitance Cgd is called the Miller capacitance.

[0046] Miller time: During transistor switching, when the drain voltage Vd begins to change drastically (usually decreasing), due to the presence of Miller capacitance Cgd, the gate voltage Vg will remain almost constant for a period of time (forming a plateau). This period is called the Miller time (also called the Miller plateau period).

[0047] Figure 2 This is a schematic diagram of the connection structure between the drive resistor and the low-voltage switching device in existing technology. For easier understanding of Miller capacitance, Figure 2 The location of the Miller capacitance Cgd in the low-voltage switching device Q1 is shown. (As shown) Figure 2 As shown, the two ends of the Miller capacitor Cgd are connected to the gate G1 and drain D1 of the low-voltage switching device Q1, respectively. To slow down the turn-on speed of the transistor (e.g., the low-voltage switching device Q1), the discharge time of the Miller capacitor Cgd can be extended by increasing the value of the drive resistor Ron. However, as... Figure 3 As shown, the depletion-type switching device Q2 does not have a direct Miller capacitance Cgd, so the conduction speed of the depletion-type switching device Q2 cannot be directly controlled by adjusting the drive resistor Ron.

[0048] To address the aforementioned issues, this application proposes a common-source cascaded power device that enables precise control of the turn-on speed of depletion-type switching devices.

[0049] Figure 4 This is a schematic diagram of the circuit connection between a common-source cascaded power device and a start-up regulation unit according to an embodiment of this application. Figure 4 As shown, the cascaded power device 200 includes: a low-voltage switching device Q1, a depletion-mode switching device Q2, a drive level conversion unit 201, a turn-off current detection unit 202, a drive current control unit 203, a current source 204, and a power supply unit 205. The source S1 of the low-voltage switching device Q1 is electrically connected to the gate G2 of the depletion-mode switching device Q2, and the drain D1 of the low-voltage switching device Q1 is electrically connected to the source S2 of the depletion-mode switching device Q2. The gate G1 of the low-voltage switching device Q1 can serve as the control terminal (i.e., the gate terminal) G of the cascaded power device 200, the source S1 of the low-voltage switching device Q1 can serve as the source terminal S of the cascaded power device 200, and the drain D2 of the depletion-mode switching device Q2 can serve as the drain terminal D of the cascaded power device 200.

[0050] The control terminal G of the common-source cascaded power device 200 can be electrically connected to the start-up adjustment unit 206. The control terminal G of the common-source cascaded power device 200 can be used to receive pulse signals transmitted by the start-up adjustment unit 206. The common-source cascaded power device 200 turns on in response to a high level pulse signal and turns off in response to a low level pulse signal.

[0051] The turn-off current detection unit 202 is electrically connected to the control terminal G and can be used to detect the turn-off current value of the control terminal G during the turn-off phase when the pulse signal is low. The drive level conversion unit 201 is electrically connected to the control terminal G, the gate G1 of the low-voltage switching device Q1, the positive voltage terminal Vdd, and the ground terminal GND, respectively. During the conduction phase when the pulse signal is high, it connects the first path L1 between the positive voltage terminal Vdd and the gate G1 of the low-voltage switching device Q1, so that the positive voltage terminal Vdd provides a drive voltage to the gate G1 of the low-voltage switching device Q1.

[0052] There is a potential difference between the gate drive voltage of the low-voltage switching device Q1 and the high-voltage side pulse signal. If the gate of the low-voltage switching device Q1 is directly connected to or receives the pulse signal, it may cause gate breakdown of the low-voltage switching device Q1, or noise generated by parasitic capacitance coupling may cause the low-voltage switching device Q1 to be erroneously turned on / off. By isolating the pulse signal from the gate G1 of the low-voltage switching device Q1 through the drive level conversion unit 201, the risk of gate breakdown of the low-voltage switching device Q1 can be reduced, and the risk of erroneous turn-on / off of the low-voltage switching device Q1 due to noise can also be reduced.

[0053] The drive current control unit 203 is electrically connected to the turn-off current detection unit 202 and the current source 204, with the current source 204 located on the first path L1. During the turn-on phase, the drive current control unit 203 controls the current source 204 to provide a drive current of a first target current value to the gate G1 of the low-voltage switching device Q1, based on a pre-set correspondence between the turn-off current and the drive current, and the turn-off current value during the turn-off phase. The first target current value is positively correlated with the turn-off current value; that is, the larger the turn-off current value, the larger the first target current value; and the smaller the turn-off current value, the smaller the first target current value. The specific magnitude of the first target current value can be determined based on the pre-set correspondence between the turn-off current and the drive current, and this application does not limit this.

[0054] like Figure 4As shown, the shutdown current value detected by the shutdown current detection unit 202 at the control terminal G is the same as the current value flowing through the start-up adjustment unit 206. Therefore, the shutdown current value detected by the shutdown current detection unit 202 can be changed by adjusting the current value flowing through the start-up adjustment unit 206. In some embodiments, the start-up adjustment unit 206 may include a drive resistor R1. By changing the resistance value of the drive resistor R1, the current flowing through the drive resistor R1 can be changed, that is, the shutdown current value detected by the shutdown current detection unit 202 can be changed.

[0055] Specifically, during the turn-off phase, since the pulse signal is at a low level, the control terminal G of the cascaded power device 200 discharges through the drive resistor R1. Therefore, the turn-off current is the current flowing through the drive resistor R1. A larger value for the drive resistor R1 indicates a slower desired turn-on of the cascaded power device 200. Conversely, a larger value for the drive resistor R1 results in a smaller turn-off current. Therefore, during the turn-on phase, based on the turn-off current value, the control current source 204 provides a smaller drive current to the gate G1 of the low-voltage switching device Q1, allowing the depletion-mode switching device Q2 and the entire cascaded power device 200 to turn on slowly, meeting the desired slow turn-on requirement.

[0056] Conversely, a smaller value for the drive resistor R1 indicates a faster turn-on of the expected cascaded power device 200. A smaller value for the drive resistor R1 also results in a larger turn-off current. Therefore, during the turn-on phase, by controlling the current source 204 to provide a larger drive current to the gate G1 of the low-voltage switching device Q1 based on the turn-off current value, the depletion-mode switching device Q2 and the entire cascaded power device 200 can be turned on quickly, meeting the expected fast turn-on requirement.

[0057] In some embodiments, the power supply unit 205 can be electrically connected to the shutdown current detection unit 202 and the positive voltage terminal Vdd, respectively, to supply power to the shutdown current detection unit 202 and the positive voltage terminal Vdd.

[0058] The common-source cascaded power device provided in this application detects the turn-off current at the control terminal of the common-source cascaded power device during the turn-off phase through a turn-off current detection unit. The drive current control unit dynamically adjusts the drive current during the conduction phase based on the magnitude of the turn-off current. If a large turn-off current is detected, the drive current is increased; if a small turn-off current is detected, the drive current is decreased. This achieves precise adjustment of the conduction speed of the depletion-type switching device, smoothing voltage / current changes during the switching process of the depletion-type switching device, reducing voltage / current spikes, and helping to suppress high-frequency oscillations and reduce voltage stress on the rectifier diode.

[0059] Figure 5This is a circuit diagram of another common-source cascaded power device in an embodiment of this application. For example... Figure 5 As shown, in some embodiments, the common-source cascaded power device 200 may further include a midpoint voltage detection unit 208. The midpoint voltage detection unit 208 is electrically connected between an intermediate node N1 and a drive current control unit 203, wherein the intermediate node N1 is the connection node between the drain D1 of the low-voltage switching device Q1 and the source S2 of the depletion-type switching device Q2. The midpoint voltage detection unit 208 can be used to output a first level to the drive current control unit 203 when the detected voltage value of the intermediate node N1 is less than or equal to a target voltage value. Wherein, when the intermediate node is at the target voltage value, the depletion-type switching device is fully turned on, that is, the target voltage value is the critical voltage value of the source S2 when the depletion-type switching device is fully turned on. The specific value can be predetermined according to actual conditions, and this application does not limit it. For example, the first level can be a high level. The drive current control unit 203 can be used to control the current source 204 to provide a drive current of a second target current value to the gate G1 of the low-voltage switching device Q1 in response to the first level output by the midpoint voltage detection unit 208. The second target current value is greater than the first target current value. The specific magnitude of the second target current value can be flexibly adjusted according to actual circumstances, and this application does not limit it in this regard.

[0060] exist Figure 5 In the illustrated embodiment, the midpoint voltage detection unit 208 detects the voltage value of the intermediate node N1. When the voltage value of the intermediate node N1 is less than or equal to the target voltage value, the output level is switched to the first level. The drive current control unit 203 determines whether the depletion-type switching device Q2 is fully turned on based on whether it receives the first level from the midpoint voltage detection unit 208. When the first level from the midpoint voltage detection unit 208 is received, it indicates that the depletion-type switching device Q2 is fully turned on. At this time, the drive current control unit 203 controls the current source 204 to provide a larger drive current to the gate G1 of the low-voltage switching device Q1, so that the low-voltage switching device Q1 can be turned on as soon as possible, reducing the power consumed by the low-voltage switching device Q1 because it cannot be turned on quickly due to insufficient current. When the depletion-type switching device Q2 is turned on, the turn-on speed of the low-voltage switching device Q1 is increased.

[0061] Figure 6 This is a circuit diagram of another common-source cascaded power device according to an embodiment of this application. Figure 6As shown, in some embodiments, the common-source cascaded power device 200 may further include a drive voltage detection unit 209, which is electrically connected between the gate G1 of the low-voltage switching device Q1 and the drive current control unit 203. The drive voltage detection unit 209 can detect the gate voltage of the low-voltage switching device Q1 and transmit it to the drive current control unit 203. The drive current control unit 203 controls the current source 204 to provide a drive current of a second target current value to the gate G1 of the low-voltage switching device Q1 when the gate voltage of the low-voltage switching device Q1 reaches the Miller plateau voltage of the low-voltage switching device Q1. The specific magnitude of the Miller plateau voltage of the low-voltage switching device Q1 can be predetermined according to actual conditions, and this application does not limit it. The second target current value is greater than the first target current value. The specific magnitude of the second target current value can be flexibly adjusted according to actual conditions, and this application does not limit it.

[0062] and Figure 5 The difference between the embodiments shown is that, Figure 6 The illustrated embodiment utilizes a drive voltage detection unit 209 to detect the gate voltage of the low-voltage switching device Q1 to determine the timing for increasing the drive current. In this embodiment, the drive voltage detection unit 209 sends the detected gate voltage of the low-voltage switching device Q1 to the drive current control unit 203. When the gate voltage of the low-voltage switching device Q1 reaches the Miller plateau voltage of the low-voltage switching device Q1, it indicates that the depletion-type switch Q2 is close to or has already been fully turned on. At this time, the drive current control unit 203 controls the current source 204 to provide a larger drive current to the gate G1 of the low-voltage switching device Q1, enabling the low-voltage switching device Q1 to turn on as quickly as possible and reducing the energy consumed by the low-voltage switching device Q1 due to insufficient current to turn on quickly. This increases the turn-on speed of the low-voltage switching device Q1 when the depletion-type switching device Q2 is on.

[0063] In some embodiments of this application, optionally, the common-source cascaded power device 200 may include not only the midpoint voltage detection unit 208, but also the drive voltage detection unit 209. The arrangement of the midpoint voltage detection unit 208 is different from... Figure 5 The midpoint voltage detection unit 208 in the illustrated embodiment is configured in the same way. The drive voltage detection unit 209 is configured in the same way. Figure 6The drive voltage detection unit 209 in the illustrated embodiment is configured in the same way, and will not be described again here. In this embodiment, the drive current control unit 203 can be used to control the current source 204 to provide a drive current of a second target current value to the gate G1 of the low-voltage switching device Q1 when it receives the first level transmitted by the midpoint voltage detection unit 208 and the gate voltage of the low-voltage switching device Q1 reaches the Miller plateau voltage of the low-voltage switching device Q1. The second target current value is greater than the first target current value.

[0064] For a cascaded power device with both a midpoint voltage detection unit 208 and a drive voltage detection unit 209, the timing for the drive current control unit 203 to control the current source 204 to increase the drive current of the low-voltage switching device Q1 is when the voltage of the intermediate node N1 between the low-voltage switching device Q1 and the depletion-mode switch Q2 is less than or equal to the target voltage, and the gate voltage of the low-voltage switching device Q1 reaches the Miller plateau voltage of the low-voltage switching device. By setting the midpoint voltage detection unit 208 and the drive voltage detection unit 209, the timing of increasing the drive current can be further precisely controlled, thereby improving the turn-on speed of the low-voltage switching device Q1 while ensuring that the depletion-mode switch Q2 is fully turned on.

[0065] Figure 7 This is a circuit diagram of another common-source cascaded power device according to an embodiment of this application. Figure 7 As shown, in some embodiments, the shutdown current detection unit 202 may include a current mirror, which can be powered by a first reference voltage provided by the first reference voltage terminal Verf1. The input branch LR of the current mirror is electrically connected to the control terminal G of the cascaded power device 200, and the output branch LC of the current mirror is electrically connected to the ground terminal GND through the first resistor R3.

[0066] In some specific embodiments, the input-side branch LR may include a first transistor T1 and a diode LD1. The first terminal of the first transistor T1 is electrically connected to the first reference voltage terminal Verf1, and the second terminal of the first transistor T1 is electrically connected to the anode of the diode LD1. The cathode of the diode LD1 is electrically connected to the control terminal G of the cascaded power device 200. By using diode LD1, the voltage signal at the control terminal G can be prevented from flowing to the current mirror when the input of the cascaded power device 200 is high, thus protecting the current mirror.

[0067] The output-side branch LC may include a second transistor T2 and a third transistor T3. The gate of the second transistor T2 is electrically connected to the gate of the first transistor T1, and the first terminal of the second transistor T2 is electrically connected to the first reference voltage terminal Verf1. The gate of the third transistor T3 is electrically connected to the second terminal of the first transistor T1, and the first terminal of the third transistor T3 is electrically connected to both the gate and the second terminal of the second transistor T2. The second terminal of the third transistor T3 is electrically connected to the ground terminal GND through a first resistor R3. The first terminal of the transistor can be the source, and the second terminal can be the drain. Alternatively, the first terminal of the transistor can be the drain, and the second terminal can be the source; this application does not limit this.

[0068] See also Figure 7 As shown, the drive current control unit 203 is electrically connected to the connection node N2 between the output branch LC and the first resistor R3. Since the current values ​​flowing through the input branch LR and the output branch LC of the current mirror are the same, the drive current control unit 203 can be used to detect the voltage value of the first resistor R3 during the turn-off phase and calculate the turn-off current value based on the voltage value and resistance value of the first resistor R3. The resistance value of the first resistor R3 can be predetermined, and this application does not limit it.

[0069] See also Figure 7 As shown, according to some embodiments of this application, optionally, the drive level conversion unit 201 may include a non-inverting buffer A1, an inverting buffer A2, a fourth transistor T4, and a fifth transistor T5. The input terminal of the non-inverting buffer A1 is electrically connected to the control terminal G of the cascaded power device 200, and the output terminal of the non-inverting buffer A1 is electrically connected to the gate of the fourth transistor T4. The first terminal of the fourth transistor T4 is electrically connected to the current source 204, and the second terminal of the fourth transistor T4 is electrically connected to the gate G1 of the low-voltage switching device Q1. When the pulse signal input to the control terminal G is high, the non-inverting buffer A1 also outputs a high level, the fourth transistor T4 is turned on, and the first path L1 between the positive voltage terminal Vdd and the gate G1 of the low-voltage switching device Q1 is connected.

[0070] The input terminal of the inverting buffer A2 is electrically connected to the control terminal G of the cascaded power device 200, and the output terminal of the inverting buffer A2 is electrically connected to the gate of the fifth transistor T5. The first terminal of the fifth transistor T5 is electrically connected to the gate G1 of the low-voltage switching device Q1, and the second terminal of the fifth transistor T5 is electrically connected to the ground terminal GND. When the pulse signal input to the control terminal G is low, the output of the inverting buffer A2 is high, the fifth transistor T5 is turned on, and the second path L2 between the gate G1 of the low-voltage switching device Q1 and the ground terminal GND is connected to discharge the gate G1 of the low-voltage switching device Q1.

[0071] like Figure 7 As shown, according to some embodiments of this application, optionally, the midpoint voltage detection unit 208 may include a comparator CP1. The non-inverting input terminal of the comparator CP1 is electrically connected to the second reference voltage terminal Verf2, and the inverting input terminal of the comparator CP1 is electrically connected to the intermediate node N1. The second reference voltage value provided by the second reference voltage terminal Verf2 can be equal to the target voltage value. Thus, when the voltage value of the intermediate node N1 detected by the inverting input terminal of the comparator CP1 is less than or equal to the second reference voltage value (i.e., the target voltage value) at the non-inverting input terminal, the comparator CP1 outputs a first level (e.g., a high level). In response to the first level output by the comparator CP1, the drive current control unit 203 controls the current source 204 to provide a larger drive current value to the gate G1 of the low-voltage switching device Q1, so that when the depletion-type switching device Q2 is turned on, the low-voltage switching device Q1 is turned on as quickly as possible.

[0072] According to other embodiments of this application, optionally, the midpoint voltage detection unit 208 may include a first diode LD2 in addition to the comparator CP1. The non-inverting input terminal of the comparator CP1 is electrically connected to the second reference voltage terminal Verf2, the anode of the first diode LD2 is electrically connected to the inverting input terminal of the comparator CP1, and the cathode of the first diode LD2 is electrically connected to the intermediate node N1. The second reference voltage value may be equal to the difference between the target voltage value and the breakdown voltage value of the first diode LD2. Thus, when the voltage value at the anode of the first diode LD2 detected at the inverting input terminal of the comparator CP1 is less than or equal to the second reference voltage value at the non-inverting input terminal (i.e., the difference between the target voltage value and the breakdown voltage value of the first diode LD2), the comparator CP1 outputs a first level (e.g., a high level). In response to the first level output by the comparator CP1, the drive current control unit 203 controls the current source 204 to provide a larger drive current value to the gate G1 of the low-voltage switching device Q1, so that when the depletion-type switching device Q2 is turned on, the low-voltage switching device Q1 is turned on as quickly as possible.

[0073] See also Figure 7 As shown, according to some embodiments of this application, optionally, the drive voltage detection unit 209 may include a first buffer OP1. The input terminal of the first buffer OP1 may be electrically connected to the gate G1 of the low-voltage switching device Q1, and the output terminal of the first buffer OP1 may be electrically connected to the drive current control unit 203. The first buffer OP1 can isolate the gate of the low-voltage switching device Q1 from the drive current control unit 203, preventing the gate drive signal from being interfered with by the load.

[0074] In some specific embodiments, the first buffer OP1 may optionally be a linear operational amplifier. The non-inverting input of the linear operational amplifier may be electrically connected to the gate G1 of the low-voltage switching device Q1, and the inverting input of the linear operational amplifier may be electrically connected to the output of the linear operational amplifier and the drive current control unit 203. The linear operational amplifier has low gate voltage attenuation, which can ensure that the voltage detected by the drive current control unit 203 is the same as or close to the actual gate G1 voltage of the low-voltage switching device Q1.

[0075] See also Figure 7 As shown, according to some embodiments of this application, optionally, the output terminal of the power supply unit 205 can be connected to the first reference voltage terminal Verf1, the second reference voltage terminal Verf2 and the positive voltage terminal Vdd respectively, for providing the first reference voltage terminal Verf1, the second reference voltage terminal Verf2 and the positive voltage terminal Vdd with their respective voltage values.

[0076] See also Figure 7 As shown, according to some embodiments of this application, optionally, the cascode cascaded power device 200 may have only three pins: a control terminal (gate terminal) G, a source terminal S, and a drain terminal D. The internal circuitry of the cascode cascaded power device can power the power supply unit 205, i.e., it is self-powered. For example, the input terminal of the power supply unit 205 can be electrically connected to the control terminal G and / or intermediate node N1 of the cascode cascaded power device 200. The power supply unit 205 can be used to receive the voltage signal from the control terminal G and / or intermediate node N1, perform voltage conversion on the voltage signal, and then supply the converted voltage to the first reference voltage terminal Verf1, the second reference voltage terminal Verf2, and / or the positive voltage terminal Vdd.

[0077] Thus, the common-source cascaded power device requires only 3 pins, without the need for additional pins. By multiplexing the detection and drive functions with at least one drive resistor, the magnitude of the drive current during the conduction phase of the common-source cascaded power device can be controlled, thereby adjusting dv / dt. This solves the defect that the traditional common-source cascaded power device structure cannot directly control the switching speed of depletion-type switching devices.

[0078] Figure 8 This is a circuit diagram of another common-source cascaded power device according to an embodiment of this application. Figure 8 As shown, unlike the embodiments described above, Figure 8The cascaded power device 200 of the illustrated embodiment may further include a power supply pin Vcc. The input terminal of the power supply unit 205 may be electrically connected to the power supply pin Vcc. The power supply unit 205 may receive the voltage signal from the power supply pin Vcc, perform voltage conversion on the voltage signal, and then supply the converted voltage to the first reference voltage terminal Verf1, the second reference voltage terminal Verf2, and / or the positive voltage terminal Vdd. Therefore, Figure 8 The common source cascaded power device shown is configured for external power supply. External power supply to the power supply unit 205 can be achieved by setting the power supply pin Vcc.

[0079] According to some embodiments of this application, optionally, the device types of the low-voltage switching device Q1 and the depletion-mode switching device Q2 can be flexibly selected according to actual conditions, and this application does not limit this. For example, in some examples, the low-voltage switching device Q1 includes, but is not limited to, silicon-based N-type field-effect transistors (Si N-MOSFETs). Silicon-based N-type field-effect transistors have advantages such as high input impedance, low conduction loss, and fast switching. The depletion-mode switching device Q2 includes, but is not limited to, depletion-mode gallium nitride field-effect transistors (d-mode GaN HEMTs) and depletion-mode junction field-effect transistors (d-mode JFETs).

[0080] Figure 9 This is a schematic diagram illustrating the voltage and current changes during the driving process of a cascaded power device based on an embodiment of this application. Vds is the voltage difference between the drain and source terminals of the cascaded power device 200, Ig is the driving current, and Vgs is the voltage difference between the gate and source terminals of the cascaded power device 200. Figure 9 As shown, according to some embodiments of this application, optionally, the conduction stage may include a first conduction sub-stage T1, a second conduction sub-stage T2, and a third conduction sub-stage T3.

[0081] Combination Figure 7 and Figure 9 As shown, the drive current control unit 203 can be used to control the current source 204 to provide a preset current value to the gate of the low-voltage switching device Q1 during the first conduction sub-stage T1. By providing a preset current value to the gate of the low-voltage switching device Q1, it helps to make the drive voltage quickly approach the threshold voltage Vth of the low-voltage switching device Q1. It should be noted that if the threshold voltage Vth of the low-voltage switching device Q1 is low, the first conduction sub-stage T1 can be omitted, and the second conduction sub-stage T2 can be performed directly.

[0082] The drive current control unit 203 can be used in the second conduction stage T2 to control the current source 204 to provide a drive current of a first target current value to the gate of the low-voltage switching device Q1. If the value of the drive resistor is larger, the value of the turn-off current is smaller. Correspondingly, the smaller the first target current value, the slower the rate of Vds decrease, and the slower the turn-on speed of the depletion-type switching device Q2. If the value of the drive resistor is smaller, the value of the turn-off current is larger. Correspondingly, the larger the first target current value, the faster the rate of Vds decrease, and the faster the turn-on speed of the depletion-type switching device Q2. Therefore, the turn-on speed of the depletion-type switching device Q2 can be adjusted by adjusting the drive resistor.

[0083] The drive current control unit 203 can be used to control the current source 204 to provide a drive current of the second target current value to the gate of the low-voltage switching device Q1 during the third conduction stage T3. By detecting the voltage value of intermediate node N1 and / or the drive voltage of the low-voltage switching device Q1, when the voltage value of intermediate node N1 is lower than a preset value, and / or when the drive voltage reaches the Miller plateau voltage, it indicates that the depletion-type switching device Q2 is fully turned on. At this time, the drive current is increased until Vgs reaches a stable voltage value. In this way, by increasing the drive current, the low-voltage switching device Q1 can be turned on quickly, reducing the Miller time of the low-voltage switching device Q1 and reducing the switching losses of the low-voltage switching device Q1.

[0084] According to some embodiments of this application, optionally, the preset current value may be less than the second target current value.

[0085] There are various ways to detect the turn-off current value and determine the first target current value. For example, in some embodiments, the drive current control unit 203 can be used, during the conduction phase of the current cycle, to control a current source to provide a drive current of the first target current value to the gate of the low-voltage switching device based on a pre-set correspondence between the turn-off current and the drive current, and the average value of the turn-off current during the turn-off phases of previous cycles. That is, the first target current value can be determined based on the average value of the turn-off current during the turn-off phases of previous cycles; the larger the average value of the turn-off current, the larger the first target current value; the smaller the average value of the turn-off current, the smaller the first target current value.

[0086] For example, in other embodiments, the drive current control unit 203 can be used to control a current source to provide a drive current of a first target current value to the gate of the low-voltage switching device during the turn-on phase of each cycle, based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value in the turn-off phase of the previous cycle. That is, the turn-off current value is detected in each cycle, and the first target current value is re-determined.

[0087] For example, in some other embodiments, the drive current control unit 203 can be used to control the current source to provide a drive current of a first target current value to the gate of the low-voltage switching device during the turn-on phase of all cycles, based on a pre-set correspondence between the turn-off current and the drive current, and the turn-off current value during the turn-off phase of the first cycle. That is, after power-on, the first target current value is detected only once, and all subsequent cycles determine and use the same first target current value according to the turn-off current value detected in the first cycle.

[0088] Based on the cascaded power device 200 with common source and common gate provided in the above embodiments, this application also proposes a switching circuit. For example... Figure 4 As shown, the switching circuit 300 includes a common-source cascaded power device 200 and a start-up adjustment unit 206. The start-up adjustment unit 206 includes a drive resistor R1. The first end of the drive resistor R1 is used to receive pulse signals, and the second end of the drive resistor R1 is electrically connected to the control terminal G of the common-source cascaded power device 200 to transmit pulse signals to the control terminal.

[0089] The switching circuit 300 provided in this application embodiment has the same beneficial effects as the common source cascade power device 200 provided in this application embodiment. For details, please refer to the specific descriptions of the common source cascade power device 200 in the above embodiments. This embodiment will not repeat them here.

[0090] In this embodiment, the driving resistor R1 is used as one configuration of the start-up adjustment unit 206. Besides this, the start-up adjustment unit 206 can be configured in other ways. For example... Figure 7 As shown, according to some embodiments of this application, optionally, the start-up adjustment unit 206 may further include a first turn-off resistor R2, and the second turn-off resistor R2 is electrically connected between the control terminal G of the common source cascaded power device 200 and the source terminal S of the common source cascaded power device 200.

[0091] During the turn-off phase, the source terminal S of the cascaded power device 200 is at a low potential. Therefore, the control terminal G of the cascaded power device 200 can also discharge through the first turn-off resistor R2. Thus, by adjusting the resistance values ​​of the drive resistor R1 and / or the first turn-off resistor R2, the turn-off current value can be changed, thereby changing the magnitude of the drive current value, and thus adjusting the turn-on speed of the depletion-type switching device Q2.

[0092] Figure 10 This is a circuit diagram of a switching circuit according to an embodiment of this application. Figure 10As shown, according to some other embodiments of this application, optionally, the start-up adjustment unit 206 may further include a second diode LD6. The anode of the second diode LD6 is used to receive pulse signals, and the cathode of the second diode LD6 is electrically connected to the first terminal of the drive resistor R1. That is, the second diode LD6 is connected in series with the drive resistor R1. The second diode LD6 is used to transmit the pulse signal through the drive resistor R1 to the control terminal G of the cascaded power device 200. The second diode LD6 and the drive resistor R1 are mainly used for power supply and transmission of drive signals, and the first turn-off resistor R2 is mainly used for adjusting the turn-off current.

[0093] Figure 11 This is a circuit diagram of another switching circuit according to an embodiment of this application. Figure 11 As shown, with Figure 10 The difference between the illustrated embodiment and the one shown is that, in Figure 11 In the illustrated embodiment, the start-up adjustment unit 206 may further include a second turn-off resistor R0. The branch containing the second diode LD6 and the drive resistor R1 is connected in parallel with the second turn-off resistor R0 at the control terminal G of the cascaded power device 200. The first turn-off resistor R2 and the second turn-off resistor R0 are mainly used to adjust the turn-off current. Power is supplied and drive signals are transmitted through the second diode LD6 and the drive resistor R1 to avoid the resistance value of the second turn-off resistor R0 being too large, resulting in insufficient power supply.

[0094] Based on the cascaded power device 200 provided in the above embodiments, this application also proposes a driving method for the cascaded power device. This driving method can, for example, be used to drive the cascaded power device 200 provided in the above embodiments.

[0095] Specifically, the driving method for cascaded power devices with common source and common gate may include the following steps:

[0096] Step 101: Receive the pulse signal transmitted by the driving resistor;

[0097] Step 102: During the turn-off phase when the pulse signal is low, detect the turn-off current value at the control terminal of the cascaded power device.

[0098] Step 103: During the conduction phase when the pulse signal is high, connect the first path between the positive voltage terminal and the gate of the low-voltage switching device so that the positive voltage terminal provides a driving voltage to the gate of the low-voltage switching device.

[0099] Step 104: During the turn-on phase, based on the pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase, the control current source provides a drive current of the first target current value to the gate of the low-voltage switching device, wherein the first target current value is positively correlated with the turn-off current value.

[0100] The specific processes of steps 101 to 104 above have been described in detail above and will not be repeated here.

[0101] The driving method for the common-source cascaded power device has the same beneficial effects as the common-source cascaded power device 200 provided in the embodiments of this application, and will not be described in detail here for the sake of brevity.

[0102] In some embodiments of this application, the driving method for cascaded power devices may optionally include the following steps:

[0103] When the voltage value of the intermediate node is detected to be less than or equal to the target voltage value, and / or when the gate voltage of the low-voltage switching device reaches the Miller plateau voltage of the low-voltage switching device, the control current source provides a drive current of a second target current value to the gate of the low-voltage switching device, the second target current value being greater than the first target current value.

[0104] In some embodiments of this application, the conduction phase may optionally include a first conduction sub-phase, a second conduction sub-phase, and a third conduction sub-phase.

[0105] In the first conduction phase, the control current source provides a drive current of a preset current value to the gate of the low-voltage switching device; in the second conduction phase, the control current source provides a drive current of a first target current value to the gate of the low-voltage switching device; and in the third conduction phase, the control current source provides a drive current of a second target current value to the gate of the low-voltage switching device.

[0106] In some embodiments of this application, optionally, step 104: during the turn-on phase, based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase, controlling the current source to provide a drive current of a first target current value to the gate of the low-voltage switching device may include the following steps:

[0107] During the turn-on phase of the current cycle, based on the pre-set correspondence between the turn-off current and the drive current and the average value of the turn-off current during the turn-off phase in the previous multiple cycles, the control current source provides a drive current of the first target current value to the gate of the low-voltage switching device.

[0108] Alternatively, during the turn-on phase of each cycle, based on the pre-set correspondence between the turn-off current and the drive current and the turn-off current value in the turn-off phase of the previous cycle, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device.

[0109] Alternatively, during the turn-on phase of all cycles, based on the pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase of the first cycle, the control current source provides a drive current of the first target current value to the gate of the low-voltage switching device.

[0110] The specific processes of each of the above steps have been described in detail above and will not be repeated here.

[0111] In summary, this application presents a driving method for the switching dv / dt of a cascaded power device based on a common source and common gate circuit, as well as the cascaded power device itself. Specifically, it combines... Figure 7 As shown, the working principle of a cascaded power device with common source and common gate is as follows:

[0112] After power-on with a pulse signal (PWM), the PWM high level is input to the device's gate (G) through the drive resistor R1 of the start-up regulation unit 206, providing energy to the internal power supply unit and simultaneously providing a drive signal to the drive level conversion unit 201. Before detecting the current signal, the following two situations exist:

[0113] 1. The power supply unit 205 inside the common source cascade power device is not powered, the turn-off current detection unit 202 is not started, and the drive current control unit 203 does not detect the current flowing through resistor R3 (i.e., the turn-off current). The first control current of the common source cascade power device is set to the minimum drive current value.

[0114] 2. The power supply unit 205 inside the cascaded power device has been established. Before the PWM output goes high, the PWM output goes low, at which point the shutdown current detection unit 202 starts working.

[0115] The current flowing through resistors R1 and R2 is mirrored to the current flowing through resistor R3. The drive current control unit 203 sets the drive current of the cascaded power device for the next n cycles by detecting the current flowing through resistor R3 (i.e., the turn-off current). When the turn-off current is small, the drive current of the cascaded power device for the next n cycles decreases accordingly; when the turn-off current is large, the drive current of the cascaded power device for the next n cycles increases accordingly. n is a positive integer.

[0116] When the cascaded power device is driven to power, the Vds voltage of the cascaded power device begins to decrease depending on the magnitude of the drive current, while the drive voltage also begins to increase. When the voltage at the intermediate node of the cascaded power device drops below Vref2 + VD2, the comparator CP1 level is reversed and sent to the drive current control unit 203. And / or, the drive voltage detection unit 209 sends the detected gate voltage to the drive current control unit 203. When the comparator CP1 level is reversed, and / or after a drive Miller plateau appears, the drive current control unit 203 controls the current source 204 to increase the drive current, causing the device drive voltage to rise rapidly, and the device to turn on quickly and fully.

[0117] By changing resistors R1 and / or R2, the turn-off current also changes, thereby adjusting the dv / dt drive current during the conduction phase of the cascaded power device.

[0118] The above embodiments are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art can make various changes and modifications without departing from the scope of this application. Therefore, all equivalent technical solutions should also fall within the scope of this application.

Claims

1. A common-source, common-gate cascaded power device, characterized in that, include: Low-voltage switching devices, depletion-mode switching devices, drive level conversion units, turn-off current detection units, drive current control units, current sources, and power supply units; The source of the low-voltage switching device is electrically connected to the gate of the depletion-type switching device, and the drain of the low-voltage switching device is electrically connected to the source of the depletion-type switching device; the control terminal of the cascaded power device is electrically connected to the drive resistor and is used to receive the pulse signal transmitted by the drive resistor. The shutdown current detection unit is electrically connected to the control terminal and is used to detect the shutdown current value of the control terminal during the shutdown phase when the pulse signal is low. The drive level conversion unit is electrically connected to the control terminal, the gate of the low-voltage switching device, the positive voltage terminal, and the ground terminal, respectively. It is used to connect the first path between the positive voltage terminal and the gate of the low-voltage switching device during the conduction phase when the pulse signal is high, so that the positive voltage terminal provides a drive voltage to the gate of the low-voltage switching device. The drive current control unit is electrically connected to the turn-off current detection unit and the current source respectively. The current source is located on the first path and is used to control the current source to provide a drive current of a first target current value to the gate of the low-voltage switching device based on a preset correspondence between the turn-off current and the drive current and the turn-off current value in the turn-off phase. The first target current value is positively correlated with the turn-off current value. The power supply unit is electrically connected to the shutdown current detection unit and the positive voltage terminal respectively, and is used to supply power to the shutdown current detection unit and the positive voltage terminal.

2. The cascaded power device according to claim 1, characterized in that, The common-source cascaded power device also includes a midpoint voltage detection unit, which is electrically connected between the intermediate node and the drive current control unit. The intermediate node is the connection node between the drain of the low-voltage switching device and the source of the depletion-type switching device. The midpoint voltage detection unit is used to output a first level to the drive current control unit when the voltage value of the intermediate node is less than or equal to the target voltage value; wherein, when the intermediate node is at the target voltage value, the depletion-type switching device is fully turned on; The drive current control unit is used to respond to the first level and control the current source to provide a drive current of a second target current value to the gate of the low-voltage switching device, wherein the second target current value is greater than the first target current value.

3. The cascaded power device according to claim 1, characterized in that, The common-source cascaded power device further includes a drive voltage detection unit, which is electrically connected between the gate of the low-voltage switching device and the drive current control unit. The drive voltage detection unit is used to detect the gate voltage of the low-voltage switching device and transmit the gate voltage to the drive current control unit. The drive current control unit is used to control the current source to provide a drive current of a second target current value to the gate of the low-voltage switching device when the gate voltage of the low-voltage switching device reaches the Miller plateau voltage of the low-voltage switching device, wherein the second target current value is greater than the first target current value.

4. The cascaded power device according to claim 1, characterized in that, The common-source cascaded power device further includes a midpoint voltage detection unit and a drive voltage detection unit; The midpoint voltage detection unit is electrically connected between the intermediate node and the drive current control unit. The intermediate node is the connection node between the drain of the low-voltage switching device and the source of the depletion-type switching device. The midpoint voltage detection unit is used to output a first level to the drive current control unit when the voltage value of the intermediate node is detected to be less than or equal to the target voltage value. The drive voltage detection unit is electrically connected between the gate of the low-voltage switching device and the drive current control unit. The drive voltage detection unit is used to detect the gate voltage of the low-voltage switching device and transmit the gate voltage to the drive current control unit. The drive current control unit is configured to control the current source to provide a drive current of a second target current value to the gate of the low-voltage switching device when it receives the first level transmitted by the midpoint voltage detection unit and the gate voltage of the low-voltage switching device reaches the Miller plateau voltage of the low-voltage switching device, wherein the second target current value is greater than the first target current value.

5. The cascaded power device according to claim 1, characterized in that, The shutdown current detection unit includes a current mirror, which is powered by a first reference voltage provided by a first reference voltage terminal. The input side branch of the current mirror is electrically connected to the control terminal of the common source cascade power device, and the output side branch of the current mirror is electrically connected to the ground terminal through a first resistor. The drive current control unit is electrically connected to the connection node between the output side branch and the first resistor. The drive current control unit is used to detect the voltage value of the first resistor during the turn-off phase, and calculate the turn-off current value based on the voltage value and the resistance value of the first resistor.

6. The cascaded power device according to claim 2 or 4, characterized in that, The midpoint voltage detection unit includes a comparator, the non-inverting input terminal of which is electrically connected to the second reference voltage terminal, and the inverting input terminal of which is electrically connected to the intermediate node. The second reference voltage value is equal to the target voltage value.

7. The common-source cascaded power device according to claim 2 or 4, characterized in that, The midpoint voltage detection unit includes a comparator and a first diode. The non-inverting input terminal of the comparator is electrically connected to the second reference voltage terminal. The anode of the first diode is electrically connected to the inverting input terminal of the comparator. The cathode of the first diode is electrically connected to the intermediate node. The second reference voltage value is equal to the difference between the target voltage value and the breakdown voltage value of the first diode.

8. The common-source cascaded power device according to claim 3 or 4, characterized in that, The drive voltage detection unit includes a first buffer, the input terminal of which is electrically connected to the gate of the low-voltage switching device, and the output terminal of which is electrically connected to the drive current control unit.

9. The cascaded power device according to claim 8, characterized in that, The first buffer is a linear operational amplifier. The non-inverting input of the linear operational amplifier is electrically connected to the gate of the low-voltage switching device, and the inverting input of the linear operational amplifier is electrically connected to the output of the linear operational amplifier and the drive current control unit.

10. The cascaded power device according to claim 1, characterized in that, The output terminal of the power supply unit is electrically connected to the first reference voltage terminal, the second reference voltage terminal, and the positive voltage terminal, and is used to provide the respective voltage values ​​to the first reference voltage terminal, the second reference voltage terminal, and the positive voltage terminal.

11. The cascaded power device according to claim 1, characterized in that, The input terminal of the power supply unit is electrically connected to the control terminal and / or intermediate node of the common source cascaded power device. The intermediate node is the connection node between the drain of the low-voltage switching device and the source of the depletion-mode switching device, and is used to receive the voltage signal of the control terminal and / or the intermediate node, and to perform voltage conversion on the voltage signal.

12. The cascaded power device according to claim 1, characterized in that, The common-source cascaded power device also includes a power supply pin. The input terminal of the power supply unit is electrically connected to the power supply pin. The power supply unit is used to receive the voltage signal from the power supply pin and to perform voltage conversion on the voltage signal.

13. The cascaded power device according to any one of claims 2-4, characterized in that, The conduction phase includes a first conduction sub-phase, a second conduction sub-phase, and a third conduction sub-phase; The drive current control unit is used to control the current source to provide a preset current value of drive current to the gate of the low-voltage switching device during the first conduction sub-stage. During the second conduction phase, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device; In the third conduction phase, the current source is controlled to provide a drive current of the second target current value to the gate of the low-voltage switching device.

14. The cascaded power device according to claim 13, characterized in that, The preset current value is less than the second target current value.

15. The cascaded power device according to claim 1, characterized in that, The drive current control unit is specifically used to control the current source to provide a drive current of a first target current value to the gate of the low-voltage switching device during the conduction phase of the current cycle, based on a pre-set correspondence between the turn-off current and the drive current and the average value of the turn-off current during the turn-off phase of the previous multiple cycles. Alternatively, the drive current control unit is specifically used to control the current source to provide a drive current of a first target current value to the gate of the low-voltage switching device based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value in the turn-off phase of the previous cycle during the turn-on phase of each cycle. Alternatively, the drive current control unit is specifically used to control the current source to provide a drive current of a first target current value to the gate of the low-voltage switching device during the conduction phase of all cycles, based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase of the first cycle.

16. A switching circuit, characterized in that, The device includes a common source cascaded power device and a startup adjustment unit as described in any one of claims 1-15. The startup adjustment unit includes a driving resistor, a first end of which is used to receive a pulse signal, and a second end of which is electrically connected to the control terminal of the common source cascaded power device for transmitting the pulse signal to the control terminal.

17. The switching circuit according to claim 16, characterized in that, The start-up adjustment unit further includes a first turn-off resistor, which is electrically connected between the control terminal of the common-source cascaded power device and the source terminal of the common-source cascaded power device.

18. The switching circuit according to claim 16, characterized in that, The start-up adjustment unit further includes a second diode, the anode of which is used to receive the pulse signal, and the cathode of which is electrically connected to the first end of the drive resistor. The second diode is used to transmit the pulse signal to the control terminal of the common source cascaded power device through the drive resistor.

19. The switching circuit according to claim 18, characterized in that, The start-up adjustment unit further includes a second turn-off resistor, and the branch containing the second diode and the driving resistor is connected in parallel with the second turn-off resistor to the control terminal of the common source cascaded power device.

20. A driving method for a cascaded power device with common source and common gate, characterized in that, The common-source cascaded power device includes the common-source cascaded power device as described in any one of claims 1-15, comprising: Receive the pulse signal transmitted by the drive resistor; During the turn-off phase when the pulse signal is low, the turn-off current value at the control terminal of the cascaded power device is detected. During the conduction phase when the pulse signal is high, the first path between the positive voltage terminal and the gate of the low-voltage switching device is connected so that the positive voltage terminal provides a drive voltage to the gate of the low-voltage switching device. During the turn-on phase, based on the pre-set correspondence between the turn-off current and the drive current, and the turn-off current value during the turn-off phase, the control current source provides a drive current of the first target current value to the gate of the low-voltage switching device, wherein the first target current value is positively correlated with the turn-off current value.

21. The driving method according to claim 20, characterized in that, The driving method further includes: When the voltage value of the intermediate node is detected to be less than or equal to the target voltage value, and / or when the gate voltage of the low-voltage switching device reaches the Miller plateau voltage of the low-voltage switching device, the current source is controlled to provide a drive current of a second target current value to the gate of the low-voltage switching device, the second target current value being greater than the first target current value, wherein the intermediate node is the connection node between the drain of the low-voltage switching device and the source of the depletion-type switching device.

22. The driving method according to claim 21, characterized in that, The conduction phase includes a first conduction sub-phase, a second conduction sub-phase, and a third conduction sub-phase; During the first conduction phase, the current source is controlled to provide a drive current of a preset current value to the gate of the low-voltage switching device; During the second conduction phase, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device; In the third conduction phase, the current source is controlled to provide a drive current of the second target current value to the gate of the low-voltage switching device.

23. The driving method according to claim 20, characterized in that, During the turn-on phase, based on the pre-set correspondence between the turn-off current and the drive current, and the turn-off current value during the turn-off phase, the control current source provides a drive current of the first target current value to the gate of the low-voltage switching device, including: During the conduction phase of the current cycle, based on the pre-set correspondence between the turn-off current and the drive current and the average value of the turn-off current during the turn-off phase in the previous multiple cycles, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device. Alternatively, during the turn-on phase of each cycle, based on the pre-set correspondence between the turn-off current and the drive current and the turn-off current value in the turn-off phase of the previous cycle, the current source is controlled to provide a drive current of the first target current value to the gate of the low-voltage switching device. Alternatively, during the conduction phase of all cycles, based on a pre-set correspondence between the turn-off current and the drive current and the turn-off current value during the turn-off phase of the first cycle, the current source is controlled to provide a drive current of a first target current value to the gate of the low-voltage switching device.

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