Oxide Field Trench (OFT) Diode Control Devices

Abstract

Embodiments of the present disclosure relate to oxide field trench (OFT) diode control devices. A device includes a controllable current source connected between a first node and a first terminal, the first terminal coupled to the cathode of the controllable diode. A capacitor is connected between the first node and a second terminal, the second terminal coupled to the anode of the controllable diode. A first switch is connected between the first node and a third terminal, the third terminal coupled to the gate of the controllable diode. A second switch is connected between the second terminal and the third terminal. A first diode is connected between the third terminal and the second terminal, the anode of the first diode preferably coupled to the third terminal.

Description

[0001] Priority claim

[0002] This application claims priority from French patent application No. 2008791, filed on August 28, 2020, the contents of which are incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field

[0003] The present disclosure relates generally to electronic circuits, and more particularly to devices for controlling controllable diodes such as OFT ("Oxide Field Trench") diodes. Background Art

[0004] Figure 1 is a subsidiary of U.S. Patent Application Publication No. 2020 / 0105946 (which is incorporated herein by reference in its entirety to the fullest extent permitted by law) Figure 1 A copy of . Figure 1 One example of an oxide field trench (OFT) diode 10 is shown.

[0005] The diode 10 includes a semiconductor substrate 20, for example, made of silicon. The diode 10 includes, for example, a cathode terminal K and an anode terminal A electrically connected to the lower surface of the substrate. The diode 10 includes trenches 22 extending from the upper surface of the substrate 20 in the substrate 20. The trenches 22 are, for example, regularly spaced apart and, for example, parallel to each other or in the shape of concentric rings.

[0006] The diode 10 includes structures 30A as described below, each structure 30A being located in the trench 22, for example, two structures 30A on either side of the diode 10. Preferably, the diode 10 further includes one or more structures 30A between the structures 30A.

[0007] In the associated trench 22, each structure 30 includes a conductive region 302 located in the upper portion of the trench 22. The region 302 is separated from the walls of the trench 22, i.e., from the substrate 20, and is separated from the walls of the associated trench 22, for example, by one or more dielectric layers 304 arranged on either side of the region 302. The region 302 and the walls of the trench 22 are separated by a short distance d, which is preferably shorter than 10 nm, for example, shorter than 7 nm.

[0008] Each structure 30 also includes a conductive region 306 extending in the trench below (or deeper than) region 302. Figure 1 In the illustrated example, regions 302 and 306 are integral, but as a variation, the two regions 302 and 306 may be separated and electrically insulated from each other by one or more dielectric layers, and then extend from the upper surface of substrate 20 .

[0009] Region 306 is, for example, located further away from the walls of trench 22 than region 302. Region 306 is separated from substrate 20, for example, by one or more dielectric layers 308, which cover the walls and bottom of trench 22. The thickness of layer 308 is, for example, greater than about 100 nm, preferably in the range of 250 nm to 1000 nm.

[0010] Structure 30A uses the same elements as structure 30. However, in structure 30A, the aforementioned distance d does not exist outside of diode 10. As an example, layer 308 then extends on the outside of diode 10 between region 302 and the wall of the associated trench 22. Layer 308 may join insulating layer 44, which covers the substrate on the periphery of the diode.

[0011] As an example, regions 302 and 306 are made of doped polysilicon, and layers 304 and 308 are made of silicon oxide.

[0012] Then, a transistor T1 can be formed in the portion of the substrate 20 that contacts each layer 304, with the region 302 in question forming the gate of the transistor T1. By way of example, the transistor T1 has an N-channel. Each transistor T1 includes a P-type doped channel region 202 (P). By way of example, each channel region 202 extends between two adjacent trenches 22 and is therefore shared by two adjacent transistors T1. Preferably, each region 202 has a central region crowned by a contact region 204 (P+, more heavily P-type doped than region 202).

[0013] Each transistor T1 also includes a drain region 206 (N-) located below the channel region 202. As an example, each drain region 206 extends between two adjacent trenches 22 and is common to adjacent transistors T1. The drain regions 206 may continue below the trenches 22 and then meet below the trenches 22. For example, the region 206 is on top of and in contact with a contact region 208 (N+), which extends over the lower portion of the substrate 20 and is electrically coupled to the terminal K.

[0014] Each transistor T1 further comprises a source region 210 (N+) preferably positioned adjacent to the layer 304. For example, the source region 210 is more heavily N-doped than the drain region 206.

[0015] In diode 10, gate region 302, source region 210, and contact region 204 of transistor T1 are preferably electrically connected to anode terminal A. Thus, diode 10 is defined by one or more transistors T1. To achieve this, conductive layer 40, which may be located on interface layer 42, covers substrate 20 and trench 22, as an example. Regions 302 and 306 extend from layer 40, or possibly interface layer 42, into trench 22.

[0016] Therefore, in Figure 1 , OFT diode 10 includes a plurality of structures 30A and may include 30. In an associated trench 22, each structure 30A, 30 includes a conductive region 302 separated from substrate 20 by a distance d of less than about 10 nm, and includes a conductive region 306 extending deeper into substrate 20 than region 302. Diode 10 is defined by one or more transistors T1, having at least one channel region 202 extending between two trenches in trench 22. Region 302 defines the gate of transistor T1 of diode 10, i.e., the gate of diode 10. Diode 10 includes a contact region 204 that electrically couples the channel region 202 of each transistor T1 of diode 10 to an anode conductive layer 40.

[0017] When the gate potential is properly controlled, Figure 1 The OFT diode 10 described has low reverse leakage current and low forward voltage drop. This makes the OFT diode 10 a good candidate to replace MOS transistors or non-controllable (gateless) diodes controlled by synchronous rectification in applications where the goal is as low a reverse current and as low a voltage drop as possible (e.g., in power applications).

[0018] It would be desirable to have an oxide field trench (OFT) diode control device that overcomes all or some of the disadvantages of known OFT diode control devices.

[0019] It would also be desirable to have a dipole comprising an OFT diode and an OFT diode control device which overcomes all or part of the disadvantages of known OFT diode control devices. In practice, such a dipole would enable, for example, the use of the dipole to replace a non-controllable diode of a circuit without requiring further modification of the circuit. Summary of the Invention

[0020] One embodiment overcomes all or some of the disadvantages of known oxide field trench (OFT) diode control devices.

[0021] One embodiment provides a dipole including an OFT diode and a device for controlling the OFT diode, which overcomes all or part of the disadvantages of known OFT diode control devices.

[0022] One embodiment provides a device comprising: a controllable current source connected between a first node and a first terminal, the first terminal being coupled to a cathode of a controllable diode; a capacitor connected between the first node and a second terminal, the second terminal being coupled to an anode of the controllable diode; a first switch connected between the first node and a third terminal, the third terminal being coupled to a gate of the controllable diode; a second switch connected between the second terminal and the third terminal; and a first diode connected between the third terminal and the second terminal, the anode of the first diode being preferably coupled to the third terminal.

[0023] According to one embodiment, a device includes a circuit configured to control a current source, a first switch, and a second switch based on a potential difference between a first terminal and a second terminal.

[0024] According to one embodiment, the circuit is configured to: control the current delivery from the source to the capacitor when the potential difference is less than a first threshold (preferably negative or zero); control the first switch to be in the on state when the potential difference is greater than a second threshold (preferably positive or zero); and control the second switch to be in the on state when the potential difference is lower than a third threshold (preferably negative or zero).

[0025] According to one embodiment: the current source is a first NPN bipolar transistor having an emitter coupled to the first node and having a collector coupled to the first terminal; the first switch is a second PNP bipolar transistor having an emitter coupled to the first node and having a collector coupled to the third terminal; and the second switch is a third NPN bipolar transistor having an emitter coupled to the second terminal and having a collector coupled to the third terminal.

[0026] According to one embodiment, a circuit includes a first resistor having a first terminal coupled to a base of a first transistor; a second resistor having a first terminal coupled to a base of a second transistor; a second diode connected between the base of the first transistor and the base of the second transistor, an anode of the second diode coupled to the base of the first transistor; and a third diode connected between the base of the second transistor and the base of the third transistor, an anode of the third diode coupled to the base of the second transistor.

[0027] According to one embodiment, the threshold voltage of the second diode is equal to the threshold voltage of the base-emitter diode of the first transistor.

[0028] According to one embodiment, the maximum voltage across the capacitor is at least partially determined by a threshold voltage of the third diode.

[0029] According to one embodiment: the first threshold is at least partially determined by a threshold voltage of a first diode; or the circuit comprises a diode, preferably a Zener diode, connected in series with the first resistor between the first terminal and the base of the first transistor, the first threshold being at least partially determined by a reverse conduction threshold voltage of the diode.

[0030] According to one embodiment, the second threshold is at least partially determined by a threshold voltage of the third diode and / or a threshold voltage of the controllable diode.

[0031] According to one embodiment: the third threshold is at least partially determined by a threshold voltage of a third diode; or, the circuit further comprises a diode connected in series with the third resistor between the first terminal and the base of the third transistor, and the third threshold is at least partially determined by a threshold voltage of the diode.

[0032] According to an embodiment: the circuit further comprises a resistor connected between the base and the second terminal of the third transistor; and / or the circuit comprises a diode connected between the base and the collector of the third transistor for desaturating the third transistor.

[0033] According to one embodiment, the device includes an inductor having a terminal connected to the second terminal and having another terminal coupled to the anode of the controllable diode.

[0034] According to one embodiment, the controllable diode is an OFT diode comprising a plurality of structures, each structure having a first conductive region separated from the substrate by a first distance shorter than about 10 nm in a trench of a substrate, and each structure having a second conductive region extending deeper in the trench than the first region, the diode being defined by one or more transistors, each transistor having at least one channel region extending between two trenches in the trench, the first conductive region defining a gate of the transistor and a gate of the diode.

[0035] Another embodiment provides a dipole comprising: the above-mentioned device, the first terminal of the device defining the cathode of the dipole, and the second terminal of the device defining the anode of the dipole; and a controllable diode, preferably an OFT diode, having a cathode connected to the first terminal of the device, an anode connected to the second terminal of the device, and a gate connected to the third terminal of the device.

[0036] Another embodiment provides a switch mode power supply comprising the above device or the above dipole. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The foregoing features and advantages, as well as other features and advantages, will be further described in the following description of specific embodiments given by way of illustration and not limitation, with reference to the accompanying drawings, in which:

[0038] Figure 1 (previously described) is a member of U.S. Patent Application Publication No. 2020 / 105946 Figure 1 a copy of which illustrates an example of an oxide field trench (OFT) diode;

[0039] Figure 2 An embodiment of a power converter according to one embodiment is schematically shown in the form of a circuit, the power converter including an OFT diode and a control device thereof;

[0040] Figure 3 The circuit is schematically shown Figure 2 An embodiment of a control device;

[0041] Figure 4 The circuit is schematically shown Figure 3 A more detailed embodiment of the control device;

[0042] Figure 5 The circuit is schematically shown Figure 4 an alternative embodiment of a control device;

[0043] Figure 6 The circuit is schematically shown Figure 4 Another alternative embodiment of the control device; and

[0044] Figure 7 The circuit is schematically shown Figure 4 Yet another alternative embodiment of the control device. DETAILED DESCRIPTION

[0045] In the various drawings, similar features are designated by similar reference numerals. In particular, common structural and / or functional features among the various embodiments may have the same reference numerals and may be arranged with the same structure, dimensions, and material properties.

[0046] For the sake of clarity, steps and elements useful for understanding the embodiments described herein have been illustrated and described in detail. In particular, conventional electronic circuits including dipoles that implement diode functions (e.g., rectification), such as switch-mode power converters or rectifier bridges, have not been shown in detail, the described embodiments being compatible with such conventional circuits.

[0047] Unless otherwise indicated, when two elements are referred to as being connected together, this means a direct connection without any intervening elements other than conductors, and when two elements are referred to as being coupled together, this means the two elements may be connected or they may be coupled via one or more other elements.

[0048] In the following disclosure, unless otherwise specified, when absolute position modifiers (such as terms "front", "back", "top", "bottom", "left", "right", etc.) or relative position modifiers (such as terms "above", "below", "upper", "lower", etc.) are mentioned, or when directional modifiers (such as "horizontal", "vertical", etc.) are mentioned, reference is made to the orientation shown in the figures.

[0049] Unless otherwise specified, the expressions "about," "approximately," "substantially," and "approximately" mean within 10%, preferably within 5%.

[0050] Figure 2 An embodiment of a switched mode power supply (SMPS) according to an embodiment is schematically shown in circuit form, comprising an oxide field trench (OFT) diode (e.g. Figure 1 In this example, the diode 10 and its control device (or circuit 6) are connected to a dipole 7 (by Figure 2 ), where the dipole 7 comprises an anode terminal 700 and a cathode terminal 702.

[0051] In this example, the switched mode power supply 5 is a galvanically isolated power supply comprising an isolation transformer 500. More specifically, switched mode power supplies are often referred to as "flyback" power supplies.

[0052] The transformer 500 includes a primary winding LP and a secondary winding LS.

[0053] The primary winding LP is connected in series with a switch IT between a terminal 502 (having an input potential Vin applied thereto) and a terminal 504 (having a reference potential GND1 applied thereto). Vin is referenced to GND1. As an example, the switch IT is connected between the winding LP and the terminal 504. In this example, the phase point of the winding LP is on one side of the terminal 504.

[0054] The switched-mode power supply 5 includes a circuit cmd1 for controlling a switch IT. The circuit cmd1 is configured to control the switch IT to an off-state and an on-state based on a difference between a setpoint value and a constant (or measured) value of an output potential Vout of the power supply 5, such that the potential Vout is regulated according to the setpoint value.

[0055] The dipole 7 and the winding LS are connected in series between a terminal 508 delivering a potential Vout and a terminal 510 applying a reference potential GND2, with the potential Vout being referenced to the reference potential GND2. A filter capacitor C is connected between the terminals 508 and 510 in parallel with the series connection of the dipole 7 and the winding LS.

[0056] In this example, the phase point of winding LS is on one side of terminal 508. In this example, anode 700 of dipole 7 is coupled (preferably connected) to terminal 510, and cathode 702 of dipole 7 is coupled (preferably connected) to winding LS.

[0057] The control device 6 includes a terminal 600 coupled (preferably connected) to the anode A of the diode 10, a terminal 602 coupled (e.g., connected) to the cathode K of the diode 10, and a terminal 604 coupled (preferably connected) to the gate terminal G of the diode 10. When the diode 10 and the device 6 are operatively coupled and form Figure 2 , terminal 600 forms the anode terminal 700 of dipole 7 and terminal 602 forms the cathode terminal 702 of dipole 7. In other words, terminals 600 and 700 coincide, and terminals 602 and 702 also coincide. In other words, terminal 600 is connected to terminal 700 of dipole 7, and terminal 602 is also connected to terminal 702 of dipole 7.

[0058] Device 6 is configured to control diode 10, that is, to provide a control potential on gate G of diode 10 based on the potential difference between its terminals 600 and 602, that is, based on the potential difference between terminals 700 and 702 of dipole 7. In the remainder of this disclosure, the potential difference between terminals 600 and 602 (respectively, 700 and 702) corresponds to the potential of terminal 600 (respectively, 700) from which the potential of terminal 602 (respectively, 702) is subtracted. In other words, the potential difference between terminals 600 and 602 (respectively, 700 and 702) is referenced to terminal 600 (respectively, 700).

[0059] Figure 3 The circuit is schematically shown Figure 2 An embodiment of the control device 6. More specifically, Figure 3 Shown Figure 2 of dipole 7, or in other words, Figure 3 Device 6 is shown connected to the OFT diode it controls, which in this example is diode 10. Figure 3 In FIG, the dipole 7 and the device 6 are bounded by dashed lines.

[0060] Device 6 includes a current source 606. Current source 606 is connected between a node 608 of device 6 and a terminal 602 of device 6. In other words, a terminal of the current source is coupled (preferably connected) to node 608 and the other terminal of current source 606 is coupled (preferably connected) to terminal 602.

[0061] The current source 606 is controllable, ie, depending on the control or control signal it receives, it provides or does not provide a positive current I flowing from the terminal 602 to the node 608 .

[0062] Device 6 includes capacitor C1. Capacitor C1 is connected between node 608 and terminal 600 of device 6. In other words, one terminal of capacitor C1 is coupled (preferably connected) to node 608 and the other terminal of capacitor C1 is coupled (preferably connected) to terminal 600.

[0063] Device 6 includes a diode D1 connected between terminals 604 and 600, with the anode of diode D1 on one side of terminal 604. In other words, the anode of diode D1 is coupled (preferably connected) to terminal 604, and the cathode of diode D1 is coupled (preferably connected) to terminal 600. Diode D1 corresponds to, for example, a single diode or a plurality of diodes connected in series, which enables adjustment of the turn-on threshold or threshold voltage of diode D1.

[0064] Device 6 includes a switch IT1. Switch IT1 is connected between node 608 and terminal 604 of device 6. In other words, one terminal of switch IT1 is coupled (preferably connected) to node 608, and the other terminal of switch IT1 is coupled (preferably connected) to terminal 604.

[0065] When the switch IT1 is turned off, the capacitor C1 may be charged by the current I delivered by the current source 606 .

[0066] When switch IT1 is turned on, it is configured to discharge capacitor C1 via diode D1, such that a non-zero positive potential, for example referenced to the potential of terminal 600, is present at terminal 604 and is therefore applied to gate G of diode 10. Thus, when switch T1 is turned on and capacitor C1 is discharged via diode D1, the threshold voltage of diode D1 at least partially determines the value of the non-zero positive potential difference applied between terminals G and A of diode 10.

[0067] Device 6 includes switch IT2. Switch IT2 is connected between terminals 600 and 604. In other words, switches IT1 and IT2 are connected in series between node 608 and terminal 600, with switch IT1 on one side of node 608, and the connection node between switches IT1 and IT2 corresponds to terminal 604 of device 6. In other words, one terminal of switch IT2 is coupled (preferably connected) to terminal 604, and the other terminal of switch IT2 is coupled (preferably connected) to terminal 600.

[0068] When the switch IT2 is turned on, the switch IT2 is configured to electrically couple the terminal 604 with the terminal 600 , ie, to short-circuit the terminal 604 to the terminal 600 .

[0069] The switches IT1 and IT2 are configured not to be turned on at the same time; however, the switches IT1 and IT2 can be turned off at the same time.

[0070] According to one embodiment, the device 6 comprises a circuit CTRL. The circuit CTRL is configured to control the current source 606 and the switches IT1 and IT2 based on or in dependence on the potential difference between its terminals 602 and 600.

[0071] More specifically, according to one embodiment, circuit CTRL is configured to control current source 606 so that it provides current I when the potential difference between terminals 600 and 602 is less than a threshold value Th1. As an example, the negative threshold value is zero. In other words, circuit CTRL is configured to control source 606 to charge capacitor C1 when diode 10 is reverse biased.

[0072] According to one embodiment, circuit CTRL is further configured to control the connection of switch IT2 when the potential difference between terminals 600 and 602 is less than a threshold value Th2. For example, threshold value Th2 is negative or zero. For example, threshold value Th2 is less than threshold value Th1. When diode 10 is reverse biased, the connection of switch IT2 short-circuits terminals G and A of diode 10, which reduces leakage current in diode 10 relative to a situation where a non-zero positive potential difference is applied between terminals G and A of reverse-biased diode 10.

[0073] According to one embodiment, circuit CTRL is further configured to control the switching on of switch IT1 when the potential difference between terminals 600 and 602 is greater than a threshold value Th3. Threshold value Th3 is positive. When diode 10 is forward biased, the switching on of switch IT1 enables a positive, non-zero potential difference to be provided between terminals 604 and 600 (and therefore, between terminals G and A), which results in a reduction in the potential difference across diode 10 relative to a situation where a zero potential difference is applied between terminals G and A of forward-biased diode 10.

[0074] According to one embodiment, the circuit CTRL is powered by the potential difference between its terminals 600 and 602. In other words, no specific power supply is provided so that the circuit CTRL can control the source 606 and the above-mentioned switches IT1 and IT2.

[0075] It is also conceivable to replace diode 10 with a conventional MOS (“metal oxide semiconductor”) transistor, which would have its source coupled to terminal 700 and its drain connected to terminal 702. However, when the potential difference between terminals 700 and 702 is positive, in order for the MOS transistor to switch on, a potential must be applied to its gate that is sufficiently greater than the potential of its source. This would require the provision of logic circuits and a specific power supply, such as a charge pump, or, for example, the provision of a circuit external to device 6, such as an auxiliary secondary winding, which is not the case in the case of control device 6.

[0076] It is also envisaged to replace the diode 10 and its control device 6 with a conventional (gateless) non-controllable diode, but the leakage current in a conventional reverse biased diode and the voltage drop across a conventional forward biased diode will be higher than the diode 10 and its control device 6.

[0077] According to one embodiment, the circuit CTRL may comprise only resistive components, a diode and possibly an inductor ( Figure 3 ). The circuit CTRL is then simpler than the control circuit, which will comprise comparators, for example implemented by operational amplifiers with dedicated power supplies, these amplifiers being configured, for example, to detect a reversal of sign or polarity of the potential difference between terminals K and A of the diode 10.

[0078] More specifically, according to one embodiment, the current source 606 and the switches IT1 and IT2 are all implemented by bipolar transistors. In this case, the circuit CTRL implements the previously described control of the current source 606 and the switches IT1 and IT2 by biasing the bipolar transistors accordingly based on the potential difference between the terminals 600 and 602.

[0079] Figure 4 A more detailed embodiment of the control device 6 is schematically shown in the form of a circuit. Figure 3 Device 6 with Figure 4 The differences between the devices 6 are described in detail here. In addition, Figure 3 Same as in Figure 4 In FIG, device 6 is shown connected to the diode it controls (in this example, diode 10), the components defining a dipole 7. Figure 4 , elements 6, 7 and CTRL are bounded by dotted lines.

[0080] In this embodiment, current source 606 is implemented by an NPN bipolar transistor. The collector of transistor 606 is coupled (preferably connected) to terminal 602. The emitter of transistor 606 is coupled (preferably connected) to node 608. The base 610 of transistor 606 is coupled (preferably connected) to circuit CTRL.

[0081] In this embodiment, the switch IT1 is implemented by a PNP bipolar transistor. The emitter of the transistor IT1 is coupled (preferably connected) to the node 608. The collector of the transistor IT1 is coupled (preferably connected) to the terminal 604. The base 612 of the transistor IT1 is coupled (preferably connected) to the circuit CTRL.

[0082] In this embodiment, switch IT2 is implemented by an NPN bipolar transistor. The emitter of transistor IT2 is coupled (preferably connected) to terminal 600. The collector of transistor IT2 is coupled (preferably connected) to terminal 604 and, therefore, to the collector of transistor IT1. The base 614 of transistor IT2 is coupled (preferably connected) to circuit CTRL.

[0083] According to one embodiment, Figure 4 As shown in , circuit CTRL includes a resistor or resistive component R1 that couples terminal 602 to base 601 of transistor 606. In other words, one terminal of resistor R1 is coupled (preferably connected) to terminal 602 and the other terminal of the resistor is coupled (preferably connected) to base 610 of transistor 606.

[0084] When the potential difference between terminals 600 and 602 is negative (diode 10 is reverse biased) and less than threshold Th1 , resistor R1 enables transistor 606 to be turned on and, more specifically, to be supplied with a positive base current. Transistor 606 then provides current I to node 608 .

[0085] According to one embodiment, Figure 4As shown in FIG, circuit CTRL further includes a resistor or resistive element R2, which couples terminal 602 to base 612 of transistor IT1. In other words, one terminal of resistor R2 is coupled (preferably connected) to terminal 602, and the other terminal of resistor R2 is coupled (preferably connected) to base 612 of transistor IT1. Circuit CTRL further includes a diode D2 connected between base 612 of transistor IT1 and base 614 of transistor IT2, with the anode of diode D2 on one side of base 612 of transistor IT1. In other words, the anode of diode D2 is coupled (preferably connected) to base 612 of transistor IT1, and the cathode of diode D2 is coupled (preferably connected) to base 614 of transistor IT2. Thus, resistor R2 and diode D2 are connected in series between terminal 602 and base 614 of transistor IT2, with base 612 of transistor IT1 coupled or connected to the node connecting diode D2 to resistor R2. Furthermore, circuit CTRL includes a diode D3 connected between base 610 of transistor 606 and base 612 of transistor IT1, with the anode of diode D3 being on one side of base 610 of transistor 606. In other words, the anode of diode D3 is coupled (preferably connected) to the terminal of resistor R1 opposite terminal 602, and the cathode of diode D3 is coupled (preferably connected) to the terminal of resistor R2 opposite terminal 602.

[0086] Preferably, the turn-on threshold of diode D3, which may correspond to a single diode or a plurality of series-connected diodes, is substantially equal to (e.g., equal to) the potential difference between the base 610 and the emitter of transistor 606 (when the latter delivers current I), i.e., equal to the turn-on threshold or threshold voltage of the base-emitter diode of transistor 606. Thus, when transistor 606 delivers current I, the potential difference between node 608 and the base 612 of transistor IT1 is zero, so that transistor IT1 is turned off and capacitor C1 is charged.

[0087] The threshold voltage of diode D2 (which may correspond to a single diode or a plurality of diodes connected in series) at least partially determines the maximum value of the potential difference across capacitor C1, and therefore determines the maximum value of the potential of node 608. In fact, when switch IT2 is closed (on), switch T1 is open (off), and source 606 delivers current I, the potential of node 608 is at most equal to the sum of the potential of terminal 600, the base-emitter voltage of transistor IT2, the potential difference across diode D2, the potential difference across diode D3, and the base-emitter voltage of transistor 606.

[0088] As an example, when: diode D2 corresponds to two diodes connected in series, each diode having a turn-on threshold equal to value Vj, for example, equal to 0.7V; when transistor IT2 is turned on, the base-emitter voltage of transistor IT2 is equal to Vj; and the potential difference across diode D3 and the base-emitter voltage of transistor 606 become zero, then the maximum voltage across capacitor C1 is equal to 3*Vj. In other words, the voltage across capacitor C1 is regulated based on the value 3*Vj.

[0089] In this embodiment, once the potential difference between terminals 600 and 602 is sufficiently negative (reverse biased diode 10), current flows through resistor R2 and diode D2 from terminal 602 to base 614 of transistor IT2, which turns on transistor IT2 and shorts terminals 604 and 600. Thus, in this embodiment, the threshold voltage of diode D2 at least partially determines threshold Th2, which in turn is negative.

[0090] Furthermore, in this embodiment, transistor 606 is turned on when the potential of terminal 602 is sufficiently higher than the potential of node 608. Thus, in this embodiment, threshold Th1 is at least partially determined by the threshold voltage of diode D1 due to the fact that the threshold voltage of diode D1 at least partially determines the potential of node 608 when switch IT1 is turned on and diode D1 is forward biased.

[0091] exist Figure 4 In device 6, when the potential difference between terminals 600 and 602 is positive (diode 10 is forward biased), transistors IT2 and 606 are turned off. Furthermore, when a positive current flowing from terminal 600 to terminal 602 is supplied to terminal 600 and the potential of node 608 is sufficiently higher than the potential of terminal 602, transistor T1 is turned on. When the potential difference between terminals 600 and 602 is positive and transistors IT2 and 606 are turned off, the potential difference between nodes 608 and 602 is defined by the sum of the potential difference between the terminals of capacitor C1 and the voltage drop across diode 10. Therefore, the threshold voltage of diode 10 at least partially determines threshold Th3. In other words, threshold Th3 is at least partially determined by the threshold voltage of diode D2 due to the fact that, immediately before switch IT1 is turned on, the threshold voltage of diode D2 at least partially determines the potential difference between the terminals of capacitor C1.

[0092] It is within the capabilities of a person skilled in the art to modify the values of the thresholds Th1, Th2, and Th3 and / or to modify the maximum value according to which the potential of the node 608 is adjusted, for example by adapting the value of the threshold voltage of the diode D2. Furthermore, it is within the capabilities of a person skilled in the art to modify the value of the potential difference applied between the terminals G and A of the diode 10 when the transistor IT1 is turned on, for example by modifying the turn-on threshold of the diode D1 and possibly by adjusting the value of the capacitor C1.

[0093] Figure 5 The circuit is schematically shown Figure 4 An alternative embodiment of the control device 6. Figure 4 Device 6 with Figure 5 The differences between the devices are detailed here. Figure 5 In, and Figure 3 and Figure 4 As in FIG, device 6 is shown connected to the diode it controls (in this example, diode 10), and the assembly of device 6 and diode 10 defines a dipole 7. Figure 5 , elements 6, 7 and CTRL are bounded by dotted lines.

[0094] Figure 5 Device 6 with Figure 4 Device 6 differs in that it includes a diode D4 (preferably a Zener diode) connected in series with resistor R1 between terminal 602 and base 610 of transistor 606, with the anode of diode D4 being on one side of base 610 of transistor 606. Diode D4 may correspond to a single diode or a plurality of diodes connected in series.

[0095] In this alternative embodiment, in order for transistor 606 to switch on and deliver the charging current I of capacitor C1, the potential of terminal 602 should be sufficiently higher than the potential of node 608 to allow the switching on of reverse-biased Zener diode D4 and the delivery of base current to transistor 606. Thus, Zener diode D4 makes it possible to lower the value of threshold value Th1, thereby regulating the delivery of charging current I of capacitor C1.

[0096] When the dipole 7 forms a switch mode power supply (eg Figure 2 When the switch-mode power supply is part of a switch-mode power supply (SPS), the threshold value Th1 is selected to be smaller than the maximum (in absolute value) negative potential difference that can exist between the terminals 600 and 602 when the switch-mode power supply is operated in discontinuous conduction mode (DCM), for example by adjusting the value of the turn-on threshold of the reverse-biased diode D4. As a result, in the discontinuous conduction mode, the capacitor C1 is not charged, and therefore, the current source 606 does not deliver the charging current I to the capacitor C1.

[0097] This makes it possible to avoid the application of a non-zero potential difference between the terminals G and A of the diode 10 between the phases in which the diode 10 is forward biased and the phases in which the diode 10 is reverse biased and its terminals G and A are short-circuited by the transistor IT2, without the forward-biased diode 10 being turned on immediately by a sufficiently low (e.g., negative) potential difference between the terminals G and A of the diode 10 to turn the diode 10 off, as is typically the case in a switched-mode power supply operating in DCM mode. In other words, this makes it possible to avoid the application of a non-zero positive potential difference between the terminals G and A of the diode 10 when the diode 10 is operating in quadrant Q1 (which would result in an increase in losses that could be assimilated to switching losses of the switched-mode power supply).

[0098] According to another alternative embodiment (not shown), in order to limit switching losses in a switched-mode power supply operating in discontinuous conduction mode, device 6 includes, instead of including diode D4 that enables threshold Th1 to be lowered, a circuit configured to short-circuit terminals 604 and 600 as soon as the potential difference between terminals K and A of diode 10 becomes weakly positive (i.e., for example, when this potential difference is greater than the turn-on threshold of diode 10, but the difference between this potential difference and the turn-on threshold of diode 10 is less than 0.1 V, for example, less than 0.05 V, or even less than 0.01 V). This weakly positive potential difference corresponds, for example, to a DC current in diode 10 of less than or equal to 100 mA. Implementing this variant embodiment using logic circuits is within the capabilities of those skilled in the art.

[0099] Figure 6 The circuit is schematically shown Figure 4 Another alternative embodiment of the control device 6. Figure 4 Device 6 with Figure 6 The differences between the devices are detailed here. Figure 6 In, and Figure 3 、 Figure 4 and Figure 5 As in FIG, device 6 is shown connected to the diode it controls (in this example, diode 10), the assembly of device 6 and diode 10 defining a dipole 7. Figure 6 , elements 6, 7 and CTRL are bounded by dashed lines.

[0100] In this variation, threshold Th2 is not at least partially determined by the threshold voltage of diode D2. More specifically, in this alternative embodiment, the maximum voltage across capacitor C1 and threshold Th2 are decorrelated from one another. In effect, in this variation, a lower threshold Th2 than in the previously described embodiments and variations is provided without modifying the maximum voltage that can exist across capacitor C1.

[0101] To this end, device 6, and more specifically its circuit CTRL, includes a diode D5 connected in series with resistor R3 between terminal 602 and the base 614 of transistor IT2. Diode D5 can be a single diode or a plurality of diodes connected in series. The cathode of diode D5 is on one side of the base 614 of transistor IT2. In other words, the cathode of diode D5 is coupled (e.g., connected) to the base 614 of transistor IT2.

[0102] In this alternative embodiment, as soon as the negative potential difference between terminals 600 and 602 (diode 10 is reverse biased) is greater than the threshold voltage of diode D5, transistor IT2 switches on and short-circuits terminals 604 and 600. By choosing diode D5 with a turn-on threshold lower than the turn-on threshold of diode D2, this makes it possible to reduce the value of the (absolute value) threshold Th2 and thus to make the short-circuit of terminals G and A of reverse-biased diode 10 faster, in order to reduce its leakage current.

[0103] Thus, in this variant, the voltage of diode D5 at least partially determines the threshold Th2.

[0104] According to one embodiment, the circuit CTRL further comprises an optional resistor R4 connected between the base 614 of the transistor IT2 and the terminal 600. This resistor enables the biasing of the transistor IT2 in the on-state to be adjusted. Figure 6 The alternative embodiment describes the provision of resistor R4, but it can also be used in relation to Figure 4 and Figure 5 The embodiments and variations described and the following will be with respect to Figure 7 In the described alternative embodiment, resistor R4 is provided.

[0105] According to one embodiment, the circuit CTRL further comprises a diode D6 for desaturating the transistor IT2. The diode D6 is connected between the base 614 and the collector 604 of the transistor IT2, the anode of the diode D6 being on one side of the base 614 of the transistor IT2. The diode D6 makes it possible to reduce the saturation in the transistor IT2 in order to accelerate the transition to the latter's off state. A similar solution can be envisaged for the transistor IT1. Although with regard to Figure 6 The alternative embodiment of FIG. 1 describes the provision of a diode D6, but this can also be provided in relation to FIG. Figure 4 and Figure 5 The embodiments and variations described and in the present description will now be Figure 7 In the described alternative embodiment, a diode D6 is provided.

[0106] Figure 7 The circuit is schematically shown Figure 4 An alternative embodiment of the control device 6. Figure 4 Device 6 with Figure 7 The differences between the devices are detailed here. Figure 7 In, with Figure 3 、 Figure 4 、 Figure 5 and Figure 6 As in FIG, device 6 is shown connected to the diode it controls (in this example, diode 10), the assembly of device 6 and diode 10 defining a dipole 7. Figure 7 , elements 6, 7 and CTRL are bounded by dashed lines.

[0107] In this variation, applicable to the previously described embodiments and variations, device 6 includes an inductor L that couples terminal 600 of device 6 to anode A of diode D. In other words, inductor L is connected between terminal 600 and anode A of diode 10. In yet other words, inductor L has one terminal coupled (preferably connected) to terminal 600 and has another terminal coupled (e.g., connected) to anode A of diode 10. Thus, in contrast to the previously described embodiments and variations in which terminal 600 is connected, for example, to anode A of diode 10, in this variation, terminal 600 is coupled to anode A of diode 10 via inductor L.

[0108] The inductor L conducts the same current as the diode 10. When the transistor IT1 is turned on, the inductor L makes it possible to limit the magnitude of the potential difference between the terminals G and A of the diode 10, or in other words, to avoid an overvoltage between the terminals G and A of the diode 10. Furthermore, when the diode 10 switches from forward bias to reverse bias, the inductor L makes it possible to more quickly bring the potential difference between the terminals G and A of the diode 10 to zero.

[0109] By way of example, the inductor L has a value ranging from a few nH to tens of nH, for example, from 5 nH to 30 nH, with the value of the inductor L being equal to 10 nH, for example. However, it is within the capabilities of those skilled in the art to adjust the value of the inductor L according to the variation of the current in the diode 10, and in particular according to the slope of this current variation. For example, the value of the inductor L can be adjusted by adjusting the length of the conductive trace or circuit connection.

[0110] In the previously described embodiments and variations, the device 6 and the diode 10 it controls define a dipole 7. The device 6 and the diode 10 are preferably formed on a semiconductor substrate (e.g., substrate 20 ( Figure 1 However, the device 6 may be provided as a first component corresponding to being implemented inside and on top of a first semiconductor substrate, and the OFT diode controlled by it may be provided as being implemented inside and on top of another semiconductor substrate.

[0111] Although the above has been about the control of device 6 Figure 1The embodiments and variations are described in the context of the OFT diode 10 , but it would be within the capabilities of a person skilled in the art to adapt the device 6 for other controllable diodes (eg other OFT diodes).

[0112] Furthermore, although the dipole 7 forms a switched mode power supply 5 ( Figure 2 ) has been described as an example, but in other circuits (for example, in circuits such as Figure 2 It will be within the capabilities of a person skilled in the art to provide the dipole 7 in other power circuits of different switched mode power supplies, or also in a voltage rectifier bridge.

[0113] According to one embodiment, the diode 10 is an OFT diode. When the voltage Vak between its anode and its cathode (based on the cathode) is positive (forward biased state) and the voltage Vga between its gate and its anode (based on the anode) is zero or positive, the OFT diode is turned on. In addition, when the voltage Vak is negative (reverse biased state) and the voltage Vga is zero or negative, the OFT diode is blocked. In this OFT diode, in the forward biased state, the higher the voltage Vga, the lower the voltage Vak. However, when switching from the forward biased state to the reverse biased state, the greater the voltage Vga during the forward biased state, the slower the discharge of its gate during the switching, and the greater the leakage current in the diode during the switching.

[0114] Therefore, according to one embodiment, the turn-on threshold of diode D1 is determined by a trade-off between the voltage Vak of forward biased diode 10 and the leakage current in diode 10 when it switches from the forward biased state to the reverse biased state.

[0115] Various embodiments and variations have been described. Certain features of these various embodiments and variations may be combined, and other variations will occur to those skilled in the art.

[0116] The value of the capacitor C1 , the value of the resistance of the circuit CTRL and the threshold voltage of the diode of the circuit CTRL may be chosen according to the target application and / or the electrical characteristics of the OFT diode that the device 6 is intended to control.

Claims

1. A device comprising: Electronic devices, including: a controllable current source coupled between the first node and a first terminal, the first terminal being coupled to the cathode of the controllable diode; a capacitor coupled between the first node and a second terminal, the second terminal being coupled to the anode of the controllable diode; a first switch coupled between the first node and a third terminal, the third terminal being coupled to the gate of the controllable diode; a second switch coupled between the second terminal and the third terminal; and A first diode is coupled between the third terminal and the second terminal, wherein an anode of the first diode is coupled to the third terminal. 2 . The device of claim 1 , further comprising a circuit configured to control the controllable current source, the first switch, and the second switch based on a potential difference between the first terminal and the second terminal.

3. The device according to claim 2, wherein the circuit is configured to: When the potential difference is less than a first threshold, controlling the controllable current source to deliver current to the capacitor; When the potential difference is greater than a second threshold, controlling the first switch to be in an on state; and When the potential difference is lower than a third threshold, the second switch is controlled to be in an on state.

4. The device according to claim 3, wherein: The controllable current source is a first bipolar transistor having an emitter coupled to the first node and a collector coupled to the first terminal; the first switch being a second bipolar transistor having an emitter coupled to the first node and a collector coupled to the third terminal; as well as The second switch is a third bipolar transistor having an emitter coupled to the second terminal and a collector coupled to the third terminal.

5. The device of claim 4, wherein the circuit comprises: a first resistor coupling the first terminal to the base of the first bipolar transistor; a second resistor coupling the first terminal to the base of the second bipolar transistor; a second diode coupled between the base of the first bipolar transistor and the base of the second bipolar transistor, an anode of the second diode coupled to the base of the first bipolar transistor; as well as A third diode is coupled between the base of the second bipolar transistor and the base of the third bipolar transistor, and an anode of the third diode is coupled to the base of the second bipolar transistor. 6 . The device of claim 5 , wherein a threshold voltage of the second diode is equal to a threshold voltage of a base-emitter diode of the first bipolar transistor. 7 . The device of claim 5 , wherein a maximum voltage across the capacitor is determined at least in part by a threshold voltage of the third diode.

8. The device of claim 5, wherein the first threshold is determined at least in part by a threshold voltage of the first diode.

9. The device of claim 5, wherein the circuit comprises a diode connected in series with the first resistor between the first terminal and the base of the first bipolar transistor, the first threshold being determined at least in part by a reverse conduction threshold voltage of the diode.

10. The device of claim 9, wherein the diode comprises a Zener diode.

11. The device of claim 5, wherein the second threshold is determined at least in part by a threshold voltage of the third diode.

12. The device of claim 11, wherein the second threshold is determined at least in part by a threshold voltage of the controllable diode.

13. The device of claim 5, wherein the third threshold is determined at least in part by a threshold voltage of the third diode.

14. The device of claim 5, wherein the circuit further comprises a diode connected in series with a third resistor between the first terminal and the base of the third bipolar transistor, the third threshold being determined at least in part by a threshold voltage of the diode.

15. The device of claim 5, wherein the circuit further comprises a resistor coupled between a base of the third bipolar transistor and the second terminal.

16. The device of claim 5, wherein the circuit comprises a diode for desaturating the third bipolar transistor, the diode being coupled between a base and a collector of the third bipolar transistor. The device according to claim 3 , wherein the first threshold value is a negative potential. The device of claim 3 , wherein the first threshold is ground. The device according to claim 3 , wherein the second threshold value is a positive potential.

20. The device of claim 3, wherein the second threshold is ground. The device according to claim 3 , wherein the third threshold value is a negative potential.

22. The device of claim 3, wherein the third threshold is ground.

23. The device of claim 1, further comprising an inductor coupled between the second terminal and an anode of the controllable diode.

24. The device of claim 1 , wherein the controllable diode is an oxide field trench (OFT) diode comprising a plurality of structures, each of the plurality of structures comprising a first conductive region and a second conductive region in a trench of a substrate, the first conductive region being separated from the substrate by a first distance, the second conductive region extending deeper in the trench than the first conductive region, the controllable diode being defined by at least one transistor having at least one channel region extending between two trenches in the trench, the first conductive region defining a gate of the at least one transistor and a gate of the controllable diode. The device of claim 24 , wherein the first distance is shorter than 10 nm.

26. A device according to claim 1, wherein the first terminal of the electronic device defines a cathode of a dipole and the second terminal of the electronic device defines an anode of the dipole; and the device further includes the controllable diode, the controllable diode having a cathode coupled to the first terminal of the electronic device, an anode coupled to the second terminal of the electronic device, and a gate coupled to the third terminal of the electronic device.

27. The device of claim 26, wherein the device is configured to define a switched mode power supply.

28. The device of claim 26, wherein the controllable diode comprises an oxide field trench (OFT) diode.

29. The device of claim 1, wherein the device is configured to define a switch mode power supply.

30. An electronic device comprising: a transformer coil having a first terminal and a second terminal; a dipole having a cathode coupled to the second terminal of the transformer coil and an anode coupled to a reference node; as well as a capacitor coupled between the first terminal of the transformer coil and the reference node; wherein the dipole comprises: a controllable diode having an anode coupled to the reference node and a cathode coupled to the second terminal of the transformer coil; as well as a control device having an input coupled to the second terminal of the transformer coil and the reference node, the control device being configured to apply a control signal to the gate of the controllable diode based on a difference between a potential at the cathode of the controllable diode and a potential at the anode of the controllable diode.

31. The electronic device of claim 30, wherein the dipole further comprises: a controllable current source coupled between the cathode and the first node; a second capacitor coupled between the first node and the reference node; a first switch coupled between the first node and the gate of the controllable diode, wherein the control device is configured to control the first switch; a second switch coupled between the gate of the controllable diode and the reference node, wherein the control device is configured to control the second switch; as well as A first diode has an anode coupled to the gate of the controllable diode and a cathode coupled to the reference node.

32. The electronic device of claim 31, wherein the dipole further comprises an inductor connected between the anode of the controllable diode and the reference node.

33. The electronic device according to claim 31, wherein the controllable current source comprises a first transistor having a first conduction terminal connected to the cathode of the controllable diode, a second conduction terminal connected to the first node, and a control terminal; and The control device includes: a first resistor coupled between a cathode of the controllable diode and the control terminal of the first transistor; a second resistor coupled between a cathode of the controllable diode and a control terminal of the first switch; a second diode having an anode coupled to the control terminal of the first switch and a cathode coupled to the control terminal of the second switch; and A third diode has an anode coupled to the control terminal of the first transistor and a cathode coupled to the control terminal of the first switch.

34. An electronic device according to claim 33, wherein the control device further comprises a fourth diode having an anode connected to the first resistor and a cathode connected to the cathode of the controllable diode, thereby coupling the first resistor between the control terminal of the first transistor and the cathode of the controllable diode.

35. The electronic device of claim 34, wherein the fourth diode comprises a Zener diode.

36. The electronic device according to claim 33, wherein the control device further comprises: a fifth diode having a cathode coupled to the control terminal of the second switch, and an anode; a third resistor coupled between the anode of the fifth diode and the cathode of the controllable diode; a fourth resistor coupled between the control terminal of the second switch and the reference node; as well as A sixth diode has an anode coupled to the cathode of the second diode and a cathode coupled to the gate of the controllable diode.

Images