Electrostatic discharge protection circuit

Abstract

Electrostatic Discharge Protection Circuit This description relates to an electrostatic discharge protection circuit (210) of a first transistor (101) comprising: - N diodes (D210-1, …, D210-N) in series between conduction terminals of said first transistor; - a second transistor (T213) in series with a third transistor (T211) between the conduction terminals of said first transistor, and a control terminal of said third transistor (T211) being connected to an anode of said N diodes (D210-1, …, D210-N); - a first inverter (INV210) connecting the control terminals of said first and second transistors; - a fourth transistor (T212) in parallel with said first transistor, a control terminal of said fourth transistor being connected to the midpoint between said second and third transistors;and - a capacitor (C211) disposed between the control terminal of said fourth transistor (T212), and a conduction terminal of said first transistor (101). Figure for the abbreviation: Fig. 2;

Description

Title of the invention: Electrostatic discharge protection circuit Technical field

[0001] The present description relates generally to electronic circuits and devices, and their protection against electrostatic discharges. The present description relates more particularly to a circuit for protection against electrostatic discharges. Prior art

[0002] The protection of electronic circuits against electrostatic discharges is an important issue to ensure the reliability and longevity of electronic circuits, and in particular integrated circuits.

[0003] An electrostatic discharge protection device is a device that is placed between two nodes of a circuit to be protected against electrostatic discharges. On the physical circuit, these two nodes are generally represented by connection pads. These two nodes may be, for example, the input and output nodes of an electronic device, or power supply nodes of an electronic device.

[0004] It would be desirable to be able to improve, at least in part, certain aspects of known electrostatic discharge protection devices. Summary of the invention

[0005] There is a need for more efficient electrostatic discharge protection circuits.

[0006] One embodiment overcomes all or part of the drawbacks of known electrostatic discharge protection circuits.

[0007] One embodiment provides an electrostatic discharge protection circuit for a first transistor of a first type comprising: - N diodes in series between a first and a second conduction terminal of said first transistor, N being an integer, the trigger voltage of the N diodes being higher, whatever the temperature, than a supply voltage; - a second transistor of the first type in series with a third transistor of a second type different from the first type between the first and second conduction terminals of said first transistor, and a control terminal of said third transistor being connected to an anode of said N diodes; - a first inverter connecting a control terminal of said first transistor to a control terminal of said second transistor; - a fourth transistor in parallel with said first transistor, a control terminal of said fourth transistor being connected to the midpoint between said second and third transistors; and - a first capacitor arranged between the control terminal of said fourth transistor, and the first conduction terminal of said first transistor.

[0008] According to one embodiment, the circuit further comprises a first resistor connecting said anode of said N diodes and the first conduction terminal of said first transistor.

[0009] According to one embodiment, N is between ten and twenty.

[0010] According to one embodiment, N is equal to fourteen.

[0011] According to one embodiment, the circuit further comprises a second resistor connecting said control terminal of said fourth transistor to said second conduction terminal of said first transistor.

[0012] According to one embodiment, the circuit further comprises a fifth transistor connecting said second resistor to said second conduction terminal of said first transistor.

[0013] According to one embodiment, the circuit further comprises a second capacitor arranged in series with the first capacitor.

[0014] According to one embodiment, the circuit further comprises a first diode arranged between the middle node of said first and second capacitors, and said second conduction terminal of said first transistor.

[0015] According to one embodiment, the circuit further comprises a second diode arranged in parallel with said second resistor.

[0016] According to one embodiment, said first conduction terminal of said first transistor is adapted to receive a reference voltage.

[0017] According to one embodiment, the reference voltage is ground.

[0018] According to one embodiment, said first, second, third, fourth transistors are transistors of the same technology.

[0019] According to one embodiment, the fifth transistor is of the same technology as said first, second, third, fourth transistors.

[0020] Circuit according to claim 12 or 13, wherein said first, second, third, fourth transistors are drift MOS transistors.

[0021] Another embodiment provides an electronic device comprising said first transistor and an electrostatic discharge protection circuit described above. Brief description of the drawings

[0022] These and other features and advantages will be set forth in detail in the following description of particular embodiments made without limitation in relation to the attached figures among which:

[0023] [Fig.l] represents, schematically and partially in the form of blocks, a part of an electronic device;

[0024] [Fig.2] represents an electrical diagram of a first embodiment of an electrostatic discharge protection circuit;

[0025] [Fig.3] represents an electrical diagram of a second embodiment of a electrostatic discharge protection circuit;

[0026] [Fig.4] represents an electrical diagram of a third embodiment of an electrostatic discharge protection circuit;

[0027] [Fig.5] represents an electrical diagram of a fourth embodiment of a electrostatic discharge protection circuit; and

[0028] [Fig.6] represents an electrical diagram of a fifth embodiment of a electrostatic discharge protection circuit. Description of the embodiments

[0029] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0030] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed.

[0031] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0032] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures

[0033] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0034] [Fig.l] represents, schematically and partially in block form, a part of an electronic device 100 equipped with an embodiment of a circuit 110 for protection against electrostatic discharges.

[0035] The electronic device 100 comprises a transistor 101 to be protected. The transistor 101 may be of different technologies described below. The transistor 101 comprises a first conduction terminal connected, preferably connected, to an output node OUT100 of the device 100, and a second conduction terminal connected, preferably connected, to a reference node GND100 adapted to receive a reference voltage, for example ground. The transistor 101 further comprises a control terminal. The transistor 101 is, moreover, characterized by its breakdown voltage between its conduction terminals BVDSS101, that is to say the limit voltage that the transistor 101 accepts between its conduction terminals.

[0036] According to a first example, the transistor 101 may be a metal-oxide-semiconductor field-effect transistor, or MOSFET transistor, or MOS transistor. In addition, the transistor 101 is an N-channel MOS transistor, or N-type MOS transistor, or NMOS transistor. In this case, the drain terminal of the transistor 101 is connected, preferably connected, to the node OUT100, and the source terminal of the transistor 101 is connected, preferably connected, to the reference node GND100.

[0037] According to a second example, the transistor 101 may be a drift metal-oxide-semiconductor field-effect transistor, or a drain-extended metal-oxide gate field-effect transistor, or drift MOSFET transistor, or drain-extended MOSFET transistor, or drift MOSFET transistor, or drift MOS transistor, or drift MOS transistor. In addition, the transistor 101 is an N-channel drift MOS transistor, or N-type drift MOS transistor, or NMOS drift transistor. An NMOS drift transistor is an NMOS transistor whose N-type doped drain region is not in direct contact with the channel-forming region, but is in contact via a drain drift region, or drain-extended region, doped more lightly with N-type, with the channel-forming region.A drift NMOS transistor has a breakdown voltage between its conduction terminals greater than a conventional NMOS transistor of similar dimensions. According to a particular example, the transistor 101 comprises a BVDSS voltage of the order of 20 V, for example equal to 17 V. In this case, the drain terminal of the transistor 101 is connected, preferably connected, to the node OUT100, and the source terminal of the transistor 101 is connected, preferably connected, to the reference node GND100. In [Fig.l], the transistor 101 is represented by the electrical symbol of a drift NMOS transistor.

[0038] It should be noted that there are also P-channel drift MOS transistors, or P-type drift MOS transistors, or PMOS drift transistors. A drift PMOS transistor is a PMOS transistor whose P-type doped drain region is not in direct contact with the channel-forming region, but is in contact via a drain drift region, or extended drain region, deeply doped with P-type, with the channel-forming region. canal formation.

[0039] According to a third example, the transistor 101 is an NPN type bipolar transistor. In this case, the collector terminal of the transistor 101 is connected, preferably connected, to the node OUT100, and the emitter terminal of the transistor 101 is connected, preferably connected, to the reference node GND100.

[0040] According to an example, the electronic device 100 further comprises an inverter circuit 102. An input terminal of the inverter circuit 102 is connected, preferably connected, to an input node IN100 of the device 100, and an output terminal of the circuit 102 is connected, preferably connected, to the control terminal of the transistor 101. The inverter circuit 102 is adapted to be powered by a supply voltage VDD101, and to be connected to the reference node GND100. According to a preferred example, the supply voltage VDD101 is the general supply voltage of the device 100.

[0041] According to one example, the electronic device 100 further comprises a pull-up resistor 103, one conduction terminal of which is connected, preferably to the output node OUT100. A second conduction terminal of the resistor 103 is adapted to be powered by a supply voltage VDD102 which may be different from the supply voltage VDD101. According to one example, the supply voltage VDD102 may be higher than the supply voltage VDD101. According to one example, the supply voltage VDD102 is an auxiliary supply voltage of the device 100.

[0042] As stated previously, and according to one embodiment, the electronic device 100 further comprises a circuit 110 for protection against electrostatic discharges. The circuit 110 is mounted so as to absorb an electrostatic discharge occurring between the nodes OUT100 and GND100. More particularly, the circuit 100 is adapted to protect the transistor 101 regardless of the variations in manufacturing, voltage, and temperature, and in particular regardless of the temperature conditions. Several embodiments of the circuit 110 are described in detail in relation to FIGS. 2 to 6.

[0043] [Fig.2] represents, schematically and partially in the form of blocks, a part of an electronic device 200 equipped with an embodiment of a circuit 210 for protection against electrostatic discharges of the type of the circuit 110 described in relation to [Fig.l].

[0044] The portion of the device 200 described in connection with [Fig. 2] is similar to the portion of the device 100 described in connection with [Fig. 1]. The elements common to the devices 100 and 200 are not described in detail again here, and only the differences between the devices 100 and 200 are highlighted.

[0045] Thus, the device 200 comprises the transistor 101, the inverter 102, the resistor 103 (not shown in [Fig.2]), and the nodes IN100, OUT100, and GND100. The device 200 differs from device 100 in that it includes an electrostatic discharge protection circuit 210 in place of circuit 110.

[0046] The circuit 210 comprises two transistors T211 and T212 of the same technology as the transistor 101. According to the example shown in [Fig.2], the transistors T211 and T212 are MOS drift transistors like the transistor 101. In addition, the transistor T212 is of the same type as the transistor 101, i.e. of the N type, and the transistor T211 is of the opposite type to the transistor 101, i.e. of the P type. The transistor T211 comprises a source terminal connected, preferably connected to the output node OUT100, and a drain terminal connected, preferably connected, to a node A210. The transistor T211 comprises a gate terminal connected, preferably connected, to a node B210. Transistor T212 comprises a source terminal connected, preferably connected, to the reference node GND100, and a drain terminal connected, preferably connected, to the output node OUT100. Transistor T212 comprises a gate terminal connected, preferably connected, to the node A210.

[0047] According to one embodiment, the transistor T211 is a trigger transistor of the circuit 210, and the transistor T212 is a power transistor adapted to direct an electrostatic discharge towards the reference node GND100. For this, the transistors T211 and T212 have, respectively, breakdown voltages between their conduction terminals BVDSS211 and BVDSS212 each equal to the breakdown voltage BVDSS211 of the transistor 101.

[0048] The circuit 210 further comprises a resistor R211 disposed between the output node OUT100 and the node B210. The resistor is sized to adapt the value of the voltage of an electrostatic discharge to the voltage level acceptable by the gate of the transistor T211. In other words, the value of the resistor is adapted to make the transistor T211 conductive only during the occurrence of an electrostatic discharge.

[0049] The circuit 210 further comprises N diodes D210-1 to D210-N, N being an integer, arranged in series between the node B210 and the reference node GND100. Here, it is said that two diodes are arranged in series, if the anode of a first diode is connected to the cathode of a second diode. In the case of the circuit 210, the cathode of the diode D210-1 is connected, preferably connected, to the node B210, and the anode of the diode D210-N is connected, preferably connected, to the reference node GND100. According to one embodiment, the integer N is between 10 and 30, for example between 10 and 20, preferably equal to 14. In practice, the diodes D210-1 to D210-N may be transistors mounted as a diode.

[0050] Diodes D210-1 to D210-N are used, with resistor R211, as a static triggering mode of circuit 210. According to one embodiment, the sum of the threshold voltages, called trigger voltage, of diodes D210-1 to D210-N is lower than the avalanche voltages of transistors T211 and T212, and is higher than the supply voltage VDD100.

[0051] The circuit 210 further comprises a capacitor C211, a transistor T213 and an inverter circuit INV211. A first conduction terminal of the capacitor C211 is connected, preferably connected, to the output node OUT100, and a second conduction terminal of the capacitor C211 is connected, preferably connected, to the node A210. The transistor T213 is of the same technology and the same type as the transistor 101. In other words, in [Fig.2], the transistor T213 is an NMOS drift transistor. The drain terminal of the transistor T213 is connected, preferably connected, to the node A210, and the source terminal of the transistor T213 is connected, preferably connected, to the reference node GND100. An input terminal of the inverter circuit INV211 is connected, preferably connected, to the output terminal of the inverter circuit 102, and an output terminal of the circuit INV211 is connected, preferably connected, to the control terminal of the transistor T213.The inverter circuit INV211 is adapted to receive the supply voltage VDD101, and to be connected to the reference node GND100.

[0052] In other words, transistor T213 is connected in series with transistor T211 between nodes OUT100 and GND100. Here, it is said that two transistors are connected in series between two nodes, if a first conduction terminal of a transistor is connected, preferably connected to a first conduction terminal of the other transistor.

[0053] Capacitor C211 is used to improve the triggering speed of transistor T212 at the time of occurrence of an electrostatic discharge, and to implement capacitive coupling at the control terminal of transistor T212.

[0054] Transistor T213 and inverter INV211 make it possible to prevent triggering of transistor T212 when transistor 101 is triggered voluntarily, i.e. when a rising edge appears on the voltage between nodes OUT100 and GND100, i.e. on the output voltage of transistor 101, which is not an electrostatic discharge.

[0055] An advantage of circuit 210 is that it provides fast-acting electrostatic discharge protection, and protection suitable for voltages up to 17 V.

[0056] [Fig. 3] represents, schematically and partially in the form of blocks, a part of an electronic device equipped 300 with an embodiment of a circuit 310 for protection against electrostatic discharges of the type of the circuit 110 described in relation to [Fig. 1].

[0057] The part of the device 300 described in relation to [Fig. 3] is similar to the parts of the devices 100 and 200 described in relation to Figures 1 and 2. Thus, the device 300 comprises the transistor 101, the inverter 102, the resistor 103 (not shown in [Fig.3]), and nodes IN100, OUT100, and GND100. The difference between devices 100 and 200, and device 300 is that device 300 includes an electrostatic discharge protection circuit 310 instead of circuits 110 and 210.

[0058] Circuit 310 is similar to circuit 210 described in connection with [Fig.2]. Elements common to circuits 210 and 310 are not described in detail again here. Only the differences between circuits 210 and 310 are highlighted.

[0059] Thus, the circuit 310 comprises: - transistors T211 and T212; - diodes D210-1 to D210-N; - resistor R211; - transistor T213; and - the inverter circuit INV201.

[0060] The difference between circuit 310 and circuit 210 is that capacitor C211 of circuit 210 is replaced by two capacitors C311 and C312 arranged in series between nodes OUT100 and A210. According to one example, capacitors C311 and C312 each have a capacitance of the order of 16 pF, which is equivalent to an equivalent capacitance for the two capacitors C311 and C312 of the order of 8 pF.

[0061] An advantage of this embodiment is that it allows for improved handling of high voltages. Indeed, the use of a single capacitor may prove insufficient with respect to the management of high voltage on the OUT100 node.

[0062] [Fig.4] represents, schematically and partially in the form of blocks, a part of an electronic device equipped 400 with an embodiment of a circuit 410 for protection against electrostatic discharges of the type of circuit 110 described in relation to [Fig.l].

[0063] The portion of device 400 described in connection with [Fig. 4] is similar to the portions of devices 100, 200, and 300 described in connection with FIGS. 1 to 3. Thus, device 400 includes transistor 101, inverter 102, resistor 103 (not shown in [Fig. 4]), and nodes IN100, OUT100, and GND100. The difference between devices 100, 200, 300 and device 400 is that device 500 includes an electrostatic discharge protection circuit 410 instead of circuits 110, 210, 310.

[0064] Circuit 410 is similar to circuit 210 described in connection with [Fig.2]. Elements common to circuits 210 and 410 are not described in detail again here. Only the differences between circuits 210 and 410 are highlighted.

[0065] Thus, circuit 410 comprises: - transistors T211 and T212; - diodes D210-1 to D210-N; - resistor R211; - capacitor C211; - transistor T213; and - the inverter circuit INV201.

[0066] The difference between circuit 410 and circuit 210 is that circuit 410 further comprises a resistor R412. According to one embodiment, a first conduction terminal of resistor R412 is connected, preferably connected, to node A210, and a second conduction terminal of resistor R412 is connected, preferably connected, to reference node GND100. According to one example, resistor R412 has a resistivity of between 1 and 100 kOhm, for example of the order of 49 kOhm.

[0067] An advantage of this embodiment is that the addition of resistor R412 forms an RC (Resistor-Capacitor) type trigger circuit with capacitor C211 of transistor T212.

[0068] [Fig. 5] represents, schematically and partially in the form of blocks, a part of an electronic device equipped 500 with an embodiment of a circuit 510 for protection against electrostatic discharges of the type of the circuit 110 described in relation to [Fig. 1].

[0069] The portion of device 500 described in connection with [Fig. 5] is similar to the portions of devices 100, 200, 300, and 400 described in connection with FIGS. 1 to 4. Thus, device 500 includes transistor 101, inverter 102, resistor 103 (not shown in [Fig. 5]), and nodes IN100, OUT100, and GND100. The difference between devices 100, 200, 300, 400 and device 500 is that device 500 includes an electrostatic discharge protection circuit 510 instead of circuits 110, 210, 310, and 410.

[0070] Circuit 510 is similar to circuit 410 described in connection with [Fig.4]. Elements common to circuits 510 and 410 are not described in detail again here. Only the differences between circuits 410 and 510 are highlighted.

[0071] Thus, the circuit 510 comprises: - transistors T211 and T212; - diodes D210-1 to D210-N; - resistor R211; - capacitor C211; - resistor R412; - transistor T213; and - the inverter circuit INV201.

[0072] The difference between circuit 510 and circuit 410 is that circuit 510 further comprises a transistor T511 for activating or deactivating the effect of resistor R412. Transistor T511 is of the same technology and type as transistor 101. In [Fig.5], transistor T511 is therefore an NMOS drift transistor.

[0073] Transistor T511 is connected in series with resistor R412 between nodes A210 and GND100. For this purpose, a drain terminal of transistor T511 is connected, preferably connected, to the second conduction terminal of resistor R12, and a source terminal of transistor T511 is connected, preferably connected, to reference node GND100. The control terminal of transistor T511, i.e. the gate terminal of transistor T511, is connected, preferably connected, to the output of inverter circuit 102.

[0074] An advantage of this embodiment is that the transistor T511 makes it possible not to activate the resistor R412 when a desired rising edge appears at the output of the transistor 101 to be protected. In other words, the transistor T511 makes it possible to avoid implementing the circuit 510 when the transistor 101 has a desired rising edge at the output.

[0075] [Fig. 6] represents, schematically and partially in block form, a part of an electronic device equipped 600 with an embodiment of a circuit 610 for protection against electrostatic discharges of the type of circuit 110 described in relation to [Fig. 1].

[0076] The portion of device 600 described in connection with [Fig. 6] is similar to the portions of devices 100, 200, 300, 400, and 500 described in connection with FIGS. 1 to 5. Thus, device 600 includes transistor 101, inverter 102, resistor 103 (not shown in [Fig. 6]), and nodes IN100, OUT100, and GND100. The difference between devices 100, 200, 300, 400, 500, and device 600 is that device 600 includes an electrostatic discharge protection circuit 610 in place of circuits 110, 210, 310, 410, and 510.

[0077] Circuit 610 is similar to circuit 310 described in connection with [Fig. 3] and circuit 410 described in connection with [Fig. 4]. Elements common to circuits 310, 410 and 610 are not described in detail again here. Only the differences between circuits 310, 410 and 610 are highlighted.

[0078] More particularly, circuit 610 is a combination of circuits 310 and 410. Thus, circuit 510 comprises: - transistors T211 and T212; - diodes D210-1 to D210-N; - resistor R211; - capacitors C311 and C312; - resistor R412; - transistor T213; and - the inverter circuit INV201.

[0079] According to one embodiment, the circuit 610 could further comprise the transistor T511 described in relation to [Fig.5].

[0080] The circuit 610 further comprises two diodes D611 and D612. A cathode terminal of the diode D611 is connected, preferably connected, to the node A210, and a terminal anode terminal of diode D611 is connected, preferably connected, to reference node GND100. A cathode terminal of diode D612 is connected, preferably connected, to the middle node between capacitors C311 and C312, and an anode terminal of diode D612 is connected, preferably connected, to reference node GND100.

[0081] An advantage of this embodiment is that the diodes D611 and D612 make it possible to reduce, and sometimes avoid, the occurrence of an antenna effect during the manufacture of the circuit 610. An antenna effect is an effect of accumulation of charges in the gate of the power transistor T212 during the performance of certain etching operations, in particular plasma etchings.

[0082] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0083] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

Claims

1. Electrostatic discharge protection circuit (110; 210; 310; 410; 510; 610) of a first transistor (101) of a first type comprising: - N diodes (D210-1, ..D210-N) in series between a first and a second conduction terminal of said first transistor (101), N being an integer, the trigger voltage of the N diodes (D210-1, ..., D210-N) being higher, whatever the temperature, than a supply voltage (VDD100); - a second transistor (T213) of the first type in series with a third transistor (T211) of a second type different from the first type between the first and second conduction terminals of said first transistor (101), and a control terminal of said third transistor (T211) being connected to an anode of said N diodes (D210-1, ..., D210-N); - a first inverter (INV210) connecting a control terminal of said first transistor (101) to a control terminal of said second transistor (T213); - a fourth transistor (T212) in parallel with said first transistor (101), a control terminal of said fourth transistor (T212) being connected to the midpoint between said second and third transistors (T213, T211); and - a first capacitor (C211; C311) arranged between the control terminal of said fourth transistor (T212), and the first conduction terminal of said first transistor (101).

2. A circuit according to claim 1, further comprising a first resistor (R211) connecting said anode of said N diodes (D210-1, ..., D210-N) and the first conduction terminal of said first transistor (101).

3. A circuit according to claim 1 or 2, wherein N is between ten and twenty.

4.

5. The circuit of claim 3, wherein N is equal to fourteen. The circuit of any one of claims 1 to 4, further comprising a second resistor (R412) connecting said control terminal of said fourth transistor (T212) to said second conduction terminal of said first transistor (101).

6. A circuit according to claim 5, further comprising a fifth transistor (T511) connecting said second resistor (R412) to said second conduction terminal of said first transistor (101).

7. A circuit according to any one of claims 1 to 6, further comprising a second capacitor (C312) arranged in series with the first capacitor (C311).

8. A circuit according to any one of claims 1 to 7, further comprises a first diode (D612) disposed between the middle node of said first and second capacitors (C311, C312), and said second conduction terminal of said first transistor (101).

9. A circuit according to any one of claims 1 to 8, further comprising a second diode (D611) arranged in parallel with said second resistor (R412).

10. A circuit according to any one of claims 1 to 9, wherein said first conduction terminal of said first transistor (101) is adapted to receive a reference voltage.

11. A circuit according to claim 10, wherein the reference voltage is ground.

12. Circuit according to any one of claims 1 to 10, wherein said first, second, third, fourth transistors (101, T211, T212, T213) are transistors of the same technology.

13. Circuit according to claim 12 in its attachment to claim 6, in which the fifth transistor (T511) is of the same technology as said first, second, third, fourth transistors (101, T211, T212, T213).

14. A circuit according to claim 12 or 13, wherein said first, second, third, fourth transistors (101, T211, T212, T213) are drift MOS transistors.

15. An electronic device (100; 200; 300; 400; 500; 600) comprising said first transistor (101) and an electrostatic discharge protection circuit (110; 210; 310; 410; 510; 610) according to any one of claims 1 to 14.

Images