IGBT Symbol Guide: Diagram, Pins, Types & How to Read It

An IGBT symbol can look very similar to a power MOSFET symbol, making the two easy to confuse at first glance.

In a motor power converter, misidentifying an IGBT as a MOSFET can lead to incorrect gate-drive or device-terminal connections.

Symbol variations across IEC and ANSI conventions, datasheets, and EDA libraries can also make identification less straightforward.

In this guide, you will learn:

• IGBT symbol variants, N-channel and P-channel, drawn side by side
• How to identify the gate, collector, and emitter on an IGBT symbol
• Why the emitter arrow points opposite to the MOSFET arrow
• When an anti-parallel freewheeling diode is shown with the IGBT
• How IEC and ANSI conventions represent IGBT symbols

IGBT Symbol Quick Reference

These six common variants cover the IGBT symbol forms you are most likely to encounter.

Figure: Common IGBT symbol representations

The emitter arrow helps identify the IGBT type, while an anti-parallel diode indicates whether a reverse-current path is provided. For a broader overview of electronic schematic symbols, see our guide to circuit symbols.

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What Does an IGBT Symbol Mean?

An IGBT symbol is a three-terminal schematic symbol representing the gate, collector, and emitter of an insulated-gate bipolar transistor.

It resembles a MOSFET but uses collector/emitter terminals and an emitter arrow.

• Gate (G) is the control terminal: The vertical plate set apart from the body, in the position a MOSFET gate occupies. It draws no meaningful steady current, so the drive power is set by how fast you charge the gate capacitance.
• Collector (C) is the high-side current terminal: The upper terminal corresponds functionally to the drain connection of a MOSFET. On a TO-247 or TO-220 package, the metal mounting tab is electrically the collector, which is why that tab is live at rail voltage.
• Emitter (E) is the low-side power terminal and gate-drive reference: The lower terminal, carrying the arrow. Gate drive is specified as VGE (gate-to-emitter), so wherever the emitter sits, your gate drive has to sit with it.

To compare the IGBT with other three-terminal transistor devices, see our complete guide to transistor symbols.

Figure: The N-channel IGBT symbol with G, C, and E labeled

Figure: N-channel IGBT symbol

IGBT Symbol Anatomy: What Each Element Means

An IGBT symbol uses several visual elements to identify the device and its terminals. The gate gap, device body, emitter arrow, and collector lead each provide clues for interpreting the symbol and distinguishing it from similar transistor symbols.

• The gap beside the gate: The gate is drawn as a line separated from the device body, with no direct connection between them. This gap represents the electrical insulation between the gate and the main conduction path.
• The vertical conduction bar: The body of the device, drawn either as one solid bar or as three short segments borrowed from the enhancement MOSFET outline. Both forms mean the same thing, and neither says anything about the current rating.
• The arrow on the emitter lead: A filled arrowhead pointing in the direction of conventional current at the emitter. On an N-channel device, it points away from the body.
• The plain collector lead: If both output leads carry arrows, you are looking at something that is not an IGBT.
• The gate lead position: Drawn on the left in most libraries, entering horizontally. Some house styles rotate the symbol so the gate enters from below, and the gap, the arrow, and the letters still decide what you are reading.

N-Channel vs P-Channel IGBT Symbols

Exactly one line differs between the two. On an N-channel IGBT symbol, the emitter arrow points away from the body; on a P-channel symbol, it points into the body. Everything else, terminal names included, is identical.

Figure: N-channel and P-channel IGBT symbols

• N-channel, arrow pointing outward: Turns on with the gate positive with respect to the emitter, typically around +15 V. Current enters the collector and leaves the emitter. This is the device inside essentially every motor drive, inverter leg, and induction hob you will open.
• P-channel, arrow pointing inward: Turns on with the gate negative with respect to the emitter. Current enters the emitter and leaves the collector.
• What does not change: The terminal letters, the gate gap, the conduction bar, and the plain collector lead are drawn identically for both polarities.

IGBT Symbol With a Freewheeling Diode

A freewheeling diode is shown anti-parallel to the IGBT, with its cathode connected to the collector and its anode connected to the emitter. The diode is not an intrinsic part of a conventional IGBT; it may be provided as a separate external component, co-packaged with the IGBT, or integrated into the same semiconductor die in a reverse-conducting IGBT (RC-IGBT).

Figure: Three IGBT symbol variants: a bare IGBT, an IGBT with a co-packaged anti-parallel diode, and a reverse-conducting IGBT with an integrated diode.

• Bare IGBT, no diode: The part offers no reverse path. For example, the IRG4PF50W, a 900 V, 51 A device in TO-247AC, is drawn this way, and an inductive load switched by it needs an external diode.
• IGBT with a co-packaged diode: The diode is a separate die inside the same package. For example, the STGP7NC60HD from STMicroelectronics (600 V, TO-220) and the FGH75T65SQD from onsemi (650 V, 75 A, TO-247-3) both ship this way, and their datasheets quote a separate junction-to-case thermal resistance for the diode.
• Reverse-conducting IGBT (RC-IGBT): The diode is monolithically integrated on the same die.

Without an appropriate freewheeling path, switching an inductive load can generate excessive voltage overshoot and damage the IGBT.

The collapsing magnetic field drives the collector well past the rated VCES, and a 600 V part fails in microseconds. Cathode orientation is the detail that people reverse. The cathode bar goes to the collector, so the diode blocks while the IGBT conducts and only carries current when the load forces it the other way.

See our diode symbol guide for a detailed explanation of diode polarity.

IGBT vs MOSFET vs BJT

Look at two places and all three devices separate cleanly.

The control terminal tells you whether the device is voltage or current-controlled, and the arrow position tells you which family it belongs to.

Figure: Symbols for IGBT, MOSFET, and BJT

Figure: The IGBT equivalent circuit, an N-channel MOSFET driving a PNP transistor

The figure above explains why the symbol is a genuine hybrid rather than a compromise.

ROHM's structure note describes the N-channel MOSFET drain and the PNP base as one common region, the N- drift layer, with the PNP emitter serving as the IGBT collector. The input really is a MOSFET, and the output really is a bipolar transistor, so the symbol reports both halves truthfully.

IEC and ANSI IGBT Symbol Conventions

Neither IEC 60617 nor ANSI/IEEE 315 fixes one single IGBT outline. Both govern how symbols are drawn on diagrams, both accept the three-terminal insulated-gate form, and the visible differences between them are matters of style rather than meaning.

It turns out that ANSI/IEEE Std 315-1975, reaffirmed in 1993, predates the commercial IGBT altogether. The standard has no dedicated IGBT entry, so vendors extended the existing transistor symbols in slightly different directions. All of those extensions are defensible, which is why a datasheet, a textbook, and an EDA library can draw one part three ways, and none of them would be wrong.

How to Read an IGBT Symbol in a Schematic Step by Step

Work through the symbol in the same order every time, and you can identify it in about ten seconds.

Use the half-bridge shown below as the example: two IGBTs stacked between the DC+ and DC− rails, with a gate driver connected to each device.

Figure: A two-IGBT half-bridge across a DC rail, with both gate drives

1. Find the gap: Confirm the gate lead stops short of the conduction bar. A gap means you are applying a voltage, not sourcing base current.
2. Follow the arrow: Pointing away from the body is N-channel. Both devices in Figure 9 are N-channel, which is normal for a half-bridge.
3. Name the rails: The upper collector goes to the positive rail. Its emitter meets the lower collector, and that junction is the switch node.
4. Check for a diode across C and E: Each device in Figure 9 has one, cathode to collector, so freewheel current from the load has a path in both switch states.
5. Locate the gate reference: The low-side emitter sits at ground, so its VGE is straightforward. The high-side emitter rides on the switch node, which is why that driver needs a bootstrap or isolated supply.
6. Confirm PINs against the datasheet: The symbol never states which physical pin is which.

The symbol tells you the emitter is the reference, and once that emitter swings between 0 V and the rail, a ground-referenced driver can no longer hold the device on.

Common Mistakes When Reading IGBT Symbols

• Reversing the emitter arrow: The drawing is not wrong; it is a different device, so no design rule check will flag it.

To fix this: on an N-channel part, the arrow points away from the body.

• Closing the gate gap: The symbol now reads as a bipolar base, and a reviewer may specify a base resistor for a device that needs a gate driver.

To fix this: leave the gate line clear of the conduction bar.

• Assuming an intrinsic body diode: A power MOSFET has one, and a standard IGBT does not, so an inductive load is left with no freewheel path.

To fix this: fit an external diode unless the datasheet shows a copack or an RC-IGBT.

• Calling the pins drain and source: The parts search then returns MOSFETs, and the gate drive gets specified against the wrong figures.

To fix this: the output stage is bipolar, so the terminals are collector and emitter.

• Trusting the symbol for pin order: KiCad alone ships eight N-channel IGBT symbols that differ in nothing but pin sequence.

To fix this: verify pin 1-2-3 against the package drawing before layout.

Conclusion

Rather than memorizing every IGBT symbol variant, use a consistent identification process: check the gap, then the arrow, then the diode, then the pin order. Those four checks separate an N-channel switch from a P-channel one, a copack part from a bare die, and a correct netlist from a swapped gate.

FAQs about IGBT symbols