IGBT
Short for Insulated-gate bipolar transistor.
Looks like a thyristor with a MOSFET gate, but it only functions ONLY as a #transistor.
Uses
-
High-power applications:
- IGBTs can simultaneously handle high voltage and high current.
- meaning it's useful for switched mode power supplies, variable frequency drives (VFDs), inverters (e.g. for photovoltaics), etc.
- Fast switching:
- useful for PWM and low-pass filters
- or for switching amplifiers used for #audio or for industrial control systems.
construction
An IGBT is made of 4 layers (NPNP) of transistor controlled by a MOS gate (see diagram below).
comparison table
| Name | Voltage rating | Current rating | Input drive | Input impedance | Output impedance | Switching speed | Cost (relative) |
|---|---|---|---|---|---|---|---|
| IGBT | Very High (>1 kV) | High (>500A) | Voltage Driven, VGE ~4-8V | High | Low | Medium | high |
| Power BJT | High (<1 kV) | High (<200A) | Current Driven, hfe ~20-200 | Low | Low | slow (μs) | Low |
| Power MOSFET | High (<1 kV) | Low (<500A) | Voltage Driven, VGS ~3-10V | High | Medium | Fast (ns) | Medium |