Modern insulated gate semiconductor switches such as Si- and SiC-MOSFETs and Si-IGBTs are far easier to use than the bipolar junction transistors and GTO (Gate Turn-Off) thyristors of decades past.

A primary reason is that they are all controlled by a voltage applied to a control terminal—the gate—that looks like a capacitor (albeit a non-linear one). Consequently, the gate only requires current to change states (according to the capacitor equation I = C * [dV / dt]), otherwise these devices act as voltage-controlled current sources, meaning that it’s entirely possible (and quite common, in fact) to drive them from a voltage source with just a resistor in series with the gate to limit the peak current (and dampen any oscillation that might result from the gate capacitance resonating with the omnipresent stray inductance).

Notably missing from the above list of switches is the GaN-HEMT (High Electron Mobility Transistor), because how to drive it very much depends on the device generation and manufacturer, hence I’ll save it for a future article. e. e. enhancement mode). That said, the gate voltage levels for fully turning on and off a conventional or “SuperJunction” Si-MOSFET are +10 V and 0 V, respectively, while both the SiC-MOSFET and Si-IGBT benefit from a somewhat higher gate voltage to fully turn on (+15 V is ideal), and will typically require a negative gate voltage to be reliably held off, especially at higher bus voltages and switching speeds (ranging from -3 V to -8 V, depending on the specific device and application).

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