A gate driver is an interface circuit used to provide a control voltage (and resulting current) to dual metal oxide semiconductor (DMOS) and insulated gate bipolar transistor (IGBT) devices used to drive motors and other devices. During operation, the gate driver input can be driven with either a logic level signal or some other low level signal. A special kind of gate driver is an isolated gate driver, where isolation is provided between the input and output, but otherwise the circuit has all the characteristics of a typical gate driver.
Isolated gate drivers generally require isolated power supplies. When gate drivers are used in a motor drive circuit, six isolated power supplies might be used, with one per each IGBT used. The power supply increases the cost of the circuit and reduces the reliability of an already complicated circuit. The wiring attached at nodes with fast changing signals also acts as an antenna for radiating radio frequency interference (RFI), which is detrimental to both the internal circuitry and radio reception in the vicinity of the circuit. Two solutions that have been proposed in the past are the use of a DC/DC converter or a charge pump. The DC/DC converter has high efficiency (80%-90% conversion efficiency), but it is relatively large and expensive. The charge pump is simple and very economical, but has low (40%) efficiency.
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