Compare punch-through IGBTs to power MOSFETs

With the combination of an easily driven MOS gate and low conduction loss, the IGBT is the device of choice for high current and high voltage applications. Now with the latest generation of PT IGBTs, the tradeoff between switching and conduction losses is balanced so that IGBTs encroach upon the high frequency, high efficiency domain of power MOSFETs. In fact, the industry trend is for IGBTs to replace power MOSFETs in switch mode power supply (SMPS) applications if the voltage is above about 300 Volts.

This trend is made possible by a significant improvement in switching speed with the latest generation of PT IGBTs while retaining the low conduction loss that is characteristic of IGBTs. In most cases, circuit designers who use these latest technology IGBTs can significantly reduce costs with little, if any sacrifice in efficiency. This paper gives an overview of PT IGBT technology, compares features and benefits with power MOSFETs, and shows performance improvements in various high frequency, high voltage SMPS applications.

Punch through IGBT structure
A PT IGBT is basically an N-channel power MOSFET constructed on a p-type substrate [1], as illustrated by the generic IGBT cross section in Figure 1.

Figure 1 PT IGBT Cross Section

Page 2: Equivalent circuit
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