There are some differences in IGBT constructions. The first difference is between a vertical or planar gate. The two figures on the left are illustrating a planar gate and the two on the right are a vertical configuration known as ‘Trench-Gate’. The planar gate style is an older technology. The second difference has to do with how the field is distributed inside the device. The second picture from the left depicts a triangular distribution of the field which is referred to as a ‘non-punch through’ design. The other three pictures depict a ‘punch through’ or ‘field stop’ design which has a change towards the bottom of the device. All these devices are presently available in market place. They do behave differently depending on the application, so it is somewhat important that the designer understands what the technology is being used to build the device. The differences will be discussed later in this application.