What are MOSFETs? – Types and Features of High Voltage Super-Junction MOSFET

In the previous section, the product positioning of Si-MOSFETs, IGBTs and SiC-MOSFETs, which in recent years have become the most important power transistors, was reviewed, and super-junction MOSFETs (hereafter “SJ-MOSFETs”), which are representative of the latest high-voltage Si MOSFETs, were summarized. This time, as specific examples of SJ-MOSFETs, we explain the ROHM line up of SJ-MOSFET products and their features.

Types of SJ-MOSFETs

Taking ROHM products as examples, SJ-MOSFETs are classified by noise, on-resistance, speed of operation, the unique structure, and other parameters. We begin with an overview of product differentiation.

This graphic shows further development from the AN series, which are standard products. For example, the AN series, further developed to reduce noise, resulted in the EN series, and efforts to increase operating speed culminated in the KN series.

This time, we will explain the development background and features of standard products and high-speed products.

Standard SJ-MOSFETs: AN Series

The AN series products were the first SJ-MOSFETs developed, with the aims of greatly reducing the drain-source on-resistance RDS(on) and the total gate charge compared with planar MOSFETs. The RDS(on) was reduced by 50%, and Qg by 40%, compared with planar MOSFETs. In terms of characteristics, the AN series are positioned as standard devices.

Low noise SJ-MOSFET: EN series

SJ-MOSFETs have such features as low on-resistances and fast switching speeds, but because of their fast operation, there is the problem that noise levels are high compared with planar devices. The EN series represents an improvement in this area. These devices combine the low-noise characteristics of planar MOSFETs and the low on-resistance characteristics of SJ-MOSFETs, and are positioned as replacements for planar MOSFETs with low on-resistances.

The graph comparing noise levels contrasts the EN series with the standard type AN series and with SJ-MOSFETs of another manufacturer; we see that the EN series, indicated in red, has lower noise. And in comparisons of on-resistances, values are achieved that are 80% lower than for planar devices and 15% below the values for the AN series.

High-speed SJ-MOSFET: KN Series

The KN series are SJ-MOSFETs which maintain the low-noise performance of the EN series while increasing operating speeds. By reducing the gate resistance Rg and gate-drain charge Qgd, switching performance was improved. Faster switching means switching losses can be reduced, for improved efficiency.

Finally, we present links to technical information pertaining to these three product series. We have described the features of each series, but to further deepen your understanding, it will be best to review the data sheet specifications and characteristic graphs.

Next time, we will explain the remaining two device types, Presto MOSTM, fast trr SJ-MOSFETs and hybrid MOS devices.

• Si-MOSFET
• IGBT
• SiC-MOSFET
• SJ-MOSFET