Arthur Woodworth

High frequency DC:DC power conversion: the influence of package parasitics

Operating power MOSFET devices at frequencies over 1 MHz will pose significant challenges to established power electronic packages such as the D2-Pak and wirebonded SO-8 devices. In this paper the high frequency parasitic impedances of a range of power electronic packages are presented. Results show that a source mounted power package technology based upon a copper clip type assembly has considerably lower parasitic impedance compared to conventional power packaging at frequencies in the range of 500 kHz to over 1 MHz. The resistance of conventional packages recorded over this range of frequencies increases significantly as the frequency approaches 1MHz. This is expected to be a result of skin effect related phenomena occurring in wire bonds and package leads. Package impedance data up to frequencies of 5 MHz is presented for a range of packages along with efficiency data recorded from devices operating in multiphase buck converter circuits.

Current handling and thermal considerations in a high current semiconductor switch package

In response to the need for a high current, low inductance, low resistance package, International Rectifier have designed the Supertab MOSFET. This new device is capable of carrying currents in excess of 200 A. The Supertab package is different from existing power MOSFET packages in that the source connection is made through a tab rather than a lead. This paper presents a discussion of the way in which a combination of experimental work and computer modelling has been used to develop this high current discrete semiconductor switch package.