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.