Non-intrusive near-field characterization of distributed effects in large-periphery LDMOS RF power transistors

Within an LDMOS high-power device, the identical and parallel transistor cells operate under different conditions due to uneven distributed thermal and loading effects. This degrades device performance and increases the risk of odd-mode oscillations. This paper demonstrates an EM-model-assisted non-intrusive near-field technique to characterize, in situ, distributed effects. We apply the proposed technique on 100 W and 200 W 0.1-um LDMOS transistors with in-package matching networks. The absolute voltages and currents of the individual drain bondwire terminals in operating LDMOS devices are experimentally quantified for the first time.