Microwave-circuit modeling of high lead-count plastic packages

A microwave-circuit model topology for elevated-paddle surface-mount packages is extended to packages with high-lead counts. Features such as irregular lead structures, long wirebonds, smaller pitches, and finite-lead thickness are all examined. The modeling technique is applied to a shrink small-outline package (SSOP-24) with the results compared to measurements of a 25 times size scale model. The circuit model is used to investigate the performance of a matched transition.