An improved small outline package for radio frequency integrated circuits

Package parasitics can significantly degrade the performance of Radio Frequency Integrated Circuits (RFIC). The most insidious problem is the loss of energy due to the mismatch between the printed circuit (PC) board transmission line and the RFIC contained in a package. Traditional small outline (SO) packages present significant reactive elements between the PC board transmission line and die. This fundamentally limits the usefulness of these packages to a few GHz. In addition, as commercial frequency bands increase above 5 GHz, SO packages need modification if they are to be useful at these frequencies. To date, physical and equivalent circuit modeling of these packages has been well understood, but limited attention has been given to SO package improvement.; If the lead frame can be modified to reduce or eliminate the reactive parasitic effects, two mutually beneficial results occur. The lead frame has a greater return loss at lower frequencies, and the useful application of the package can be extended to higher frequencies. The most direct method to accomplish this is to design the lead frame as a CPW-like transmission line system from the PC board to the wire bond connection point. A set of new equations have been developed that predict the performance of Embedded Coplanar Waveguide with Finite Ground (ECPWFG) transmission lines, which are implemented into an SO package body. Prototypes of these packages have been constructed and measured to verify the accuracy of the ECPWFG equations. The modified lead frame has been shown to double the useful application bandwidth of the package from 5 GHz to 10 GHz. Circuit models of the new lead frame have been developed and presented. In addition, three dimensional electromagnetic simulations have been completed to extend the work beyond what was obtained with constructed prototype packages.