Design rules for improving predictability of on-chip antenna characteristics in the presence of other metal structures

The impact of on-chip metal interference structures, such as a power grid, local clock trees and data lines, on on-chip antenna performance has been investigated. A power grid significantly changes the input impedance and the phase of S/sub 12/ for an antenna pair, and reduces |S/sub 12/|. However, the addition of extra metal structures in the presence of a power grid has a much attenuated impact on the antenna characteristics. The reduction in |S/sub 12/| can be traded for increased predictability of antenna performance. Exploiting this observation, a set of design rules for increasing the predictability of on-chip antenna characteristics is proposed.