Waveguide packaging at mm-wave frequencies

Waveguides can be used as both packaging cases and interconnection media between chips. No bond wires are needed in this packaging technique and, consequently, it can be used in millimetre wave circuits and systems. However, a chip inserted in a waveguide introduces additional unwanted propagation modes and reduces an effective bandwidth of the structure. The paper analyses the effects of the substrate thickness and of the placement of the chip on the bandwidth of WR6 and WR10 waveguide packages for typical GaAs and InP chip dimensions. The conditions for an optimum placement of the chip and a maximum bandwidth are derived and confirmed by a rigorous 3D electromagnetic simulation. Based on this analysis, the jig for testing of chips packaged in WR10 waveguide is designed, constructed and measured. Some performance problems are identified and confirmed through electromagnetic simulation. An improved jig design is then proposed.