Computational study of millimeter-wave metal-pin photonic bandgap waveguides for use as ultrahigh-speed bandpass wireless interconnects

Much above present computer clock rates of about 3 GHz, problems with signal integrity, cross-coupling, and radiation may render continuous metallic interconnects impractical. An emerging possibility is to use bandpass wireless interconnects wherein the baseband digital bit stream amplitude-modulates a millimeter-wave carrier. This approach is enabled by the recent development of THz-class silicon transistors (R.F. Service, Science, vol. 293, no. 5531, p. 786, 2001) and advances in understanding the waveguiding physics provided by photonic bandgap (PBG) structures. In principle, bandpass wireless interconnects could transmit increasingly fast digital bit streams in smaller waveguides by modulating higher-frequency RF carriers. This paper is a computational-modeling study of a 2D PBG waveguiding structure which could be used to implement such a bandpass wireless interconnect. Using the finite-difference time-domain (FDTD) method, we study the transmission characteristics of a candidate PBG array of metal rods in air for the TM-polarization case. A frequency-independent surface impedance model (A. Taflove and S.C. Hagness, Computational Electrodynamics: The Finite-Difference Time-Domain Method, 2nd ed. Norwood, MA, Artech House, 2000) is used to permit estimation of the PBG stopband characteristics and the transmission losses of the PBG waveguide.