Measurement Technique and Simulation Methodology

Abstract

Modern technology trend is pushing the performance requirements for chip–chip interconnects in the microwave frequency band (typically above 10–12 GHz). Now, we have a paradigm where mixed signal and complex PCB layouts are required to operate optimally even up to X-band (8–12 GHz). For such cases where the interconnect dimensions are of the order of wavelength, transmission line effects become the dominant factor. We then benchmark the performance criteria by measuring reflection, crosstalk, propagation loss, delay and dispersion. Operating at microwave frequency range also necessitates that the interconnect design process takes into consideration the characteristic impedance of the line as well as source/load impedance matching. A working design is helped manifolds by accurate modeling approach; some of these are described in previous chapters. We may model interconnect as lossless transmission line. But in real applications, at microwave frequency range, such transmission lines will display frequency dependent losses. This will result in signal integrity issues like deterministic jitter etc. Thus, it is imperative that we validate the models by carrying out accurate measurements. In the modeling approach, we have presented analytical method of determining the various performance criteria. But, such analytical approach cannot be stated as ‘exact’. To obviate resource intensive physical iteration, it is always preferred to do electromagnetic simulation of the structure. Using analytical techniques in conjunction with EM simulation reduces the time-to-market of the device. In this chapter, we present an overview of the measurement techniques as well as EM simulations for the purpose of evaluating high-speed interconnect designs.