S-Parameter Modeling and Analysis of RGLC Interconnect for Signal Integrity

In high speed applications, the clock rates have approached giga-hertz ranges. Signal integrity has become a critical issue and is posing severe challenges to the designers. This necessitates interconnects capable of supporting broadband signals without degradation. In signal integrity analysis, Sparameters are labeled as the behavioral model that can be used for describing the behavior of linear and passive interconnects. Sparameters describes how precise waveforms such as sine waves, scatter from the ends of interconnects. S-parameter matrix elements and analytical information that each element contains gives the precise behavior of interconnects. Here a new analytical formulation is proposed, which is used to extract the Sparameters of the RLCG interconnects that is based on the impedance profile of network. The impedances extracted are used for estimation of return loss (S11) and insertion losses (S21) of interconnect. Calculation is a complicated task and depends on impedance profile, time delays of transmission line segment and frequency of wave. S-parameters are obtained by considering interconnect as a two port network with a source and matched impedance terminations (Z0=50Ω). S-parameter analysis of lumped and distributed models of interconnects such as RC, RLC and RLGC and modified RGLC model is carried out for performance evaluation. Simultaneously, Time Domain Reflectrometry (TDR) analysis of all the models of interconnects is performed to know impedance discontinuities. In TDR analysis, the incident waveforms is a step edge and the reflected wave is referred as the time domain reflection response. The results are compared for optimum performances in metrics of insertion loss (S21) and return loss (S11) in dB/magnitude scale along with TDR response of interconnect models.