High-Speed System Modeling And Analysis Based On Cavity Resonant Theory

As clock frequency increases, many kinds of high-frequency effects, such ascrosstalk, reflection, ringing, simultaneous switching noise, ground bounce, etc, arebecoming more and more important in the high-speed system. Electrical integrity,including signal integrity, power integrity, and electromagnetic integrity, poses a bigchallenge for system design. In order to shorten the period and decrease the cost ofproduction design, system performance must be predicted before fabrication. Structuresviolating electrical integrity must be found by engineers using all kinds of systemsimulation tools. These structures should be redesigned to meet with electrical integrity.In the processing of system simulation, nonlinear active components are involved andcan be represented by IBIS model or Spice model. But frequency-domain datum(S-parameter, Z-parameter or Y-parameter) can’t be connected directly with activecomponents to implement the time-domain simulation. So, an effective way toimplement the time-domain simulation of a system is highly desired.At present, there are mainly three ways to implement the time-domain simulationof a system: modeling frequency-domain datum of a system, segmenting and linearizingnonlinear active components, and modeling the network structures of a system. Themost effective method is modeling the network structures of a system, which model thenetwork structures of a system in nature directly. In this thesis, some novel modelingmethods and fast algorithms are proposed for modeling the network structures of asystem and the efficiency and precision of these methods is analyzed in detail. The maincontributions of this thesis are as follows:1. A fast double-frequency approximation is proposed to improve the low efficiencyand the bad precision of the cavity resonant model for power/ground planes.According to the characteristic that the impedance of the high-order modes isinductive and not varies linearly with frequency f within the modeled bandwidth, aSpice-compatible cavity resonant model for power/ground planes is obtained bysingle segment of second-order LC circuit approximating the impedance ofhigh-order modes. High precision, high efficiency and validity of this model arevalidated by error analysis and frequency-domain simulation.2. A novel Spice-compatible Cavity resonant Transmission Line model is proposed byreducing2-D cavity resonator to1-D cavity resonator. It is noted that the boundary condition of2-D plane cavity resonator is perfect magnetic conductor and is stillpreserved in the reducing process. But this boundary condition is not suitable fortransmission lines. The method of modifying parameters of the cavity resonantmodel is presented by analyzing parameters of1-D ideal cavity resonator, and thenthe model for a single-ended microstrip line with fringe field is obtained. Byanalyzing the fringe field and gap field, the model for a single-ended microstrip lineis generalized to two-signal parallel coupled microstrip lines and multiple parallelcoupled microstrip lines, and then the complete cavity resonant theory of multipleparallel coupled microstrip lines is shown. Finally, the correctness of this theory isdemonstrated by experiments.3. The cavity resonant transmission line model consists of infinite cavity resonantmodes and the frequency-domain and time-domain simulation of this model can notbe implemented in fact. Generally, infinite modes are replaced by finite modes. Thisway will introduce some error. In order to improve the low efficiency and the badprecision of the cavity resonant transmission line model, both double-frequencyapproximation and Padé approximation are proposed. The double-frequencyapproximation uses single segment of LC circuit to approximate the impedance ofhigh-order modes and the number of modes used is constant, namely twice as manyas the number of modes in the bandwidth of the model. Its main disadvantage isthat it can not adjust neatly the balance between the precision and the efficiency. So,this approximation is only suitable for transmission lines with fewer modes withinthe frequency bandwidth range of the model. While Padé approximation usesmultiple segments of LC circuits to approximate the impedance of high-ordermodes and the number of modes used varies with the number of segments ofmodified circuits. Since it can adjust neatly the balance between the precision andthe efficiency, it has the better precision and higher efficiency in simulatingtransmission lines with more modes within the frequency range of the model.4. A novel model for a non-ideal stripline is presented based on the impedanceexpression of mode decomposition. In this model, two ideal transformers are onlyintroduced for each of striplines to implement the coupling between the plane modeand transmission line mode. So, the efficiency of this model is very high. Finally,the validity of this model for non-ideal stripline is demonstrated by the time andfrequency domain simulation.