A new simulation model for nonlinearity of SAW resonator filters
In the design stage of SAW duplexers for 3G handsets, a new simulation method which is predictable for the frequency characteristics of the nonlinearity has been desired in order to improve the intermodulation distortion and/or the triple beet. Recent SAW duplexers consist of not only ladder type filters but also DMS filters. In this paper, a novel simulation method of nonlinear signals, which is applicable for not only one-port SAW resonators but also DMS filters, has been proposed. Basic calculation model of the nonlinear current is derived by introducing nonlinear terms to the piezoelectric fundamental equation. In order to apply this model to IDT structure, we extend the equation to summation model of multi point electrodes. Good agreement between calculated results and measured values has been obtained.
A circuit model for nonlinear simulation of radio-frequency filters using bulk acoustic wave resonators
This paper describes a circuit model for the analysis of nonlinearity in the filters based on radio- frequency (RF) bulk acoustic wave (BAW) resonators. The nonlinear output is expressed by a current source connected parallel to the linear resonator. Amplitude of the nonlinear current source is programmed proportional to the product of linear currents flowing in the resonator. Thus, the nonlinear analysis is performed by the common linear analysis, even for complex device structures. The analysis is applied to a ladder-type RF BAW filter, and frequency dependence of the nonlinear output is discussed. Furthermore, this analysis is verified through comparison with experiments.
Far-field dispersal modeling for fuel-air-explosive devices
A computer model for simulating the explosive dispersal of a fuel agent in the far-field regime is described and is applied to a wide variety of initial conditions to judge their effect upon the resulting fuel/air cloud. This work was directed toward modeling the dispersal process associated with Fuel-Air-Explosives devices. The far-field dispersal regime is taken to be that time after the initial burster charge detonation in which the shock forces no longer dominate the flow field and initial canister and fuel mass breakup has occurred. The model was applied to a low vapor pressure fuel, a high vapor pressure fuel and a solid fuel. A strong dependence of the final cloud characteristics upon the initial droplet size distribution was demonstrated. The predicted fuel-air clouds were highly non-uniform in concentration. 18 refs., 86 figs., 4 tabs.