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 new simulation method for nonlinear characteristics of SAW devices
In recent years, the linearity performance of the RF front end part of mobile phone handsets is a one of very hot topics. In such a situation, the requirement of high linearity to SAW duplexers has become strong. In this paper, a novel simulation method for nonlinear signals has been proposed. The nonlinear stress and current are represented by introducing nonlinear terms into the piezoelectric fundamental equations. They are connected as voltage and current sources in the electrical equivalent circuit of a SAW device, and the nonlinear signals observed at arbitrary external terminals are estimated. Very good agreement between the simulation and the measured values has been obtained for the third-order harmonic and IMD of SAW resonators.
Calculation of Complex Radiant Heat Load From Surrounding Radiator Surface Temperatures
Abstract A method for calculating the radiant heat exchange between an absorber and individual radiating components in its surroundings is reported. Radiator surface temperatures, ambient and absorber temperatures, and configuration factors for radiating components in the surroundings are used in the customary radiant heat exchange formulae. Simplified methods for calculating or estimating configuration factors for radiators of various shapes solely from angles, subtended at the absorber by the radiators are presented. The method has been verified in the laboratory under controlled conditions and has been used to advantage in the field studies. The method has advantages over the globe therometer method in certain applications.