The Research On Nonlinear Modeling Of RF Front-end Devices

With the rapid development of the industry,the structure of wireless electronic products such as mobile phones has become more and more complex,and the difficulty of design a device which can fulfill the criterion of communication has become hader.In complex systems,the nonlinearity of radio frequency front-end devices such as tunable capacitors and conductive foams,which were originally regarded as linear devices,has gradually become more and more significant in the radiated spurious disturbance test,and has gradually entered the view of scientific researchers and has become the key to restrict the performance of the circuit system.Therefore,in order to shorten the cycle of R&D and reduce the costs of R&D,we urgently need to establish an equivalent behavioral-level model libarary for the tunable capacitor and the conductive foam.The main research content of this paper can be summarized as follows:1.In this paper,the problem of excessive radiation spurs of mobile phones is located on the undesirable characteristics of tunable capacitors and conductive foams by the method of on-site substitution.By introducing the small-signal C-V characteristic of varactor diode and the tunneling effect,the mechanism of the radiation spurious generation of the tunable capacitor and the conductive foam is analyzed.2.Based on the theory of radio frequency testing,this paper constructs an automated harmonic test system for tunable capacitors and conductive foams.The test system fully considers the assembly scene of the device,and has designed dedicated test fixtures for tunable capacitors and conductive foams.At the same time,in order to reduce the influence of the fixture on the test results,the through-reflection-delay calibration method and the full-wave simulation de-embedding calibration method were used to calibrate the harmonic test platform of the tunable capacitor and conductive foam.3.In this paper,a behavior-level model library of tunable capacitors and conductive foams is constructed based on a full-parameter simulation system.The use of symbols to define device nonlinear modeling methods and linear-nonlinear modeling methods not only improves the accuracy of the model but also increases the applicability of the model.4.This article writes an automated harmonic spurious test system plug-in for tunable capacitors and conductive foams.At the same time,it uses Python and simulation optimization software to perform joint optimization simulations.While improving the efficiency of test modeling,it also avoids the interference of human factors and improves the consistency of test results.5.This paper verifies the correctness and predictability of the non-referenced model by comparing the simulation results of the built model library with the actual measurment results under the new test conditions.The experimental results show that the prediction error of the tunable capacitor model is within 0.4d Bm in the normal working range.In summary,based on the detection of radiated spurious interference,this article has completed the analysis of the nonlinear sources of the tunable capacitance and conductive foam of the RF front-end,and formed an integrated test process from testing,modeling to packaging.The establishment of this model library is worthwhile to the design of industrial electronic equipment.