Research On Modeling, Analyzing And Measurement System For Microwave Nonlinear Circuit

This paper firstly studied the transistor modeling techniques, and then extracted small and large signal models of microwave power devices based on conventional modeling methods. Aiming at getting the nonlinear characteristics of these devices, we adopted the entire frequency domain harmonic balance method to analyze its linear and nonlinear subnet, which had the advantage of simple operation and time-efficiency when compared with traditional harmonic balance method. Finally, a new expression of nonlinear scattering function was presented on the basis of traditional nonlinear expression, and its characteristic was discussed.Different from linear S parameter, nonlinear scattering function was a function of frequency, amplitude, phase and DC bias, and all the harmonics should be taken into consideration. To attain the nonlinear scattering function, we constructed a test system based on Digital Oscillograph. Especially we did a research on the calibrated method of the test system and finally finished relative hardware design and software program. After measuring the microwave devices with the test system of nonlinear scattering function, we found the result was consistent with the characteristic. The result validated the accuracy and stability of the test system and also showed that it could be used to extract large signal nonlinear scattering function. The next step is to use the nonlinear scattering function to design nonlinear circuit.