The Research Of Simulation Technology For Nonlinear Scattering Function Based On Harmonic Balance

Microwave active circuit design and research has been the main topics in the field of microwave technology, it has accumulated a wealth of knowledge and experience In theory and practice, Small-signal S parameters can be said that played a decisive role here, But in the large-signal state, microwave devices usually work in nonlinear area, the traditional small-signal S parameters have been unable to meet our design requirements for nonlinear devices. Thus, we propose a characterization of large-signal operating characteristics—nonlinears cattering function. We first proposed the concept in theory, and give it a clear definition and physical meaning, as well as, we build a complete test system to measure it effectively.The contents of this paper are mainly from the theory of microwave power device model. According to the nonlinear scattering function modeling techniques to obtain nonlinear scattering function.We also to build a test system to measure the actual power devices to attain nonlinear scattering function, so we can compare those to draw final conclusions. First of all, this paper start with the traditional FET modeling methods, establish small-signal model of the microwave power FET, and then test FET DC characteristic curve, fitted to its large-signal model, at last,we use harmonic balance method to analysis nonlinear model. The harmonic balance algorithm is different from the past, where we have put forward the concept of transformation matrix, using the whole frequency domain harmonic balance algorithm, makes the efficiency of calculation has been greatly enhanced. The same time, we build a new system based on the one last year, we extended the frequency to 20GHz, joined the phase calibration, and add a duner after the second port,get the fourth,fifth and sixth lines of the nonlinear scattering function.Finally, the paper compares the test results and simulation results attain satisfactory conclusion.