Computer-aided analysis and design of microwave mixers using a modified time-domain method

We a computer-aided design (CAD) program that can be used for the design, analysis and investigation of microwave mixers. Accurate models for both the active and passive microwave components and devices are incorporated in the program, which essentially consists of two main parts: a CAD procedure and a computer-aided analysis (CAA) procedure. The CAA procedure is based on a modified time domain analysis method in which the state, output, and nonlinear equations are formulated for the microwave network. This results in a system of nonlinear-differential, difference, and algebraic equations which are solved at each time step as the solution advances. When the change of the time response from cycle to cycle is within a prescribed acceptable tolerance the steady state is declared to be reached. Then the final microwave period is detected and analyzed using a discrete Fourier transform algorithm in order to determine the frequency response of the circuit together with all its other important parameters.