Nonlinear Simulation Methods for Active Microwave Circuits: A Review of the Art and Novel Trends

This paper discusses in detail, two techniques for the analysis of non-linearelectronic circuit. The first technique is an automated version of thetraditional time domain solution method (Transient Analysis). For a givencircuit topology the state equations are generated by computer and solvednumerically. The second technique involves the use of a hybrid timefrequencydomain approach and is known as harmonic balance (Steady StateAnalysis). The formulation and solution methods adopted for both methodsare outlined in detail. Emphasis is placed throughout an application tomicrowave circuits. In order to illustrate the properties of each method,sample analyses for two main circuits are given. The first circuit is that of alinear amplifier operating at 12 GHz and driven into saturation. The secondcircuit is that of a nonlinear frequency doubler, doubling from 7-14 GHz.Some advanced applications are discussed in order to further highlight therelative advantages and disadvantages of each technique. Finally it is shownhow a non-linear CAD package can be produced which allows circuitoptimization in a similar way to that allowed by linear CAD programs.Some remaining problems which need more investigations and possiblefuture work are highlighted.