An approach is presented for the analysis of the nonlinear behavior of analog integrated circuits. The approach is based on a variant of the Volterra series approach for frequencydomain analysis of weakly nonlinear circuits with one input port, such as amplifiers, and with more than one input port, such as analog mixers and multipliers. By coupling numerical results with symbolic results, both obtained with this method, insight into the nonlinear operation of analog integrated circuits can be gained. For accurate distortion computations, the accuracy of the transistor models is critical. A MOS transistor model is discussed that allows us to explain the measured fourth-order nonlinear behavior of a 1-GHz CMOS upconverter. Further, the method is illustrated with several examples, including the analysis of an operational amplifier up to its gain-bandwidth product. This example has also been verified experimentally. Index Terms---Analog integrated circuits, harmonic distortion, nonlinear ...

INTRODUCTION The Volterra series technique has been used extensively in various applications in the area of nonlinear circuit analysis and optimization (see e.g. references [1]--[28]). Examples are in the (i) analysis of intermodulation in small signal amplifiers [6]--[12], (ii) determination of oscillation frequency and amplitude in near sinusoidal oscillators [3]--[5], (iii) analysis of mixers with moderate local oscillator levels [13, 14], analysis of communication systems [14]--[18], and (v) analysis of noise in nonlinear networks [24]--[28]. The use of the Volterra series technique basically involves two steps: (i) first, from specified input signal frequencies to determine all relevant Volterra transfer functions of the network, and (ii) next, to determine the output response from the non-linear network based on specified amplitudes of the input signals. One limitation in the use of Volterra series is that the determination of Volterra transfer functions is usually limi

LUNSFORD II, PHILIP J. The Frequency Domain Behavioral Modeling and Simulation of Nonlinear Analog Circuits and Systems. (Under the direction of Michael B. Steer.) A new technique for the frequency-domain behavioral modeling and simulation of nonautonomous nonlinear analog subsystems is presented. This technique extracts values of the Volterra nonlinear transfer functions and stores these values in binary files. Using these files, the modeled substem can be simulated for an arbitrary periodic input expressed as a finite sum of sines and cosines. Furthermore, the extraction can be based on any circuit simulator that is capable of steady state simulation. Thus a large system can be divided into smaller subsystems, each of which is characterized by circuit level simulations or lab measurements. The total system can then be simulated using the subsystem characterization stored as tables in binary files.

The paper provides an overview on the state of the art and future trends in physics-based electron device modelling for the computer-aided design of monolithic microwave IC’s. After a review of the main physics-based approaches to microwave modelling, special emphasis is placed on innovative developments relevant to circuit-oriented device performance assessment, such as efficient physics-based noise and para-metric sensitivity analysis. The use of state-of-the-art physics-based analytical or numerical models for circuit analysis is dis-cussed, with particular attention to the role of intermediate be-havioural models in linking multidimensional device simulators with circuit analysis tools. Finally, the model requirements for yield-driven MMIC design are discussed, with the aim of point-ing out the advantages of physics-based statistical device modelling; the possible use of computationally efficient ap-proaches based on device sensitivity analysis for yield optimi-zation is also considered.

An efficient distortion analysis methodology is presented for analog and RF circuits that utilizes linear-centric circuit models to generate individual distortion contributions due to each nonlinear component in a circuit. The per-nonlinearity distortion results are obtained via a straightforward postsimulation step that is simpler and more efficient than the Volterra series-based approaches and does not require high-order devicemodel derivatives. For this reason, the order of analysis can be significantly higher than that for a Volterra series-based implementation while fully accounting for all distortion effects using most existing device models. Moreover, the proposed methodology can also analyze per-nonlinearity distortion for active switching mixers and switch capacitor circuits when they are modeled as periodically time-varying weakly nonlinear systems. The proposed methodology provides important design insights regarding the relationships between design parameters and circuit linearity, hence, the overall system performance. Circuit examples are used to demonstrate the efficacy of the proposed approach, and interesting insights are observed for RF switching mixers in particular.

RF front-end architectures of today's wireless applications need to meet tough requirements on nonlinear distortion to minimize unwanted effects such as crosstalk. An analysis of the nonlinear behavior of analog communication circuits or architectures is not straightforward. This paper presents a modified Volterra series approach to the simulation of nonlinear systems described at the architectural level. The total computed response is decomposed in its nonlinear contributions and the main nonlinearities can be identified. This yields a better insight into the system's nonlinear behavior and allows simplifications. The simplified system can then be simulated more efficiently. The implementation is only based on vector calculation to minimize the computation time, and has been applied to a complete 5 GHz WLAN receiver front-end.