Volterra series and their applications to analog integrated circuit design
In this chapter it is investigated how weakly nonlinear behavior of an analog integrated circuit can be computed. The emphasis here is on obtaining insight. Therefore, less attention is paid to numerical methods such as time-domain analysis followed by a Fourier transform, which is the classical SPICE approach [Royc 89, Hspi 96], or harmonic balance methods. Such methods compute the response of a nonlinear circuit by iteration, and the final result is a list of numbers, which do not indicate which nonlinearities in the circuit are mainly responsible for the observed nonlinear behavior. Hence such methods are suitable for verification of circuits that have already been designed. When simulations show that the specifications regarding the nonlinear behavior are not met, then these methods do not present information from which designers can derive which circuit parameters or circuit elements they have to modify in order to obtain the required specifications. Such valuable information can be obtained with the use of Volterra series. The price that is paid for this extra insight is that the analysis is limited to weakly nonlinear behavior only.
KeywordsHarmonic Distortion Loop Gain Nonlinear Feedback Volterra Series Volterra Operator
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