In this work a multi-input block oriented approach for the analysis of distortion effects induced by interfering signals in nonlinear circuits is presented. With the proposed model distortion signals at an arbitrary input port can be investigated. Based on a series reversion approach for the nonlinear behavior, analytical expressions for the spectral components arising from intermodulations between distortion and nominal input signal are derived.

This paper presents how the optimization of continuous-time (CT) Σ∆ modulators by scaling the loop filter coefficients affects the signal transfer function (STF) and in which way the method can be used to reduce peaking in the STF. It is shown that, depending on the initial design, it is possible to define optimized parameter sets with increased performance and remaining flat STF or sets with constant performance and reduced STF peaking. Therefore, the system is first described as switched system to analyse its behaviour in the state space. The different effects of the optimization method on the STF are demonstrated on two example systems with differently designed noise transfer functions (NTF).

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Abstract. This work deals with the conducted susceptibility of nonlinear analog circuits with respect to substrate noise. The substrate coupling mechanism is modeled by a passive three-terminal network that is obtained by means of the finite element method with a subsequently performed model order reduction. Applying this substrate model to the bulk terminal of MOS transistors in integrated analog circuits, it is possible to examine the influence of substrate noise on the circuit's functionality. By means of a block-oriented approach, analytic expressions for the output behavior of the circuits are found. The utilized multi-input Wiener model separates the linear dynamic from the nonlinear static circuit properties. Due to this separation the frequency response of both signals, i.e.,input signal and substrate noise, respectively, can be identified, and hence, the frequency range in which the circuit is most susceptible to substrate noise. Since the nonlinear static behavior of each MOS transistor depends on two signals, truncated multivariate Taylor series expansions of the nonlinear elements are performed on the basis of the EKV model description (Enz et al., 1995). The proposed modeling is illustrated by a simple example.

This paper presents a method to design continuoustime Σ∆ modulator with reduced peaking of the signal transfer function (STF). It is demonstrated that the approach is suitable for designing a flat STF while the anti-aliasing properties of the continuous time system can be retained. In addition, the presented method reduces the number of additional circuit elements needed for a flat STF frequency response. Experimental verification of the approach is presented.