This paper presents an approach to analyse the stability of continuous time Σ∆ data converters and shows a new method to define optimized parameter sets without a large number of simulations. Thereby the converter is described as a switched system. The presented analysis is based on a state space description which is utilized to express the properties of a stable behaviour. It is shown how the analysis method can be used to optimize the filter coefficients of the modulator by scaling the integrators outputs

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.

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.

Abstract. Im Hinblick auf die Optimierung von zeitkontinuierlichen ΣΔ-Wandlern ist ein genaues Verständnis der dynamischen Eigenschaften des Systems von essentieller Bedeutung. In dieser Arbeit wird der ΣΔ-Modulator dafür in die Klasse der Mixed-Signal Systeme eingeordnet und als Übertragungssystem mit geschalteter Rückkopplung betrachtet. Mit diesem Switched-System-Modell können unter Zuhilfenahme einer geeigneten Zustandsraumdarstellung die Signalamplituden der internen Integratoren sowie die Maximalamplitude am Quantisierereingang bestimmt werden. Unter Verwendung einer Worst-Case Analyse ist es damit möglich, Aussagen über den Aussteuerbereich der Integratoren sowie der maximal stabilen Eingangsamplitude zu treffen. Die Vorgehensweise wird anhand eines Beispielmodulators dargestellt.

Abstract. In this contribution, a system identification procedure of a two-input Wiener model suitable for the analysis of the disturbance behavior of integrated nonlinear circuits is presented. The identified block model is comprised of two linear dynamic and one static nonlinear block, which are determined using an parameterized approach. In order to characterize the linear blocks, an correlation analysis using a white noise input in combination with a model reduction scheme is adopted. After having characterized the linear blocks, from the output spectrum under single tone excitation at each input a linear set of equations will be set up, whose solution gives the coefficients of the nonlinear block. By this data based black box approach, the distortion behavior of a nonlinear circuit under the influence of an interfering signal at an arbitrary input port can be determined. Such an interfering signal can be, for example, an electromagnetic interference signal which conductively couples into the port of consideration.