Discrete-time simulation of continuous-time ΣΔ modulators with arbitrary input signals

In this paper, we present a method for fast lifting-based simulations of continuous-time (CT) Sigma Delta (ΣΔ) modulators with arbitrary input signal waveforms. Our approach allows for a very time-efficient simulation of important modulator parameters such as inter-modulation distortion, the response to a spread spectrum input or blocker signals, and evaluation of its signal transfer function. The proposed method exploits the fact that every finite length CT signal can be decomposed into a sum of sinusoidal signals by providing a computationally efficient algorithm which allows for a lifting based simulation of CT ΣΔ modulators for an input signal consisting of an arbitrary number of sinusoidal signals. Matlab based simulations demonstrate the validity of our approach and show that despite the increased complexity compared to ordinary lifting, the speed advantage over CT-simulations in Simulink is preserved.