Abstract: “In this paper SIMSIDES-based behavioral simulation of a 4th order Hybrid ΣΔ (HΣΔ) modulator was carried out to define electrical characteristics of an Analog Building Block (ABB), specifically a fully differential OTA. A set of experiments based on analytical models was defined to analyze the overall performance of the Switched Capacitor (SC) ΣΔ modulator in order to translate the design considerations into a set of values that the design at transistor level can be established by the desired performance of the chosen architecture. In accordance with this design strategy, a fully differential CFCFC OTA was designed according to design rules of a 130nm CMOS process. Simulation results show that an open-loop gain A0 = 60dB, and unity-gain bandwidth f0dB = 1.0GHz are enough to obtain a Signal-to-Noise Ratio (SNR) of 68dB (±1dB) when this OTA is added to the DT ΣΔ modulator. Furthermore the hand-made small-signal analysis of the chosen OTA topology allow us to obtain an analytic design mode”

Keywords: High level simulation, ΣΔ modulation, OTA, small-signal analysis, analog design, teaching