3. Sigma-Delta ADCs with Improved Interferer Robustness

This article reviews the application and the requirements of Sigma-Delta ADCs with improved interferer robustness. While most power efficient state-of-the-art architectures for Sigma-Delta ADCs are based on forward compensated loop filters, these architectures are known to feature gain in their signal transfer function at out-of-band frequencies. In applications, where interferer and blocker signals are present outside the band of interest, gain at these frequencies consequently increases the required dynamic range or the necessary pre-processing complexity, e.g. within the preceding filter stages. More recently, increasing attention was dedicated to improved signal transfer functions of Sigma-Delta ADC’s, such that—by intrinsically attenuating the interferers within the Sigma-Delta loop filter—pre-processing stages can be relaxed or even omitted, and the dynamic range can be reduced. In this contribution, the state-of-the-art of Sigma-Delta ADCs is reviewed with respect to interferer robustness from system level on.