Reliability aware design of low power continuous-time sigma–delta modulator

Abstract

Circuit reliability has become a major bottleneck due to ageing degradation. In this paper, reliability-aware methodology and ageing analysis of low power sigma–delta (ΣΔ) modulator are presented. HCI and NBTI are considered as the dominating ageing effects. A second order continuous-time (CT) ΣΔ modulator is implemented for medical application. Ageing estimation is performed at both behavioral and transistor level. Results at behavioral level and transistor level show that the feedback loop in CT ΣΔ modulator is more sensitive and less reliable than the analog loop filter. Comparing with HCI, NBTI is the dominating ageing effect in the designed CT ΣΔ modulator.