Increasing the robustness of digital circuits with ring oscillator clocks

Abstract

Technology scaling enables lower supply voltages, but also increases power density of integrated circuits. In this context, power integrity becomes a major concern in the implementation of highperformance designs. This paper analyzes the influence of Ring Oscillator Clocks (ROCs) on mitigating the impacts of voltage noise. A design with an ROC as the clock source is able to work correctly even in the presence of severe and unpredictable voltage emergencies, without degrading the average performance and power metrics of the circuit. ROCs offer an instantaneous and continuous adaptation to the environment conditions, thus reducing the margins used to prevent timing failures. ROCs provide robustness independently of the power delivery network, thus relaxing the constraints required for the design of the PCB and package. As a by-product, the inherent jitter generated by ROCs produces a spreadspectrum effect that reduces electromagnetic emissions.