Reliable non-zero skew clock trees using wire width optimization

Abstract

Recognizing that routing constraints and process variations make non-zero skew inevitable, this paper describes a novel methodology for constructing reliable low-skew clock trees. The algorithm efficiently calculates clock-tree delay sensitivities to achieve a target delay and a target skew. Moreover, the sensitivities also show that wires should be widened as opposed to lengthened to reduce skew since the former improves reliability while the latter reduces it. This paper introduces the concept of designing reliable clock nets with process-insensitive skew.