Design and Algorithm for Clock Gating and Flip-flop Co-optimization

Abstract

This work firstly investigates the problem of how designing data-driven (i.e., toggling based) clock gating can be closely integrated with the synthesis of flip-flops, which has never been addressed in the prior clock gating works. Our key observation is that some internal part of a flip-flop cell can be reused to generate its clock gating enable signal. Based on this, we propose a newly optimized flip-flop wiring structure, called eXOR-FF, in which an internal logic can be reused for every clock cycle to decide if the flip-flop is to be activated or inactivated through clock gating, thereby achieving area saving (thus, leakage as well as dynamic power saving) on every pair of flip-flop and its toggling detection logic. Then, we propose a comprehensive methodology of placement/timing-aware clock gating exploration that provides two unique strengths: best suited for maximally exploiting the benefit of eXOR-FFs and precise analyses on the decomposition of power consumptions and timing impact, and translating them into cost functions in core engine of clock gating exploration.