Paper Review: Activity-Driven Clock Design

Abstract
In this paper, we investigate reducing the power consumption of a synchronous digital system by minimizing the total power consumed by the clock signals. We construct activity-driven clock trees wherein sections of the clock tree are turned off by gating the clock signals. Since gating the clock signal implies that additional control signals and gates are needed, there exists a tradeoff between the amount of clock tree gating and the total power consumption of the clock tree.We exploit similarities in the switching activity of the clocked modules to reduce the number of clock gates. Assuming a given switching activity of the modules, we propose three novel activity-driven problems: a clock tree construction problem, a clock gate insertion problem, and a zero-skew clock gate insertion problem. The objective of these problems is to minimize system’s power consumption by constructing an activity-driven clock tree.We propose an approx- imation algorithm based on recursive matching to solve the clock tree construction problem. We also propose an exact algorithm employing the dynamic programming paradigm to solve the gate insertion problems. Finally, we present experimental results that verify the effectiveness of our approach. This paper is a step in understanding how high-level decisions (e.g., behavioral design) can affect a low-level design (e.g., clock design).

Paper Location
IEEEXplore

Citation
[1] a. Farrahi, a. Srivastava, G. Tellez, and M. Sarrafzadeh, "Activity-driven clock design," IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, vol. 20, 2001, pp. 705-714.
Positive

• Takes the problem at hand and rethings how it should be approached. A very novel method of doing things!
• Uses fairly standard graph theory notation to set up the problem
• Provides proof of its theorems, unlike many other papers.

Negative

• Should include gate sizing comparison for leakage reduction
• Not necessarily true that a 'random bit pattern' will produce a reasonable benchmark for them to compare against.