Value assignment of adjustable delay buffers for clock skew minimization in multi-voltage mode designs

In synchronous circuit designs, clock skew is difficult to minimize because a single physical layout of a clock tree must satisfy multiple constraints in a complicated power mode environment where certain modules may operate with different voltages. In this paper, we use adjustable delay buffers (ADB) whose delays can be tuned or adjusted to minimize clock skew under different power modes. Assuming that the positions of k ADBs are already determined, we propose a linear-time optimal algorithm which assigns the values of ADBs so that the skew is optimal among all possible ADB assignments. We also propose an efficient heuristic to determine good positions for ADBs. Our results show significant improvement when compared to cases without ADBs.