Clock skew optimization continues to be an important concern in circuit designs. To overcome the influence caused by PVT variations, the automatic skew synchronization scheme can dynamically adjust and reduce the clock skew after a chip is manufactured. There are two key components in the skew synchronization scheme: Adjustable Delay Buffer (ADB) and Phase Detector (PD). Most previous researchers have emphasized on ADB placement issues. In this paper, we show that the connection between FFs and PDs can also greatly influence the final clock skew due to the insertion of the PDs. We first analyze the influence of PD connection structures. Then we propose an algorithm to generate a PD connection structure which achieves the minimum influence to the clock skew. Our experimental results are very encouraging.

Clock skew minimization has been an important design constraint. However, due to the complexity of Process, Voltage, and Temperature (PVT) variations, the minimization of clock skew has faced a great challenge. To overcome the influence of PVT variations, several previous works proposed Post Silicon Tuning (PST) architecture to dynamically balance the skew of a clock tree. In the PST architecture, there are two main components: Adjustable Delay Buffer (ADB) and Phase Detector (PD). Most previous works focus on determining good positions of ADBs in a PST design. In this paper, we first show that which pairs of FFs are connected to PDs, called PD structure, also greatly influence the complexity of hardware control for a PST design. Without careful planning of a PD structure, we need large number of control signals to adjust the delays of ADBs. In addition, we also show that a PD structure may influence the accuracy of the clock skew. Among possible connection structures, this paper proposes an efficient PD structure which not only simplifies the hardware control but also minimizes the clock skew of a PST design.