A practical clock tree synthesis for semi-synchronous circuits

In this paper, we propose a new clock tree synthesis method for semi-synchronous circuits. A clock tree obtained by the proposed method is a multi-level multi-way clock tree such that a clockinput timing of each register is a multiple of a predefined unit delay and the length of interconnection from a parent node to its child is upper bounded. The clock trees are constructed for several practical circuits. The size of each clock tree is comparable to a zero skew clock tree. In order to assure the practical quality, they are examined under the five delay conditions, which cover various environmental and manufacturing conditions. As a result, they are proved stable under each condition and improve the clock speed up to 17.3 % against the zero skew clock trees. Keywords Semi-synchronous, clock-input timing, clock scheduling, environmental and manufacturing conditions, zero skew clock tree, various timing clock tree. 1