Method and System for Setup/Hold Characterization in Sequential Cells

A method for integrated circuit cell characterization, the method comprising:

• providing a first and a second sequential cells with cross-connected inputs, the first and the second sequential cells being substantially identical, wherein a clock input of the first sequential cell is coupled to the data input of the second sequential cell, thereby forming a first node, and wherein a clock input of the second sequential cell is coupled to the data input of the first sequential cell, thereby forming a second node;
• providing a first periodic signal to the first node and providing a second periodic signal to the second node, the first and the second periodic signal being launched by a trigger signal;
• detecting a first state transition in an output signal of the first sequential cell;
• fetching a first number of elapsed cycles of the first periodic signal until the first state transition in the first sequential cell;
• detecting a second state transition in an output signal of the second sequential cell;
• and
• fetching a second number of elapsed cycles of the second periodic signal until the second state transition in the second sequential cell.

An integrated circuit cell timing characterization circuit comprising:

• a first sequential cell coupled to a first clock signal and a second clock signal, the first clock signal being a clock for the first sequential cell and the second clock signal being an input data for the first sequential cell;
• a second sequential cell coupled to the first clock signal and the second clock signal, the second clock signal being a clock for the second sequential cell and the first clock signal being an input data for the second sequential cell;
• a first counter coupled to the first clock signal;
• a first fetch unit coupled to the first counter and to an output of the first sequential cell;
• a second counter coupled to the second clock signal;
• and
• a second fetch unit coupled to the second counter and to an output of the second sequential cell.