Patent ID: 6877121

Claim:
A method for testing a circuit including AC coupled interconnects, the circuit having a transmitting IC and a receiving IC that are coupled together by an AC interconnection, each IC having a Boundary Scan Cell (BSC) connected to a reference clock, the method comprising: generating an AC signal based on the reference clock and a value held in the BSC of the transmitting IC, the AC signal having a first phase if a first value is held in the BSC, and a second phase if a second value is held in the BSC; generating, for the receiving IC, a sync pulse signal based on a test reset signal; capturing, in the BSC of the receiving IC, a default phase of said AC signal in response to said sync pulse signal; sampling a phase of the AC signal; comparing the default phase with the sampled phase of the AC signal; and generating a phase decode signal based on said comparing.