Defective capacitors in AC-coupled interconnections can significantly reduce the
performance of interconnection channels. Step pulse response is often used to see
ISI of a channel. In this paper, the response of a step pulse is proposed to be
measured for the purpose of testing AC-coupling capacitors. Hysteresis buffer is
used to measure ISI at regular intervals, which is not necessarily same as bit
interval. The hysteresis range is iteratively programmed to measure the ISI
signals. The result of proposed method showed great capabilities of detecting
defective AC-coupling capacitors.