| 摘要 |
PURPOSE: To suppress ringings, occurring on a transmission line in conformity with the situation of a packaged system even when high-speed operation with small signal amplitude. CONSTITUTION: Dummy wiring 25 is provided simulating actual wiring 26, that connects semiconductor integrated circuits 2, 6 on a circuit board. The integrated circuits have a data output circuit 28 with a variable slew rate and a circuit 29 for measuring signal delay time from a signal send-out point to a signal reflection point (characteristic impedance mismatch point) by using the dummy wiring 25. Signal transition time of the output circuit is determined, by using the delay time obtained by the measuring circuit. The transition time is at least twice the delay time, which extends from the send-out point to the nearest branch of the wiring. This enables transmission of signals with mitigated reflection by the nearest reflection point.
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