Impedance matching commonly and independently

摘要

A semiconductor device is easy for high accuracy impedance matching against differences in impedance of a transmission line and a package wire. A semiconductor chip having external output buffers and a packaging circuit are included. Each external output buffer has a first output portion whose internal impedance is adjusted commonly with other external output buffers in accordance with impedance control data and a second output portion whose internal impedance is adjusted independently of other external output buffers. Both of the first and second output portions are connected in parallel to a common output terminal. Common adjustment by the first output portion can cope with impedance of the transmission line and individual adjustment by the second output portion can cope with a difference of package wires.