US Patent 7106093 Semiconductor device

A semiconductor device having a plurality of cascaded IC's (14, 15, 16), wherein the matching impedance between a signal transmission path (12) connected to an external signal transmission path and an input-side or output-side IC (14, 16) is set at 50 ohms which is equal to the characteristics impedance of the external signal transmission path. The matching impedance between a internal signal transmission path (13) and an input-side or output-side IC or intermediate IC is set at 200 ohms which is higher than the 50 ohms. The semiconductor device reduces the current dissipation and can operate at a higher speed.