| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a signal transmission circuit reducing a communicative waveform distortion during signal transmission. Ž<P>SOLUTION: Output data of a digital output signal are transmitted from a terminal A to a signal line 4 via an output buffer circuit 2 and an output impedance unit 3. The terminal A is also connected to an impedance variation unit 6 via an impedance control unit 5. The impedance variation unit 6 switches an impedance for terminating the signal line 4. When the output data transition from a high level to a low level, an impedance of the output impedance unit is changed in setting from XΩ to ∞Ω. At such a time, the impedance variation unit 6 switches the impedance for terminating the signal line 4 from ∞Ω to a characteristic impedance ZΩ of the signal line 4 through the impedance control unit 5. Thus, a reflection on the signal line 4 can be prevented and a waveform distortion can be suppressed. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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