| 摘要 |
PURPOSE:To increase a current capacity and to reduce a gate width by securing such a constitution where an FET which directly drives a termination resistance has the threshold voltage lower than that of another FET. CONSTITUTION:The open drain FET Q20 and Q21 and a current source FET Q22 have the threshold voltage levels of about -0.6V lower than the threshold voltage level of about -0.2V of other FET Q1, Q2, Q8 Q9, etc., of an internal circuit. Thus an output circuit consists of the FETs having different threshold voltage levels. In this respect, the bias circuits using the FETs of the same characteristics are set to the FETs having different threshold voltage levels respectively in terms of the matching properties of the element characteristics. The output waveform of the output circuit has the improved rise characteristics compared with the conventional output waveform. For instance, the output waveform of this new output circuit suffices with about 30ps against about 40ps required for the conventional waveform in terms of the output waveform levels 20-80%. |
