| 摘要 |
PURPOSE:To increase the speed of switching operation by constituting a precise current switching type switching unit by using only NPN transistors. CONSTITUTION:When one of digital input sources B1T1, B1T2... is applied with a higher voltage than logic reference potential Vth, the base potential of NPN transistor TR35 becomes higher than that of NPN TR36, so that the collector current of NPN TR42 will flow via TR35. As a result, the base potential of NPN TR29 becomes lower than that of NPN TR30. Therefore, since precise current I flows through TR30, this appears at output bus 60 as an output. When the digital input voltage is lower than potential Vth, the operation is completely inverse of the above-mentioned one and current I flows from the ground via TR29 and never appears at the output bus. This circuit constitution can shorten the settling time extremely and reduce the glitches. |
