| 摘要 |
PURPOSE:To provide an output buffer circuit which can be easily designed and has high working speed and a low noise level. CONSTITUTION:A level sense circuit 103 detects that an output terminal OUT is set at a low level in a switching period when the terminal OUT is changed to a low level from a high level. Thus an AND gate 104 outputs a low level and an n-channel MOSFET 105 becomes non-conductive. Then the effective transistor size of a MOSFET which drives the terminal OUT is reduced and therefore the current flowing to a GND supply wiring is reduced. Thus the noises produced in the GND wiring can be suppress without deteriorating the high speed performance of a buffer and despite the reduction of the switching speed when the terminal OUT is set at a level close to the GND potential. |
