| 摘要 |
PURPOSE:To always improve the trailing characteristic of a logic circuit effectively by providing a differentiating capacitor for supplying a conduction drive signal to a base of a pull-down transistor(TR) and a circuit feeding back a potential at an emitter follower output to a base of the pull-down TR. CONSTITUTION:A base bias condition of pull-down TRs Q21,Q22 is changed in response to a load condition of an output of emitter followers 11, 12 and when a residual charge of an external load is much, the residual charge increases the base bias level to increase the conduction drive level of the TRs Q21, Q22. Moreover, the potential at the output of the emitter followers 11, 12 is fed back to the base of the pull-down TRs Q21, Q22 in terms of DC and a charge/discharge current able to be supplied as a conduction drive signal to the base of the pull-down TRs Q21, Q22 from differentiating capacitors C1, C2 is increased at the transient state detection. Thus, the leading characteristic of the logic circuit using the emitter followers 11, 12 as the output stage is always effectively improved independently of the external load. |
