| 摘要 |
<p>An output voltage driver apparatus for an ECL circuit driving a capacitive load (CL) which comprises an emitter follower means (117) having an output emitter (118) and a reference emitter (120). The output emitter is connected to the capacitive load. A pull-down transistor means (123) is connected to the output emitter and provides a transient pull-down current for a capacitive load when the output voltage swings from a high level to a low level. A biasing means (125) is connected between the reference emitter of the emitter follower means and the pull-down transistor means so that the pull-down transistor means is biased to turn on when the voltage at the output emitter is higher than the voltage at the reference emitter by a turn-on voltage. Because the capacitive load will hold the voltage of the output emitter higher than that of the reference emitter until the capacitance of the load is discharged, the pull-down transistor means provides a transient pull-down current which speeds up the switching time of the emitter couple logic circuit.</p> |
