Output Driver With Controlled Rise/Fall Times
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
An emitter follower output driver is proposed, the slew rate of which can be arbitrarily adjusted. For that purpose, the input of the output driver is provided with a capacitor which is charged via a first constant current source and discharged via a second constant current source. The desired slew rate is obtained by suitably dimensioning the two constant current sources. The figure shows a circuit diagram. Capacitor C at the input of the circuit is charged by current IC of the first constant current source 1. Current ID of the second constant current source 2, which comprises a difference amplifier T3, T4, controlled by a read amplifier (not shown), discharges capacitor C. If current ID = 2 x IC, the leading and the trailing edge are equal.