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Output Driver With Controlled Rise/Fall Times

IP.com Disclosure Number: IPCOM000062683D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09

Publishing Venue

IBM

Related People

Authors:
Klein, W Klink, E Wernicke, FC [+details]

Abstract

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.