Integrated Active Feedback Rise Time Slow-Down Technique
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
This article describes a very efficient rise time slow-down technique involving the use of active feedback in a modified bootstrap configuration and featuring a minimal increase in delay time, additional components and chip area. A typical push-pull driver circuit, illustrated by Fig. 1, operates with rise and fall times in the order of tr = 135 ps and tf = 224 ps, respectively, with driver delays at 50% signal level of tdp = 234 ps and tdn = 387 ps for positive and negative transitions. Fig. 2 shows only the output section of the driver for the purpose of illustrating the application of the integrated active feedback technique. In the case of a positive transition, as output node 9 is rising, capacitor C914 is feeding signal to the base of amplifier Q14 (transistor) which starts pulling current from node 3.