Open-Line Detect Differential Driver Circuit for Chips
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
This circuit produces a differential off-chip transmission-line driver function with the added capability to determine whether one and/or both transmission lines are open. The transmission line is open if the physical transmission line is open or the terminator is missing. This open-line function raises a logic signal high when the open-line condition is present. The figure shows a schematic of the Open-Line Detect Differential Driver Circuit. The circuit is implemented around on-chip cascode current switch logic. The logic used has two levels of cascode or stacking. The logic signals at the top level of stacking swing around the KRF1 reference voltage, and the logic signals at the second or bottom level of stacking swing around the KRF2 reference voltage.