Off-Chip Receiver With Variable Threshold
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Circuitry is disclosed for semiconductor applications which provides a variable receiver threshold as a function of receiver output. As a result, the receiver's threshold is lowered or raised in a direction so as to increase its noise margin. A time delay before the threshold is changed produces a hysteresis in the receiver's gain curve as a function of input transition time. The circuit is shown in the figure. D1 and D3 are low Schottky barrier diodes (SBDs); the other diodes are high Schottky barrier diodes. Transistors T1 and T3 along with diodes D1 and D2 plus associated parts form the receiver of a semiconductor chip. D1 acts to isolate the circuit from the transmission line with the off-chip signal connected to IN. The threshold of the input circuit is VBE (of T1) + Vf (of D2) - Vf (of D1).