Variable delay circuit for producing a delay which varies as a hyperbolic function of the current intensity
AssigneeBull SAS
InventorRoland Marbot
Life of this patent
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Abstract
The variable delay device 10 includes an ECL gate 11 associated with an adjusting circuit 23 acting on the resistance of resistive load elements 14, 15 of transistors 12, 13 and the resistive load element 18 of the current source 16 at the gate 11 to cause the current produced by the source 16 to vary linearly while keeping the voltage at the collectors of the transistors 12, 13 constant. The range of variation of the resistances is selected in such a way that the delay between the input signals IN, IN* and OUT, OUT* varies substantially linearly. The invention is particularly applicable to systems for digital data transmission at a very high rate, of more than 1 gigabit per second.
Claims17
An variable delay device (10), comprising at least one differential amplifier (11) having first and second transistors (12, 13), a current source (16) for supplying current to said first and second transistors, first and second variable resistive load elements (14, 15) serially connected with said first and second transistors, respectively, varying means (123, 18a-18d) connected to said current source for varying current intensity supplied from the current source to produce a variable delay and maintaining means (23, 14a-14d, 15a-15d) for maintaining the voltages across each of said first and second load elements at a substantially constant value regardless of the current intensity flowing through said first and second load elements, whereby said variable delay varies as a hyperbolic function of the current intensity produced by the current source.
Dependencies are inferred from the claim text.