US 2004/0070409 A1Published application

Adaptive reference voltage method and system

AssigneeDell Products L.P.

InventorJames B. Mobley

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Abstract

An adaptive reference voltage method and system analyzes a received bus signal to evaluate voltage swing characteristics and adjusts the reference voltage for reading the signal to a level that compensates for variations in margins between high and low signal switching values such as are introduced by noise. A bus input signal analyzer circuit incorporated in an integrated circuit analyzes the bus signal received at the integrated circuit to adjust the reference voltage used by the integrated circuit. In one embodiment, the bus input signal analyzer circuit applies a feedback loop to adapt the reference voltage by setting high and low input values to a reference voltage generation circuit with the reference voltage centered between the high and low values, such as results from a resistor divider network.

Claims20

Dependent claims

A system for adapting a reference voltage signal used by an integrated circuit to determine if a bus input signal is high or low, the system comprising:

a reference voltage generator circuit having a low voltage input, a high voltage input and a reference voltage output, the reference voltage generator circuit operable to output the reference voltage signal from a low voltage signal received at the low voltage input and a high voltage signal received at the high voltage input;
a bus input signal analyzer circuit interfaced with the bus input signal, the low voltage input, the high voltage input and the reference voltage output, the bus input signal analyzer circuit operable to compare bus input signal voltage swing characteristics with the low voltage, high voltage and reference voltage signals and to output a low voltage offset signal and a high voltage offset signal;
a low voltage input generator circuit interfaced with the reference voltage generator circuit low voltage input and the bus input signal analyzer circuit, the low voltage input generator circuit operable to generate a voltage for the low voltage input from the low voltage offset signal and a low voltage reference signal;
and
a high voltage input generator circuit interfaced with the reference voltage generator circuit high voltage input and the filter circuit, the high voltage input generator circuit operable to generate a voltage for the high voltage input from the high voltage offset signal and a high voltage reference signal.

2 more elements

Dependencies are inferred from the claim text.