Arbitrator with no metastable voltage levels on output
AssigneeHewlett-Packard Development Company, L.P.
InventorGerard M Blair
Life of this patent
Estimating the term…
Abstract
An arbiter that includes a phase comparator receiving two input signals. The outputs of the phase comparator are propagated to a first SR type flip-flop. The outputs of the first SR type flip-flop are propagated to a second SR type flip-flop. The outputs of the second SR type flip-flop indicate which of the two input. signals changed first. The phase comparator can enter a metastable state. The first flip-flop reduces the magnitude of signal swing away from the power supply rails caused by the metastable state. The second flip-flop prevents any signal swing away for a power supply rail is not propagated to an output.
Claims18
An arbiter, comprising:
- a phase comparator having a first output that propagates a first metastable voltage level when a first input and a second input transition;
- a first flip-flop receiving said first metastable voltage level and having a second output that propagates a second metastable voltage level in response to said first metastable voltage level;
- and,
- a second flip-flop receiving said second metastable voltage level and having a third output that does not propagate a metastable voltage level when said second metastable voltage level is received.
An arbiter, comprising:
- a phase comparator, said phase comparator having a first input, a second input, a first output, and a second output, wherein at least one of said first output and said second output changes from a first output state to a metastable output state when said first input and said second input switch from a first voltage level to a second voltage level at nearly the same time;
- a first feedback circuit receiving said first output and said second output and producing a first feedback circuit output and a second feedback circuit output;
- and,
- a second feedback circuit receiving said first feedback circuit output and said second feedback circuit output.
A method of arbitrating between signals, comprising:
- comparing a first signal and a second signal to each other wherein the result of said comparing is one of a metastable state and a stable state;
- latching and propagating said stable state to a second latching stage if said result of said comparing is a stable state;
- and
- propagating a reduced version of said metastable state to said second latching stage if said result of said comparing is a metastable state.
A method of arbitrating between signals, comprising:
- comparing a first signal and a second signal to each other wherein the result of said comparing is one of a metastable state and a stable state;
- latching and propagating said stable state to a second latching stage if said result of said comparing is a stable state;
- propagating a reduced version of said metastable state to said second latching stage if said result of said comparing is a metastable state;
- and
- latching said stable state with said second latching stage and not latching said reduced version of said metastable state with said second latching stage.
An arbiter, comprising:
- phase comparison means that can enter a metastable state producing metastable voltages on at least one output;
- latching means that receives said metastable voltages;
- and,
- output means that receives a latched signal from said latching means and produces an output signal without metastable voltages.
Dependencies are inferred from the claim text.