High-speed data sampler with input threshold adjustment
Method and apparatus for sampling a high-speed digital signal include providing a data signal to a differential data input circuit, an offset control signal, and a strobe pulse. In response to the strobe pulse, the data signal is resolved into an output logic state based to a relatively greater extent on the differential data signal and to a relatively lesser extent on the offset control signal.
1. A data sampling system for resolving a high speed data signal, comprising:
a circuit that samples and resolves the high speed data signal in response to a strobe signal, including:
input means for accepting the high speed data signal and affecting a resolution of a logic state of the high speed data signal;
offset input means for accepting an offset signal and affecting the resolution of the logic state of the high speed data signal to a lesser extent than the input means affects the resolution; and
offset control means for generating the offset signal based on an expectation of a future value of the high speed data signal, wherein the offset control means is adapted to generate an offset signal that causes the circuit to favor resolving to a logic state that is an inverse of the most recently resolved logic state.
2. A data sampling system for resolving a high speed data signal, comprising:
a circuit that samples and resolves the high speed data signal in response to a strobe signal, including:
input means for accepting the high speed data signal and affecting a resolution of a logic state of the high speed data signal;
offset input means for accepting an offset signal and affecting the resolution of the logic state of the high speed data signal to a lesser extent than the input means affects the resolution; and
offset control means for generating the offset signal based on an expectation of a future value of the high speed data signal, wherein the offset signal affects a rate of the resolution of the logic state such that an offset signal tending to favor resolution of a first logic value causes the circuit to output the first logic value more rapidly than without the offset signal.