Signal receiver with skew-tolerant strobe gating
A gating signal for masking overhead transitions in a data-strobe signal is generated adaptively based on timing events in the incoming data-strobe signal itself to yield a gating window that opens and closes deterministically with respect to active edges of the data-strobe signal.
1. A method of operation within an integrated-circuit component, the method comprising:
receiving, via an external timing signal link, a timing signal having a sequence of data-timing transitions preceded by one or more preamble transitions and succeeded by one or more postamble transitions;
generating a control pulse having a width not greater than a time interval between an initial one of the data-timing transitions and a final one of the data-timing transitions;
logically combining the control pulse and the timing signal to generate a gating pulse having a time-varying phase relative to an internal timing domain of the integrated-circuit component; and
logically combining the gating pulse and the first timing signal to produce a gated instance of the timing signal that lacks the one or more preamble transitions and the one or more postamble transitions.
2. The method of claim 1 wherein generating the control pulse comprises generating the control pulse synchronously with respect to a clock signal that establishes the internal timing domain such that the control pulse has a fixed phase relation to the internal timing domain.
3. The method of claim 1 wherein the timing signal has a time-varying phase relative to the internal timing domain.
4. The method of claim 3 wherein generating the gating pulse having the time-varying phase relative to the internal timing domain comprises varying a phase of at least one edge of the gating pulse relative to the internal timing domain in accordance with the time-varying phase of the timing signal.
5. The method of claim 1 wherein the control pulse comprises a leading edge and a trailing edge separated by a first time interval that corresponds to the width of the control pulse, and wherein logically combining the control pulse and the timing signal comprises generating a leading edge of the gating pulse in response to a falling edge of the timing signal that occurs during the first time interval.
6. The method of claim 1 wherein logically combining the control pulse and the timing signal comprises logically ANDing the control pulse with an inverted instance of the timing signal to generate a leading edge of the gating pulse.
7. The method of claim 1 wherein logically combining the control pulse and the timing signal comprises sampling the control pulse in response to one or more falling edges of the gated instance of the timing signal to generate a trailing edge of the gating pulse.
8. The method of claim 1 wherein the data-timing transitions are offset from one another by a bit-time interval, the method further comprising shifting a phase of the first timing signal by half the bit-time interval prior to logically combining the gating pulse with the first timing signal.
9. The method of claim 1 wherein generating the control pulse having the width not greater than the time interval between the initial and final ones of the data-timing transitions comprises generating the control pulse with a width that nominally matches the time interval between the initial and final ones of the data-timing transitions.
10. The method of claim 1 wherein generating the control pulse having the width not greater than the time interval between the initial and final ones of the data-timing transitions comprises generating a leading edge of the control pulse prior to the initial one of the data-timing transitions and generating a trailing edge of the control pulse prior to the final one of the data-timing transitions such that a time interval between the leading and trailing edges of the control pulse is skewed relative to the time interval between the initial and final ones of the data-timing transitions.
11. An integrated-circuit component comprising:
a timing input to receive a timing signal having a sequence of data-timing transitions preceded by one or more preamble transitions and succeeded by one or more postamble transitions; and
gating circuitry to:
generate a control pulse having a width not greater than a time interval between an initial one of the data-timing transitions and a final one of the data-timing transitions; and
logically combine the control pulse and the timing signal to generate a gating pulse having a time-varying phase relative to an internal timing domain of the integrated-circuit component; and
logically combine the gating pulse and the timing signal to produce a gated instance of the timing signal that lacks the one or more preamble transitions and the one or more postamble transitions.
12. The integrated-circuit component of claim 11 wherein the gating circuitry to generate the control pulse comprises circuitry to generate the control pulse synchronously with respect to a clock signal that establishes the internal timing domain such that the control pulse has a fixed phase relation to the internal timing domain.
13. The integrated-circuit component of claim 11 wherein:
the timing signal has a time-varying phase relative to the internal timing domain; and
the gating circuitry to logically combine the control pulse and the timing signal to generate the gating pulse having the time-varying phase relative to the internal timing domain comprises circuitry to vary a phase of at least one edge of the gating pulse relative to the internal timing domain in accordance with the time-varying phase of the timing signal.
14. The integrated-circuit component of claim 11 wherein the control pulse comprises a leading edge and a trailing edge separated by a first time interval that corresponds to the width of the control pulse, and wherein the gating circuitry to logically combine the control pulse and the timing signal comprises circuitry to generate a leading edge of the gating pulse in response to a falling edge of the timing signal that occurs during the first time interval.
15. The integrated-circuit component of claim 11 wherein the gating circuitry to logically combine the control pulse and the timing signal comprises circuitry to logically AND the control pulse with an inverted instance of the timing signal to generate a leading edge of the gating pulse.
16. The integrated-circuit component of claim 11 wherein the gating circuitry to logically combine the control pulse and the timing signal comprises circuitry to sample the control pulse in response to one or more falling edges of the gated instance of the timing signal to generate a trailing edge of the gating pulse.
17. The integrated-circuit component of claim 11 wherein the data-timing transitions are offset from one another by a bit-time interval, the integrated-circuit component further comprising circuitry to shift a phase of the first timing signal by half the bit-time interval prior to logically combining the gating pulse with the first timing signal.
18. The integrated-circuit component of claim 11 wherein the gating circuitry to generate the control pulse having the width not greater than the time interval between the initial and final ones of the data-timing transitions comprises circuitry to generate the control pulse with a width that nominally matches the time interval between the initial and final ones of the data-timing transitions.
19. The integrated-circuit component of claim 11 wherein the gating circuitry to generate the control pulse having the width not greater than the time interval between the initial and final ones of the data-timing transitions comprises circuitry to generate (i) a leading edge of the control pulse prior to the initial one of the data-timing transitions and (ii) a trailing edge of the control pulse prior to the final one of the data-timing transitions such that a time interval between the leading and trailing edges of the control pulse is skewed relative to the time interval between the initial and final ones of the data-timing transitions.
20. An integrated-circuit component comprising:
a timing input to receive a timing signal having a sequence of data-timing transitions preceded by one or more preamble transitions and succeeded by one or more postamble transitions; and
means for:
generating a control pulse having a width not greater than a time interval between an initial one of the data-timing transitions and a final one of the data-timing transitions; and
logically combining the control pulse and the timing signal to generate a gating pulse having a time-varying phase relative to an internal timing domain of the integrated-circuit component; and
logically combining the gating pulse and the timing signal to produce a gated instance of the timing signal that lacks the one or more preamble transitions and the one or more postamble transitions.