Measuring skew using on-chip sampling
AssigneeSun Microsystems, Inc.
InventorsDean Liu, Gin S. Yee, Tyler J. Thorp, Pradeep R. Trivedi
Life of this patent
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Abstract
A method and apparatus to determine skew of an on-chip signal without physical probing of the on-chip signal on the chip is provided. The method and apparatus use an externally generated reference signal that is distributed to one or more on-chip samplers that input the on-chip signal. Then, by modulating the externally generated reference signal, transitions of the on-chip signal can be detected at the one or more on-chip samplers so that the skew of the on-chip signal can be determined.
Claims18
A method for measuring skew of an on-chip signal on a computer chip, comprising:
- distributing an externally generated reference signal to the computer chip;
- inputting the externally generated reference signal and the on-chip signal to a first on-chip sampler, wherein the first on-chip sampler is disposed on a first portion of the computer chip;
- inputting the externally generated reference signal and the on-chip signal to a second on-chip sampler, wherein the second on-chip sampler is disposed on a second portion of the computer chip;
- selectively modulating the externally generated reference signal to determine at least one transition of the on-chip signal at the first portion and the second portion;
- and
- determining skew of the on-chip signal between the first portion and the second portion dependent upon an output from the first on-chip sampler and an output from the second on-chip sampler.
An on-chip sampler that is used to measure skew of an on-chip signal, comprising:
- an inverting/buffering stage that inputs an externally generated reference signal and generates a first control signal and a second control signal that are used in the on-chip sampler,
- a first stage that inputs the on-chip signal and outputs a signal to the second stage based on the first and second control signals;
- and
- a second stage that inputs the signal outputted from the first stage based on the first and second control signals,
- wherein the externally generated reference signal is modulated to detect a transition on the on-chip signal.
A distribution of on-chip samplers, comprising:
- a first on-chip sampler disposed on a first portion of a computer chip;
- a second on-chip sampler disposed on a second portion of the computer chip;
- and
- a last on-chip sampler disposed on a last portion of the computer chip,
- wherein an externally generated reference signal and an on-chip signal serves as inputs to the first, second, and last on-chip samplers.
Dependencies are inferred from the claim text.