Modulation noise estimation mechanism
First Claim
1. A method of estimating modulation noise for use in a transmitter having a phase locked loop, said method comprising the steps of:
- calculating an average of historical samples of phase error samples produced by said phase locked loop;
subtracting said average from a current phase error sample to yield a normalized phase error;
generating an exception event if said normalized phase error exceeds a threshold; and
repeating said steps of calculating, subtracting and generating over a period of time and outputting a failure indication if the number of exception events exceeds a maximum criteria and a pass indication otherwise.
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Abstract
An on-chip reduced complexity modulation noise estimation mechanism for performing nonlinear signal processing to analyze modulation noise to determine whether a semiconductor device under test complies with the performance criteria set by specifications or a standard corresponding thereto. When used in a two-point transmitter modulation architecture, the mechanism relies on the fact that the noise statistics at the output of the transmitter can be determined by observing the phase error output of the phase detector within the phase locked loop. In the digital embodiment of the mechanism, the phase error signal is compared to a configurable threshold value to generate an exception event. If the number of exception events exceeds a configurable max_fail value after comparisons of a configurable number of phase error samples, the test fails. A pass/fail signal is output reflecting the result of the test. The test comprises a configurable number of test samples to permit flexibility in the tradeoff between the time required to complete the test versus the statistical reliability of the test result, i.e. the probability of it correctly determining whether the tested device complies with target specifications.
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Citations
35 Claims
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1. A method of estimating modulation noise for use in a transmitter having a phase locked loop, said method comprising the steps of:
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calculating an average of historical samples of phase error samples produced by said phase locked loop;
subtracting said average from a current phase error sample to yield a normalized phase error;
generating an exception event if said normalized phase error exceeds a threshold; and
repeating said steps of calculating, subtracting and generating over a period of time and outputting a failure indication if the number of exception events exceeds a maximum criteria and a pass indication otherwise. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An apparatus for estimating modulation noise for use in a transmitter having a phase locked loop, comprising:
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means for calculating an average of historical samples of phase error samples produced by said phase locked loop;
means for subtracting said average from a current phase error sample to yield a normalized phase error;
means for generating an exception event if said normalized phase error exceeds a threshold; and
means for repeating said functions of calculating, subtracting and generating over a period of time and outputting a failure indication if the number of exception events exceeds a maximum criteria and a pass indication otherwise. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An apparatus for estimating modulation noise in a transmitter, comprising:
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first means for estimating frequency deviation errors of a signal output from said transmitter utilizing measurements of a phase error signal observed within a phase locked loop in said transmitter;
second means for comparing a plurality of phase error signal samples over a period of time to a threshold and generating an exception event each time a phase error signal sample exceeds said threshold; and
generating a failure indication if the number of exception events exceeds a criteria and generating a pass indication otherwise. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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Specification