Signal Integrity Measurement Systems and Methods Using a Predominantly Digital Time-Base Generator
First Claim
1. A tester for testing a circuit under test, comprising:
- a time-base generator for generating a time-base signal as a function of a first clock signal, said time-base generator including;
modulation circuitry for generating a rapidly varying phase signal as a function of said first clock signal; and
a phase filter for receiving the rapidly varying phase signal and filtering therefrom unwanted high-frequency phase components so as to output the time-base signal; and
a sampler for sampling a signal under test as a function of the time-base signal so as to output a sampled signal.
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Abstract
Signal-integrity measurement systems and methods utilizing unique time-base generation techniques for controlling the sampling of one or more signals under test. A time-base generator made in accordance with the present disclosure includes a phase filter and modulation circuitry that generates a rapidly varying phase signal as a function of the output of a sigma-delta modulator. The phase filter filters unwanted high-frequency phase components from the rapidly varying phase signal. The filtered signal is used to clock one or more samplers so as to create sampling instances of the signal(s) under test. The sampling instances are then analyze using any one or more of a variety of techniques suited to the type of signal(s) under test.
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Citations
77 Claims
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1. A tester for testing a circuit under test, comprising:
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a time-base generator for generating a time-base signal as a function of a first clock signal, said time-base generator including; modulation circuitry for generating a rapidly varying phase signal as a function of said first clock signal; and a phase filter for receiving the rapidly varying phase signal and filtering therefrom unwanted high-frequency phase components so as to output the time-base signal; and a sampler for sampling a signal under test as a function of the time-base signal so as to output a sampled signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A method of testing a circuit under test, comprising:
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stimulating the circuit under test to produce a response signal under test; generating a rapidly varying phase signal as a function of a first clock signal; filtering the rapidly varying phase signal to remove unwanted high-frequency phase components so as to generate a fine resolution time-base signal; and sampling the response signal under test as a function of the time-base signal so as to provide a sampled signal under test. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72)
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73. A method of providing a time-base generator for a tester, comprising:
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determining a target sampling frequency for the tester; defining a bandwidth for a phase filter, the phase filter having a frequency response; providing a sigma-delta modulator as a function of the frequency response of the phase filter; simulating the sigma-delta modulator with a waveform so as to provide a simulation; selecting a finite-length sequence at the output of the simulation; and providing a sampler for sampling test data in response to the output of said sigma-delta modulator. - View Dependent Claims (74, 75, 76, 77)
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Specification