Test system with high accuracy time measurement system
First Claim
1. A method of operating an automatic test system of the type having a time measurement circuit characterized in that the time measurement circuit has a mode of operation for repetitive events to increase the resolution of the time measurements comprising:
- a) introducing time variation into the signal before measuring the timing of an event within the signal;
b) repetitively measuring the timing of the event within the signal;
c) averaging the time measurements to thereby determine the timing of the event in a resolution greater than the resolution of the time measurements.
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Abstract
An automatic test system for testing semiconductor devices. The test system includes time measurement circuitry. The time measurement circuitry can be programmed to operate in a single-shot mode or a higher resolution, repetitive-measurement mode. To simplify the design and construction of the system, the same time measurement circuit is used in both measurement modes. To provide higher resolution in the repetitive measurement mode, variation is introduced into the signal to be measured and resulting measurements are averaged. Any bias introduced by the variation is subtracted from the averaged value.
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Citations
20 Claims
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1. A method of operating an automatic test system of the type having a time measurement circuit characterized in that the time measurement circuit has a mode of operation for repetitive events to increase the resolution of the time measurements comprising:
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a) introducing time variation into the signal before measuring the timing of an event within the signal;
b) repetitively measuring the timing of the event within the signal;
c) averaging the time measurements to thereby determine the timing of the event in a resolution greater than the resolution of the time measurements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An automatic test system of the type having a time measurement circuit characterized in that the time measurement circuit has a mode of operation for repetitive events to increase the resolution of the time measurements, operated according to a method comprising:
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a) introducing time variation into the signal before measuring the timing of an event within the signal;
b) repetitively measuring the timing of the event within the signal;
c) averaging the time measurements to thereby determine the timing of the event in a resolution greater than the resolution of the time measurements. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A CMOS integrated circuit chip adapted to increase the resolution of repetitive measurements in an automatic test system, comprising:
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a) a time stamp circuit having an input and an output, the output representing time measurements with a first predetermined resolution;
b) a variable delay element connected to the input of the time stamp circuit;
c) an averaging circuit connected to the output of the time stamp circuit having an input coupled to the output of the time stamp circuit and an output providing time measurements with a second resolution, greater than the first predetermined resolution. - View Dependent Claims (20)
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Specification