Calibrated automatic test system
First Claim
1. An automatic test system for testing an electronic device comprising:
- a. a programmable test station for generating test function digital codes;
b. a test head having;
a plurality of output pin means for connection to a device disposed to be tested; and
a plurality of CMOS integrated circuit means, a different one of which is coupled to each of said plurality of output pin means, each for providing test signals to a different pin of said device under test;
c. external calibration means selectively connectable to each of said output pin means of said test head for receiving said test signals and for deriving therefrom error correction factors for calibrating each of said CMOS integrated circuit means; and
d. error correction memory means for storing said error correction factors therein and for altering said test function digital codes from said test station with said error correction factors to produce intermediate signals which cause the correct test signal to be applied to each output pin when said intermediate signals are each applied to said plurality of CMOS integrated circuit means.
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Accused Products
Abstract
A calibrated automatic test system includes a test station for generating digital test function codes and a test head containing a plurality of I/O pins for connection to a device under test. Each I/O pin includes a pin electronics circuit responsive to the digital test function codes for providing test signals to the device under test. The pin electronics circuits are inexpensive CMOS IC'"'"'s and lack the accuracy needed to test VLSI devices at the frequencies of interest. An external calibration unit is connected to each I/O pin and data measurements are taken which represent the performance of the CMOS IC'"'"'s. The data measurements are converted to calibrated function codes representing desired data values which are then stored in correction memory circuits which respond to nominal digital test function codes and substitute in their places calibrated function codes which are then supplied to the pin electronics circuits.
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Citations
14 Claims
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1. An automatic test system for testing an electronic device comprising:
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a. a programmable test station for generating test function digital codes; b. a test head having; a plurality of output pin means for connection to a device disposed to be tested; and a plurality of CMOS integrated circuit means, a different one of which is coupled to each of said plurality of output pin means, each for providing test signals to a different pin of said device under test; c. external calibration means selectively connectable to each of said output pin means of said test head for receiving said test signals and for deriving therefrom error correction factors for calibrating each of said CMOS integrated circuit means; and d. error correction memory means for storing said error correction factors therein and for altering said test function digital codes from said test station with said error correction factors to produce intermediate signals which cause the correct test signal to be applied to each output pin when said intermediate signals are each applied to said plurality of CMOS integrated circuit means. - View Dependent Claims (2)
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3. An automatic test system for testing electrical devices comprising:
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a. a programmable test station for generating test functions represented by digital test codes; b. test head means coupled to said test station for providing output means for connection to a device disposed to be tested; c. a plurality of circuit means, one for each output means of said test head means for providing test data to said device under test in response to calibrated digital test codes; d. calibration means selectively connectable to said test head for deriving calibrated digital test codes to be selectively substituted for said digital test codes generated by said test station; and e. error correction memory means for storing said calibrated digital test codes. - View Dependent Claims (4, 5, 6, 7)
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8. An automatic test system for testing electrical devices comprising:
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a. a programmable test station; b. a multipin connector controlled by said test station, said multipin connector including electronic circuits for each pin of said connector for executing predetermined test functions; c. correction memory means associated with each of said electronic circuits for providing codes representing calibrated test functions; and d. external calibration means selectively connectable to said multipin connector for determining said codes to be stored in said correction memory means. - View Dependent Claims (9, 10, 11, 12)
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13. A method of calibrating an automatic test system for testing electrical devices comprising the steps of:
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a. connecting a calibration circuit including a memory to an output pin of said automatic test system; b. initiating a plurality of test functions from said automatic test system, each having a distinct digital code; c. applying said distinct digital codes of step b. to said output pin; d. measuring the data produced at said output pin by each of said distinct digital codes with said calibration circuit and storing said data is said memory; e. determining a desired data value at said output pin for each of said distinct digital codes; f. determining a data correction factor from the measured data of step d. and the desired data value of step e. for each distinct digital code applied to said output pin in step c.; and g. storing said data correction factor in an error correction memory associated with said output pin of said automatic test system. - View Dependent Claims (14)
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Specification