Continuous application and decompression of test patterns to a circuit-under-test
First Claim
1. A method, comprising:
- receiving a compressed test pattern of bits at one or more input channels of a decompressor;
decompressing the compressed test pattern into a decompressed test pattern of bits as the compressed test pattern is being received by the decompressor; and
applying the decompressed test pattern to scan chains of the circuit-under-test,wherein the number of the one or more input channels is fewer than the number of the scan chains to which the decompressed test pattern is applied, andwherein the decompressing the compressed test pattern comprises logically combining bits of the compressed test pattern with bits stored in the decompressor and generating during a time period a greater number of decompressed test pattern bits than the number of compressed test pattern bits provided to the decompressor during the same time period.
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Accused Products
Abstract
A method for applying test patterns to scan chains in a circuit-under-test. The method includes providing a compressed test pattern of bits; decompressing the compressed test pattern into a decompressed test pattern of bits as the compressed test pattern is being provided; and applying the decompressed test pattern to scan chains of the circuit-under-test. The actions of providing the compressed test pattern, decompressing the compressed test pattern, and applying the decompressed pattern are performed synchronously at the same or different clock rates, depending on the way in which the decompressed bits are to be generated. A circuit that performs the decompression includes a decompressor such as a linear feedbackstate machine adapted to receive a compressed test pattern of bits. The decompressor decompresses the test pattern into a decompressed test pattern of bits as the compressed test pattern is being received. The circuit further includes scan chains for testing circuit logic, the scan chains coupled to the decompressor and adapted to receive the decompressed test pattern.
164 Citations
19 Claims
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1. A method, comprising:
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receiving a compressed test pattern of bits at one or more input channels of a decompressor; decompressing the compressed test pattern into a decompressed test pattern of bits as the compressed test pattern is being received by the decompressor; and applying the decompressed test pattern to scan chains of the circuit-under-test, wherein the number of the one or more input channels is fewer than the number of the scan chains to which the decompressed test pattern is applied, and wherein the decompressing the compressed test pattern comprises logically combining bits of the compressed test pattern with bits stored in the decompressor and generating during a time period a greater number of decompressed test pattern bits than the number of compressed test pattern bits provided to the decompressor during the same time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A circuit, comprising:
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a decompressor adapted to receive a compressed test pattern of bits and decompress the test pattern into a decompressed test pattern of bits as the compressed test pattern is being received by the decompressor, the number of bits in the compressed test pattern being less than the number of bits in the decompressed test pattern, the decompressor comprising one or more input logic gates adapted to receive the compressed test pattern of bits and logically combine the compressed test pattern of bits with bits stored within the decompressor; and scan chains for testing circuit logic, the scan chains being coupled to the decompressor and adapted to receive the decompressed test pattern, the number of scan chains coupled to the decompressor being greater than the number of input logic gates. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification