Built-in self test circuit
First Claim
1. A built-in self test circuit comprising:
- a pattern generator;
a functional block subjected to a self test on the bases of an output from said pattern generator;
a space compressor for compressing a test result of said functional block; and
a comparator for comparing an output from said space compressor with an expected value and outputting a comparison result,wherein said functional block includes a plurality of modules having the same function and has a data input bit width O (positive integer) and a data output bit width M (positive integer),said pattern generator is constituted by a linear feedback shift register, having an output bit width P which is an integer satisfied by the equation O/N<
=P <
O/(N+1) where N is an integer more than 2, for generating a pseudorandom pattern and an iterative pseudorandom pattern output unit for distributing outputs from said linear feedback shift register in units of N outputs and outputting, to said functional block, an iterative pseudorandom pattern output having an iterative O-bit width (O=P*N) of the pseudorandom pattern output from said linear feedback shift register every P bits,said space compressor has a function of spatially compressing the M outputs from said functional block into L outputs (positive integer and M>
L), andsaid pattern generator, said functional block, said space compressor, and said comparator are built into a semiconductor chip into which other functional elements are built.
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Abstract
A built-in self test circuit includes a pattern generator, a functional block subjected to a self test on the basis of an output from the pattern generator, a space compressor for compressing a test result of the functional block, and a comparator for comparing an output from the space compressor with an expected value and outputting a comparison result. The functional block has O (positive integer) inputs and M (positive integer) outputs. The pattern generator is constituted by a linear feedback shift register, having an output bit width P (P=O/N) which is 1/N of the inputs O of the functional block, for generating a pseudorandom pattern and an iterative pseudorandom pattern output unit for distributing outputs from the linear feedback shift register in units of N outputs and outputting, to the functional block, an iterative pseudorandom pattern output having an iterative O-bit width (O=P*N) of the pseudorandom pattern output from the linear feedback shift register every P bits. The space compressor has a function of spatially compressing the M outputs from the functional block into L outputs (positive integer and M>L). The pattern generator, the functional block, the space compressor, and the comparator are built into a semiconductor chip into which other functional elements are built.
122 Citations
10 Claims
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1. A built-in self test circuit comprising:
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a pattern generator; a functional block subjected to a self test on the bases of an output from said pattern generator; a space compressor for compressing a test result of said functional block; and a comparator for comparing an output from said space compressor with an expected value and outputting a comparison result, wherein said functional block includes a plurality of modules having the same function and has a data input bit width O (positive integer) and a data output bit width M (positive integer), said pattern generator is constituted by a linear feedback shift register, having an output bit width P which is an integer satisfied by the equation O/N<
=P <
O/(N+1) where N is an integer more than 2, for generating a pseudorandom pattern and an iterative pseudorandom pattern output unit for distributing outputs from said linear feedback shift register in units of N outputs and outputting, to said functional block, an iterative pseudorandom pattern output having an iterative O-bit width (O=P*N) of the pseudorandom pattern output from said linear feedback shift register every P bits,said space compressor has a function of spatially compressing the M outputs from said functional block into L outputs (positive integer and M>
L), andsaid pattern generator, said functional block, said space compressor, and said comparator are built into a semiconductor chip into which other functional elements are built. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A built-in self test circuit comprising:
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a plurality of pattern generators; and a plurality of functional blocks subjected to a self test on the basis of outputs from said pattern generators; a plurality of space compressors for compressing test results of said functional blocks; a time compressor for comparing an output from said time compressor with an expected value and outputting a comparison result, wherein each of said functional blocks includes a plurality of modules having the same function and has a data input bit width O (positive integer) and a data output bit width M (positive integer), each of said pattern generators is constituted by a linear feedback shift register, having an output bit width which is an integer satisfied by the equation O/N<
=P<
O/(N+1) where N is an integer more than 2, for generating a pseudorandom pattern and an iterative pseudorandom pattern output unit for distributing output from said linear feedback shift register in units of N outputs and outputting, to said functional block, an iterative pseudorandom pattern output having an iterative O-bit width (O=P*N) of the pseudorandom pattern output from said linear feedback shift register every P bits,each of said space compressors has a function of spatially compressing the M outputs from said functional block into L outputs (positive integer and M>
L),said time compressor receives an output from each of said space compressors and supplying a time-compressed output to said comparator, and said plurality of pattern generators, said plurality of functional blocks, said plurality of space compressors, said time compressor, and said comparator are built into a semiconductor chip into which other functional elements are built. - View Dependent Claims (9)
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10. A built-in self test circuit comprising:
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a pattern generator; and a functional block subjected to a self test on the bases of an output from said pattern generator, wherein said functional block includes a plurality of modules having the same function and has a data input bit width O (positive integer) and a data output bit width M (positive integer), said pattern generator is constituted by a linear feedback shift register, having an output bit width P which is an integer satisfied by the equation O/N<
=P <
O/(N+1) where N is an integer more than 2, for generating a pseudorandom pattern and an iterative pseudorandom pattern output unit for distributing outputs from said linear feedback shaft register in units of N outputs and outputting, to said functional block, an iterative pseudorandom pattern output having an iterative O-bit width (O=P*N) of the pseudorandom pattern output from said linear feedback shift register every P bits,a test result is checked on the basis of an output from said functional block, and said pattern generator and said functional block are built into a semiconductor chip into which other functional elements are built.
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Specification