Decompressor/PRPG for applying pseudo-random and deterministic test patterns
First Claim
1. A method for operating a decompressor/PRPG comprising:
- in a pseudo-random phase of operation;
inputting an initial value;
generating from the initial value a set of pseudo-random test patterns; and
outputting the pseudo-random test patterns;
in a deterministic phase of operation;
inputting a compressed deterministic test pattern;
decompressing the compressed deterministic test pattern into a decompressed deterministic test pattern as the compressed deterministic test pattern is being input, the decompressing including logically combining one or more bits of the compressed deterministic test pattern with bits stored within the decompressor/PRPG; and
outputting the decompressed deterministic test pattern.
2 Assignments
0 Petitions
Accused Products
Abstract
A novel decompressor/PRPG on a microchip performs both pseudo-random test pattern generation and decompression of deterministic test patterns for a circuit-under-test on the chip. The decompressor/PRPG has two phases of operation. In a pseudo-random phase, the decompressor/PRPG generates pseudo-random test patterns that are applied to scan chains within the circuit-under test. In a deterministic phase, compressed deterministic test patterns from an external tester are applied to the decompressor/PRPG. The patterns are decompressed as they are clocked through the decompressor/PRPG into the scan chains. The decompressor/PRPG thus provides much better fault coverage than a simple PRPG, but without the cost of a complete set of fully-specified deterministic test patterns.
-
Citations
18 Claims
-
1. A method for operating a decompressor/PRPG comprising:
-
in a pseudo-random phase of operation; inputting an initial value; generating from the initial value a set of pseudo-random test patterns; and outputting the pseudo-random test patterns; in a deterministic phase of operation; inputting a compressed deterministic test pattern; decompressing the compressed deterministic test pattern into a decompressed deterministic test pattern as the compressed deterministic test pattern is being input, the decompressing including logically combining one or more bits of the compressed deterministic test pattern with bits stored within the decompressor/PRPG; and outputting the decompressed deterministic test pattern. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A circuit comprising:
-
a decompressor/PRPG; control circuitry coupled to the decompressor/PRPG and operable to cause the decompressor/PRPG to generate, in a pseudo-random phase of operation, a set of pseudo-random patterns and to generate, in a deterministic phase of operation, a set of decompressed deterministic test patterns from a set of provided compressed deterministic patterns, the control circuitry comprising one or more logic gates that receive the compressed deterministic patterns during the deterministic phase of operation and logically combine the compressed deterministic patterns with bits stored within the decompressor/PRPG; circuit logic; and scan chains coupled to the circuit logic and operable to receive test patterns generated by the decompressor/PRPG and to capture responses to the test patterns generated by the circuit logic, wherein the decompressor/PRPG is operable to decompress a compressed deterministic test pattern as the compressed deterministic test pattern is being provided to the decompressor/PRPG. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
-
-
15. A system, comprising:
-
means for inputting an initial value, generating from the initial value a set of pseudo-random test patterns, and outputting the pseudo-random test patterns; and means for inputting a compressed deterministic test pattern, decompressing the compressed deterministic test pattern into a decompressed deterministic test pattern as the compressed deterministic test pattern is being input, the decompressing including logically combining one or more bits of the compressed deterministic test pattern with stored bits, and outputting the decompressed deterministic test pattern. - View Dependent Claims (16, 17, 18)
-
Specification