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US 4,340,857 AGranted
Device for testing digital circuits using built-in logic block observers (BILBO's)
AssigneeSiemens Aktiengesellschaft
InventorPatrick P. Fasang
Life of this patent
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Abstract
A device for testing a digital electronic circuit, having a first BILBO for generating a pseudo-random test pattern, a second BILBO for analyzing a parallel-input signature, a decoder and at least one status indicator for indicating the status of a circuit under test.
Claims16
A device for testing a digital electronic circuit, comprising in combination:
- (a) first BILBO means for generating a pseudo-random test pattern, said first BILBO means being connected to inputs of said circuit under test and having a serially connected chain of storage elements and input modifying means connecting the output of at least one storage element to the input of another;
- (b) second BILBO means for analyzing a parallel-input signature, said second BILBO means being connected to outputs of said circuit under test and having a serially connected chain of storage elements and input modifying means connecting the output of at least one storage element to the input of another;
- (c) a decoder having:
- (ca) inputs connected to outputs of said second BILBO means for receiving input signals having a predetermined combination of logic levels when said circuit under test is fault-free and having a combination of logic levels different from the predetermined combination when the circuit under test is faulty;
- and
- (cb) an output for delivering a first output signal when said circuit under test is fault-free and for delivering a second output signal when said circuit under test is faulty;
- (d) at least one status indicator connected to the output of said decoder for indicating the status of said circuit under test;
- and
- (e) means for controlling said first and second BILBO means and said decoder in dependence on a master clock signal.
6 more elements
Dependencies are inferred from the claim text.