synthesizing circular decompressors
AssigneeSynopsys, Inc.
InventorEmil I. Gizdarski
Life of this patent
Estimating the term…
Abstract
Methods and apparatuses are described for decompressing and routing test data. Some embodiments feature an integrated circuit (IC) that includes two or more shift registers configured to shift in the test data. Each of the two or more shift registers can include two or more sequential elements configured such that a scan chain in the set of scan chains receives inputs from at most one sequential element in each of the two or more shift registers. At least one shift register in the two or more shift registers can be configured as a circular shift register. The IC can also include a logic network coupled between the two or more shift registers and the set of scan chains such that the set of scan chains receives the decompressed test data from the two or more shift registers via the logic network.
Claims27
An integrated circuit (IC) for decompressing test data from a tester and routing the decompressed test data into a set of scan chains within a circuit under test, the IC comprising:
- a decompressor circuit, which comprises:
- two or more shift registers configured to receive and shift the test data,
- wherein each of the two or more shift registers includes two or more sequential elements;
- and
- wherein at least one shift register in the two or more shift registers is configured as a circular shift register;
- and
- a logic network configured to receive the shifted test data from the two or more shift registers and generate the decompressed test data, wherein the logic network is coupled between the two or more shift registers and the set of scan chains which receives the decompressed test data from the logic network, wherein each logic gate in the logic network receives test data from at most one sequential element in each of the two or more shift registers.
A system, comprising:
- a tester configured to generate test data;
- and
- an integrated circuit comprising:
- a set of scan chains;
- and
- a decompressor circuit to decompress the test data and shift the decompressed test data into the set of scan chains during a plurality of shift cycles, wherein the decompressor circuit comprises:
- two or more shift registers configured to receive and shift the test data,
- wherein each of the two or more shift registers includes two or more sequential elements;
- and
- wherein at least one shift register in the two or more shift registers is configured as a circular shift register;
- and
- a logic network configured to receive the shifted test data from the two or more shift registers and generate the decompressed test data, wherein the logic network is coupled between the two or more shift registers and the set of scan chains which receives the decompressed test data from the logic network, wherein each logic gate in the logic network receives test data from at most one sequential element in each of the two or more shift registers.
A method for constructing a decompressor circuit for decompressing test data from a tester and routing the decompressed test data into a set of scan chains within a circuit under test, the method comprising:
- receiving the set of scan chains;
- receiving two or more shift registers configured to receive and shift the test data from the tester;
- wherein each of the two or more shift registers includes two or more sequential elements;
- and
- wherein at least one shift register in the two or more shift registers is configured as a circular shift register;
- and
- coupling a logic network between the two or more shift registers and the set of scan chains, wherein the logic network is configured to receive the shifted test data from the two or more shift registers and generate the decompressed test data, and wherein the set of scan chains receives the decompressed test data from the logic network, wherein each logic gate in the logic network receives test data from at most one sequential element in each of the two or more shift registers.
Dependencies are inferred from the claim text.