Circuit for improved diagnosability of defects in a fuse scan structure
AssigneeLSI Logic Corporation
InventorGregory Crowell
Life of this patent
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Abstract
An apparatus comprising a first control circuit, a second control circuit, a latch circuit and a flip-flop. The first control circuit may be configured to generate a first control signal in response to (i) an input signal from a fuse and (ii) one or more read signals. The latch circuit may be configured to change status in response to the first control signal. The second control circuit may be configured to change the state of the latch circuit in response to (i) one or more read signals and (ii) one or more set signals. The flip-flop may be configured to capture the state of the fuse in response to changing the state of the latch circuit with the first control circuit or the second control circuit.
Claims18
An apparatus comprising:
- a first control circuit configured to generate a first control signal in response to (i) an input signal from a fuse and (ii) one or more read signals;
- a latch circuit configured to change states in response to said first control signal;
- a second control circuit configured to change the state of said latch circuit in response to (i) said one or more read signals and (ii) one or more set signals;
- a flip-flop configured to capture the state of said fuse in response to changing the state of said latch circuit with said first control circuit or said second control circuit;
- and
- a third control circuit configured to (i) capture data from a previous scan of said flip-flop and (ii) set said latch circuit to one or more states in response to one or more write signals and said one or more read signals.
A method comprising the steps of:
- (A) generating a first control signal in response to an input signal from a fuse and one or more read signals;
- (B) changing the state of a latch circuit with said first control signal and said one or more read signals;
- (C) changing the state of said latch circuit if said fuse has blown;
- (D) capturing the state of said fuse with a flip-flop in response to changing the state of said latch circuit;
- (E) capturing data from a previous scan of said flip-flop;
- and
- (F) chancing the state of said latch circuit in response to step (E).
An apparatus comprising:
- means for generating a first control signal in response to an input signal from a fuse and one or more read signals;
- means for changing the state of a latch circuit with said first control signal;
- means for changing the state of a latch circuit if said fuse has blown prior to testing said fuse;
- means for capturing data from a previous scan of a flip-flop, and
- means for writing to said latch circuit in response to (i) capturing data from a previous scan of said flip-flop and (ii) one or more write signals.
Dependencies are inferred from the claim text.