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A method implements effective testing of a sense amplifier for an eFuse without having to program or blow the eFuse. After initial processing of the sense amplifier, testing determines whether the sense amplifier can generate a valid “0” and “1” before programming the eFuse. A first precharge device and a second precharge device that normally respectively precharge a true sense node and a complement sense node to a high voltage are driven separately. For testing, one of the precharge devices is conditionally held off to insure the sense amplifier results in a “0” and “1”. This allows the testing of the sense amplifier devices as well as down stream connected devices. Once testing is complete, both precharge devices are controlled in tandem.

Inventors: Anthony Gus Aipperspach, David Howard Allen, Louis Bernard Bushard, Phil Christopher Felice Paone, Gregory John Uhlmann
Original Assignee: International Business Machines Corporation
Primary Examiner: Richard Elms
Secondary Examiner: Nam Nguyen
Attorney: Joan Pennington
Current U.S. Classification: 365/201; 365/203; 365/205; 365/225.7

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Citations

Cited PatentFiling dateIssue dateOriginal AssigneeTitle
US7224633Dec 8, 2005May 29, 2007International Business Machines CorporationeFuse sense circuit

Referenced by

Citing PatentFiling dateIssue dateOriginal AssigneeTitle
US7672185Jan 3, 2007Mar 2, 2010International Business Machines CorporationMethod and apparatus to monitor circuit variation effects on electrically programmable fuses

Claims

1. A method for testing of a sense amplifier for an eFuse to determine whether the sense amplifier can generate a valid “0” and “1” before programming the eFuse, said method comprising the steps of:

providing a first precharge signal applied to a first precharge device of the sense amplifier;

providing a second precharge signal applied to a second precharge device of the sense amplifier; and

selectively controlling said first and second precharge devices for providing a respective output resulting from both an unblown and a blown eFuse of the sense amplifier with the eFuse being unblown.

2. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 1 wherein said first precharge device and said second precharge device respectively precharge a true sense node and a complement sense node of the sense amplifier to a high voltage during normal operation.

3. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 2 wherein selectively controlling said precharge devices for providing a respective output resulting from both an unblown and a blown eFuse of the sense amplifier with the eFuse being unblown includes turning off said second precharge device early and applying sensing control signals to true and complement sides of the sense amplifier to set the sense amplifier into the same state that occurs when the eFuse is blown without having to blow the eFuse.

4. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 2 wherein selectively controlling said precharge devices for providing a respective output resulting from both an unblown and a blown eFuse of the sense amplifier with the eFuse being unblown includes selectively controlling said precharge devices for providing a “0” and “1” output of the sense amplifier with the eFuse being unblown.

5. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 2 wherein selectively controlling said precharge devices for providing a respective output resulting from both an unblown and a blown eFuse of the sense amplifier with the eFuse being unblown includes applying sensing control signals to a first control transistor coupled to said first precharge device and a second control transistor coupled to said second precharge device.

6. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 5 includes implementing said control transistor and said second control transistor with a respective N-channel field effect transistor.

7. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 2 wherein the sense amplifier includes a cross-coupled inverter circuit coupled between said true sense node and said complement sense node of the sense amplifier and wherein selectively controlling said precharge devices for providing a respective output resulting from both an unblown and a blown eFuse of the sense amplifier with the eFuse being unblown includes applying sensing control signals to a first pull-up transistor coupled between said cross-coupled inverter circuit and a voltage supply rail and a second pull-down transistor coupled to between said cross-coupled inverter circuit and a ground potential.

8. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 7 includes implementing said pull-up transistor and said pull-down transistor with a respective P-channel field effect transistor and an N-channel field effect transistor.

9. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 2 includes implementing said first precharge device and said second precharge device with a respective P-channel field effect transistor.

10. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 2 includes providing the eFuse coupled to said true sense node.

11. The method for implementing effective testing of a sense amplifier for an eFuse as recited in claim 2 includes providing a reference resistor coupled to said complement sense node.

Drawings