| 摘要 |
PURPOSE: In-circuit memory array bit cell threshold voltage distribution measurement is provided to improve the throughput by eliminating the overhead of the platform tester/device under test handshaking. CONSTITUTION: A method of operating a non-volatile memory(110) comprising an array of bit cells(126), the method comprising: selecting between an operational power supply and a test power supply, the test power supply being on-chip programmable; operating the non-volatile memory(110) in an operational mode if the operational power supply is selected; and operating the non-volatile memory(110) in a test mode if the test power supply is selected; wherein in the test mode a threshold voltage distribution of the array of bit cells(126) in the non-volatile memory(110) is measured over a range of voltage values from a first voltage value to a last voltage value, wherein the voltage values comprise the first and last voltage values and a plurality of voltages between the first and last voltage values, and wherein operating the non-volatile memory(110) in the test mode comprises: selecting and applying the test power supply to the non-volatile memory(110); setting a word line voltage to the first voltage value; reading the array of bit cells(126) in the non-volatile memory(110); determining whether bit cells(126) are conducting; determining if the word line voltage has the last voltage value; changing the word line voltage by a fraction of a value of the test power supply in the direction of the last voltage value if the word line voltage does not have the last voltage value; and repeating the reading the array of bit cells(126), the determining whether bit cells(126) are conducting, the determining if the word line voltage has the last voltage value, and the changing the word line voltage until the word line voltage has the last voltage value.
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