| 摘要 |
PURPOSE: A semiconductor memory device is provided to judge whether a period of an oscillation signal of a self refresh ring oscillator is normal by monitoring an output oscillation signal of the self refresh ring oscillator using a DQ pad using an output buffer. CONSTITUTION: A plurality of tuning signal generation units(10) output a plurality of tuning signals by tuning an address and a test mode enable signal enabled in a special test mode. A decoding unit(20) outputs a plurality of selection signals by decoding the above plurality of tuning signals. A self refresh ring oscillation unit(30) controls a period of a self refresh oscillation signal and then outputs it according to the above plurality of control signals. And an output buffer(40) outputs the self refresh oscillation signal by the above test mode enable signal.
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