Patent ID: 7323900
Filing Date: 2008-01-29
Classification: G01R,G11C,H04L

Abstract:
1. A semiconductor memory device for adjusting an output impedance of a data output driver, comprising: a reference signal generating unit for generating a reference signal; a comparing unit for comparing the reference signal with a test signal applied to a test pad to thereby output an adjusted value to the test pad after adjusting the adjusted value until the test signal is equal to the reference signal; an impedance measuring unit for measuring an impedance of the test pad based on the adjusted value to output the test signal to the comparing unit; an impedance adjusting unit for adjusting an impedance of a data input/output pad so as to have an impedance value corresponding to the adjusted value outputted when the test signal is equal to the reference signal; an impedance control unit for controlling the comparing unit so that the adjusted value is outputted when the test signal is equal to the reference signal; and a reference signal control unit for controlling the reference signal generating unit to adjust a voltage level of the reference signal.