Random telegraph noise (RTN), caused by the capture/emission of electrons from oxide traps is regarded as one of the most serious reliability issues in scaleddown CMOS devices [1-3]. Proper characterization of oxide traps is important to understand the RTN phenomena and to reduce their influence on device reliability. In this paper, we propose a novel method to characterize oxide traps that participate in RTN by using ‘charging history effects’ in traps. In this method, changes in the frequency of the high/low drain currents in RTN due to the charging history are monitored instead of the time-scale parameters that are usually used, such as the capture/emission time τc/τe. This method is particularly effective for multi-trap RTN.