Sense amplifier signal margins and process sensitivities [DRAM]

A method for determining the signal margins of a sense amplifier based on the time required for the sense amplifier to achieve a given voltage separation is presented. The sense-time method generates a continuous curve whose peak value corresponds to the desired signal margin voltage and can be easily refined to provide additional precision. The method is illustrated by examining the behavior of a DRAM sense amplifier/bitline system with respect to the effects of imbalance in the parameters that most significantly affect its operation. The results of this study provide a link between the fluctuations inherent in integrated circuit processing technology and the variability of DRAM refresh times.