A sense amplifier circuit for sensing the state of the first node and its sensing method and computer system

摘要

The present invention relates to a single-ended sense amplifier circuit for sensing the state of a bit line in a read-only memory. The sense amplifier includes an output to indicate the state of the bit line in response to the input and bit line voltage levels. The precharge circuit is coupled to an input for charging the input to a first voltage level when the input is disconnected from the bit line. The discharge circuit is connected between the bit line and the input. In a first embodiment, the discharge circuit includes a field effect transistor coupled as a cascode device for connecting and disconnecting an input to a bit line. The discharge circuit is connected to the bit line when the discharge voltage level exceeds the threshold voltage level of the discharge circuit. Further, the sense amplifier circuit includes a sum-of-margining circuit connected to the bit line to charge the bit line with a voltage level whose discharge voltage level is lower than the first voltage level that is lower than the drain voltage by the predetermined noise margin voltage.