Patent ID: 7545695

Claim:
An asynchronous sense amplifier for a read only memory (ROM), comprising: a current-mirror circuit including three common terminal pairs and two transistor pairs, wherein the first common terminal pair includes a common voltage terminal and a voltage output terminal, the second common terminal pair includes a first current sink terminal and a second current sink terminal, the third common terminal pair includes a first power supply terminal and a second power supply terminal, the first transistor pair connects the first common terminal pair to the second common terminal pair, and the second transistor pair connects the first common terminal pair to the third common terminal pair; the current flowing from the first power supply terminal through the first current sink terminal is the same to the current flowing from the second power supply terminal through the second current sink terminal; a first negative feedback inverter connected to the voltage output terminal of the current-mirror circuit; a second negative feedback inverter connected to the output of the first negative feedback inverter; a first transistor group connected to the first current sink terminal of the current-mirror circuit; a second transistor group connected to the second current sink terminal of the current-mirror circuit; and a feedback transistor supplying a pull-down current to the first current sink terminal, wherein the feedback transistor is controlled by the output of the first negative feedback inverter, and the feedback transistor is smaller than any transistor of the second transistor group.