In accordance with an embodiment, a circuit includes a sense amplifier circuit configured to sense a difference between a first current based on a direct memory bit and a second current based on a complementary memory bit. The direct memory bit is coupled to a first input of the sense amplifier circuit, and the complementary memory bit is coupled to a second input of the sense amplifier circuit. A controller is configured to, during a sense operation, selectively add a first margin current to the first current, and during the sense operation, selectively add a second margin current to the second current.