A circuit includes a memory cell having a ground reference node, a switch coupled to the ground reference node, and a mode changing circuit having an output coupled to the switch. The mode changing circuit is configured to change a logic state of the output between a first output logic state and a second output logic state in response to a change in an operational voltage and/or temperature, thereby set the memory cell in a first mode in which the ground reference node is at first reference level or in a second mode in which the ground reference node is at a second reference level different from the first reference level.