1. A method for operating a programmable memory device, comprising: storing a value as a state in a first memory cell and as a complementary state in a second memory cell; determining the state of the first memory cell using a first self-biased sensing circuit and the complementary state of the second memory cell using a second self-biased sensing circuit; and comparing in a differential manner an indication of the state of the first memory cell to a reference indication of the complementary state of the second memory cell to determine the value.