A sense amplifier (1300, 1500) is provided for sensing the state of a
toggling type magnetoresistive random access memory (MRAM) cell without
using a reference. The sense amplifier (1300, 1500) employs a
sample-and-hold circuit (1336, 1508) combined with a current-to-voltage
converter (1301, 1501), gain circuit (1303), and cross-coupled latch
(1305, 1503) to sense the state of a bit. The sense amplifier (1300,
1500), first senses and holds a first state of the cell. The cell is
toggled to a second state. Then, the sense amplifier (1300, 1500) compares
the first state to the second state to determine the first state of a
toggling type memory cell.
