Patent ID: 8189357

Claim:
A memory comprising: a memory array comprising a memory cell; a sense amplifier comprising a first terminal, coupled to the memory cell, and a second terminal; and a reference circuit comprising: a first reference cell having a first reference threshold voltage for providing a first reference current, based on a first reference word line voltage, when the memory cell is read with a word line voltage; a second reference cell having a second reference threshold voltage for providing a second reference current, based on a second reference word line voltage, when the memory cell is read with the word line voltage; and a switch for selectively providing one of the first and the second reference currents to the second terminal in response to a control signal, wherein the first and the second reference word line voltages correspond to different voltage levels; wherein when a threshold voltage of the memory cell and the first reference threshold voltage correspond to a similar first voltage level, the threshold voltage of the memory cell and the first reference threshold voltage correspond to substantially a same threshold voltage variation of temperature effect and a cell current of the memory cell and the first reference current correspond to substantially a same current variation of temperature effect; and wherein when the threshold voltage of the memory cell and the second reference threshold voltage correspond to a similar second voltage level, the threshold voltage of the memory cell and the second reference threshold voltage correspond to substantially a same threshold voltage variation of temperature effect and the cell current of the memory cell and the second reference current correspond to substantially a same current variation of temperature effect.