Charge mirror-based sensing for ferroelectric memory
Methods, systems, and devices for a sensing scheme that extracts the full or nearly full remnant polarization charge difference between two logic states of a ferroelectric memory cell or cells is described. The scheme employs a charge mirror to extract the full charge difference between the two states of a selected memory cell. The charge mirror may transfer the memory cell polarization charge to an amplification capacitor. The signal on the amplification capacitor may then be compared with a reference voltage to detect the logic state of the memory cell.
1. A method of operating a ferroelectric memory cell, comprising:
selecting the ferroelectric memory cell for a sensing operation, wherein the ferroelectric memory cell is in electronic communication with an amplification capacitor through a charge mirror;
extracting at least a portion of a charge stored in the ferroelectric memory cell through the charge mirror based at least in part on selecting the ferroelectric memory cell;
extracting at least a portion of a charge stored in the amplification capacitor through the charge mirror based at least in part on the extraction of the portion of the charge stored in the ferroelectric memory cell; and
comparing a voltage of the amplification capacitor to a reference voltage, wherein the voltage of the amplification capacitor is based at least in part on the portion of the charge extracted from the amplification capacitor.
2. The method of claim 1 , further comprising:
applying a voltage to the amplification capacitor, wherein the charge stored in the amplification capacitor is based at least in part on the applied voltage to the amplification capacitor; and
selecting the ferroelectric memory cell after charging the amplification capacitor.
3. The method of claim 1 , further comprising:
applying a voltage to a ferroelectric capacitor of the ferroelectric memory cell, wherein the ferroelectric memory cell is selected after applying the voltage to the ferroelectric capacitor.
4. The method of claim 1 , wherein the portion of the charge extracted from the amplification capacitor is based at least in part on a logic state of the ferroelectric memory cell.
5. The method of claim 1 , wherein the portion of the charge extracted from the amplification capacitor is based at least in part on a mirror ratio of the charge mirror.
6. The method of claim 1 , further comprising:
electrically isolating the ferroelectric memory cell from the charge mirror; and
performing a write-back operation to the ferroelectric memory cell based at least in part on comparing the voltage of the amplification capacitor to the reference voltage.
7. The method of claim 1 , wherein comparing the voltage of the amplification capacitor to the reference voltage comprises:
activating a sense amplifier.