Charge extraction from ferroelectric memory cell
A ferroelectric capacitor of a memory cell may be in electronic communication with a sense capacitor through a digit line. The digit line may be virtually grounded during memory cell sensing, limiting or avoiding voltage drop across the digit line, and allowing all or substantially all of the stored charge of the ferroelectric capacitor to be extracted and transferred to the sense capacitor. Virtually grounding the digit line may be achieved by activating a switching component (e.g., a p-type field-effect transistor) that is electronic communication with the digit line. The charge of the ferroelectric capacitor may be transferred through the switching component. A sense amplifier may compare the voltage of the sense capacitor to a reference voltage in order to determine the stored logic state of the memory cell.
1. A method of operating a ferroelectric memory cell comprising a first capacitor, comprising:
activating a switching component that is electrically positioned between a sense capacitor and a digit line to virtually ground the digit line, wherein a source node of the switching component is coupled with a first terminal of a second capacitor and is configured to virtually ground the digit line based at least in part on a charge associated with the second capacitor;
applying, while the switching component is activated and the digit line is virtually grounded, a charging voltage to the sense capacitor coupled with the switching component;
applying, by a reference component that comprises one or more memory cells, a reference voltage to a reference capacitor; and
comparing a voltage of the sense capacitor to the reference voltage of the reference capacitor based at least in part on applying the charging voltage to the sense capacitor.
2. The method of claim 1 , further comprising:
charging the sense capacitor that is in electronic communication with the ferroelectric memory cell while the digit line is virtually grounded based at least in part on applying the charging voltage.
3. The method of claim 1 , wherein the switching component comprises a transistor, and the method further comprises:
electrically isolating the sense capacitor from the charging voltage after applying the charging voltage.
4. The method of claim 3 , wherein activating the switching component comprises:
applying, from a first voltage source coupled with the first terminal of the second capacitor, a second charging voltage to the second capacitor; and
electrically isolating the first terminal of the second capacitor from the first voltage source after applying the second charging voltage to the second capacitor, wherein the charge associated with the second capacitor is based at least in part on the second charging voltage having been applied to the second capacitor.
5. The method of claim 1 , wherein the charging voltage applied to the sense capacitor is positive.
6. The method of claim 3 , wherein the transistor comprises a p-type field-effect transistor (FET).
7. The method of claim 1 , wherein charging the sense capacitor comprises:
transferring a stored charge of the ferroelectric memory cell to the sense capacitor while the switching component is activated and the digit line is virtually grounded.
8. The method of claim 1 , wherein the sense capacitor and the reference capacitor have a same capacitance.