Method and apparatus for measuring current as in sensing a memory cell
AssigneeMicron Technology, Inc.
InventorR. Jacob Baker
Life of this patent
Estimating the term…
Abstract
Apparatus and methods sense or measure an input current, such as a current indicating a logic state of a memory cell. A sensing circuit includes an amplifier, a capacitor, a current source circuit, a clocked comparator and a clocked counter. The current source circuit operates responsive to an output of the comparator to supply or withdraw current to and from the capacitor during respective charging and discharging intervals. The count in the clocked counter results from periodic comparisons of the capacitor voltage with a reference voltage and is, therefore, related to the logic state of the memory cell. The magnitude of current supplied during charging is less than the magnitude withdrawn during discharging, allowing use of a smaller counter.
Claims30
A sensing circuit, comprising:
- an amplifier comprising an amplifier input for receiving a signal from a resistive memory cell and an amplifier output;
- a capacitor comprising a first plate coupled to said amplifier output and a second plate;
- a current source circuit comprising a control node and a current node supplying a current at said first plate of said capacitor;
- and
- a comparator comprising a first comparator input coupled to said capacitor, a second comparator input, and a comparator output, coupled to said control node of said current source;
- and
- a counter, coupled to said comparator output.
An integrated circuit, comprising:
- a substrate;
- circuitry formed at a surface of said substrate, said circuitry comprising:
- an array of resistive memory elements;
- a sensing line extending across said array, connected to a set of resistive memory elements in the array;
- and
- sensing circuitry, comprising:
- an amplifier comprising an amplifier input for receiving a signal from one of said resistive memory elements in said set and an amplifier output;
- a capacitor comprising a first plate coupled to said amplifier output and a second plate;
- a current source circuit comprising a control node and a current node supplying a current at said first plate of said capacitor;
- and
- a comparator comprising a first comparator input coupled to said capacitor, a second comparator input, and a comparator output, coupled to said control node of said current source;
- and
- a counter, coupled to said comparator output.
A digital processing system, comprising:
- a processor;
- and
- a resistive memory device coupled to said processor via a bus, said resistive memory device comprising a sensing circuit for sensing a resistive state of a resistive memory cell in said resistive memory device, said sensing circuit comprising:
- an amplifier comprising an amplifier input for receiving a signal from one of said resistive memory elements and an amplifier output;
- a capacitor comprising a first plate coupled to said amplifier output and a second plate;
- a current source circuit comprising a control node and a current node supplying a current at said first plate of said capacitor;
- and
- a comparator comprising a first comparator input coupled to said capacitor, a second comparator input, and a comparator output, coupled to said control node of said current source;
- and
- a counter, coupled to said comparator output.
Dependencies are inferred from the claim text.