# US 9,435,867 B2 · Multi-bit magnetic memory cell

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- Number: US 9,435,867 B2
- Document ID: US9435867B2
- Status: Granted
- Kind: B2
- Application number: 14/887,351
- Filed: 2015-10-20
- Published: 2016-02-11
- Granted: 2016-09-06
- Earliest claimed: 2011-08-02
- Assignees: Ramot at Tel-Aviv University Ltd.
- Applicants: Ramot At Tel Aviv University Ltd.
- Inventors: Alexander Gerber; Amir Segal
- Web page: https://patentgrep.com/patent/US9435867B2

## CPC

- G01R 33/07: Hall effect devices
- G01R 15/202: {using Hall-effect devices (Hall elements in arrangements for measuring electrical power G01R21/08)}
- G11C 11/16: using elements in which the storage effect is based on magnetic spin effect
- G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell}
- G11C 11/165: {Auxiliary circuits}
- G11C 11/1673: {Reading or sensing circuits or methods}
- G11C 11/1675: {Writing or programming circuits or methods}
- G11C 11/18: using Hall-effect devices
- G11C 11/5607: {using magnetic storage elements}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G11C: STATIC STORES (semiconductor memory devices H10B)

## Abstract

Apparatus includes a first Hall sensor having a first terminal, a second terminal, a third terminal and a fourth terminal and a second Hall sensor having a fifth terminal, a sixth terminal, a seventh terminal and an eighth terminal. A conductor connects the third terminal to the fifth terminal. A processor is configured to measure a first potential between the fourth terminal and the sixth terminal while transferring a first current from the first terminal to the seventh terminal via the conductor, to measure a second potential between the first terminal and the seventh terminal while transferring a second current from the fourth terminal to the sixth terminal via the conductor, and to determine a resultant voltage generated by the first and second Hall sensors in response to the first and second potentials.

## Claims

### Claim 1

Apparatus, comprising:
a first Hall effect sensor having a first terminal, a second terminal, a third terminal and a fourth terminal;
a second Hall effect sensor having a fifth terminal, a sixth terminal, a seventh terminal and an eighth terminal;
a conductor connecting the third terminal to the fifth terminal; and
a processor, which is configured to measure a first potential between the fourth terminal and the sixth terminal while transferring a first bias current from the first terminal to the seventh terminal via the conductor, to measure a second potential between the first terminal and the seventh terminal while transferring a second bias current from the fourth terminal to the sixth terminal via the conductor, to determine a resultant voltage generated by the first and second Hall effect sensors in response to the first and second potentials, and to determine a value stored in the first and second Hall effect sensors responsive to the determined resultant voltage.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein at least one of the first and second Hall effect sensors generates normal Hall voltages.

### Claim 3 (depends on 1)

The apparatus according to claim 1, wherein least one of the first and second Hall effect sensors generates extraordinary Hall voltages.

### Claim 4

A method, comprising:
providing a first Hall effect sensor having a first terminal, a second terminal, a third terminal and a fourth terminal;
providing a second Hall effect sensor having a fifth terminal, a sixth terminal, a seventh terminal and an eighth terminal;
connecting the third terminal to the fifth terminal by a conductor;
while transferring a first current from the first terminal to the seventh terminal via the conductor, measuring a first potential between the fourth terminal and the sixth terminal;
while transferring a second current from the fourth terminal to the sixth terminal via the conductor, measuring a second potential between the first terminal and the seventh terminal;
determining a resultant voltage generated by the first and second Hall effect sensors in response to the first and second potentials; and
determining a value stored in the first and second Hall effect sensors responsive to the determined resultant voltage.

### Claim 5 (depends on 4)

The method according to claim 4, wherein at least one of the first and second Hall effect sensors generates normal Hall voltages.

### Claim 6 (depends on 4)

The method according to claim 4, wherein least one of the first and second Hall effect sensors generates extraordinary Hall voltages.

### Claim 7 (depends on 4)

The method according to claim 4, wherein the first Hall effect sensor comprises a plurality of ferromagnetic layers separated by a non-magnetic spacer layer.

### Claim 8 (depends on 1)

The apparatus according to claim 1, wherein the first Hall effect sensor comprises a plurality of ferromagnetic layers separated by a non-magnetic spacer layer.