Non-linear magnetic field sensors and current sensors
The invention provides a magnetic field sensor or current sensor which can exhibit a substantially linear relationship between the sensor signal and the logarithm of the magnetic field or current. The sensor may be used as a wide dynamic range sensor which can offer a constant relative sensitivity and a uniform SNR over several decades. The design of the sensor device may be implemented in discrete magnetic field sensors or current sensors as well as in integrated current sensors in ICs comprising MRAM modules.
1. A sensor device ( 30 ) comprising:
at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) connected in series or in parallel, each magnetic sensor element (R 0 , R 1 , . . . , Rn−1) having a sensitivity (S 0 , S 1 , . . . , Sn−1), wherein the sensitivity (S 0 , S 1 , . . . , Sn−1) of each magnetic sensor element (R 0 , R 1 , . . . , Rn−1) differs from the sensitivity (S 0 , S 1 , Sn−1) of any other magnetic sensor element (R 0 , R 1 , . . . , Rn−1), each of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) outputs a sensor signal over a rang of a sensed parameter, and a sum of each of the sensor signals of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) fits a non-linear function of the sensed parameter over the range of the sensor device ( 30 ).
2. The sensor device ( 30 ) according to claim 1 , wherein the non-linear function is a quasi-log function.
3. The sensor device ( 30 ) according to claim 1 , wherein each of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) have identical geometry and size.
4. The sensor device ( 30 ) according to claim 1 , wherein at least one of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) has a different geometry and size.
5. The sensor device ( 30 ) according to claim 1 , wherein at least one of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) is split into at least two sub-elements (R 1 ′ and R 1 ″) connected to each other in parallel or in series.
6. The sensor device ( 30 ) according to claim 5 , further comprising:
a conductor line ( 36 ) positioned under the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
7. The sensor device ( 30 ) according to claim 1 , further comprising:
a conductor line ( 36 ) positioned under the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
8. The sensor device ( 30 ) according to claim 7 , wherein said conductor line ( 36 ) shows a different width at a position of at least one of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
9. The sensor device ( 30 ) according to claim 1 , further comprising:
a bypass current path ( 37 ).
10. The sensor device ( 30 ) according to claim 1 , wherein the device ( 30 ) further comprises:
at least one magnetic shield ( 33 ).
11. The sensor device ( 30 ) according to claim 10 , wherein said magnetic shield ( 33 ) is placed near at least one magnetic sensor element (R 0 , R 1 , . . . , Rn−1).
12. A method of manufacturing a sensor device ( 30 ), the method comprising:
providing at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) connected in series or in parallel, each magnetic sensor element (R 0 , R 1 , . . . , Rn−1) having a sensitivity (S 0 , S 1 , . . . , Sn−1), whereby the sensitivity (S 0 , S 1 , . . . , Sn−1) of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) is set such that the sensitivity (S 0 , S 1 , . . . , Sn−1) of each magnetic sensor element differs from the sensitivity (S 0 , S 1 , . . . , Sn−1) of any other of the magnetic sensor elements (R 0 , R 1 , . . . , Rn−1), wherein the sensor device ( 30 ) is a non-linear sensor device.
13. The method according to claim 12 , wherein the sensor device ( 30 ) is a quasi-logarithmic or logarithmic sensor device.
14. The method according to claim 12 , wherein setting the sensitivity (S 0 , S 1 , . . . , Sn−1) of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) further comprises:
changing at least one of geometry and size of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
15. The method according to claim 12 , wherein setting the sensitivity (S 0 , S 1 , . . . , Sn−1) of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) is performed by further comprises:
splitting up at least one of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
16. The method according to claim 15 , wherein setting the sensitivity (S 0 , S 1 , . . . , Sn−1) of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) further comprises:
providing a magnetic shield ( 33 ) near at least one of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
17. The method according to claim 12 , wherein setting the sensitivity (S 0 , S 1 , . . . , Sn−1) of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) further comprises:
providing a magnetic shield ( 33 ) near at least one of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
18. The method according to claim 12 , further comprising:
providing a conductor line ( 36 ) under the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
19. The method according to claim 18 , wherein providing a conductor line ( 36 ) under at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) comprises:
providing a conductor line ( 36 ) having a different width at the position of at least one of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1).
20. A sensor device ( 30 ) comprising:
at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) connected in series or in parallel, each magnetic sensor element (R 0 , R 1 , . . . , Rn−1) having a sensitivity (S 0 , S 1 , . . . , Sn−1), wherein each of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) outputs a sensor signal over a range of a sensed parameter, and a sum of each of the sensor signals of the at least two magnetic sensor elements (R 0 , R 1 , . . . , Rn−1) fits a non-linear function of the sensed parameter over the range of the sensor device ( 30 ).