Single-package bridge-type magnetic field sensor

Abstract

A magnetoresistive sensor bridge utilizing magnetic tunnel junctions is disclosed. The magnetoresistive sensor bridge is composed of one or more magnetic tunnel junction sensor chips to provide a half-bridge or full bridge sensor in a standard semiconductor package. The sensor chips may be arranged such that the pinned layers of the different chips are mutually antiparallel to each other in order to form a push-pull bridge structure. The sensor chips are then interconnected using wire bonding. The chips can be wire-bonded to various standard semiconductor leadframes and packaged in inexpensive standard semiconductor packages. The bridge design may be push-pull or referenced. In the referenced case, the on-chip reference resistors may be implemented without magnetic shielding.

What is claimed is: 
     
         1 . A single-package bridge-type magnetic field sensor, comprising:
 one or more pairs of MTJ or GMR magnetoresistive sensor chips, wherein the sensor chips are adhered to a die attach area of a standard semiconductor package;   wherein each of the sensor chips includes a reference resistor with a fixed resistance and a sensing resistor with a resistance varying in response to a magnetic field;   wherein each of the reference resistor and the sensing resistor includes a plurality of MTJ or GMR magnetoresistive sensor elements electrically interconnected as a single magnetoresistive element in a matrix, the matrix including adjacent rows of sensor elements and adjacent columns of sensor elements where adjacent magnetoresistive elements in each column are directly connected in series; and   wherein the sensing resistor has a transfer curve that is linearly proportional to an applied magnetic field in an operating magnetic field range.   
     
     
         2 . The single-package bridge-type magnetic field sensor as in  claim 1 , wherein the sensor is a half-bridge sensor comprising one sensor chip. 
     
     
         3 . The single-package bridge-type magnetic field sensor as in  claim 1 , wherein the sensor is a full-bridge sensor comprising a pair of sensor chips, wherein one of the pair of sensor chips is rotated 180 degrees with respect to the other. 
     
     
         4 . The single-package bridge-type magnetic field sensor as in  claim 1 , the magnetoresistive elements are patterned in a strip-like shape including but not limited to an elliptical, a rectangular, or a diamond shape. 
     
     
         5 . The single-package bridge-type magnetic field sensor as in  claim 1 , wherein the magnetoresistive elements of the reference resistor are patterned in a different shape aspect ratio from that of the magnetoresistive elements of the sensing resistor. 
     
     
         6 . The single-package bridge-type magnetic field sensor as in  claim 1 , wherein the reference resistor is screened from an applied magnetic field by one or more magnetic shields. 
     
     
         7 . The single-package bridge-type magnetic field sensor as in  claim 3 , wherein the sensor chips are tested and sorted before assembly in order to better match their transfer curve characteristics. 
     
     
         8 . The single-package bridge-type magnetic field sensor as in  claim 1 , wherein the sensor comprising a plurality of bond pads of the sensor chips are designed such that more than one wire bond may be attached to each side of the magnetoresistive elements. 
     
     
         9 . The single-package bridge-type magnetic field sensor as in  claim 1 , wherein the magnetoresistive sensor chips are wire bonded to each other and a leadframe in order to produce a bridge sensor. 
     
     
         10 . The single-package bridge-type magnetic field sensor as in  claim 9 , wherein the leadframe and sensor chips are encapsulated in plastic to form a standard semiconductor package.