Contactless 360° absolute angular CMOS microsystem based on vertical Hall sensors

A Theory of Magnetic Angle Sensors With Hall Plates and Without Fluxguides

“…Thus, magnets with the mirror symmetry (9) fulfill (6). All magnets with rotational shape belong to this group, but also block-shaped magnets do -even more general shapes are thinkable.…”

“…These can be magnetoresistors (MR) like, e.g., anisotropic magneto-resistors (AMR) [1] or giant magneto-resistors (GMR) [2][3][4][5] or tunnelling magneto-resistors (TMR). Alternatively one may also use vertical Hall effect devices (VHall) [6]. MRs respond to the angle between the in-plane component of the field and their in-plane reference direction, which is defined by layout or pre-magnetization during the manufacturing process.…”

Angular position device with 2D low-noise Hall microsensor

“…These instruments are required for various consumer, automotive, security control, industrial and other applications, including detection of the rotor position in electric motors and engines, the position of the steering wheels in aircrafts, mining and cars, wireless networks, tilt robot, refrigerators, washing machines position, etc. Currently, the well-known potentiometers with ohmic contact permanently touching a ring-shaped resistive layer are wide-spread [1][2][3]. The main drawbacks of this type of angular devices are the heavy wear, limited lifetime, poor reliability and great susceptibility to harsh environment.…”

“…Particularly promising for their high performance, low cost, contactless detection possibility of full 0-360 • angle range, repeatability and small size are the angular devices consisting of magnetic actuating systems and magneticfield sensors. Nevertheless, the use of very sensitive GMR or AMR as transducing element in these setups involves some disadvantages, such as incompatibility with silicon integrated processes and limited measurement angle range resulting from the non-linear output [3,4]. A trade-off approach between the IC compatibility, low price, reliability, accuracy, simplicity and performance is a rotating permanent magnet located over mutually perpendicularly placed silicon microsensors, such as linear Hall plates or lateral bipolar magnetotransistors [1,3,[5][6][7].…”

“…Nevertheless, the use of very sensitive GMR or AMR as transducing element in these setups involves some disadvantages, such as incompatibility with silicon integrated processes and limited measurement angle range resulting from the non-linear output [3,4]. A trade-off approach between the IC compatibility, low price, reliability, accuracy, simplicity and performance is a rotating permanent magnet located over mutually perpendicularly placed silicon microsensors, such as linear Hall plates or lateral bipolar magnetotransistors [1,3,[5][6][7]. These two-dimensional (2D) microsystems detect simultaneously two in-plane x-y magneticfield components B x and B y , providing complete information about: (i) the value of the resulting magnetic field B(B x ,B y ) by the sine and cosine output signals as a function of the rotation angle ϕ, and (ii) the angle value ϕ of the turning magnet relative to its reference position.…”