From Three-Contact Vertical Hall Elements to Symmetrized Vertical Hall Sensors with Low Offset

CMOS Vertical Hall Magnetic Sensors on Flexible Substrate

“…However, for voltage-mode driven Hall sensors, even after the current spinning operation, a small residual offset is still possible because of the junction field effect and the carrier velocity saturation, which may cause some non-linearity. This residual offset can be suppressed by the orthogonal coupling of four identical Hall sensors [17]. It may be noted that in the current mode, the voltage at the output terminals (commonmode voltage) remains constant.…”

“…For better sensitivity and reduced offset, the VHS presented here uses an optimized symmetric 4-folded 3-contact (4F 3C) structure with current-spinning technique. The 4-folded structure has been chosen here as, among several possible geometries [12]- [15], this structure is known to result in high resolution and low offset performance [16], [17]. Extending the preliminary work reported in [18], this paper also presents the results from an extensive physical simulation and behavioural modelling of current-mode VHSs on flexible substrate and provides guidelines for the device size, shape, and performance optimization.…”

A Novell Hall Magnetometer Using Dynamic Offset Cancellation

“…The very important key characteristic of the Hall sensors is the offset voltage Voff, which is its output signal in the absence of magnetic field [1][2][3]. It depends on power supply, temperature, mechanical stress and sometimes it is larger than the Hall voltage VH (B).…”

“…But, after applying this method, the residual offset is large since the matched Hall plates are not identical. An alternative effort to reduce the initial offset Voff, is the spinning current method [3][4][5], or "dynamic offset cancellation" [1]. In the spinning-current method, the direction of current flow in a single symmetrical Hall plate is made to spin around an axis through the center of the Hall plate.…”

“…At the same time, the output voltage is sampled at the Hall contact pair which is perpendicularly oriented to the current flow [2]. The very common Hall sensors are four terminal devices [1,[6][7][8][9][10], where one pair of opposite terminals serves as drive contacts and the other pair as sense contacts; consequently Hall sensors can be operated in two [1] or four [3] different modes. During an offset cancelling measurement cycle, the drive current is spatially rotated through these modes and the corresponding output signals are averaged [1,[6][7][8][9][10].…”