Horizontal Hall effect sensor with high maximum absolute sensitivity

The sensitivity of conventional Hall effect sensors is strongly limited by the well-known short-circuit effects. Many researches were devoted to reduce offset and noise, but few works were carried out to improve the sensitivity. Here, a new shape of integrated horizontal Hall effect device is presented. This particular shape has been developed in order to minimize the short-circuit effects in the sensor, allowing to reduce its length to width ratio and consequently to reduce its average resistance. Thus, the biasing current of this sensor can be significantly increased in order to obtain a higher absolute sensitivity than for conventional devices. Such a Hall effect device needs a specific biasing circuit which is also presented, first in a simple version and second in an improved one. A resolution of 32 μT has been reached on a bandwidth of 5 Hz to 1 kHz with a 39×9.2 μm² sensor biased with a current of 2.07 mA, the corresponding absolute sensitivity being 195 mV/T. The maximal absolute sensitivity of a so shaped device can be increased as much as needed by increasing its width-to-length ratio, without loss on the current related sensitivity.