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 ¡ £¢ ¥¤ §¦ has been reached on a bandwidth of © to © with a ¡ £ "! #¢ ¥¤ §$ % sensor biased with a current of ¢ "! & (' $ 0) , the corresponding absolute sensitivity being ¨$ 01 32 ¦ . 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.

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In recent years, a lot of attention has been paid to carbon nanotube (CNT) networks and their applications to electronic devices. Many studies concentrate on the percolation threshold and the characterization of the conduction in such materials. Nevertheless, no theoretical study has yet attempted to characterize the CNT features inside finite size CNT networks. We present a theoretical approach based on geometrical and statistical considerations. We demonstrate the possibility of explicitly determining some relations existing between two neighbor CNTs and their contact efficiency in random networks of identical CNTs. We calculate the contact probability of rigid identical CNTs and we obtain a probability of 0.2027, which turns out to be independent of the CNT density. Based on this probability, we establish also the dependence of the number of contacts per CNT as a function of the CNT density. All the theoretical results are validated by very good agreement with Monte Carlo simulations.

In this paper we discuss the conception and performances of a monolithic microsystem for magnetic field measurement built in standard 0.6pm CMOS technology. It is shown that 5.2 microTesla resolution over 1 kHz bandwidth (5 to 1 kHz) can be achieved by combining a smart Hall effect based sensing device and appropriate analog conditioning electronics. The study focuses on the methods used to drive up the sensor's sensitivity and to drive down the system's noise level in order to achieve the abovementioned resolution. A new circuitry is proposed for biasing the sensor.