As is known in the art, one type of conventional current sensor uses a Hall effect element, which generates a voltage in response to a magnetic field associated with a current passing through a conductor. Typical current sensors of this type include a Hall effect elements mounted on a dielectric material, for example a circuit board. Typically, a ferrous core (flux concentrator) is used in proximity to the Hall effect element.
Another type of conventional current sensor uses a magnetoresistance element, which changes resistance in response to a magnetic field associated with a current passing through a conductor. A fixed electrical current is directed through the magnetoresistance element, thereby generating a voltage output signal proportional to the magnetic field. Conventional current sensors of this type use an anisotropic magnetoresistance (AMR) element mounted on a dielectric material, for example a circuit board.
Various parameters characterize the performance of current sensors, including sensitivity and linearity. Sensitivity is related to a change in the resistance of the magnetoresistance element or a change in output voltage from the Hall effect element in response to a change in magnetic field. Linearity is related to the degree to which the resistance of the magnetoresistance element or the output voltage from the Hall effect element varies in direct linear proportion to the magnetic field.
Various types of magnetic field sensing elements (e.g., Hall effect elements and magnetoresistance elements) are known to have different characteristics, including, but not limited to, different sensitivities, different linearities, and also different hysteresis characteristics in response to a magnetic field. It is also known that a particular type of magnetic field sensing element, for example, a Hall effect element, can have a substantially different sensitivity when fabricated on substrates comprised of different materials, for example, Silicon (Si) and Gallium Arsenide (GaAs).
Typical current sensors tend to be undesirably large, both in terms of height and circuit board area. Typical current sensors also tend to be restricted in dynamic range, i.e., they tend to saturate at large currents, which generate large magnetic fields, and/or they tend to be inaccurate at small sensed currents, which generate small magnetic fields. It would, therefore, be desirable to provide a current sensor having a reduced size, improved accuracy, and/or improved dynamic range.
While conventional current sensors are described above as having particular disadvantages, it will be appreciated that conventional external magnetic field sensors and also conventional electrical signal isolators suffer from the same disadvantages. It would, therefore, be desirable to provide an external magnetic field sensor and also an electrical signal isolator having a reduced size, improved accuracy, and/or improved dynamic range.