Electrical circuit which is linearly responsive to changes in magnetic field intensity

Claim 1

A circuit for measuring the intensity of a magnetic field, said circuit comprising: (a) a magnetic field sensing device for sensing said magnetic field intensity, said magnetic field sensing device being adapted to produce an electrical output signal (U in ), said electrical output signal (U in ) being dependent on an electrical input signal (U D ) received at an electrical control input and said magnetic field intensity, the electrical output signal (U in ) of said magnetic field sensing device having a sensitivity (K H ) to said magnetic field intensity and a sensitivity (K E ) to said electrical input signal (U D ); (b) an amplifier, said amplifier being adapted to receive said electrical output signal of said magnetic sensing device (U in ) and amplify said electrical output signal of said magnetic sensing device (U in ) by an amplification factor (K V ) to produce an amplified output signal (U O ). (c) a potentiometer, said potentiometer being adapted to receive said amplified output signal (U O ) and damp said amplifier output signal (U O ) by a damping factor (K D ) to produce said electrical input signal (U D ) Wherein U D =U O K D and (d) feedback means for connecting said potentiometer to said electrical control input of said magnetic field sensing device, so that said magnetic field sensing device can receive said input signal (U D ) from said potentiometer, said magnetic field sensing device, said amplifier and said potentiometer being adapted so that the product of (i) the sensitivity (K E ) of said magnetic field sensing device to said electrical input signal (U D ); (ii) the amplification factor (K V ) of said amplifier; and (iii) the damping factor (K D ) of said potentiometer, is much greater than unity, so that said amplifier output signal (U O ) is substantially linearly related to said magnetic field intensity.