A novel CMOS Hall effect sensor

• The proposed sensor makes use of a parasitic vertical BJT.
• The Hall effect appears as a current through the emitter of the BJT.
• The BJT senses and amplifies the Hall current by β + 1 and can regain lost sensitivity when biased with lower current.
• Lower Hall plate bias current results in lower Joule heating which is favorable for μ-Hall applications.
• The new method is compatible with standard CMOS processes.

This paper reports on a new technique for sensing the Hall effect in an integrated CMOS device. Contrary to traditional Hall plates where sensor contacts comprise of highly doped, low ohmic contacts, the proposed sensor makes use of a parasitic vertical pnp bipolar junction transistor (BJT) to sense and amplify the Hall current caused by the Lorentz force in the presence of a perpendicular magnetic field. The Hall effect appears as a current through the emitter of the BJT. The BJT forward gain implies a direct gain of at least β + 1 in the measured signal in comparison to traditional methods.