A CMOS bipolar transistor with a locally doped base in the proximity of the emitter as a magnetic field sensor

A comparative study of a CMOS lateral magnetoresistor structure and a novel structure, with a locally doped base in the proximity of the emitter, is presented. For both structures a differential approach is used. The results indicate that the two locally doped p⁺-stripes restrict the injection of electrons from the emitter to the vertical direction, dramatically changing the path of the electrons flowing from the emitter laterally to the collectors. This in turn leads to a more effective deflection, by the magnetic field, of the electrons contributing to the collector current. As a result the magnetic sensitivity of the device is increased by more then three times