Design of a digital gauss meter for precision magnetic field measurements

The design of a precision gauss meter for measuring magnetic fields is presented. The instrument utilizes a Hall element probe as a transducer and features an analog front end capable of amplifying dc and ac signals. A 16-bit analog-to-digital converter interfaces the analog section to a microcontroller-based digital section which corrects nonlinearities in the Hall element probe as well as gain errors in the amplifiers. The specifications called for 0.25% dc accuracy and an ac bandwidth of 10 kHz. SPICE models were used to determine the frequency response, noise characteristics, and temperature effects of the Hall element probe and the analog section. Finally, the analog section and the Hall element probe were calibrated separately and configuration information was created for storage in EEPROM memory.