Design of an AC excitation hall sensor front-end system with 12-bit SAR ADC

Hall effect sensors have been utilized in several applications that range from industrial and biomedical. It has been deployed alongside magnetic nano-beads into an assay as part of a protein detection platform. However, the hall voltage can be affected by several interfering noise signals in the form of supply hum, dc offsets, temperature variations, circuit induced noises, etc. A possible method that can reduce the effect of these signals is by utilizing an AC excitation line instead of DC. This was demonstrated on this paper as well as the design of a suitable front-end detecting system with a digital output. Such front-end consisted of a chopper stabilized instrumentation amplifier and a bandpass filter based on PMOS pseudoresistors, while the digital back-end consisted of a 12-bit Successive Approximation Register A/D converter. The system was designed using TSMC 0.18 um 1P6M technology.