A CMOS Magnetic Hall Sensor Using a Switched Biasing Amplifier

A compact CMOS magnetic Hall sensor that includes both a Hall plate and readout circuit is proposed. In order to achieve a low-noise and low-power operation, the sensor employs a switched biasing amplifier with a chopper. The prototype has been implemented and fabricated in a high-voltage 0.18
$\ \mu{\rm m}$
CMOS process and occupies 0.624
${\rm mm}^{2}$
. Owing to the switched biasing amplifier, the input-referred noise is reduced from 41
$\mu{\rm T}\surd{\rm Hz}$
to 25
$ \mu {\rm T}/\surd{\rm Hz}$
. The entire sensor consumes 4.5 mW with a 3.3 V supply voltage.