  Magnetometers based on quantum mechanical processes enable high sensitivity
and long-term stability without the need for re-calibration, but their
integration into fieldable devices remains challenging. This paper presents a
CMOS quantum vector-field magnetometer that miniaturizes the conventional
quantum sensing platforms using nitrogen-vacancy (NV) centers in diamond. By
integrating key components for spin control and readout, the chip performs
magnetometry through optically detected magnetic resonance (ODMR) through a
diamond slab attached to a custom CMOS chip. The ODMR control is highly uniform
across the NV centers in the diamond, which is enabled by a CMOS-generated
$\sim$2.87 GHz magnetic field with <5% inhomogeneity across a large-area
current-driven wire array. The magnetometer chip is 1.5 mm$^2$ in size,
prototyped in 65-nm bulk CMOS technology, and attached to a 300$\times$80
$\mu$m2 diamond slab. NV fluorescence is measured by CMOS-integrated
photodetectors. This on-chip measurement is enabled by efficient rejection of
the green pump light from the red fluorescence through a CMOS-integrated
spectral filter based on a combination of spectrally dependent plasmonic losses
and diffractive filtering in the CMOS back-end-of-line (BEOL). This filter
achieves $\sim$25 dB of green light rejection. We measure a sensitivity of 245
nT/Hz$^{1/2}$, marking a 130$\times$ improvement over a previous CMOS-NV sensor
prototype, largely thanks to the better spectral filtering and homogeneous
microwave generation over larger area.
