A Portable Wideband CMOS NMR Spectrometer for Multinuclear Molecular Fingerprinting

We present a small wideband CMOS nuclear magnetic resonance (NMR) spectrometer capable of multinuclear molecular fingerprinting (molecular structure determination). The spectrometer combines a small permanent magnet and a wideband digitally assisted CMOS radio frequency (RF) transceiver integrated circuit (IC) that operates in the RF frequency range from 1 to 100 MHz. This small, thus broadly deployable, NMR system can find applications in online, on-site, or on-demand multinuclear molecular fingerprinting. Concretely, the wideband spectrometer performs NMR spectroscopy with nuclear spins from
$^{1}$
H,
$^{19}$
F, and
$^{2}$
H with a spectral resolution down to 0.07 ppm to determine structures of molecules containing these nuclear spins; it can also perform NMR with the nuclear overhauser effect (NOE), which is an important modality that further enhances the capability for molecular fingerprinting (we demonstrate the NOE by reading the
$^{19}$
F NMR signal that is enhanced via heteronuclear magnetization transfer from
$^{1}$
H spins). The wideband operation of the CMOS RF transceiver IC is made possible by integrating a delay-locked loop (DLL) with a broad locking range. The RF receiver (RX) part of the IC achieves an input-referred noise less than 1.2 nV/
$\surd $
Hz across the entire bandwidth of 1–100 MHz, while the RF transmitter (TX) part employs a digital power amplifier.