A low-power high-sensitivity single-chip receiver for NMR microscopy

Abstract

In this paper, we present a fully-integrated receiver for NMR microscopy applications manufactured in a 0.13μm CMOS technology. The design co-integrates a 10-turn planar detection coil together with a complete quadrature, low-IF downconversion receiver on a single chip, which operates from a single 1.5V supply with a total power dissipation of 18mW. The detector’s measured time-domain spin sensitivity is 3×10131Hspins/Hz at 7T. Additionally, the paper discusses two important aspects of NMR microscopy using planar detection coils: the link between the detection coil’s spin sensitivity and the achievable image SNR and the correction of image artifacts induced by the inhomogeneous sensitivity profile of planar detection coils. More specifically, we derive analytical expressions for both the theoretical image SNR as a function of the coil’s spin sensitivity and the sensitivity correction for a known coil sensitivity profile in CTI MR imaging experiments. Both expressions are validated using measured data in the imaging section of the paper. Thanks to the improved spin sensitivity of the utilized integrated receiver chip compared to a previously presented design, we were able to obtain sensitivity corrected images in a 7T spectroscopy magnet with isotropic resolutions of 9.6μm and 5μm with single-shot SNRs of 37 and 15 in relatively short imaging times of 4.4h and 24h, respectively.