A low power CMOS receiver for a tissue monitoring NMR spectrometer

This paper presents a low power CMOS nuclear magnetic resonance (NMR) receiver chip for monitoring of small tissue samples within the human body. We present preliminary results from a prototype spectrometer focused on the phosphorus (³¹P) spectra operated in a 5 Tesla B₀ magnet. The prototype, fabricated in a 130nm CMOS technology, occupies an active area of 0.215mm² and consumes 4mA from a single 1.5V supply. The low-IF receiver chip exploits Q enhanced voltage multiplication, includes a down converting RF frontend, a frequency synthesizer operating at 86MHz and 2^nd order sigma-delta ADCs. Measured results from the prototype are used to validate the circuit architectural decisions.