A CMOS differential receiver dedicated to nuclear magnetic resonance applications

This paper examines the design and implementation of a 21 MHz CMOS differential or so-called dual-path receiver (DPR) dedicated to nuclear magnetic resonance (NMR) spectrometer. This receiver features a CMOS chip incorporated with two mini-Coils and other circuitries. Herein we discuss the design and implementation of the DPR chip as the core part of this new NMR system. The DPR consists of two differential low-noise amplifiers, voltage buffers, phase shifters and variable gain amplifiers in order to accurately cancel the effect of the background NMR signal. We put forward the design and analysis of the DPR chip and thereafter demonstrate and discuss the simulation and experimental results. Based on these results, the front-end receiver achieves a voltage gain of 80 dB at a low input referred noise of 2.7 nV/√Hz. The chip is designed in a 0.13-µm CMOS technology and occupies an area of 1 mm × 2 mm. As per experimental results, this device can be used n the future low-cost NMR technologies.