A New Receiver Front-End for Simultaneous Dual-Frequency NMR Applications

摘要

To obtain certain information such as metabolic concentrations in neural or muscular tissues and other applications, it is necessary to design nuclear magnetic resonance (NMR) transmitters/receivers capable of operating at multiple frequencies, while maintaining a good performance at each frequencies. We have proposed a new NMR receiver front-end for simultaneous detection of proton and carbon nucleus. The system consists of two reception coils for carbon and hydrogen analysis, a multiband low-noise amplifier (LNA) for increasing the voltage level and a network for passive amplification, noise figure minimization and decreasing mutuality effect between two coils. The proposed coil set was designed, simulated and analyzed and also the signal to noise ratio (SNR) with quality factor have been calculated for it by simulation. The LNA has been designed in a 0.18 mu m CMOS technology and its gains for carbon and proton NMR signals are 45 and 48 dB, respectively. The input referred noise for both signals is lower than 0.4 nV/sqrt(Hz) and the power consumption is 4 mA from a single 1.8 V supply.