Application of undersampling technique for the design of an NMR signals digital receiver RID D-5411-2011

In this article, undersampling technique theory and design, realization, and workbench test of a low-cost digital MRI (magnetic resonance imaging) receiver are reported. The authors first discuss classic analog receiver architecture, reporting its disadvantages, and then present a receiver with a complete description of the electronic circuit. The intended use of the subsystem should be as a radiofrequency (RF) receiver chain in a low-cost dedicated MRI scanner (e.g., suitable for musculoskeletal limbs studies). The digital receiver consists of a passband (antialiasing) filter, an ADC (analog to digital converter) to digitalize the signal with the undersampling technique, and a DDC (digital down converter) for the frequency translation and filtering to process the signal using a PC. The use of the DDC guarantees perfect signals quadrature and high-performance filtering; moreover, it is adaptable to each modification of the system because of its programmability. Detailed specifications and hardware design of the digital receiver that is designed to be used in a dedicated MR scanner is provided, guaranteeing top performance and low cost. (C) 2006 Wiley Periodicals, Inc