A fully-integrated detector for NMR microscopy in 0.13μm CMOS

Abstract

In this paper, we present a fully integrated receiver for NMR microscopy applications realized in a 0.13 μm CMOS technology. The chip co-integrates a planar detection coil together with a complete low-IF downconversion receiver consisting of a low noise amplifier, a quadrature downconversion mixer, a baseband amplifier stage and line drivers. The chip operates from a single 1.5 V supply and consumes about 12 mA of current. The active chip area is about 350×450 μm 2 . The detector's measured input referred voltage noise density at the operating frequency of 300 MHz is 260 pV/ √ Hz resulting in a measured spin sensitivity of 2×10 13 spins/ √ Hz. Preliminary imaging experiments demonstrate the chip's capability of recording micron resolution MR images in imaging times which significantly advance the state-of-the-art.

On the influence of strong magnetic field on MOS transistors

“…However in such a system, the electronics has to work under the strong magnetic field, which may be very challenging. Although integrated systems working under 1.5T and 3T for magnetic tracking within human body MRI scanners have been recently demonstrated [7], as well as integrated circuits working under 7T for NMR micro-imaging [8], no deep study has been provided yet on the influence of strong magnetic field on electronics. However, engineers who develop electronic systems for MRI instrumentation know that electronic circuits may exhibit curious behaviour in such environment, and a few experiments carried out twenty years ago have already reported strong influences of high magnetic field on commercial Field Effect Transistors [9] [10].…”

Compact electron spin resonance skin oximeter: Properties and initial clinical results

“…We overcome this problem using a combination of pulses with relatively low power (as just noted), modern low‐noise amplifiers that do not need to be protected from such pulses, and introducing a “field jump” protocol to the pulse sequence 21 . Last but not least, modern MW technology makes it possible to produce such low‐power systems in a small form‐factor, even based on single‐chip designs 28 making them potentially usable on a wide scale at a very low cost.…”