A 5–780-MHz Transceiver ASIC for Multinuclear NMR Spectroscopy in 0.13-μm BiCMOS
Frederik Dreyer, Daniel Krüger, Sander Baas, Aldrik H. Velders, Jens Anders
Abstract
In this paper, we present a broadband (5-780MHz) transceiver ASIC optimized for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{ \boldsymbol {1}}\text{H}$ </tex-math></inline-formula> and X-nuclei nuclear magnetic resonance (NMR) with external custom-designed microcoils. The NMR-on-a-chip transceiver is realized in a 0.13 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> BiCMOS technology, consumes an area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1100 \boldsymbol {\times }900\mu \text{m}\,\,\boldsymbol {^{2}}$ </tex-math></inline-formula> , and integrates a quadrature receiver, consisting of a low-noise amplifier, a quadrature downconversion mixer, and intermediate-frequency variable gain amplifiers, a power amplifier, and a frequency synthesizer on a single chip. An extensive noise analysis of the BJT-based low-noise amplifier with regard to the optimum source impedance provides simplified expressions for an optimized LNA design for broadband NMR-on-a-chip applications. The NMR-on-chip transceiver provides a measured state-of-the-art input-referred voltage noise of 610pV/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sqrt {\text {Hz}}$ </tex-math></inline-formula> and a maximum RX gain of 66dB. In combination with an external, custom-designed solenoidal microcoil, the presented NMR-on-a-chip transceiver achieves a state-of-the-art normalized <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{ \boldsymbol {1}}\text{H}$ </tex-math></inline-formula> spin sensitivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.2 \boldsymbol {\times } 10^{ \boldsymbol {17}}$ </tex-math></inline-formula> spins <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$/\sqrt {\text {Hz}}\cdot \text {T}^{ \boldsymbol {2}}/\text{m}$ </tex-math></inline-formula> with an untuned, i.e. broadband front-end. Proof of concept NMR experiments on multiple nuclei ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{ \boldsymbol {1}}\text{H}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{ \boldsymbol {2}}\text{H}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{ \boldsymbol {13}}\text{C}$ </tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{ \boldsymbol {19}}\text{F}$ </tex-math></inline-formula> ) verify the applicability of the proposed untuned, broadband approach.