A 0.1 MHz to 200 MHz high-voltage CMOS transceiver for portable NMR systems with a maximum output current of 2.0 App

This paper presents a single-chip high-voltage transceiver ASIC for low-field NMR spectroscopy. The chip integrates an adjustable high-voltage (HV) H-bridge power amplifier (PA) with a PLL frequency synthesizer and a quadrature low intermediate frequency (low-IF) receiver, achieving a measured input-referred voltage noise density of 1.1 nV / ✓Hz. The operating frequency of the chip is from 0.1 MHz to 200 MHz, supporting all relevant Larmor frequencies for low-field mobile and portable NMR. The PA consists of four isolated 50 V NMOS transistors, isolated gate drivers with a digitally adjustable deadtime control, high-frequency level shifters, and a TX-control logic that supports bootstrapping of the integrated high-side drivers. The output current can be defined by an adjustable voltage supply from 0 V to 50 V, delivering a maximum current of 2.0 App into a non-tuned 3 mm NMR coil and up to 8.3 App into a parallel tuned NMR coil. Inside a custom-designed 1.1 T portable NMR magnet, the system achieves a spin sensitivity of 1.1 × 10 ¹⁶ spins/ ✓Hz and a concentration sensitivity of 1mM/✓Hz.