A 7 GHz VCO-based EPR spectrometer incorporating a UWB data link

This paper presents an electron paramagnetic resonance (EPR) detection system that can wirelessly transmit continuous wave (CW) EPR data over distances up to 30 cm with minimal degradations in SNR. The proposed system comprises a VCO-based EPR-on-a-chip (EPRoC) sensor with a spin sensitivity of $2 \times {10^{12}}\;{\text{spins}}/\sqrt {{\text{Hz}}} $, a 14-bit oversampling ΣΔ-modulator, a 7 GHz bandwidth-tunable ultra-wideband (UWB) transmitter chip, and a custom-designed 2 GHz-bandwidth elliptical dipole antenna. On the receiver side, we directly digitize the antenna signal and recover the EPR signal in the digital domain via a discrete Fourier transform (DFT)-based demodulation scheme. The presented platform is the first wirelessly connected EPR detection system that allows for in-situ EPR experiments using EPRoC detectors under variable operation conditions while enabling direct wireless access to the experimental data. The estimated bit error rate (BER) of the link at a distance of 10 cm from the transmitter is 1×10
^-7
.