A Compact C-band EPR-on-a-chip Transceiver in 130-nm SiGe BiCMOS

We present a chip-integrated C-band transceiver for electron paramagnetic resonance (EPR) spectroscopy, implemented in a 130-nm SiGe BiCMOS technology. The presented EPR-on-a-chip transceiver displays an excellent minimum in-band noise Figure of 0.82 dB and a peak in-band output power $P_{\mathrm{sat}}$ of 9.8 dBm. Furthermore, the presented chip provides a wide operating frequency range from 6 GHz to 8 GHz, which is crucial for detecting wideband EPR signals. The receiver and two-stage four-way combined power amplifier provide (conversion) gains of 32.8 dB and 13 dB, respectively. In proof-of-concept EPR measurements using an off-chip PCB coil as a detector and the standard EPR sample BDPA ($\alpha,\gamma$-bisdiphenylene-$\beta$-phenylallyl), the presented chip achieves a competitive spin sensitivity of $8\times 10^{10}$ spins/$\sqrt{\mathrm{Hz}}$ over an active volume of 31 n1.