**5. Conclusions**

The OFDM signal in the UHF band for various broadcasting and communication services can severely aggravate the selectivity performance of the MedRadio RF receiver through the IM2 distortion. We have presented an analytic investigation on how the OOB OFDM signal induces the IM2 distortion and leads to the SNR degradation at the RF receiver. We also have performed theoretical analysis on how the OFDM-induced IM2 distortion can be equivalently translated to a two-tone-induced IM2 distortion. As a result, we have introduced an offset parameter *Poffset* for compensating the difference between the multi-tone and two-tone effects. The designed MedRadio low-IF RF receiver is fabricated in a 65 nm CMOS process. Two design techniques have been described, one for the IM2 calibration through the gate bias tuning at the passive mixer's FETs, and the other for the dc offset calibration through the body bias tuning at the subsequent TIA's FETs. The proposed RF receivers have shown significant OOB CIR improvements, and the measured maximum tolerable CIR performances are between −40.2 and −71.2 dBc for the two-tone blocker and between −70 and −77 dBc for the single-tone blocker. To the author's best knowledge, this work is the first to present the analytical and experimental investigations on the OFDM-induced OOB selectivity performances in the MedRadio RF receiver for the biomedical and biosensor applications. The results of this work will be essential to enhance the selectivity performance of the MedRadio RF receiver and guarantee reliable and robust wireless communication services in implanted and wearable biomedical devices.

**Author Contributions:** Conceptualization, Y.L., S.C. and H.S.; circuit design and measurements, Y.L., J.K. and H.S.; formal analysis, H.S.; investigation, Y.L. and S.C.; data curation and visualization, Y.L., J.K. and H.S.; supervision, H.S. All authors participated for all other aspects. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the National Research Foundation of Korea under Grant No. 2020R1A2C1008484 and Kwangwoon Research Grant in 2020.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
