Feature: RF and microwave


Figure 8: Transmit SFDR and output power vs frequency (before phase rotation calibration)


for more efficient signal transmission. Figures 8 and 9 show how we preserve the transmit output power of the system while still obtaining a drastic improvement in SFDR aſter running the calibration process. SFDR is a critical metric in RF systems, representing the ratio


between the fundamental signal and the strongest spur within the bandwidth of interest. Post-calibration measurements revealed a substantial increase in SFDR, confirming the effectiveness of the de-correlation efforts. Te system now operates with a cleaner spectral profile, which is essential for applications requiring high linearity and low distortion. Te improvements in output power and SFDR were consistent


across the tested frequency range, indicating that the calibration and shielding techniques are not frequency dependent. Tis suggests that the methodology can be generalised to other


configurations or future revisions of the Quad-Apollo MxFE platform. Te calibration process proved to be repeatable and scaleable,


showing consistent results across multiple channels and frequency ranges. Importantly, the improvements were achieved without compromising JESD link stability, confirming the robustness of the approach in real-world system conditions. Tese results validate the effectiveness of combining hardware


and soſtware techniques for spur mitigation, and open the door for further optimisation. Future work may explore automating the phase rotation process, integrating real-time spur monitoring and extending the methodology to other platforms or IC configurations. Ultimately, this work contributes to the broader goal of enabling cleaner, more reliable signal chains in next- generation RF systems.


Figure 9: Transmit SFDR and output power vs frequency (after phase rotation calibration) 40 April 2026 www.electronicsworld.co.uk


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