Xilinx RFSoC Platform Evaluation Demonstrates Suitability for Critical Low-Level RF Control Systems

The increasing demand for compact and efficient radio frequency systems drives innovation in integrated hardware platforms, and researchers are now rigorously evaluating the potential of Xilinx RFSoC technology for demanding applications beyond traditional telecommunications. Shreeharshini Dharanesh Murthy, Victoria Moore, Qiang Du, and colleagues, including Angel Jurado, Michael Chin, and Keith Penney, present a comprehensive assessment of RFSoC performance in the context of Low-Level RF control systems, crucial for maintaining stability in particle accelerators. This work establishes, for the first time, a quantitative comparison between RFSoC-based designs and conventional approaches, focusing on critical metrics like signal fidelity and phase noise. By detailing the advantages and challenges of adopting this new architecture, the team provides essential guidance for engineers developing the next generation of high-performance LLRF systems and opens the door to more compact and efficient accelerator technologies.

The direct-sampling architecture minimizes end-to-end latency, reaching 300 nanoseconds, a substantial improvement over systems relying on intermediate frequency stages. The system exhibits excellent channel-to-channel isolation, exceeding 80 dB, which minimizes signal leakage and distortion.

Detailed characterization of the integrated analog-to-digital and digital-to-analog converters reveals strong performance, including high signal-to-noise ratios and low distortion. This predictable and repeatable latency is crucial for stable control, ensuring precise operation of the accelerator or laser. The study employed a direct conversion architecture implemented on a Xilinx ZCU208 Evaluation Board, leveraging the integrated high-speed data converters and programmable logic. Scientists used a CLK104 RF Clock Add-on Card to establish a stable timing reference, ensuring accurate signal generation and processing. This approach facilitated real-time signal processing and feedback control, allowing for dynamic adjustment of the RF parameters and optimization of the system performance. Scientists achieved substantial improvements in clock jitter performance by optimizing the clocking architecture, reducing jitter to as low as 80 femtoseconds, a considerable reduction from the standard configuration. These measurements confirm a significant reduction in jitter and improved sampling clock phase noise, highlighting the effectiveness of refined PLL configuration and loop filter parameters. Further characterization of the integrated Digital-to-Analog Converter (DAC) revealed a Signal-to-Noise Ratio (SNR) of 69.

43 dB, a Spurious-Free Dynamic Range (SFDR) of 76. 97 dBc, and an Effective Number of Bits (ENOB) of 10. 992 bits at a 500MHz tone frequency. These wideband measurements demonstrate the DAC’s ability to meet the stringent requirements of closed-loop LLRF controllers, exceeding an SFDR of 88 dBc within a 200kHz bandwidth, comparable to conventional LLRF systems. Analog-to-Digital Converter (ADC) characterization yielded an SNR of 55.

78 dB, an SFDR of 79. 48 dBc, and an ENOB of 8. 972 bits, confirming its suitability for high-precision signal acquisition. Scientists also measured channel-to-channel isolation in the ZCU208, achieving greater than 80 dB, which is comparable to performance in conventional systems and critical for minimizing signal distortion and maintaining system stability in multi-channel RF applications. However, the authors acknowledge that initial investment costs and the need for specialized expertise represent important considerations.