Design, implementation, and RFSoC-based validation of a multi-path RF front-end for wideband spectrum analysis

This paper presents the design, implementation, and validation of a scalable multi-path radio frequency (RF) front-end engineered to extend the spectral analysis capabilities of SDR-class systems. The architecture features five individually filtered reception paths and a tunable local oscillator (LO), supporting both direct sampling and frequency down-conversion to enable clean acquisition across the 10 MHz–8 GHz range. A simulation-guided methodology was employed using a custom harmonic-aware simulation framework that models harmonic distortion and aliasing behavior to inform optimal LO selection and filter planning. The front-end was realized with high-performance discrete components, with each path tailored to ensure spectral isolation and alias-free operation under nonlinear conditions. Comprehensive experimental characterization was performed through three dedicated measurement setups and three independent acquisition sets. Key metrics include insertion loss (11–26 dB), noise figure (13–39 dB), 1 dB compression point (up to 12.8 dBm), and third-order linearity, with OIP3 values reaching 30 dBm and IIP3 exceeding 45 dBm. Group delay was directly measured with 10 MHz resolution and remained confined within 10–15 ns with sub-nanosecond variation. All measurements were obtained using calibrated, high-precision RF instrumentation to ensure traceability and consistency. Functional validation was conducted through real-time integration with a RealDigital RFSoC 4x2 board, confirming full-band signal acquisition and frequency translation across all reception paths. The discrete-component architecture ensures replicability, transparency, and design flexibility, making it well suited for advanced spectrum monitoring, cognitive radio systems, and reconfigurable SDR platforms requiring wideband, low-distortion, and high-dynamic-range RF front-ends.