Wideband Vector Signal Generation Using Multiple Narrowband Phase-Coherent Synchronous Signal Channels

This paper introduces two novel frequency-stitching-based methods for wideband vector signal generation. Employing narrowband, phase-coherent, and synchronous transmitters equipped with low-speed and high-resolution digital-to-analog converters, these methods facilitate the generation of wideband vector signals. The first method is customized for instrumentation, emphasizing on periodic test signals, while the second method is tailored for real-time applications, capitalizing on the frequency domain modulation characteristics of orthogonal frequency division multiplexing (OFDM) signals. Additionally, the paper presents a frequency domain calibration technique using multi-tone signals to address nonidealities in frequency-stitching-based transmitters. Proof-of-concept validation experiments conducted at X-band (9.6 GHz) and D-band (129.6 GHz) demonstrate the efficacy of the proposed methods and calibration technique in generating wideband vector signals, achieving up to 8 GHz bandwidth and an error vector magnitude as low as 0.3% when generating a 7.2 GHz 256-QAM OFDM signal.