Adaptive Low PAPR Spectral Stitching for Wideband Microwave Component Measurement

Abstract

Wideband multitone signals are widely used in broadband system identification, channel sounding, and nonlinear measurement, but their direct synthesis is limited by the bandwidth and memory of arbitrary waveform generators (AWGs). Frequency-domain stitching extends the available bandwidth, yet existing methods mainly correct intersegment mismatch after measurement without jointly controlling the waveform’s peak-to-average power ratio (PAPR). This article proposes a low-PAPR multitone synthesis method for frequency-domain stitching. A three-segment active-tone spectrum is constructed with power-boosted overlap regions. Paired overlap tones are assigned identical phases. This design improves the boundary signal-to-noise ratio (SNR) and enables direct phase-difference alignment without delay-induced phase-slope estimation. The proposed adaptive stitching-aware iterative projection algorithm (ASIPA) alternates between time-domain clipping and frequency-domain constraint restoration. It reduces PAPR while preserving the target amplitude spectrum, overlap phase symmetry, and total active-tone power. Adaptive parameter control and a dual-window patience stopping (DWPS) criterion are introduced to improve convergence stability. Fixed-point and Bussgang-based analyses characterize the iterative behavior and clipping distortion. ASIPA achieves the lowest PAPR among the tested stitching-feasible methods, reaching 2.32 dB under the nominal configuration. Hardware validation further reduces the worst case amplitude and phase mismatches from 4.0 % and 2.0° for representative state-of-the-art frequency-domain stitching methods to below 0.8 % and 0.3°, respectively.