Implementation of a Cross-Spectrum FFT Analyzer for a Phase-Noise Test System in a Low-Cost FPGA

Figure 6

Cross-correlation phase-noise measurement with the APPH6040. The DUT was ultra-low-phase-noise 100 MHz OCXO. The grey trace shows a measurement with only one correlation. The blue trace shows a measurement with correlations in stage 0 (5–50 MHz), correlations in stage 1 (0.5–5 MHz), and so on. Both measurements were performed with the internal reference sources of the APPH6040. Same measurement time of ca. 11 sec for both measurements.