Direct Digital Simultaneous Phase-Amplitude Noise and Allan Deviation Measurement System

Published

October 28, 2024

Author(s)

Marco Pomponio, Archita Hati, Craig Nelson

Abstract

In this paper, we present a direct digital measurement system capable of simultaneously measuring phase noise, amplitude noise, and Allan deviation with and without cross-correlation. The residual phase noise of the single-channel system achieves L(1 Hz) = −143 dBc/Hz for a 10 MHz input signal, and an Allan deviation noise floor of 3.2 × 10−15 at 1 second averaging time (τ ). The systems' performance improves as expected with cross-correlation, resulting in an average limited residual white noise floor of −185 dBc/Hz after only a few minutes of averaging, an improvement of 30 dB compared to a single-channel system. It also reaches an average limited flicker phase noise floor of L(1 Hz) = −160 dBc/Hz within a span of less than two days, with an Allan deviation of 5 × 10−16 @ τ = 1 second. To the best of our knowledge, this represents the lowest noise performance ever reported for a digital measurement system. Our solution is based on a pair of high-performance analog-to-digital converters and a single system-on-a-chip (SoC) with multiple processors and a field programmable gate array (FPGA). The architecture allows for processing all data samples in real-time without dead-time between calculation frames, enabling the fastest averaging possible during cross-correlation.

Citation

IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Letters

Volume

4

Pub Type

Journals

Download Paper

https://doi.org/10.1109/OJUFFC.2024.3487147

Local Download

Keywords

Allan Deviation, Amplitude Noise, Analog-to-Digital Converter (ADC), Cross Correlation, Digital Down Conversion, Direct Digital Measurement, Field Programmable Gate Array (FPGA), Phase Noise.

Citation

Pomponio, M. , Hati, A. and Nelson, C. (2024), Direct Digital Simultaneous Phase-Amplitude Noise and Allan Deviation Measurement System, IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Letters, [online], https://doi.org/10.1109/OJUFFC.2024.3487147, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957735 (Accessed October 7, 2025)