PM-AM Correlation Measurements and Analysis

Published

May 24, 2012

Author(s)

David A. Howe, Archita Hati, Craig W. Nelson, Danielle G. Lirette

Abstract

We measure and analyze effects of nonlinear mixing of phase-noise modulation (PM) and amplitude-noise modulation (AM) in an oscillating signal by real-time correlations measured in the cross power spectral density (CPSD). We outline sensitive measurements of PM-AM correlation coefficients by means of a time-averaged CPSD measurement technique. Separate but simultaneous PM and AM measurements using a two-channel cross-correlation spectrum analyzer, quantifies the relevant effects of intermodulation mixing with excellent sensitivity compared to traditional 3IM measurements and the scatter-plot correlation technique. Time-averaged cross-spectrum measurements provide good estimates of correlation coefficients as a function of Fourier frequency (f). We use normalized PM-AM CPSD measurements of a 645 MHz quartz-MEMs oscillator as an example and find that 1/f PM-AM CPSD is exactly correlated, even for very widely differing levels of PM and AM noise, in which individual PSDs of PM and AM differ by >40 Db (or, greater than a factor of 10,000). We also verify that white-PM noise has uncorrelated PM-AM CPSD.

Proceedings Title

Proceedings of the 2012 IEEE International Frequency Control Symposium

Conference Dates

May 22-24, 2012

Conference Location

Baltimore, MD

Conference Title

2012 IEEE International Frequency Control Symposium

Pub Type

Conferences

Keywords

3IM, Amplitude noise, Correlation, Cross-spectrum, Digital AM measurement, Digital PM measurement, Duffing, IM3, Intercept, MEMS, Nonlinear, Phase noise, Resonator

Citation

Howe, D. , Hati, A. , Nelson, C. and Lirette, D. (2012), PM-AM Correlation Measurements and Analysis, Proceedings of the 2012 IEEE International Frequency Control Symposium, Baltimore, MD (Accessed July 6, 2025)