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|Author(s):||David A. Howe; Archita Hati; Craig W. Nelson; Danielle G. Lirette;|
|Title:||PM-AM Correlation Measurements and Analysis|
|Published:||May 24, 2012|
|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.|
|Conference:||2012 IEEE International Frequency Control Symposium|
|Proceedings:||Proceedings of the 2012 IEEE International Frequency Control Symposium|
|Pages:||pp. 1 - 5|
|Dates:||May 22-24, 2012|
|Keywords:||3IM,Amplitude noise,Correlation,Cross-spectrum,Digital AM measurement,Digital PM measurement,Duffing,IM3,Intercept,MEMS,Nonlinear,Phase noise,Resonator|