Phase noise frequency distribution of SC and AT quartz crystal resonators

Phase noise measurements of 1100 quartz crystal resonators have been collected and analyzed. The focus of the analysis is on the nature and characteristics of the variations, or distribution, of phase noise in groups of similarly produced resonators. Crystal cuts represented in the study include the SC and AT, of various overtones, ranging in frequency from 18.754250 MHz to 111.250 MHz. The phase noise data displayed as histograms show nonnormal distributions. The nonnormal nature of the histograms is accentuated by the limitation of the reference crystal which introduces a skewness to the distribution. A technique that aids in the reduction of this problem is described. The isolation and identification of the various modes observed in multimodal distributions assists in the control or elimination of any associative causes and narrows the observed screening variances, improving resonator yields