Drive level dependence versus residual phase noise of fifth overtone AT cut quartz crystals

Currently no valid method of choosing low noise AT cut crystals during crystal manufacturing is available within the crystal manufacturing industry. Drive level dependence (DLD) is a parameter, which can be readily measured by most crystal manufacturers. This paper makes a comparison of DLD measurements to residual phase noise measurements of fifth overtone AT crystals with fixed electrical parameters from various manufacturers. A discussion of crystal manufacturing methods pertaining to reproducibility of low noise fifth overtone AT crystals is also briefly discussed.