ECA 512

Abstract

Methods are described which permit determination of fhe values of the equivalent electrical parameters of piezoelectric quartz crystal units, utilizing automated measuring equipment. The methods described make use of standard coaxial terminations, standard calibrated mismatched terminations, coaxial air-lines, and short-circuit terminations for both calibration of the instrument/ test fixture error terms, and for verification of instrument performance. These coaxial standards, designed for 50 ohm systems, are readily available, and can be standardized in terms of national standards of impedance over very wide frequency ranges. <br>The measurement methods described are intended to provide standard reference values of the electrical equivalent parameters. Manufacturers and users may employ any other methods of measurement de sired,10,12 however, when other methods are used, the values obtained shall be correlated to those obtained by the reference methods. <br>This standard is concerned only with the equivalent electrical network which approximates the admittance/ impedance characteristic of a crystal unit over a relatively narrow range of frequencies near an isolated mode of vibration, at a particular excitation level. Non-linear amplitude behavior, or the presence of interfering modes of vibration, not only interfere with the actual measurement, also render the accepted equivalent network representation invalid.