Measurement of quartz crystal unit parameters – Part 11: Standard method for the determination of the load resonance frequency fL and the effective load capacitance CLeff using automatic network analyzer techniques and error correction
|Publication Date:||1 October 2010|
|ICS Code (Piezoelectric devices):||31.140|
This part of IEC 60444 defines the standard method of measuring load resonance frequency fL at the nominal value of CL, and the determination of the effective load capacitance CLeff at the nominal frequency for crystals with the figure of merit M > 4.
This gives good results in a frequency range up to 200 MHz. This method allows the calculation of load resonance frequency offset ΔfL, frequency pulling range ΔfL1,L2 and pulling sensitivity S as described in 2.2.31 of IEC 60122-1:2002. In contrary to the simple method of IEC 60444-4, this measurement technique avoids the use of physical load capacitors, and allows higher accuracy, better reproducibility and correlation to the application. It extends the upper frequency limit from 30MHz by the method of IEC 60444-4 to 200MHz approximately. This method is based on the error-corrected measurement technique of IEC 60444-5:1995, and therefore allows the measurement of fLand CLeff together with the determination of the equivalent crystal parameters in one sequence without changing the test fixture.
With this method the frequency fL is searched where the reactance XC of the crystal has the opposite value of the reactance of the load capacitance.
Furthermore this method allows to determine the effective load capacitance CLeff at the nominal frequency fnom.