BS EN 60444-11:2010

Specifies the standard method of measuring load resonance frequency f[L] at the nominal value of C[L], and the determination of the effective load capacitance C[Leff] at the nominal frequency for crystals with the figure of merit M > 4.

This part of IEC 60444 defines the standard method of measuring load resonance frequency f_L at the nominal value of C_L, and the determination of the effective load capacitance C_Leff at the nominal frequency for crystals with the figure of merit M > 4.

M, according to Table 1 of IEC 60122-1:2002, is expressed in the following equation:

This gives good results in a frequency range up to 200 MHz. This method allows the calculation of load resonance frequency offset Δf_L, frequency pulling range Δf_L1,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 f_L and C_Leff together with the determination of the equivalent crystal parameters in one sequence without changing the test fixture.

With this method the frequency f_L is searched where the reactance X_C of the crystal has the opposite value of the reactance of the load capacitance.

Furthermore this method allows to determine the effective load capacitance C_Leff at the nominal frequency f_nom.