BS IEC 62047-32-2019 pdf free download – Semiconductor devices — Micro- electromechanical devices Part 32: Test method for the nonlinear vibration of MEMS resonators.
This part of lEC 62047 specifies the test method and test condition for the nonlinear vibrationof MEMS resonators. The statements made in this document apply to the development andmanufacture for MEMS resonators.
2Normative references
The following documents are referred to in the text in such a way that some or all of theircontent constitutes requirements of this document. For dated references,only the editioncited applies. For undated references, the latest edition of the referenced document (includingany amendments) applies.
IEC 62047-1,Semiconductor devices – Micro-electromechanical devices – Part 1:Terms anddefinitions
3 Terms and definitions
For the purposes of this document,the terms and definitions given in lEC 62047-1 and thefollowing apply.
IEC Electropedia: available at http://www.electropedia.org
Iso Online browsing platform: available at http://www.iso.orglobp
3.1
nonlinear vibration
vibration whose displacement has a nonlinear relationship with the elastic restoring force, withthe change of the vibration amplitude
3.2
nonlinear jump
jump phenomenon of the frequency response curve when the vibration amplitude exceeds acertain threshold
3.3
frequency deviation
deviation of the vibration frequency of the resonator in a closed-loop system from the naturalfrequency of the resonator
4Test parameters of nonlinear vibration of the resonators
Test parameters of nonlinear vibration of the resonators are:
a) amplitude-frequency response of the nonlinear vibration，A(o);b) phase-frequency response of the nonlinear vibration，P(o);
c) bending factor of the amplitude-frequency response, b ;
d) amplitude threshold for the nonlinear jump,
e) frequency deviation of the self-exciting closed-loop system,
f) frequency deviation of the phase-locked closed-loop system,
g) frequency deviation of the burst-exciting closed-loop system,
5 Test method for the amplitude-frequency response and phase-frequency
response of the nonlinear vibration
5.1 Test system
A test system consists of the following equipments:
a) laser vibrometer;
b) micro-optical apparatus;
c) signal generator;
d) vacuum chamber;
e) mounting fixture;
f) vacuum pump;
g) angle valve.
The test system is illustrated in Figure 1 .
5.2 Test conditions
a) Keep the ambient temperature within 23 °C ± 5 °C.
b) Maintain the vacuum degree of the vacuum chamber according to the actual operation of the resonator.
c) Adjust the micro-optical apparatus to restrict the laser spot within the surface of the resonator.
d) For transparent resonators, the laser beam should illuminate on the metal layer on the resonator to enhance the reflected laser intensity.
e) The connection of the resonator, the installing base and the vacuum chamber should be strong enough.
f) For out-of-plane vibrating resonators, the surface of the installing base should be parallel
to the horizontal plane.For in-plane vibrating resonators, the surface of the installing baseshould be set to a certain angle about the horizon level, to ensure enough intensity of thereflected laser into the detector.
g) The vacuum pump and the vacuum chamber should be connected with flexible bellows in
case of the vibration propagation from the pump to the chamber.
h) The angle valve should be tightly shut off to well maintain the vacuum level, and then the
pump turned off before operating the test procedure.
5.3Test procedures
a) Set the frequency of the vibration excitation according to the estimated value of the
natural frequency of the resonator.And then implement the initial frequency scan aroundthe natural frequency within a wide range. The amplitude frequency response and thephase frequency response can be measured according to the vibration displacement ofthe resonators.And record the resonant frequency of the resonator.
b) Reset the vibration excitation parameters to implement the frequency scan for the second
time: reducing the interval of the frequency scan to half of that set in the initial frequencyscan and reducing the range of the frequency scan to ten times of the half-powerbandwidth of the amplitude frequency response. The amplitude frequency response andthe phase frequency ‘response can be measured according to the vibration displacementof the resonators.And record the resonant frequency of the resonator.
c)Compare the resonant frequencies obtained by the initial and the second tests. lf the
discrepancy in the resonant frequencies is smaller than 1 ppm1 of the resonant frequencymeasured in the second test, either the initial or the second test result can be deemed asthe accurate amplitude frequency response and the phase frequency response. lf thediscrepancy in the resonant frequencies exceeds 1 ppm of the resonant frequencymeasured in the second test,the third time frequency scan with further small frequencyinterval should be implemented，until the discrepancy in last tested resonant frequencyand the previous one is smaller than that 1 ppm of the resonant frequency measured inthe last test.BS IEC 62047-32 pdf download.