EEVblog #626 – Ceramic Capacitor Voltage Dependency

Dave explains, shows, and measures a potentially big trap with using high value ceramic capacitors.
Is your 10uF capacitor really 10uF in your circuit? You might be shocked!
Those humble X7R caps you think are a “stable” dielectric? think again…

Class II and above ceramic capacitors can vary their capacitance drastically with DC bias voltage level and also the applied AC voltage.
Links:
http://www.murataamericas.com/murata/murata.nsf/promo_dcbias.pdf
http://www.avx.com/docs/masterpubs/mccc.pdf
http://www.ece.ucdavis.edu/vcl/asap/asap_v1/docs/X7R_C.pdf
http://psearch.murata.com/capacitor/product/GRM21BR60J106KE19%23.html
http://www.murata.com/products/design_support/simsurfing/outline.html
http://www.avx.com/SpiApps
Capacitor Tutorial – Ceramics & Impedance
https://www.youtube.com/watch?v=TDDoi70cxw0
The piezoelectric effect demonstrated:
https://www.youtube.com/watch?v=KFCRB4d991E

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