Hi Robert, some additional notes to the answers of John (was there another reply ..... ;-) . besides having piezo-effect - which indeed is neglectible for class-1 (C0G or NP0) ceramic capacitors - ceramic capacitors also exhibit dielectric absorption. This also yields C0G capacitors, and there are large differences between them. I have seen good ones, having DA-values below 0.01%, but also C0G ceramic capacitors having DA-values of almost 0.5%. Especially when using ceramic capacitors in fast settling filters or S&H circuits, this DA-behaviour will be important too. I recall a problem we had with a bluetooth-loopfilter using a C0G capacitor, the radio ran out of spec (5-slot packet freq. drift over 40KHz). Using another type of capacitor in this loopfilter solved the problem. So, if this is important for you too, then look for ceramic capacitors with low DA-values. More information related to this can be found in an article written by Bob Pease (understand capacitor soakage ..........): http://www.national.com/rap/Application/0,1570,28,00.html regards, Bart appl. eng. www.yageo.com Dear fellow scientists/engineers: We are pondering about using class 1 SMD ceramic capacitors in a loop filter design. Does anyone know if class 1 capacitors have piezo-effect? I don't even know what dielectric materials are used in those caps so any info will be highly appreciated. Best Regards, Robert Tsai ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu -------------------------------------------------------------------------------------------- The information contained in this communication is confidential and may be legally privileged. It is intended solely for the use of the individual or entity to whom it is addressed and others authorized to receive it. If you are not the intended recipient you are hereby notified that any disclosure, copying, distribution or taking any action in reliance of the contents of this information is strictly prohibited and may be unlawful. YAGEO Corporation is neither liable for the proper nor the complete transmission of the information contained in this communication nor for any delay in its receipt. --------------------------------------------------------------------------------------------- ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu