Measured Data on Ceramic Filters


Some data on Murata ceramic filters is available from the Murata website. The measured data provided here is an extension of that from the manufacturer to the situation where the input and output impedances for the filter do not match the specifications. This results in changes to the filter centre frequency and bandwidth, and increased ripple. However these changes may be acceptable in some applications.

The application of these filters called for a 330 ohm input impedance in an FSK receiver. The data shown below indicates that the ripple in such a case is relatively minor provided that the output impedance is approximately as specified. Centre frequency and bandwidth are not affected significantly by variations from the specified impedances.

The ceramic filter, purchased locally, was not identified other than its centre frequency and bandwidth. The type number is estimated from the manufacturer's data obtained from their website.
The following figures use a linear scale.

Figure 1. Measured data for 2K input and 2K output impedance

Figure 2. Measured data for 330 ohm input and 330 ohm output impedance

Figure 3. Measured data for 330 ohm input and 2K output impedance

Figure 4. Bottom view of CFWLA package

First created 31 October 2004.
© Ken Sarkies 2006