Overview

This part of IEC 62575 gives practical guidance on the use of RF BAW filters which are used in telecommunications, measuring equipment, radar systems and consumer products. IEC 62575-2 includes a large number of various kinds of filter configurations, of which the operating frequency range is from approximately 500 MHz to 10 GHz and the relative bandwidth is about 1 % to 5 % of the centre frequency. General information, standard values and test conditions will be included in the upcoming IEC 62575-1. RF BAW filters are now widely used in mobile communications. While the RF BAW filters meet various requirements, many of them can be classified within a few fundamental categories. Standard specifications, given in IEC 62575, and national specifications or detail specifications issued by manufacturers, provide the available combinations of nominal frequency, pass bandwidth, ripple, shape factor, terminating impedance, etcetera. These specifications are compiled to include a wide range of RF BAW filters with standardized characteristics. It cannot be over-emphasized that the user should, wherever possible, select RF BAW filters from these specifications, when available, even if it may lead to making small modifications to his circuit to enable standard filters to be used. This applies particularly to the selection of the nominal frequency. This standard corresponds to a generally expressed desire on the part of both users and manufacturers for guidance on the use of RF BAW filters, so that the filters may be used to their best advantage. To this end, general and fundamental characteristics have been explained in this part of IEC 62575. It is neither the aim of this standard to explain theory, nor to attempt to cover all the eventualities which may arise in practical circumstances. This standard draws attention to some of the more fundamental questions, which should be considered by the user before he places an order for an RF BAW filter for a new application. Such a procedure shall protect the user against unsatisfactory performance. The features of these RF BAW filters are their small size, light weight, adjustment-free, high stability and high reliability. RF BAW filters add new features and applications to the field of surface acoustic wave (SAW) filters and dielectric resonator filters. Nowadays, RF BAW filters with low insertion attenuation are widely used in various applications in the gigahertz range. RF BAW filters are becoming rapidly popular as miniature and low insertion attenuation filters for mobile communication application. RF BAW resonator filters can realize low insertion attenuation easily and a smaller size than that of the RF SAW filters with the same bandwidth. Their feasible bandwidth is, however, limited by employing piezoelectric materials, design methods and so on. It is desirable for users to understand these factors for RF BAW resonator filters. This standard explains the principles and characteristics of RF BAW resonator filters. Usually RF BAW filters employ a filter configuration called the ladder filter, which is composed of multiple RF BAW resonators. They are classified into two types: film bulk acoustic resonators (FBAR) and solidly mounted resonators (SMR). It is of prime interest to a user that the filter characteristics satisfy a particular specification. The selection of tuning networks and RF BAW filters to meet that specification should be a matter of agreement between user and manufacturer. Filter characteristics are usually expressed in terms of insertion attenuation as a function of frequency. A standard method for measuring insertion attenuation is described in IEC 60862-1. Insertion attenuation characteristics are further specified by nominal frequency, minimum insertion attenuation or maximum insertion attenuation, passband ripple and shape factor. The specification is to be satisfied between the lowest and highest temperatures of the specified operating temperature range and before and after environmental tests. The responsible committee is DKE/K 642 "Piezoelektrische Bauteile zur Frequenzstabilisierung und -selektion" ("Piezoelectric and dielectric devices for frequency control and selection") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.

Document: references other documents

Responsible national committee

DKE/K 642 - Piezoelektrische Bauteile zur Frequenzstabilisierung und -selektion