DESIGN OF A UMTS MONOBLOCK FILTER
USING AN EQUIVALENT CIRCUIT APPROACH
Panayotis Kyriazidis*, Stelios Tsitsos*
* Department of Informatics and Communications, Technological and Educational
Institute (ΤΕΙ) of Serres, Magnesias End, GR-62124, Serres, Greece
Α computer-aided synthesis technique for a UMTS ceramic filter is presented in this work.
The technique uses an accurate equivalent circuit (extracted from first electromagnetic
principles) as the basic design and tuning tool. This circuit is subsequently modified and
optimised to meet the desired frequency characteristics. The changes in the equivalent
circuit parameter values provide useful information for the necessary structural changes.
Keywords: ceramic filters; equivalent circuits; parameter extraction; CAD; UMTS.
The rapid development of today’s mobile communications industry has produced a huge
number of compact and inexpensive hand-held communication sets which employ very
small sized filters suitable for GSM, DCS, UMTS and other technologies. One technique
for the miniaturisation of these filters is the use of high dielectric constant and low loss
ceramic materials. However, the performance of such components often departs from the
desired frequency response during manufacturing and as a result a considerable amount
of time is spent on trimming. In this work an improved CAD design technique is presented
which can be employed to provide reliable components “straight out of the box”.
Computer-aided analysis techniques of ceramic filters have been presented in [1-2]. A
CAD synthesis technique has been presented in  for the design of a PCS ceramic filter.
This technique makes use of an equivalent circuit as the basic design and tuning tool and
it is expanded here in the design of a UMTS ceramic filter. The equivalent circuit is based
on the extraction of equivalent circuit parameters from first electromagnetic principles [1-
2] and provides an accurate model for ceramic mon