Patent ID: 9130538
Filing Date: 2015-09-08
Classification: H03H

Abstract:
1. A SAW filter comprising: a balanced port and an unbalanced port; a first DMS track wherein two input transducers are arranged in the first DMS track and connected to the unbalanced port; and a second DMS track that is arranged geometrically parallel to the first DMS track, wherein two output transducers are arranged in the second DMS track and are connected to the balanced port; wherein the first DMS track and the second DMS track each have four coupling transducers; wherein four coupling lines connect a respective coupling transducer from the first and second DMS tracks to one another and are thus an electrical series interconnection of the first and second DMS tracks; wherein the coupling transducers of the first DMS track have finger arrangements causing a phase in each of respective adjacent ones of the coupling lines to differ by 180 degrees; wherein the transducers in each DMS track are arranged between two respective end reflectors that bound the respective DMS track; wherein ground connections of the input transducers point toward the second DMS track and are connected between the first and second DMS tracks to a common inner ground line that is arranged in a space between the first and second DMS tracks and both ends of which are connected to a respective ground connection point; wherein, in the second DMS track, ground connections of the output transducers point toward the first DMS track and are connected to a second inner line, which is arranged between the first and second DMS tracks and which is at zero potential; wherein the common inner ground line and the second inner line cross the coupling lines, with a respective dielectric being arranged between the common inner ground line and also the second inner line and the coupling lines in a crossing region such that the second inner line and the common inner ground line are electrically isolated from each other and from the coupling lines; wherein each of the first and second DMS tracks contains a middle reflector that divides each DMS track into two track halves; wherein the ground connections of two innermost coupling transistors disposed in the first DMS track are connected by a first middle line; wherein the middle reflector disposed in the first DMS track is connected to the first middle line and to the common inner ground line; and wherein there are no lines crossing each other beyond the first DMS track towards the unbalanced port and no lines crossing each other beyond the second DMS track toward the balanced port.