Filter module with enhanced temperature ruggedness in smaller size
A filter module comprises a first terminal, a second terminal, and a filter disposed along each signal path extending from the first terminal to the second terminal, the filter including a plurality of series resonators and a plurality of shunt resonators disposed between the series resonators and a ground, at least one resonator among the plurality of series resonators and the plurality of shunt resonators being a first type of resonator with a temperature compensating layer for better temperature coefficient of frequency, at least one resonator among the plurality of series resonators and the plurality of shunt resonators being a second type of resonator without a temperature compensating layer.
1 . A filter module comprising:
a first terminal;
a second terminal; and
a filter disposed along each signal path extending from the first terminal to the second terminal, the filter including a plurality of series resonators and a plurality of shunt resonators disposed between the series resonators and a ground, at least one resonator among the plurality of series resonators and the plurality of shunt resonators being a first type of resonator with a temperature compensating layer, at least one resonator among the plurality of series resonators and the plurality of shunt resonators being a second type of resonator without a temperature compensating layer, the at least one of the plurality of series resonators and the plurality of shunt resonators being the first type of resonator including a series resonator that is disposed between series resonators of the second type connected to the first terminal and the second terminal, respectively, and that is a resonator most responsible for raising a skirt steepness or a channel insertion loss of the filter.
2 . The filter module of claim 1 wherein each of the plurality of series resonators and the plurality of shunt resonators is one of a bulk acoustic wave (BAW) resonator, a film bulk acoustic wave resonator, and a solidly-mounted resonator (SMR).
3 . The filter module of claim 1 wherein the filter is a bandpass filter, each of the plurality of shunt resonators being the second type of resonator.
4 . The filter module of claim 1 wherein the filter is a bandpass filter, each of the plurality of the shunt resonators being the first type of resonator.
5 . The filter module of claim 1 wherein the filter is a notch filter, each of the plurality of shunt resonators being the second type of resonator.
6 . The filter module of claim 1 wherein the filter is a notch filter, each of the plurality of the shunt resonators being the first type of resonator.
7 . The filter module of claim 1 wherein the filter includes a plurality of the first type of resonators with a temperature compensating layer, at least two of the plurality of the first type of resonators having different thicknesses of their respective temperature compensating layers, the plurality of the first type of resonators including a plurality of the first type of series resonators, a thickness of the temperature compensating layer of a series resonator most responsible for raising a skirt steepness or a channel insertion loss of the filter being thicker than that of other series resonators of the first type.
8 . The filter module of claim 1 wherein the filter includes a plurality of the first type of resonators with a temperature compensating layer, at least two of the plurality of the first type of resonators having different thicknesses of their respective temperature compensating layers, the plurality of the first type of resonators including a plurality of the first type of shunt resonators, a thickness of the temperature compensating layer of a shunt resonator most responsible for raising a skirt steepness or a channel insertion loss of the filter being thicker than that of other shunt resonators of the first type.
9 . The filter module of claim 1 wherein the at least one of the plurality of series resonators and the plurality of shunt resonators being the first type of resonator includes a shunt resonator that is disposed between shunt resonators of the second type.
10 . A radio frequency module comprising:
a packaging substrate configured to receive a plurality of components; and
a filter module implemented on the packaging substrate, the filter module including a first terminal, a second terminal, and a filter disposed along each signal path extending from the first terminal to the second terminal, the filter including a plurality of series resonators and a plurality of shunt resonators disposed between the series resonators and a ground, at least one resonator among the plurality of series resonators and the plurality of shunt resonators being a first type of resonator with a temperature compensating layer, at least one resonator among the plurality of series resonators and the plurality of shunt resonators being a second type of resonator without a temperature compensating layer, the at least one of the plurality of series resonators and the plurality of shunt resonators being the first type of resonator being disposed between shunt resonators of the second type and being a shunt resonator most responsible for raising a skirt steepness or a channel insertion loss of the filter.
11 . The radio frequency module of claim 10 wherein the radio frequency module is a front-end module.
12 . The radio frequency module of claim 10 wherein the filter is a bandpass filter, each of the plurality of the series resonators being the first type of resonator.
13 . A mobile device comprising:
an antenna configured to receive a radio frequency signal; and
a front end system configured to communicate with the antenna, the front end system including a filter module including a first terminal, a second terminal, and a filter disposed along each signal path extending from the first terminal to the second terminal, the filter including a plurality of series resonators and a plurality of shunt resonators disposed between the series resonators and a ground, at least one resonator among the plurality of series resonators and the plurality of shunt resonators being a first type of resonator with a temperature compensating layer, at least one resonator among the plurality of series resonators and the plurality of shunt resonators being a second type of resonator without a temperature compensating layer, the at least one of the plurality of series resonators and the plurality of shunt resonators being the first type of resonator being disposed between shunt resonators of the second type and being a shunt resonator most responsible for raising a skirt steepness or a channel insertion loss of the filter.
14 . The radio frequency module of claim 10 wherein the filter includes a plurality of the first type of resonators with a temperature compensating layer, at least two of the plurality of the first type of resonators having different thicknesses of their respective temperature compensating layers, the plurality of the first type of resonators including a plurality of series resonators, a thickness of the temperature compensating layer of a series resonator most responsible for raising a skirt steepness or a channel insertion loss of the filter being thicker than that of other series resonators of the first type.
15 . The radio frequency module of claim 10 wherein the filter includes a plurality of the first type of resonators with a temperature compensating layer, at least two of the plurality of the first type of resonators having different thicknesses of their respective temperature compensating layers, the plurality of the first type of resonators including a plurality of shunt resonators, a thickness of the temperature compensating layer of the shunt resonator most responsible for raising the skirt steepness or the channel insertion loss of the filter being thicker than that of other shunt resonators of the first type.
16 . The mobile device of claim 13 wherein the filter includes a plurality of the first type of resonators with a temperature compensating layer, at least two of the plurality of the first type of resonators having different thicknesses of their respective temperature compensating layers, the plurality of the first type of resonators including a plurality of series resonators, a thickness of the temperature compensating layer of a series resonator most responsible for raising a skirt steepness or a channel insertion loss of the filter being thicker than that of other series resonators of the first type.
17 . The mobile device of claim 13 wherein each of the plurality of series resonators and the plurality of shunt resonators is one of a bulk acoustic wave (BAW) resonator, a film bulk acoustic wave resonator, and a solidly-mounted resonator (SMR).
18 . The mobile device of claim 13 wherein the filter is a notch filter, each of the plurality of the series resonators being the first type of resonator.
19 . The mobile device of claim 13 wherein the filter is a notch filter, each of the plurality of the shunt resonators being the first type of resonator, and each of the plurality of series resonators being the second type of resonator.
20 . The mobile device of claim 13 wherein the filter includes a plurality of the first type of resonators with a temperature compensating layer, at least two of the plurality of first type of resonators having different thicknesses of their respective temperature compensating layers, the plurality of the first type of resonators including a plurality of shunt resonators, a thickness of the temperature compensating layer of the shunt resonator most responsible for raising the skirt steepness or the channel insertion loss of the filter being thicker than that of other shunt resonators of the first type.