CN216146311U - Bulk acoustic wave filter circuit and filter assembly - Google Patents
Bulk acoustic wave filter circuit and filter assembly Download PDFInfo
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Abstract
The utility model relates to the technical field of filters, and provides a bulk acoustic wave filter circuit and a filter assembly. The bulk acoustic wave filter circuit comprises an input terminal, an output terminal, a grounding terminal, a plurality of thin film bulk acoustic resonators connected in series and a plurality of thin film bulk acoustic resonators connected in parallel; one ends of the film bulk acoustic resonators connected in parallel are sequentially connected to nodes between the first film bulk acoustic resonator and the sixth film bulk acoustic resonator, and the other ends of the film bulk acoustic resonators connected in parallel are connected with a grounding terminal; the first film bulk acoustic resonator and the third film bulk acoustic resonator are positioned on a first straight line where the input terminal and the output terminal are positioned, the second film bulk acoustic resonator, the fourth film bulk acoustic resonator, the seventh film bulk acoustic resonator and the ninth film bulk acoustic resonator are positioned on a first side of the first straight line, and the eighth film bulk acoustic resonator is positioned on a second side of the first straight line; the filter provided by the utility model can allow signals with specific frequencies to pass through.
Description
Technical Field
The utility model belongs to the technical field of filters, and particularly relates to a bulk acoustic wave filter circuit and a filter assembly.
Background
In recent years, with the continuous development of 5G wireless communication technology, mobile communication is realized by utilizing higher frequency bands and frequency band recombination, which puts increasing demands on miniaturization, high frequency bandwidth, integration and flexibility of relevant radio frequency components.
Film Bulk Acoustic Resonator (FBAR) filters are gradually replacing traditional surface Acoustic wave filters and ceramic filters by virtue of their excellent characteristics of small size, high resonant frequency, high quality factor, large power capacity, good roll-off effect and the like, and have a larger and larger market share in the field of radio frequency filters, and play a great role in the field of 5G wireless communication radio frequencies.
However, most of the research on the film bulk acoustic resonator filter is focused on the manufacturing method, and the research on the specific structure of the film bulk acoustic resonator filter is less.
SUMMERY OF THE UTILITY MODEL
The embodiment of the utility model provides a bulk acoustic wave filter circuit and a filter assembly, and aims to provide a novel circuit structure of a bulk acoustic wave filter.
In a first aspect, an embodiment of the present invention provides a bulk acoustic wave resonator filter circuit with a center frequency of 3700MHz, including an input terminal, an output terminal, a ground terminal, a plurality of thin film bulk acoustic resonators connected in series, and a plurality of thin film bulk acoustic resonators connected in parallel;
the plurality of series thin film bulk acoustic resonators comprise a first thin film bulk acoustic resonator, a second thin film bulk acoustic resonator, a third thin film bulk acoustic resonator, a fourth thin film bulk acoustic resonator, a fifth thin film bulk acoustic resonator and a sixth thin film bulk acoustic resonator which are connected in sequence, and the plurality of series thin film bulk acoustic resonators are connected in series between the input terminal and the output terminal;
the plurality of film bulk acoustic resonators connected in parallel comprise a seventh film bulk acoustic resonator, an eighth film bulk acoustic resonator and a ninth film bulk acoustic resonator; one end of each of the seventh film bulk acoustic resonator, the eighth film bulk acoustic resonator and the ninth film bulk acoustic resonator is connected to each node between the first film bulk acoustic resonator and the sixth film bulk acoustic resonator in sequence; the other ends of the seventh to ninth film bulk acoustic resonators are connected to the ground terminal respectively;
the first film bulk acoustic resonator and the third film bulk acoustic resonator are positioned on a first straight line where the input terminal and the output terminal are positioned, the second film bulk acoustic resonator, the fourth film bulk acoustic resonator, the fifth film bulk acoustic resonator, the sixth film bulk acoustic resonator, the seventh film bulk acoustic resonator and the ninth film bulk acoustic resonator are positioned on a first side of the first straight line, and the eighth film bulk acoustic resonator is positioned on a second side of the first straight line;
the first film bulk acoustic resonator, the second film bulk acoustic resonator and the third film bulk acoustic resonator form a first V shape, the second film bulk acoustic resonator, the third film bulk acoustic resonator and the fourth film bulk acoustic resonator form a second V shape, the fourth film bulk acoustic resonator, the fifth film bulk acoustic resonator and the sixth film bulk acoustic resonator form a third V shape, the third film bulk acoustic resonator, the fourth film bulk acoustic resonator and the fifth film bulk acoustic resonator are located on a straight line, openings of the first V shape and the third V shape face the second side, an opening of the second V shape faces the first side, an angle of the first V shape and the angle of the second V shape are larger than 90 degrees, and an angle of the third V shape is smaller than 90 degrees.
The filter in the embodiment of the present invention includes a plurality of thin film bulk acoustic resonators connected in series between an input terminal and an output terminal, and a plurality of thin film bulk acoustic resonators connected in parallel between nodes of the plurality of thin film bulk acoustic resonators connected in series. After the signal passes through the plurality of thin film bulk acoustic resonators connected in series and the plurality of thin film bulk acoustic resonators connected in parallel, the signal with a specific frequency can be allowed to pass through the input terminal and reach the output terminal.
With reference to the first aspect, in one possible implementation manner, the series resonance frequency and the parallel resonance frequency of the plurality of series thin film bulk acoustic resonators are the same; the series resonance frequency and the parallel resonance frequency of the plurality of film bulk acoustic resonators connected in parallel are the same.
With reference to the first aspect, in one possible implementation manner, the series resonance frequency of the plurality of series thin film bulk acoustic resonators is the same as the parallel resonance frequency of the plurality of parallel thin film bulk acoustic resonators.
With reference to the first aspect, in one possible implementation manner, the area of the first film bulk acoustic resonator is 3470 μm2-3530μm2The area of the third film bulk acoustic resonator and the area of the fourth film bulk acoustic resonator are 3270 mu m2-3330μm2The area of the second film bulk acoustic resonator, the area of the fifth film bulk acoustic resonator and the area of the ninth film bulk acoustic resonator are 3970 μm2-4030μm2The area of the sixth film bulk acoustic resonator is 2770 mu m2-2830μm2The area of the seventh film bulk acoustic resonator is 5370 mu m2-5430μm2The area of the eighth film bulk acoustic resonator is 5850 μm2-5950μm2。
With reference to the first aspect, in a possible implementation manner, the layout of the bulk acoustic wave filter circuit mainly includes a sacrificial layer, a lower electrode layer, an upper electrode layer, a difference frequency layer, and an aperture layer, where the difference frequency layer corresponds to only the plurality of thin film bulk acoustic resonators connected in parallel, and the aperture layer is provided with a plurality of release holes.
The upper electrode layer has a thickness of
The thickness of the lower electrode layer is
The thickness of the piezoelectric layer is
The thickness of the difference frequency layer is
Illustratively, the release holes have a diameter of 15 μm to 25 μm.
In some embodiments, each of the film bulk acoustic resonators has a plurality of release channels, and each of the release channels corresponds to at least one of the release holes.
With reference to the first aspect, in a possible implementation manner, the layout of the bulk acoustic wave filter circuit includes a first layout area to a fourteenth layout area;
the first layout area, the third layout area and the fifth layout area are grounding terminal layout areas, the second layout area is a layout area of an input terminal, and the fourth layout area is a layout area of an output terminal; the third layout area is positioned at the lower part of the layout of the filter, and the first layout area, the fifth layout area, the second layout area and the fourth layout area are respectively arranged at two sides of the layout of the filter;
the sixth layout area to the eleventh layout area are the first thin film bulk acoustic resonator to the sixth thin film bulk acoustic resonator, respectively; the sixth layout area to the eleventh layout area are respectively connected in series between the second layout area and the fourth layout area;
the twelfth version area to the fourteenth version area are the seventh film bulk acoustic resonator to the ninth film bulk acoustic resonator, respectively; the twelfth layout area is positioned at the upper part of the seventh layout area, one end of the twelfth layout area is respectively connected with the sixth layout area and the seventh layout area, and the other end of the twelfth layout area is connected with the first layout area; the thirteenth layout area is positioned at the lower part of the eighth layout area, one end of the thirteenth layout area is respectively connected with the eighth layout area and the ninth layout area, and the other end of the thirteenth layout area is connected with the third layout area; the fourteenth layout area is positioned at the upper part of the eleventh layout area, one end of the fourteenth layout area is respectively connected with the tenth layout area and the eleventh layout area, and the other end of the fourteenth layout area is connected with the fourth layout area;
the sixth layout area and the eighth layout area are positioned on a first straight line where the second layout area and the fourth layout area are positioned, the seventh layout area, the ninth to twelfth layout areas and the fourteenth layout area are positioned on a first side of the first straight line, and the thirteenth layout area is positioned on a second side of the first straight line;
the sixth layout area, the seventh layout area and the eighth layout area form a first V shape, the seventh layout area, the eighth layout area and the ninth layout area form a second V shape, and the ninth layout area, the tenth layout area and the eleventh layout area form a third V shape; eighth version region, ninth version region and tenth version region are located a straight line, the opening of first V style of calligraphy and third V style of calligraphy all faces the second side, the opening of second V style of calligraphy is towards first side, the angle of first V style of calligraphy and second V style of calligraphy is greater than 90, the angle of third V style of calligraphy is less than 90.
In a second aspect, an embodiment of the present invention further provides a bulk acoustic wave filter assembly, including any one of the bulk acoustic wave filter circuits described above.
Drawings
Fig. 1 is a schematic circuit diagram of a bulk acoustic wave filter circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a layout structure of a bulk acoustic wave filter circuit according to an embodiment of the present invention;
FIG. 3 is a schematic layout diagram of a sacrificial layer of the bulk acoustic wave filter circuit shown in FIG. 2;
FIG. 4 is a layout diagram of a lower electrode layer of the bulk acoustic wave filter circuit shown in FIG. 2;
fig. 5 is a layout diagram of an upper electrode layer of the bulk acoustic wave filter circuit shown in fig. 2;
FIG. 6 is a layout diagram of a difference frequency layer representation of the bulk acoustic wave filter circuit shown in FIG. 2;
FIG. 7 is a layout schematic of an aperture layer of the bulk acoustic wave filter circuit shown in FIG. 2;
fig. 8 is an amplitude-frequency characteristic curve of the bulk acoustic wave filter circuit according to the embodiment of the present invention.
In the figure: 11-input terminal, 12-output terminal, 21-first film bulk acoustic resonator, 22-second film bulk acoustic resonator, 23-third film bulk acoustic resonator, 24-fourth film bulk acoustic resonator, 25-fifth film bulk acoustic resonator, 26-sixth film bulk acoustic resonator, 31-seventh film bulk acoustic resonator, 32-eighth film bulk acoustic resonator, 33-ninth film bulk acoustic resonator, 41-release hole.
Detailed Description
The 5G technology promotes the comprehensive upgrade of a radio frequency system of a mobile phone terminal, and the requirement of a filter is greatly increased for adding a communication function of a new frequency band based on the multiplied increase of the number of antenna channels of a base station. The film bulk acoustic resonator filter can work in a high frequency band of 6 GHz-60 GHz, supports a steep filtering curve of high-challenge frequency band allocation and has good out-of-band rejection capability. In addition, the low loss characteristic of the film bulk acoustic resonator filter can compensate the higher loss of a plurality of frequency bands integrated at the front end of the radio frequency, improve the signal receiving capability and the service life of a battery, and has become a new momentum of 5G mobile communication.
However, most of the current researches on the film bulk acoustic resonator filter are focused on the preparation method, and the researches on the specific structure are less. It is now highly desirable to use a filter centered at 3700MHz with a 1dB bandwidth greater than 60MHz, with a suppression of greater than 35dBc at 3550MHz and 3850 MHz.
In view of the above problems, embodiments of the present invention provide a bulk acoustic wave filter circuit including an input terminal, an output terminal, a ground terminal, a plurality of series thin film bulk acoustic resonators, and a plurality of parallel thin film bulk acoustic resonators. The film bulk acoustic resonators connected in series comprise a first film bulk acoustic resonator, a second film bulk acoustic resonator, a third film bulk acoustic resonator, a fourth film bulk acoustic resonator, a fifth film bulk acoustic resonator and a sixth film bulk acoustic resonator which are connected in sequence, and the film bulk acoustic resonators connected in series are connected between an input terminal and an output terminal. The plurality of film bulk acoustic resonators connected in parallel comprise a seventh film bulk acoustic resonator, an eighth film bulk acoustic resonator and a ninth film bulk acoustic resonator; one end of the seventh film bulk acoustic resonator, one end of the eighth film bulk acoustic resonator and one end of the ninth film bulk acoustic resonator are sequentially connected to each node of the film bulk acoustic resonators connected in series; the other ends of the seventh to ninth film bulk acoustic resonators are connected to a ground terminal.
And the first film bulk acoustic resonator and the third film bulk acoustic resonator are located on a first straight line where the input terminal and the output terminal are located, wherein the second film bulk acoustic resonator, the fourth film bulk acoustic resonator, the fifth film bulk acoustic resonator, the sixth film bulk acoustic resonator, the seventh film bulk acoustic resonator and the ninth film bulk acoustic resonator are located on a first side of the first straight line, and the eighth film bulk acoustic resonator is located on a second side of the first straight line. The first film bulk acoustic resonator, the second film bulk acoustic resonator and the third film bulk acoustic resonator form a first V shape, the second film bulk acoustic resonator, the third film bulk acoustic resonator and the fourth film bulk acoustic resonator form a second V shape, the fourth film bulk acoustic resonator, the fifth film bulk acoustic resonator and the sixth film bulk acoustic resonator form a third V shape, the third film bulk acoustic resonator, the fourth film bulk acoustic resonator and the fifth film bulk acoustic resonator are positioned on a straight line, the openings of the first V shape and the third V shape face the second side, the opening of the second V shape faces the first side, the angle of the first V shape and the angle of the second V shape are larger than 90 degrees, and the angle of the third V shape is smaller than 90 degrees.
The bulk acoustic wave filter circuit includes a plurality of thin film bulk acoustic resonators connected in series between an input terminal and an output terminal, and a plurality of thin film bulk acoustic resonators connected in parallel between nodes of the plurality of thin film bulk acoustic resonators connected in series. When the signals pass through the input terminal and pass through the plurality of thin film bulk acoustic resonators connected in series and the plurality of thin film bulk acoustic resonators connected in parallel, filtering of the signals in a specific frequency band can be realized, and therefore the signals with specific central frequency are output.
Fig. 1 shows a schematic circuit diagram of a bulk acoustic wave filter circuit according to an embodiment of the present invention. Referring to fig. 1, the bulk acoustic wave filter circuit includes an input terminal 11, an output terminal 12, a ground terminal, a plurality of thin film bulk acoustic resonators connected in series, and a plurality of thin film bulk acoustic resonators connected in parallel. The plurality of series thin film bulk acoustic resonators include a first thin film bulk acoustic resonator 21, a second thin film bulk acoustic resonator 22, a third thin film bulk acoustic resonator 23, a fourth thin film bulk acoustic resonator 24, a fifth thin film bulk acoustic resonator 25, and a sixth thin film bulk acoustic resonator 26, which are connected in sequence. The plurality of parallel thin film bulk acoustic resonators include a seventh thin film bulk acoustic resonator 31, an eighth thin film bulk acoustic resonator 32, and a ninth thin film bulk acoustic resonator 33.
Among them, the first to sixth thin film bulk acoustic resonators 21 to 26 are connected in series between the input terminal 11 and the output terminal 12. And the first to sixth thin film bulk acoustic resonators 21 to 26 have the same first series resonance frequency and first parallel resonance frequency. Specifically, in the present application, the second thin film bulk acoustic resonator 22 and the third thin film bulk acoustic resonator 23 are connected in series, and the fourth thin film bulk acoustic resonator 24 and the fifth thin film bulk acoustic resonator 25 are connected in series, so that the areas of the second thin film bulk acoustic resonator 22, the third thin film bulk acoustic resonator 23, the fourth thin film bulk acoustic resonator 24, and the fifth thin film bulk acoustic resonator 25 are increased, and the reliability of the filter is improved.
One end of the seventh thin film bulk acoustic resonator 31 is connected to a node between the first thin film bulk acoustic resonator 21 and the second thin film bulk acoustic resonator 22, and the other end is connected to a ground terminal. The eighth thin film bulk acoustic resonator 32 has one end connected to a node between the third thin film bulk acoustic resonator 23 and the fourth thin film bulk acoustic resonator 24, and the other end connected to a ground terminal. The ninth thin film bulk acoustic resonator 33 has one end connected to a node between the fifth thin film bulk acoustic resonator 25 and the sixth thin film bulk acoustic resonator 26, and the other end connected to a ground terminal. And the seventh to ninth thin film bulk acoustic resonators 31 to 33 have the same second series resonance frequency and second parallel resonance frequency.
The first thin film bulk acoustic resonator 21 and the third thin film bulk acoustic resonator 23 are located on a first straight line where the input terminal 11 and the output terminal 12 are located, the second thin film bulk acoustic resonator 22, the fourth thin film bulk acoustic resonator 24, the fifth thin film bulk acoustic resonator 25, the sixth thin film bulk acoustic resonator 26, the seventh thin film bulk acoustic resonator 31, and the ninth thin film bulk acoustic resonator 33 are located on a first side of the first straight line, and the eighth thin film bulk acoustic resonator 32 is located on a second side of the first straight line;
specifically, the first thin film bulk acoustic resonator 21, the second thin film bulk acoustic resonator 22, and the third thin film bulk acoustic resonator 23 form a first V shape, the second thin film bulk acoustic resonator 22, the third thin film bulk acoustic resonator 23, and the fourth thin film bulk acoustic resonator 24 form a second V shape, the fourth thin film bulk acoustic resonator 24, the fifth thin film bulk acoustic resonator 25, and the sixth thin film bulk acoustic resonator 26 form a third V shape, the third thin film bulk acoustic resonator 23, the fourth thin film bulk acoustic resonator 24, and the fifth thin film bulk acoustic resonator 25 are located on a straight line, openings of the first V shape and the third V shape face the second side, an opening of the second V shape faces the first side, an angle of the first V shape and the second V shape is greater than 90 °, and an angle of the third V shape is less than 90 °.
Illustratively, in the embodiment of the present invention, the first series resonance frequency of the plurality of series thin film bulk acoustic resonators is the same as the second parallel resonance frequency of the plurality of parallel thin film bulk acoustic resonators, so as to form a specific center frequency.
As shown in fig. 2, the embodiment of the present invention provides an overall layout of a bulk acoustic wave filter with a frequency center of 3700 MHz. The total layout of the filter in fig. 2 includes first to fourteenth layout areas. The first layout area 101, the third layout area 103, and the fifth layout area 105 are ground terminal layout areas, the second layout area 102 is a layout area of the input terminal 11, and the fourth layout area 104 is a layout area of the output terminal 12. The third layout area 103 is located at the lower part of the layout of the filter, and the first and fifth layout areas 101 and 105, and the second and fourth layout areas 102 and 104 are respectively disposed at both sides of the layout of the filter. The sixth layout area 106 to the eleventh layout area 111 are the first thin film bulk acoustic resonator 21 to the sixth thin film bulk acoustic resonator 26, respectively, and the sixth layout area 106 to the eleventh layout area 111 are connected in series between the second layout area 102 and the fourth layout area 104, respectively. The twelfth layout area 112 to the fourteenth layout area 114 are the seventh thin film bulk acoustic resonator 31 to the ninth thin film bulk acoustic resonator 33, respectively. The twelfth layout area 112 is located above the seventh layout area 107, and has one end connected to the sixth layout area 106 and the seventh layout area 107, respectively, and the other end connected to the first layout area 101. The thirteenth layout area 113 is located at a lower portion of the eighth layout area 108, and has one end connected to the eighth layout area 108 and the ninth layout area 109, respectively, and the other end connected to the third layout area 103. The fourteenth layout area 114 is located at an upper portion of the eleventh layout area 111, and has one end connected to the tenth layout area 110 and the eleventh layout area 111, respectively, and the other end connected to the fourth layout area 104.
As can be seen from the layout, the sixth and eighth layout areas 106 and 108 are located on a first line where the second and fourth layout areas 102 and 104 are located (as shown by the dotted line between the second and fourth layout areas 102 and 104 in fig. 2), the seventh, ninth to twelfth layout areas 107, 109 to 112 and fourteenth layout area 114 are located on a first side of the first line, and the thirteenth layout area 113 is located on a second side of the first line. The sixth layout area 106, the seventh layout area 107 and the eighth layout area 108 form a first V-shape, the seventh layout area 107, the eighth layout area 108 and the ninth layout area 109 form a second V-shape, and the ninth layout area 109, the tenth layout area 110 and the eleventh layout area 111 form a third V-shape. Wherein the eighth layout area 108, the ninth layout area 109 and the tenth layout area 110 are located on a straight line, the openings of the first V-shape and the third V-shape are both directed to the second side of the first straight line, the opening of the second V-shape is directed to the first side of the first straight line, the specific angle of the first V-shape and the second V-shape is greater than 90 degrees, and the angle of the third V-shape is less than 90 degrees.
In some embodiments, the area of the film bulk acoustic resonator is controlled to be 4000 μm2-80000 μm2 in consideration of the easiness of process implementation. In the same circuit, the area difference of each film bulk acoustic resonator in the circuit should be as small as possible in the design of each film bulk acoustic resonator, and the difference is generally less than 4 times.
In some embodiments, in order to obtain a bulk acoustic wave filter with a specific center frequency, the areas and positions of the first to ninth thin film bulk acoustic resonators 21 to 33 may be adjusted. Illustratively, the area of the first film bulk acoustic resonator 21 is 3470 μm2-3530 μm2, the area of the third film bulk acoustic resonator 23 and the area of the fourth film bulk acoustic resonator 24 are 3270 μm2-3330 μm2, the area of the second film bulk acoustic resonator 22, the area of the fifth film bulk acoustic resonator 25 and the area of the ninth film bulk acoustic resonator 33 are 3970 μm2-4030 μm2, the area of the sixth film bulk acoustic resonator 26 is 2770 μm2-2830 μm2, the area of the seventh film bulk acoustic resonator 31 is 5370 μm2-5430 μm2, and the area of the eighth film bulk acoustic resonator 32 is 5850 μm2-5950 μm 2.
In some embodiments, the layout of the bulk acoustic wave filter circuit includes primarily a sacrificial layer, a lower electrode layer, an upper electrode layer, a difference frequency layer, and an aperture layer. The difference frequency layer corresponds to the plurality of film bulk acoustic resonators connected in parallel, and the plurality of film bulk acoustic resonators connected in series do not have the difference frequency layer. The difference frequency layer is used for realizing the frequency difference between the film bulk acoustic resonators connected in parallel and the film bulk acoustic resonators connected in series, so that a filter is formed, and the filtering of the phase specific frequency is realized. In general, the second series resonance frequency and the second parallel resonance frequency of the thin film bulk acoustic resonators connected in parallel are lower than the first series resonance frequency and the first parallel resonance frequency of the thin film bulk acoustic resonators connected in series, and the first series resonance frequency is equal to the second parallel resonance frequency.
Specifically, the film bulk acoustic resonator may be a pentagon, each of the resonators has 5 sides, and the resonators are connected to each other by one side of each resonator.
In order to form an air cavity of the film bulk acoustic resonator and realize the reflection of acoustic waves, an orifice layer is specially arranged, a plurality of release holes are formed in the orifice layer, and each release channel of each film bulk acoustic resonator at least corresponds to one release hole. Specifically, the diameter of the release hole is 15 μm to 25 μm.
For example, each resonator may have a plurality of release channels (e.g., five), one release hole for each release channel, and release gas may enter the release channels through the release holes, then enter the sacrificial layer region to etch the sacrificial layer material away into gas, and then be exhausted through the release channels and the release holes. In addition, if the space of the filter is tight, two release channels can share one release hole. In addition, in the probe test area, a probe (for example, a GSG probe) needs to be used for testing the chip, so that the piezoelectric layer needs to be etched away, and the lower electrode is exposed for testing.
In some embodiments, the thicknesses of the upper electrode, the lower electrode, and the piezoelectric layer may be adjusted to achieve a particular center frequency by further adjusting the resonator area.
Illustratively, to obtain a filter having a center frequency of 3700MHz, the upper electrode layer has a thickness of
The thickness of the lower electrode layer is
The thickness of the piezoelectric layer is
In some embodiments, the difference frequency layer has a thickness of
In some embodiments, the release holes may be 15 μm to 25 μm in diameter.
Specifically, the layout to be used in the process of manufacturing the bulk acoustic wave filter with the center frequency of 3700MHz mainly includes a layout of the sacrificial layer, a layout of the lower electrode, a layout of the upper electrode, a layout of the difference frequency layer, and a layout of the orifice layer, as shown in fig. 3 to 7.
Fig. 3 is a layout of a sacrificial layer in which the first to ninth thin film bulk acoustic resonators 21 to 33 are respectively disposed.
The first sacrificial region layout 201 to the sixth sacrificial region layout 206 correspond to the first thin film bulk acoustic resonator 21 to the sixth thin film bulk acoustic resonator 26, which are connected in series, respectively. The seventh to ninth sacrifice region layouts 207 to 209 correspond to the seventh to ninth thin film bulk acoustic resonators 31 to 33 connected in parallel, respectively.
Specifically, each resonator is provided with 5 sides, and the part of each resonator extending out of the horn shape is a release channel, and each resonator may have a plurality of release channels, and each resonator is provided with 5 release channels in the present application. The released gas enters the release channel through the release hole, then enters the sacrificial layer area to corrode the sacrificial layer material to become gas, and then is discharged through the release channel and the release hole.
Fig. 4 is a layout of the lower electrode layer, including a layout of the input terminal 11, the output terminal 12, and the ground terminal.
The layout of the lower electrode layer includes seven layout regions, wherein the first lower electrode layout region 301, the third lower electrode layout region 301, and the fifth lower electrode layout region 305 are connected to the ground terminal, the second lower electrode layout region 302 is connected to the input terminal 11, and the fourth lower electrode layout region 304 is connected to the output terminal 12.
Specifically, the first lower electrode layout area 301 corresponds to the seventh thin film bulk acoustic resonator 31, the second lower electrode layout area 302 corresponds to the first thin film bulk acoustic resonator 21, the third lower electrode layout area 303 corresponds to the eighth thin film bulk acoustic resonator 32, the fourth lower electrode layout area 304 corresponds to the sixth thin film bulk acoustic resonator 26, the fifth lower electrode layout area 305 corresponds to the ninth thin film bulk acoustic resonator 33, the sixth lower electrode layout area 306 corresponds to the second thin film bulk acoustic resonator 22 and the third thin film bulk acoustic resonator 23, and the seventh lower electrode layout area 307 corresponds to the fourth thin film bulk acoustic resonator 24 and the fifth thin film bulk acoustic resonator 25.
Fig. 5 is a layout of the upper electrode layer, including a first upper electrode layout area 401, a second upper electrode layout area 402, and a third upper electrode layout area 403. The first upper electrode layout area 401 corresponds to the first film bulk acoustic resonator 21, the second film bulk acoustic resonator 22, and the seventh film bulk acoustic resonator 31, the second upper electrode layout area 402 corresponds to the third film bulk acoustic resonator 23, the fourth film bulk acoustic resonator 24, and the eighth film bulk acoustic resonator 32, and the third upper electrode layout area 403 corresponds to the fifth film bulk acoustic resonator 25, the sixth film bulk acoustic resonator 26, and the ninth film bulk acoustic resonator 33.
Fig. 6 is a layout of a difference frequency layer, which includes a first difference frequency layout region 501 corresponding to the seventh thin film bulk acoustic resonator 31, a second difference frequency layout region 502 corresponding to the eighth thin film bulk acoustic resonator 32, and a third difference frequency layout region 503 corresponding to the ninth thin film bulk acoustic resonator 33.
Fig. 7 is a layout of an aperture layer that includes a plurality of release apertures 41, surrounding each resonator. One for each discharge hole 41. The released gas enters the release channels through the release holes 41 and then enters the sacrificial layer area to corrode the sacrificial layer material into gas, and then is discharged through the release channels and the release holes 41. In addition, in the probe test area on the hole layer layout, if a probe (for example, a GSG probe) is required to be used for testing the chip, the piezoelectric layer needs to be etched away, and the lower electrode GSG is exposed for testing.
In this example, the bulk acoustic wave filter of 3700MHz prepared as described above was tested, and the test results are shown in fig. 8. Curve 1 is the variation of S (2,1) with frequency of the bulk acoustic wave filter (left vertical axis). Curve 2 is the return loss of S (1,1) of the bulk acoustic wave filter (right vertical axis), and curve 3 is the return loss of S (2,2) of the bulk acoustic wave filter (right vertical axis). As can be seen from FIG. 8, the 1dB bandwidth is about 92MHz, and the suppression levels at 3550MHz and 3850MHz are 43dBc and 48dBc, respectively.
The embodiment of the utility model also provides a bulk acoustic wave filter assembly which comprises any one of the bulk acoustic wave filter circuits. All technical effects of the bulk acoustic wave filter circuit are achieved, and are not described herein again.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the utility model, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A bulk acoustic wave filter circuit includes an input terminal, an output terminal, a ground terminal, a plurality of series thin film bulk acoustic resonators, and a plurality of parallel thin film bulk acoustic resonators;
the plurality of series thin film bulk acoustic resonators comprise a first thin film bulk acoustic resonator, a second thin film bulk acoustic resonator, a third thin film bulk acoustic resonator, a fourth thin film bulk acoustic resonator, a fifth thin film bulk acoustic resonator and a sixth thin film bulk acoustic resonator which are connected in sequence, and the plurality of series thin film bulk acoustic resonators are connected in series between the input terminal and the output terminal;
the plurality of film bulk acoustic resonators connected in parallel comprise a seventh film bulk acoustic resonator, an eighth film bulk acoustic resonator and a ninth film bulk acoustic resonator; one end of each of the seventh film bulk acoustic resonator, the eighth film bulk acoustic resonator and the ninth film bulk acoustic resonator is connected to each node between the first film bulk acoustic resonator and the sixth film bulk acoustic resonator in sequence; the other ends of the seventh to ninth film bulk acoustic resonators are connected to the ground terminal respectively;
the first film bulk acoustic resonator and the third film bulk acoustic resonator are positioned on a first straight line where the input terminal and the output terminal are positioned, the second film bulk acoustic resonator, the fourth film bulk acoustic resonator, the fifth film bulk acoustic resonator, the sixth film bulk acoustic resonator, the seventh film bulk acoustic resonator and the ninth film bulk acoustic resonator are positioned on a first side of the first straight line, and the eighth film bulk acoustic resonator is positioned on a second side of the first straight line;
the first film bulk acoustic resonator, the second film bulk acoustic resonator and the third film bulk acoustic resonator form a first V shape, the second film bulk acoustic resonator, the third film bulk acoustic resonator and the fourth film bulk acoustic resonator form a second V shape, the fourth film bulk acoustic resonator, the fifth film bulk acoustic resonator and the sixth film bulk acoustic resonator form a third V shape, the third film bulk acoustic resonator, the fourth film bulk acoustic resonator and the fifth film bulk acoustic resonator are located on a straight line, openings of the first V shape and the third V shape face the second side, an opening of the second V shape faces the first side, an angle of the first V shape and the angle of the second V shape are larger than 90 degrees, and an angle of the third V shape is smaller than 90 degrees.
2. The bulk acoustic wave filter circuit according to claim 1, wherein the series resonance frequency and the parallel resonance frequency of the plurality of series thin film bulk acoustic resonators are the same; the series resonance frequency and the parallel resonance frequency of the plurality of film bulk acoustic resonators connected in parallel are the same.
3. The bulk acoustic wave filter circuit according to claim 1 or 2, wherein a series resonance frequency of the plurality of series thin film bulk acoustic resonators is the same as a parallel resonance frequency of the plurality of parallel thin film bulk acoustic resonators.
4. The bulk acoustic wave filter circuit according to claim 1, wherein the first thin film bulk acoustic resonator has an area of 3470 μm2-3530μm2The area of the third film bulk acoustic resonator and the area of the fourth film bulk acoustic resonator are 3270 mu m2-3330μm2The area of the second film bulk acoustic resonator, the area of the fifth film bulk acoustic resonator and the area of the ninth film bulk acoustic resonator are 3970 μm2-4030μm2The area of the sixth film bulk acoustic resonator is 2770 mu m2-2830μm2The area of the seventh film bulk acoustic resonator is 5370 mu m2-5430μm2The area of the eighth film bulk acoustic resonator is 5850 μm2-5950μm2。
5. The bulk acoustic wave filter circuit according to claim 1, wherein the layout of the bulk acoustic wave filter mainly includes a sacrificial layer, a lower electrode layer, an upper electrode layer, a difference frequency layer, and an aperture layer, the difference frequency layer corresponds to only the plurality of thin film bulk acoustic resonators connected in parallel, and a plurality of release apertures are opened in the aperture layer.
6. The bulk acoustic wave filter circuit according to claim 5, wherein the upper electrode layer has a thickness of
The thickness of the lower electrode layer is
The thickness of the piezoelectric layer is
The thickness of the difference frequency layer is
。
7. The bulk acoustic wave filter circuit of claim 5, wherein the release holes have a diameter of 15 μm to 25 μm.
8. The bulk acoustic wave filter circuit according to claim 5, wherein a plurality of release channels are provided on each of the thin film bulk acoustic resonators, and each of the release channels corresponds to at least one of the release holes.
9. The bulk acoustic wave filter circuit according to claim 1, wherein the layout of the bulk acoustic wave filter includes first to fourteenth layout areas;
the first layout area, the third layout area and the fifth layout area are grounding terminal layout areas, the second layout area is a layout area of an input terminal, and the fourth layout area is a layout area of an output terminal; the third layout area is positioned at the lower part of the layout of the filter, and the first layout area, the fifth layout area, the second layout area and the fourth layout area are respectively arranged at two sides of the layout of the filter;
the sixth layout area to the eleventh layout area are the first thin film bulk acoustic resonator to the sixth thin film bulk acoustic resonator, respectively; the sixth layout area to the eleventh layout area are respectively connected in series between the second layout area and the fourth layout area;
the twelfth version area to the fourteenth version area are the seventh film bulk acoustic resonator to the ninth film bulk acoustic resonator, respectively; the twelfth layout area is positioned at the upper part of the seventh layout area, one end of the twelfth layout area is respectively connected with the sixth layout area and the seventh layout area, and the other end of the twelfth layout area is connected with the first layout area; the thirteenth layout area is positioned at the lower part of the eighth layout area, one end of the thirteenth layout area is respectively connected with the eighth layout area and the ninth layout area, and the other end of the thirteenth layout area is connected with the third layout area; the fourteenth layout area is positioned at the upper part of the eleventh layout area, one end of the fourteenth layout area is respectively connected with the tenth layout area and the eleventh layout area, and the other end of the fourteenth layout area is connected with the fourth layout area;
the sixth layout area and the eighth layout area are positioned on a first straight line where the second layout area and the fourth layout area are positioned, the seventh layout area, the ninth to twelfth layout areas and the fourteenth layout area are positioned on a first side of the first straight line, and the thirteenth layout area is positioned on a second side of the first straight line;
the sixth layout area, the seventh layout area and the eighth layout area form a first V shape, the seventh layout area, the eighth layout area and the ninth layout area form a second V shape, and the ninth layout area, the tenth layout area and the eleventh layout area form a third V shape; eighth version region, ninth version region and tenth version region are located a straight line, the opening of first V style of calligraphy and third V style of calligraphy all faces the second side, the opening of second V style of calligraphy is towards first side, the angle of first V style of calligraphy and second V style of calligraphy is greater than 90, the angle of third V style of calligraphy is less than 90.
10. A bulk acoustic wave filter assembly comprising a bulk acoustic wave filter circuit according to any one of claims 1 to 9.
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| CN202121489985.0U CN216146311U (en) | 2021-06-30 | 2021-06-30 | Bulk acoustic wave filter circuit and filter assembly |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202121489985.0U CN216146311U (en) | 2021-06-30 | 2021-06-30 | Bulk acoustic wave filter circuit and filter assembly |
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| CN216146311U true CN216146311U (en) | 2022-03-29 |
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