CN115296643A - FBAR filter circuit - Google Patents

FBAR filter circuit Download PDF

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Publication number
CN115296643A
CN115296643A CN202211049886.XA CN202211049886A CN115296643A CN 115296643 A CN115296643 A CN 115296643A CN 202211049886 A CN202211049886 A CN 202211049886A CN 115296643 A CN115296643 A CN 115296643A
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CN
China
Prior art keywords
module
fbar filter
filter circuit
circuit
inductor
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Pending
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CN202211049886.XA
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Chinese (zh)
Inventor
李国强
李陈阳
胡晗
罗添友
衣新燕
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South China University of Technology SCUT
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South China University of Technology SCUT
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Priority to CN202211049886.XA priority Critical patent/CN115296643A/en
Publication of CN115296643A publication Critical patent/CN115296643A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezo-electric or electrostrictive material
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects

Abstract

The invention belongs to the technical field of filters, and discloses an FBAR filter circuit. The FBAR filter circuit comprises a filtering module, a resonance module and a cancellation module; the input end of the filtering module is connected with one end of the resonance module, and the other end of the resonance module is connected with the input end of the FBAR filter circuit; connecting the input end of the counteracting module with the input end of the filtering module, and connecting the output end of the counteracting module with the output end of the FBAR filter circuit; the input end of the resonance module is the input end of the FBAR filter circuit, and the output end of the filtering module is the output end of the FBAR filter circuit; the resonance module is used for forming a transmission zero at the high-frequency end of the stop band of the FBAR filter circuit; the cancellation module is used for forming a second path, and when the working frequency is in a low-frequency stop band of the FBAR filter, the signal passes through the cancellation circuit. The out-of-band rejection is significantly improved without introducing more loss and degrading the in-band insertion loss.

Description

FBAR filter circuit
Technical Field
The invention relates to the technical field of filters, in particular to an FBAR filter circuit.
Background
A film bulk acoustic resonator filter (film bulk acoustic resonator) is manufactured by means of techniques such as mems and thin film techniques using a silicon substrate. The filter is mainly used for filtering unwanted radio frequency signals and improving the performance of a transmitting path or a receiving path. The FBAR filter of the present stage has already a higher characteristic than the general SAW filter.
At present, the whole communication equipment is smaller and smaller, the frequency resource is more and more crowded, and a high-performance filter is more important. With the rapid development of wireless communication and wireless access, frequency resources are more and more crowded, and guard intervals between frequency bands of different communication systems are smaller and smaller. On the one hand, this puts more strict requirements on the frequency spectrum and power of each system transmitting end, ensures that the transmitted signal has higher linearity and cannot be increased at will to increase the communication distance or reliability. Meanwhile, the environment of the receiving end is worse, and particularly for smaller and smaller mobile products, the interference is increased, and the receiving sensitivity and the interference resistance are improved.
The prior art discloses an FBAR filter circuit, comprising: one end of the cross coupling module is connected with the first end of the filtering module and then used as the input end of the FBAR filter circuit, the other end of the cross coupling module is connected with the third end of the filtering module, and the third end of the filtering module is used as the output end of the FBAR filter circuit; or one end of the cross coupling module is connected with the third end of the filtering module and then serves as the output end of the FBAR filter circuit, and the other end of the cross coupling module is connected with the fourth end of the filtering module; the cross coupling module is used for forming a transmission zero point at a high frequency band outside a pass band of the FBAR filter circuit, so that out-of-band rejection can be improved, components in the cross coupling module cannot cause the chip volume of an original FBAR filter to be greatly increased, introduction of an inductor can be reduced, and more loss and in-band insertion loss cannot be introduced.
The prior art discloses a FBAR filter circuit design, which includes: the input end of the filter module is connected with one end of the first resonance module, the output end of the filter module is connected with one end of the second resonance module, the other end of the first resonance module is grounded, and the other end of the second resonance module is grounded; the input end of the filtering module is the input end of the FBAR filter circuit, and the output end of the filtering module is the output end of the FBAR filter circuit; the first resonance module and the second resonance module are used for forming one or two transmission zero points on the stop band of the FBAR filter circuit, so that out-of-band suppression can be improved, the chip volume of the filter module cannot be greatly increased due to components in the resonance module, more loss cannot be introduced, and in-band insertion loss cannot be deteriorated.
The prior art discloses an FBAR filter circuit structure, which includes: the input end or the output end of the filter module is connected with one end of the resonance module, and the other end of the resonance module is grounded; the input end of the filtering module is the input end of the FBAR filter circuit, and the output end of the filtering module is the output end of the FBAR filter circuit; the resonant module is used for forming a transmission zero at the stop band of the FBAR filter circuit, thereby improving out-of-band rejection. And the components in the resonance module can not cause the chip volume of the filter module to be greatly increased, and more loss and in-band insertion loss can not be introduced.
The prior art discloses a circuit structure of an FBAR filter, which includes a filtering module and a notch module, where the notch module is connected to an input end or an output end of the filtering module, and is used to form a transmission zero at a stop band of the FBAR filter circuit. According to the invention, the notch module and the filtering module which are connected in series are adopted, the notch module can form a transmission zero point on the stop band of the FBAR filter circuit, so that out-of-band rejection can be improved, and the position of the transmission zero point of the FBAR filter circuit can be accurately controlled by adjusting the resonant frequency of the first resonator in the notch module.
The prior art discloses an FBAR filter, which comprises a cancellation circuit having an input connected to an input of the FBAR filter circuit and an output connected to an output of the FBAR filter circuit, the cancellation circuit being configured to form a second path, wherein a signal passes through the cancellation circuit when an operating frequency is in a stop band of the FBAR filter and passes through the FBAR filter circuit when the operating frequency is in a pass band of the FBAR filter. This application can realize high suppression at the stop band low frequency end through increasing offset circuit, and components and parts among the offset circuit can not cause FBAR filter's chip volume to increase by a wide margin, can not introduce more losses and worsen the in-band insertion loss.
Disclosure of Invention
The present invention provides an FBAR filter circuit to overcome the problems of increasing the filter stages to improve out-of-band rejection, achieving the rejection effect only at the low frequency end or the high frequency end, suppressing one of them, introducing more loss, and deteriorating in-band insertion loss in the prior art.
In order to solve the technical problems, the technical scheme of the invention is as follows:
an FBAR filter circuit comprises a filtering module, a resonance module and a cancellation module;
the input end of the filtering module is connected with one end of the resonance module, and the other end of the resonance module is connected with the input end of the FBAR filter circuit;
connecting the input end of the counteracting module with the input end of the filtering module, and connecting the output end of the counteracting module with the output end of the FBAR filter circuit;
the input of the resonance module is the input of the FBAR filter circuit,
the output end of the filtering module is the output end of the FBAR filter circuit;
the resonance module is used for forming a transmission zero at the high-frequency end of the stop band of the FBAR filter circuit;
the counteracting module is used for forming a second path, and when the working frequency is in the low-frequency stop band of the FBAR filter, the signal passes through the counteracting circuit;
when the operating frequency is at the passband of the FBAR filter, a signal passes from the FBAR filter circuit.
Preferably, the filtering module comprises a series circuit and a plurality of parallel circuits;
the series circuit is formed by connecting a plurality of resonators in series, one end of the series circuit is an input end of the FBAR filter circuit, and the other end of the series circuit is an output end of the FBAR filter circuit;
each parallel circuit is formed by connecting resonators and grounding inductors in series, one end of each resonator in each parallel circuit is connected between adjacent series resonators or between any end in the series circuit and the adjacent resonators, and one end of each grounding inductor in each parallel circuit is grounded.
Preferably, the resonator is a film bulk acoustic resonator, and the film bulk acoustic resonator adopts an air cavity structure, a bulk silicon etching type or a solid assembly type structure.
Preferably, the number of the thin film bulk acoustic resonators connected in series in the series circuit is greater than or equal to 1;
the number of the parallel circuits is greater than or equal to 1.
Preferably, the series circuit further comprises an input lead inductance and an output lead inductance;
one end of the input lead inductor is an input end of the filtering module, the other end of the input lead inductor is connected with the thin film bulk acoustic resonator connected in series and then is connected with one end of the output lead inductor, and the other end of the output lead inductor is an output end of the filtering module.
Preferably, the input lead inductance and the output lead inductance are any one of a bonding wire, an inductance realized by a GaAs substrate, an inductance realized by a ceramic sheet, and a surface-mounted inductance.
Preferably, the resonance module includes: a capacitor C1 and an inductor L1 connected in series;
the cancellation module includes: an inductor L2, an inductor L3, and a transmission line TL1;
one end of the capacitor C1 is connected with the input lead inductor, and the other end of the inductor L1 is grounded;
one end of the inductor L2 is an input end of the cancellation module, and the other end of the inductor L2 is connected to one end of the inductor L3 and one end of the transmission line TL1, respectively;
the other end of the inductor L3 is an output end of the offset circuit;
the other end of the transmission line TL1 is grounded.
Preferably, the capacitance value range of the capacitor C1 is 0.1pF to 3pF; the inductance value range of the inductor L1 is 0.5 nH-5 nH.
Preferably, the inductance L1 has a value of 3.5nH, the inductance L2 has a value of 3.2nH, the electrical length of the transmission line TL1 is 1.7 °, and the characteristic impedance value is 55 Ω.
Compared with the prior art, the technical scheme of the invention has the beneficial effects that:
the resonance module is used for forming a transmission zero point at the high-frequency end of the stop band of the FBAR filter circuit, the counteracting module is used for forming a second path, and when the working frequency is in the low-frequency stop band of the FBAR filter, signals pass through the counteracting circuit, so that out-of-band rejection can be improved, the size of a chip of the filter module cannot be greatly increased due to components in the resonance module, and more loss and in-band insertion loss cannot be introduced.
Drawings
Fig. 1 is a schematic diagram of an FBAR filter circuit of embodiment 1;
FIG. 2 is a circuit schematic of a filtering module;
FIG. 3 is a diagram of an amplitude-frequency characteristic corresponding to a filter module;
fig. 4 is a circuit schematic diagram of an FBAR filter circuit of embodiment 1;
fig. 5 is a schematic diagram of an amplitude-frequency characteristic curve corresponding to the FBAR filter circuit of embodiment 1.
Detailed Description
The invention is further described with reference to the drawings and the following detailed description, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.
Unless otherwise indicated, reagents and materials used in the following examples are commercially available.
Example 1
As shown in fig. 1, the FBAR filter circuit provided in the present embodiment includes a resonance module 10, a cancellation module 20, and a filtering module 30
The input end of the filtering module 30 is connected to one end of the resonance module 10, and the other end of the resonance module 10 is connected to the output end of the FBAR filter circuit;
the input end of the counteracting module 20 is connected with the input end of the filtering module 30, and the output end of the counteracting module 20 is connected with the output end of the FBAR filter circuit;
the input end of the resonance module 10 is the input end of the FBAR filter circuit, and the output end of the filtering module 30 is the output end of the FBAR filter circuit;
the resonant module 10 is used to form a transmission zero at the high-frequency end of the stop band of the FBAR filter circuit, and the cancellation module 20 is used to form a second path, through which the signal passes when the operating frequency is in the low-frequency stop band of the FBAR filter circuit.
According to the FBAR filter circuit design, the values of the components in the resonance module are adjusted, so that a transmission zero is formed in the stop band of the FBAR filter circuit, and out-of-band rejection can be improved.
The offset module has the same amplitude as the FBAR filter circuit at the frequency point to be improved with out-of-band rejection and has a phase difference of 180 degrees, so that the offset module forms a second path, and when the working frequency is in the stop band of the FBAR filter, the signal passes through the second path.
As shown in fig. 2, the filtering module 30 includes: one series circuit 301 and 3 parallel circuits 302;
the series circuit 301 is formed by connecting 4 resonators in series, one end of the series circuit 301 is an input end of the filter module 30, and the other end of the series circuit 301 is an output end of the filter module 30;
each parallel circuit 302 is formed by connecting a resonator and a grounding inductor in series, one end of the resonator in each parallel circuit is connected between adjacent series resonators or between any one end in the series circuit and an adjacent resonator, and one end of the grounding inductor in each parallel circuit is grounded.
In this embodiment, the resonator is a film bulk acoustic resonator, and the film bulk acoustic resonator adopts an Air cavity (Air gap) structure.
The series circuit is formed by connecting 4 film bulk acoustic resonators in series.
In the following description, a series circuit is described by taking an example in which 4 thin film bulk acoustic resonators are connected in series, and as shown in fig. 2, a series circuit 301 is formed by sequentially connecting a thin film bulk acoustic resonator X1, a thin film bulk acoustic resonator X2, a thin film bulk acoustic resonator X3, and a thin film bulk acoustic resonator X4 in series.
The series circuit 301 further includes an input lead inductance L6 and an output lead inductance L7;
one end of the input lead inductor L6 is an input end of the filter module, the other end of the input lead inductor L6 is connected to the thin film bulk acoustic resonator connected in series and then connected to one end of the output lead inductor L7, and the other end of the output lead inductor L7 is an output end of the filter module 30.
As shown in fig. 2, an input lead inductance L6 is connected between the film bulk acoustic resonator X1 and the input terminal of the FBAR filter circuit 30, and an input lead inductance L7 is connected between the film bulk acoustic resonator X4 and the output terminal of the FBAR filter circuit 30.
The number of parallel circuits is 3.
As shown in fig. 2, one end of the film bulk acoustic resonator X5 is connected between the film bulk acoustic resonator X1 and the film bulk acoustic resonator X2, and the other end of the film bulk acoustic resonator X5 is grounded after being connected in series with a grounding inductor L8;
one end of the film bulk acoustic resonator X6 is connected between the film bulk acoustic resonator X2 and the film bulk acoustic resonator X3, and the other end of the film bulk acoustic resonator X6 is grounded after being connected with a grounding inductor L9 in series;
one end of the film bulk acoustic resonator X7 is connected between the film bulk acoustic resonator X3 and the film bulk acoustic resonator X4, and the other end of the film bulk acoustic resonator X7 is grounded after being connected with the grounding inductor L10 in series.
The input lead inductance L6 and the output lead inductance L7 are bonding wires.
Corresponding to the amplitude-frequency characteristic curve of the FBAR filter circuit shown in fig. 2, the abscissa represents frequency in GHz and the ordinate represents attenuation in dB, as shown in fig. 3.
As shown in fig. 4, the resonance module includes: a capacitor C1 and an inductor L1 connected in series; one end of the capacitor C1 is connected between the input lead wire inductor and the adjacent film bulk acoustic resonator, and the other end of the inductor L1 is grounded;
the cancellation module includes: an inductor L2, an inductor L3, and a transmission line TL1;
one end of the inductor L2 is an input end of the cancellation module, and the other end of the inductor L2 is connected with one end of the inductor L3 and one end of the transmission line TL1 respectively; the other end of the inductor L3 is an output end of the offset circuit; the other end of the transmission line TL1 is grounded.
The capacitance value range of the capacitor C1 is 2pF, and the inductance value of the inductor L1 is 3.5nH; the inductance of the inductor L2 is 3.2nH, the electrical length of the transmission line TL1 is 1.7 °, and the characteristic impedance is 55 Ω.
Example 2
This example is substantially the same as the scheme of example 1, except that:
in this embodiment, the resonator is a film bulk acoustic resonator, and the film bulk acoustic resonator adopts a Solid-State Mounted Resonator (SMR) structure.
The input lead inductance L6 and the output lead inductance L7 are inductances realized by using GaAs substrates.
The series circuit is formed by connecting 5 film bulk acoustic resonators in series.
The number of parallel circuits is 4.
The capacitance range of the capacitor C1 is 0.1pF, and the inductance range of the inductor L1 is 0.5 nH-5 nH.
The inductance value of the inductor L1 is 0.5nH; the inductance value of the inductor L2 is 5nH.
Example 3
This example is substantially the same as the protocol of example 1, except that:
the input lead inductance L6 and the output lead inductance L7 are inductances realized by ceramic chips and surface-mounted inductances.
The series circuit is formed by connecting 2 film bulk acoustic resonators in series.
The number of parallel circuits is 1.
The capacitance value range of the capacitor C1 is 3pF, and the inductance value of the inductor L1 is 5nH; the inductance of the inductor L2 is 1nH.
Comparative example 1
As shown in fig. 2, the present comparative example provides an FBAR filter circuit including: one series circuit 301 and 3 parallel circuits 302;
the series circuit 301 is formed by connecting 4 resonators in series, one end of the series circuit 301 is an input end of the filter module 30, and the other end of the series circuit 301 is an output end of the filter module 30;
each parallel circuit 302 is composed of a resonator and a grounding inductor connected in series, one end of the resonator in each parallel circuit is connected between adjacent series resonators or between any end in the series circuit and an adjacent resonator, and one end of the grounding inductor in each parallel circuit is grounded.
In the comparative example, the resonator is a film bulk acoustic resonator, and the film bulk acoustic resonator adopts an Air cavity (Air gap) structure.
The series circuit is formed by connecting 4 film bulk acoustic resonators in series.
In the following description, a series circuit is described by taking an example in which 4 thin film bulk acoustic resonators are connected in series, and as shown in fig. 2, the series circuit 301 is composed of a thin film bulk acoustic resonator X1, a thin film bulk acoustic resonator X2, a thin film bulk acoustic resonator X3, and a thin film bulk acoustic resonator X4 which are connected in series in this order.
The series circuit 301 further includes an input lead inductance L6 and an output lead inductance L7;
one end of the input lead inductor L6 is an input end of the filter module, the other end of the input lead inductor L6 is connected to the thin film bulk acoustic resonator connected in series and then connected to one end of the output lead inductor L7, and the other end of the output lead inductor L7 is an output end of the filter module 30.
As shown in fig. 2, an input lead inductance L6 is connected between the film bulk acoustic resonator X1 and the input terminal of the FBAR filter circuit 30, and an input lead inductance L7 is connected between the film bulk acoustic resonator X4 and the output terminal of the FBAR filter circuit 30.
The number of parallel circuits is 3.
As shown in fig. 2, one end of the film bulk acoustic resonator X5 is connected between the film bulk acoustic resonator X1 and the film bulk acoustic resonator X2, and the other end of the film bulk acoustic resonator X5 is grounded after being connected in series with a grounding inductor L8;
one end of the film bulk acoustic resonator X6 is connected between the film bulk acoustic resonator X2 and the film bulk acoustic resonator X3, and the other end of the film bulk acoustic resonator X6 is grounded after being connected with a grounding inductor L9 in series;
one end of the film bulk acoustic resonator X7 is connected between the film bulk acoustic resonator X3 and the film bulk acoustic resonator X4, and the other end of the film bulk acoustic resonator X7 is grounded after being connected with the grounding inductor L10 in series.
The input lead inductance L6 and the output lead inductance L7 are bonding wires.
Corresponding to the amplitude-frequency characteristic curve of the FBAR filter circuit shown in fig. 2, the abscissa represents frequency in GHz and the ordinate represents attenuation in dB, as shown in fig. 3.
And (3) evaluating the experimental effect:
in embodiment 1, the cancellation module 20 is provided, and the value of the inductance L1 is 3.5nH; the value of the inductance L2 is 3.2nH, the electrical length of the transmission line TL1 is 1.7 °, the characteristic impedance value is 55 Ω, and the resonant module 10. The corresponding amplitude-frequency characteristic curve is shown in fig. 5, a transmission zero is generated at 2GHz, and comparing fig. 3 with fig. 5, the attenuation at 2GHz in fig. 3 is about 28dB, and the attenuation at 2GHz in fig. 5 is about 45dB, so that the out-of-band rejection is improved by about 17 dB.
In the design of the FBAR filter circuit in embodiment 1 of the present invention, the input terminal of the filtering module is connected to one end of the resonance module, and the other end of the resonance module is connected to the input terminal of the FBAR filter circuit; the input end of the counteracting module is connected with the input end of the filtering module, and the output end of the counteracting module is connected with the output end of the FBAR filter circuit; the input end of the resonance module is the input end of the FBAR filter circuit, and the output end of the filtering module is the output end of the FBAR filter circuit; the resonance module is used for forming a transmission zero point at FBAR filter circuit's stop band high-frequency end, and the offset module is used for forming the second passageway, and when operating frequency was in FBAR filter's low-frequency stop band, the signal passed through from the offset circuit to can improve out-of-band suppression, and the components and parts in the resonance module can not cause the chip volume of filtering module to increase by a wide margin, can not introduce more losses and deteriorate in-band insertion loss.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (10)

1. An FBAR filter circuit is characterized by comprising a filtering module, a resonance module and a cancellation module;
the input end of the filtering module is connected with one end of the resonance module, and the other end of the resonance module is connected with the input end of the FBAR filter circuit;
connecting the input end of the counteracting module with the input end of the filtering module, and connecting the output end of the counteracting module with the output end of the FBAR filter circuit;
the input of the resonance module is the input of the FBAR filter circuit,
the output end of the filtering module is the output end of the FBAR filter circuit;
the resonance module is used for forming a transmission zero at the high-frequency end of the stop band of the FBAR filter circuit;
the counteracting module is used for forming a second path, and when the working frequency is in a low-frequency stop band of the FBAR filter, signals pass through the counteracting circuit;
when the operating frequency is in the pass band of the FBAR filter, a signal passes from the FBAR filter circuit.
2. The FBAR filter circuit of claim 1 wherein the filtering module comprises a series circuit and a plurality of parallel circuits;
the series circuit is formed by connecting a plurality of resonators in series, one end of the series circuit is an input end of the FBAR filter circuit, and the other end of the series circuit is an output end of the FBAR filter circuit;
each parallel circuit is formed by connecting resonators and grounding inductors in series, one end of each resonator in each parallel circuit is connected between adjacent series resonators or between any end in the series circuit and the adjacent resonators, and one end of each grounding inductor in each parallel circuit is grounded.
3. The FBAR filter circuit of claim 2, wherein the resonator is a thin film bulk acoustic resonator, the thin film bulk acoustic resonator being of an air cavity structure, a bulk silicon etched type or a solid state fabricated type.
4. The FBAR filter circuit according to claim 2 or 3, wherein the number of thin film bulk acoustic resonators connected in series in the series circuit is 1 or more;
the number of the parallel circuits is greater than or equal to 1.
5. The FBAR filter circuit of claim 4, wherein the series circuit further comprises an input lead inductance and an output lead inductance;
one end of the input lead inductor is an input end of the filtering module, the other end of the input lead inductor is connected with the thin film bulk acoustic resonator connected in series and then is connected with one end of the output lead inductor, and the other end of the output lead inductor is an output end of the filtering module.
6. The FBAR filter circuit of claim 5,
the input lead inductance and the output lead inductance are any one of a bonding wire, an inductance realized by adopting a GaAs substrate, an inductance realized by adopting a ceramic chip and a surface-mounted inductance.
7. The FBAR filter circuit of claim 5, wherein the resonance module comprises: a capacitor C1 and an inductor L1 which are connected in series; one end of the capacitor C1 is connected with the input lead inductor, and the other end of the inductor L1 is grounded.
8. The FBAR filter circuit of claim 5, wherein the cancellation module comprises: an inductor L2, an inductor L3, and a transmission line TL1;
one end of the inductor L2 is an input end of the cancellation module, and the other end of the inductor L2 is connected to one end of the inductor L3 and one end of the transmission line TL1, respectively;
the other end of the inductor L3 is an output end of the offset circuit;
the other end of the transmission line TL1 is grounded.
9. The FBAR filter circuit of claim 7, wherein the capacitance C1 has a capacitance value ranging from 0.1pF to 3pF;
the inductance value range of the inductor L1 is 0.5 nH-5 nH.
10. The FBAR filter circuit of claim 8, wherein the inductance L1 has a value of 3.5nH, the inductance L2 has a value of 3.2nH, the transmission line TL1 has an electrical length of 1.7 °, and a characteristic impedance value of 55 Ω.
CN202211049886.XA 2022-08-30 2022-08-30 FBAR filter circuit Pending CN115296643A (en)

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Application Number Priority Date Filing Date Title
CN202211049886.XA CN115296643A (en) 2022-08-30 2022-08-30 FBAR filter circuit

Publications (1)

Publication Number Publication Date
CN115296643A true CN115296643A (en) 2022-11-04

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CN202211049886.XA Pending CN115296643A (en) 2022-08-30 2022-08-30 FBAR filter circuit

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