Configurable microacoustic RF filter

Abstract

Configurable microacoustic RF filter, including: - a first goal (110) and a second goal (120); - a first filter section (140) comprising at least one microacoustic resonator connected in series and at least one microacoustic resonator connected in shunt connection, wherein the first filter section (140) is coupled to the first port (110); - a switch (160) with a first terminal (161) connected to the first filter section (140), a second terminal (162) and a third terminal (163); - a second filter section (150) comprising at least one microacoustic resonator connected in series and at least one microacoustic resonator connected in shunt connection, wherein the second filter section (150) is coupled to the third terminal (163) of the switch and the second port (120); further comprising - a further switch (210) with a first terminal (211) coupled to the second gate (120), and a second terminal (212) coupled to the second terminal (162) of the switch (160), and a third terminal (213) coupled to the second filter section (150).

Description

Technical area

[0001] The present disclosure relates to a microacoustic RF filter. In particular, the present disclosure relates to a microacoustic RF filter comprising subsections of series-connected and shunt-connected microacoustic resonators. background

[0002] Microacoustic RF filters are widely used in electronic communication systems to select the desired signal from the received signal spectrum or to shape the transmitted signal. The RF filter should have the lowest possible insertion loss in the passband to reduce overall RF losses, and requires high out-of-band attenuation to avoid crosstalk or enable the parallel use of different services, such as 4G / 5G services and Wi-Fi services. Since the in-passband insertion loss and the out-of-band attenuation in the stopband region outside the passband are related to each other, both requirements—that is, both low insertion loss and high out-of-band attenuation—are difficult to achieve.

[0003] Conventional communication devices, such as smartphones, may use a low-insertion-loss filter with appropriate out-of-band attenuation, which is activated when no interfering signal is present in the stopband region, and another filter with high out-of-band attenuation and correspondingly more insertion loss in the passband, which is activated when an interfering signal is present in the stopband region. A switch can select one of the two parallel filters depending on the attenuation requirements in the stopband region. However, this solution requires two parallel RF filters, which is space-consuming and costly.

[0004] It is an object of the present disclosure to provide a microacoustic RF filter that selectively enables low insertion loss or high out-of-band attenuation at a lower cost.

[0005] It is a further object of the present disclosure to provide a microacoustic RF filter that selectively enables low insertion loss or high out-of-band attenuation and that requires less space.

[0006] It is yet another object of the present disclosure to provide a communication device having an RF filter that selectively enables low insertion loss or high out-of-band attenuation at a lower cost.

[0007] US 9 860 006 B1 describes a multiplexer comprising filters connected to each other at a common terminal, a low-frequency filter with a first passband, and a high-frequency filter with a second passband higher than the first passband. The low-frequency filter comprises a first-stage filter section having at least one first elastic wave resonator located on the common terminal side among at least two elastic wave resonators, and a second-stage filter section comprising a second elastic wave resonator different from the at least one first elastic wave resonator.A reflection coefficient in the second passband when the filter section of the first stage is considered as a single component from the common terminal side is larger than a reflection coefficient in the second passband when the filter section of the subsequent stage is considered as a single component from the common terminal side.

[0008] US 2018 / 0019730 A1 describes a radio-frequency front-end circuit including a first filter having a first passband and connected to a common antenna terminal, a second filter having a second passband and connected to the common antenna terminal, a switch including a common terminal and select terminals, the common terminal being connected to the first filter, and a third filter connected to one of the select terminals and arranged between the switch and an input / output terminal. A reflection coefficient of the first filter alone in the second passband, viewed from the common terminal of the antenna, is greater than a reflection coefficient of the third filter alone in the second passband, viewed from the common terminal of the antenna.

[0009] US 2013 / 0033337 A1 describes an acoustic wave filter with piezoelectric thin-film resonators, in which at least two of the piezoelectric thin-film resonators comprise: a substrate; a piezoelectric film located on the substrate; a lower electrode and an upper electrode extending over at least a part of the piezoelectric film; a mass load film for frequency control located in a resonance region in which the lower electrode and the upper electrode oppose each other and having a shape different from that of the resonance region;and a temperature compensation film having a temperature coefficient of elastic constant opposite in sign to that of the piezoelectric film, wherein at least a part of the temperature compensation film is disposed between the lower electrode and the upper electrode in the resonance region, and the areas of the mass load films of the at least two piezoelectric thin-film resonators are different from each other; Brief description

[0010] According to the present disclosure, one or more of the above objects are achieved with a configurable microacoustic RF filter having the features of present claim 1.

[0011] The microacoustic RF filter according to the present disclosure comprises a first and a second port, a first and a second filter subsection, and a switch. The switch selects between the first filter subsection and a daisy-chain of the first and second filter subsections, so that the microacoustic RF filter is configurable depending on the attenuation requirements. The switches are arranged near the filter sections. The first and the second filter subsections each comprise at least one series-connected and at least one shunt-connected microacoustic resonator. In particular, the first and the second filter subsections can have the same structure or comprise identical circuits. The first and the second filter subsections are arranged symmetrically, so that their daisy-chaining results in a ladder-type microacoustic RF filter.The filter is configurable to have a first filter length or a second filter length, depending on the selection of either the first filter section alone or the concatenation of the first and second filter sections. Accordingly, the filter is configurable to provide lower attenuation in the stopband and, accordingly, the passband, or higher attenuation in the stopband and, accordingly, the passband.

[0012] According to embodiments, the configurable microacoustic RF filter may comprise only a first port and a second port, requiring a further switch to either select the second filter subsection or bypass the second filter subsection, depending on the switching state of the switch and the further switch. When the second filter subsection is bypassed, the first filter subsection is only active between the first and second ports. When the second subsection is selected, the concatenation of the first and second filter subsections is activated between the first and second ports. Alternatively, a third port connected to the switch may be provided, so that the switch can select the first filter subsection only between the first and third ports or enable the concatenation of the first and second filter subsections between the first and second ports.

[0013] According to embodiments, a shunted inductor may be coupled to the third terminal of the switch to compensate for the parasitic capacitance of the switch relative to ground potential. If the other switch is used, another shunted inductor may also be coupled to the other switch to compensate for the parasitic capacitance of this switch relative to ground potential. The shunted compensation inductors are provided at those terminals of the switches that are connected to the second filter subsection. The inductance value of the shunted inductor(s) is obtained by a narrowband approximation such that it compensates or substantially compensates for the parasitic capacitance of the switch. The inductance value of the shunted compensation inductors may be represented as L, where L=1 / (ω2*2 Cp), to achieve an ideal compensation of the parasitic capacitances of the switches. Alternatively, L can also be set to L=1 / (ω2*2 Cp)±20%, so that the inductance lies within the range of ± 20% of the ideal value in order to at least substantially compensate for the parasitic capacitances of the switches. The term ω represents the angular frequency of interest, such as the frequency at which compensation is to be applied. This inductor can also be used to improve the matching of the RF filter, so the term ω can represent the frequency that provides a good result for matching the entire filter. Accordingly, the term ω can represent the angular frequency at which compensation is to be applied, or at which a good result is achieved for matching the entire filter, or a combination of both. The term 2 Cp represents the capacitance value of the parasitic capacitances of each of the switches.

[0014] According to embodiments, the first and second filter subsections should be symmetrical with respect to their first and second ports. The first and second filter subsections may comprise either a T-configuration or a PI configuration. A first and a second filter subsection of the T-configuration may comprise two series-connected microacoustic resonators and a microacoustic resonator shunted to the node between the two series-connected resonators. Each of the two ports of the T-configuration filter section provides a series-connected and a shunted resonator, so that the T-configuration is symmetrical.

[0015] The first and second filter sections of a PI configuration may comprise a series-connected microacoustic resonator and corresponding shunt-connected microacoustic resonators connected to the two ports of the series-connected microacoustic resonator. Each of the two ports of the PI configuration filter section provides a shunt-connected and a series-connected resonator, so that the PI configuration is symmetrical.

[0016] In the case of a PI configuration, the shunt-connected resonators can be sized so that the capacitance value is lower than usual, thus providing a reduced capacitance to compensate for the parasitic capacitance of the switches connected to the PI configuration resonator. Alternatively, compensation inductors are also possible. Inductors can also provide filter matching.

[0017] According to embodiments, one or more additional filter sections may be cascaded between the other filter subsection and the other switch connected to the second port. The one or more additional filter sections are added by one or more additional switches to enable or bypass the activation of the corresponding additional filter section. In particular, third and fourth switches may be provided to enable a bypass channel or enable a third filter subsection, allowing a third degree of stopband attenuation to be activated depending on operating requirements.

[0018] One or more of the above objects are also achieved by a communication device having the features of claim 16.

[0019] The communication device comprises one of the configurable microacoustic RF filters described above and a detector that detects the signal of an interferer in the stopband range of the RF filter. The detector is configured to generate a detection signal indicating the presence or absence of the interference signal. The switches of the configurable RF filter are controlled and adjusted depending on the state of the detection signal.

[0020] The communication device enables moderate stopband attenuation when no interferer is detected in the stopband. The insertion loss within the passband, which corresponds to the stopband attenuation, is at a relatively low level, and the received signal strength of the desired signal is assumed to be high. If an interferer is detected, one or more filter subsections are activated to increase the stopband attenuation and block the interfering signal. In this case, the insertion loss within the passband is greater, which may require additional amplification of the desired signal to achieve sufficient signal strength for further processing within the receive circuitry of the communication device.In this configuration, additional stopband attenuation is achieved to block the interferer signal at the expense of higher insertion loss in the passband and higher power consumption to amplify the received signal. A configurable microacoustic RF filter according to the present disclosure enables adaptive reception to avoid crosstalk or interference from another RF service, while saving space and the number of filter components for implementing the configurable RF filter.

[0021] It is to be understood that both the foregoing general description and the following detailed description are exemplary only and are intended to provide an overview or framework for understanding the nature and character of the claims. The accompanying drawings are included to facilitate understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments and, together with the description, serve to explain the principles and operations of various embodiments. Like elements in different figures of the drawings are designated by like reference numerals.

[0022] The drawings show: Fig. 1 a block diagram of a configurable microacoustic RF filter; Fig. 2 a block diagram of another configurable microacoustic RF filter; Fig. 3 a filter section according to a T-configuration; Fig. 4 a transmission diagram showing transmission curves of configurations of the RF filter according to Fig. 2 using T-sections; Fig. 5 a filter section with a PI configuration; Fig. 6 a transmission diagram showing transmission curves of configurations of the RF filter according to Fig. 2 using PI subsections; Fig. 7A and Fig. Figure 7B shows a simplified model of a lumped element switch or a compensation inductor to compensate for the parasitic capacitance of the switch; Fig. 8 a configurable microacoustic RF filter using compensation inductors; Fig. 9 a transmission diagram showing transmission curves for configurations of the RF filter according to Fig. 8 represents; Fig. 10 is a block diagram of yet another configurable microacoustic RF filter; Fig. 11 a transmission diagram showing transmission curves for configurations of the RF filter in Fig. 10; and Fig. 12A and Fig. 12B a variant for implementing a filter section according to a T-configuration or PI configuration. Detailed description of embodiments

[0023] Fig. 1 shows a block diagram of a configurable microacoustic RF filter according to the principles of the present disclosure. The RF filter includes a first port 110, a second port 120, and a third port 130. A first filter subsection 140 is connected to port 110. Another terminal of filter section 140 is connected to a switch 160. Switch 160 includes three ports 161, 162, 163, wherein port 161 can be selectively coupled to one of ports 162, 163 depending on a control signal applied to switch 160. Switch 160 is a so-called SP2T (single pole double through) circuit. Port 163 of switch 160 is connected to a second filter subsection 150, which is further connected to second filter port 120. The second gate 162 of the switch 160 is connected to the third filter gate 130.

[0024] During operation, switch 160 can be controlled to connect gates 161 and 162 such that only filter section 140 between filter gates 110, 130 is active. Alternatively, switch 160 can be controlled to couple gates 161 and 163 such that the daisy-chain or series connection of filter sections 140, 150 between filter gates 110, 120 is active.

[0025] The filter sections 140, 150 preferably have the same structure. The filter sections 140, 150 can be symmetrical, so that the impedance seen through each terminal of the sections is identical. The sections 140, 150 comprise at least one series-connected microacoustic resonator and at least one shunt-connected microacoustic resonator connected between a terminal of the series-connected resonator and a ground potential terminal. Preferably, the sections 140, 150 are either circuits with a T configuration or circuits with a PI configuration, as explained in more detail below.

[0026] Fig. Figure 2 shows a block diagram of another embodiment of a configurable microacoustic RF filter. The filter according to Fig. 2 includes a third switch 210 with a first terminal 211 connected to gate 120, a second terminal 212 connected to the second terminal 162 of switch 160, and a third terminal 213 connected to filter section 150. Switches 160, 210, and coupling terminals 162, 212, bypass filter section 150, so that only filter section 140 between gates 110, 120 is active. When switches 160, 210 are selected such that terminals 163, 213 are enabled, the chain of filter sections 140, 150 between gates 110, 120 is active. Switches 160, 210 are arranged within the filter near the filter section 150 to be switched.

[0027] Fig. Figure 3 shows a filter subsection according to a T-configuration. The T-configuration section comprises a series connection of a first and a second resonator 331, 332, which are arranged between two ports 320, 330. The node between the resonators 331, 332 is coupled to the ground terminal 334 via a shunt resonator 333. The series resonators 331, 332 can be represented by "S" and the shunt resonator 333 by "P", so that a T-section comprises an SPS topology. The T-configuration section is symmetrical at both ports 320, 330, so that a larger filter formed from two or more concatenated T-configuration sections has a ladder-type configuration. The filter sections 140, 150 according to Fig. 1 and Fig. 2 may include a T-configuration section as shown in Fig. 3. More than one T-configuration section within the filter sections 140, 150 is also possible.

[0028] Now, with reference to Fig. 4 shows a transmission diagram showing the transmission curves 410, 430 of different switched configurations of the filter according to Fig. 2 when the filter sections 140, 150 are implemented as T-sections, as in Fig. 3. A comparative transmission curve 420 is also shown in Fig. 4. In particular, the transmission curve 410 represents the transmission of the filter according to Fig. 2 when the PLC topology of filter 140 is selected such that switches 160, 210 bypass section 150. Transfer curve 420 represents the curve for a reference or comparison ladder-type topology without switches, such as a PLCPS topology, which may be a chain of an PLC filter and another PLC filter. Transfer curve 430 represents the filter according to Fig. 2, wherein the switches 160, 210 are designed such that the sections 140, 150 between the gates 110, 120 are active, resulting in a selected PLC configuration. As can be seen from Fig. As can be seen from Figure 4, the transmission curve 420 exhibits higher attenuation in the stopband region than curve 410, since the higher-order conductor-type topology increases the stopband attenuation. In the passband region 401, curve 420 lies slightly below curve 410, so the insertion loss is increased. As can be seen from Fig. 4, the matching of the filter of curve 430 is worse than that of the filter of curve 420, which may be due to the parasitic capacitances to ground potential resulting from the switches 160, 210. Furthermore, a peak is visible in the region 431, which is also caused by the parasitic capacitances of the switches 160, 210 to ground potential. On the other hand, the configurable microacoustic RF filter according to Fig. 2 an increase in attenuation from curve 410 to curve 430 in the stopband range, which is useful in the event that an interfering signal may be present in the stopband range that needs to be suppressed. This may be the case if there is crosstalk from another channel in the received spectrum or if another service, such as a Wi-Fi signal, is present in the stopband range. In this case, the switches 160, 210 are selected such that the filter sections 140, 150 are active and chained to achieve higher attenuation out of band according to curve 430 and to suppress the Wi-Fi signal upon reception of the desired signal of the passband 401.

[0029] Fig. Figure 5 shows a filter section according to a PI configuration that can be used for the filter sections 140, 150. The PI section according to Fig. 5 includes the first and second gates 520, 530 and a series-connected resonator 531 arranged between the gates 520, 530. The first and second shunt-connected resonators 532, 533 are connected from the terminals of the series-connected resonator 531 to the ground terminal 534.

[0030] Now, with reference to Fig. 6 Transmission curves for the filter according to Fig. 2, wherein the filter sections 140, 150 are implemented as PI sections, as in Fig. 5. The transmission curve 610 represents a PSP topology for the filter 140 when the switches 160, 210 bypass the section 150. The curve 620 represents a PSPSP topology as a reference or comparison example without any switches. The curve 630 represents the transmission curve of the filter according to Fig. 2 with PI configuration sections in filter sections 140, 150, where switches 160, 210 are selected such that sections 140, 150 are chained and active between ports 110, 120. The state of switches 160, 210 is such that ports 163, 213 are enabled. Curve 630 exhibits high out-of-band attenuation close to comparison curve 620 for the comparative ladder-type topology without switches. In passband region 601, the selected higher-order ladder-type structure exhibits higher insertion loss than the lower-order ladder-type structure. It should be noted that the use of PI blocks for the filter sections 140, 150 avoids a peak at the upper edge of the passband in the region 631, which differs from the embodiment in which T-blocks are used, as in Fig. 4. Although switches 160, 210 have parasitic capacitances relative to ground potential, these capacitances are arranged in parallel with the preceding and following resonators 532, 533 of the PI configuration block within filter section 150, so that the parasitic effect does not appear in the transfer curve. On the other hand, adding inductors in the PI configuration can improve the filter's matching.

[0031] Now, with reference to Fig. 7A and Fig. 7B shows the effect of the parasitic capacitance of the switches and a solution for compensation. Fig. Figure 7A shows a simplified lumped-element model for switches 160, 210. The simplified model includes a circuit 710 with a series connection of an inductor, a resistor, and another inductor with two shunt capacitors, each having a capacitance Cp. The series inductors have a relatively low inductance, such as about 0.25 nH, and the series resistor has a relatively low resistance in the range of about 1.0 Ω. Accordingly, the series path can be almost neglected, so that the resulting element is the parallel connections of the two capacitors, resulting in a total parasitic capacitance of 2 Cp.

[0032] In Fig. 7B shows the parasitic capacitance of a switch at 720. The parasitic shunt capacitor 720 is in Fig. 4 for the peak 431 at a frequency f spikeat approximately 2200 MHz. This can be canceled out with a compensation element, such as a negative capacitance connected in parallel with the parasitic capacitance 720, or a narrowband approximation of such a negative capacitance, which is an inductor. The inductance value of the inductor according to the narrowband approximation is ideally 1 / (ω 2 2Cp). In practice, the inductance L of the compensating inductor 730 is in the range of 1 / (ω 2 2Cp) ± 20%. The angular frequency ω represents the frequency at which the peak 431 is located and is, in the case of Fig. 4 at about 2200 MHz.

[0033] Fig. Figure 8 shows a block diagram of a configurable microacoustic RF filter using compensation inductors. The filter according to Fig. 8 has the basic structure of the Fig. 2, wherein additional inductors 810, 820 are connected from the nodes between terminals 163 and 213 of switches 160, 210 and the corresponding terminals of filter section 150 to the ground potential terminal. The compensation inductors 810, 820 are arranged according to the method described in connection with Fig. 7B are designed to compensate the parasitic capacitances 2 Cp of the switches 160, 210. The result of the compensation can be determined from the Fig. 9, which is based on T-sections for sections 140, 150, so that it corresponds to the Fig. 4 shown transmission diagram for the uncompensated case. As can be seen from Fig. As can be seen in Figure 9, the upper right flank of the passband of curve 930 is flat in region 931, so it has no peak. While the compensation inductors 810, 820 are particularly useful for compensating for a peak introduced by T-sections in the filter sections 140, 150, such compensation inductors can also be used in conjunction with PI sections implementing the filter sections 140, 150 and helping to improve the matching of the overall filter. The inductance of the inductor can be calculated according to the formulas mentioned above, where the term ω represents the angular frequency at which a good result for the matching of the overall filter is achieved.

[0034] Fig. 10 shows a block diagram in which an additional filter subsection 1030 is cascaded with the filter sections 140, 150 by respective switches 1010, 1020, which enable the activation of an additional filter section 1030 or a bypass. In particular, the switch 1010 has a terminal 1011 connected to the filter section 150. The switch 1020 is connected to the terminal 213 of the switch 210 at its terminal 1021. The terminals 1012, 1022 of the switches 1010, 1020 are connected to each other to enable a bypass of the filter section 1030. The terminals 1013, 1023 of the switches 1010, 1020 are connected to the third filter section 1030. An additional chaining order is also possible using a further filter stage and a preceding and following switch between the filter section 1030 and the terminal 1023 of the switch 1020 (in Fig. 10 not shown) is possible. Fig. 10 also shows an example of a matching network 1040 of a series inductor and a shunted capacitor connected between the switch 210 and the external gate 120.

[0035] Depending on the detection of an interference signal, the switches 160, 1010, 1020, 210 are selected either in a bypass state or in a state in which one or more of the additional filter sections 150, 1030 are selected. The configurations of the filters according to Fig. 10 are used in conjunction with the transmission diagram of Fig. 11. In a first configuration P1, the switches 160, 210 are selected to bypass the additional filter sections 150, 1030, so that only the filter section 140 between the external ports 110, 120 is active, forming, in an example where PI sections are used, a ladder-type PSP filter configuration. The transfer curve for this configuration is shown at 1110, which has the lowest attenuation factor in the stopband region and the lowest insertion loss in the passband region 1101. The second configuration P2 is designed such that the switch 160 enables the second filter section 150 and the switches 1010, 1020 bypass the filter section 1030, forming, in this example, a ladder-type PSPSP filter configuration. The corresponding transmission curve is shown at 1120, which has increased stopband attenuation and increased insertion loss in the passband.In the third configuration P3, the switches 1010, 1020 are selected so that the third filter subsection 1030 is enabled, so that the filter according to . Fig. 10 is a concatenation of filter sections 140, 150, 1030, which in this example is a PSPSPSP ladder-type filter configuration. The corresponding transmission curve is shown at 1130 and shows an even higher stopband attenuation as well as an even higher insertion loss in the passband region 1101. As can be seen from the Fig. 10 and Fig. As can be seen in Figure 11, appropriate adjustment of the switches in the configurable microacoustic RF filter allows selection of three different attenuation levels depending on the detected interference level in the stopband range. A detector in a communications device can determine the interference level and select one of the three possible configurations P1, P2, P3 and the attenuation levels 1110, 1120, 1130 to achieve sufficient suppression of the interferer. The detector generates a corresponding detection signal indicating the degree of presence or absence of the interferer and adjusts the switches depending on the detection signal.However, the insertion loss in the passband also increases with increasing stopband attenuation, so more electrical power may be required to amplify the signal at terminal 120 to a desired level suitable for further signal processing in the downstream receiving circuitry. While increased attenuation requires increased power consumption, power consumption is reduced when the interference level is lower or no interferer is detected, so either transmission curve 1120 or 1110 is selected.

[0036] The resonators 140, 150, 1030 can be implemented using an acoustic filter technology, in which the switches 160, 1010, 1020, 210 can be implemented as semiconductor switches using semiconductor CMOS technology. The chip with the switches can be positioned on top of the chip so that the acoustic filters keep parasitic effects as small as possible. The acoustic filters can be formed from microacoustic resonators, such as surface acoustic wave resonators and / or bulk acoustic wave resonators using a piezoelectric substrate, as is known to those skilled in the art.

[0037] Fig. 12A shows a filter subsection according to another implementation of a T-configuration. The subsection includes an impedance element 1211 connected between the shunt resonator 333 and the ground terminal 334. The impedance element 1211 is connected in series with the shunt resonator 333. The impedance element 1211 may be formed by an inductor to introduce a finite transfer zero into the filter transfer function.

[0038] Fig.Figure 12B shows a filter subsection according to another implementation of a PI configuration. A corresponding impedance element 1212 and 1213 is connected between the shunt resonators 532 and 533, respectively, and the ground terminal 534. The impedance elements 1212 and 1213 can be formed by inductors to introduce a finite transfer zero into the filter transfer function. The aforementioned alternative T and PI sections can be used for the filter subsections 140, 150, and 1030.

[0039] In summary, a configurable microacoustic RF filter can be formed from a series cascade of individual filter subsections, such as T or PI blocks, where a T block has an SPS configuration and a PI block has a PSP configuration. The switches within the filter topology either bypass filter sections or add filter sections toward a minimum filter. The switches are located within the filter near the two or more filter subsections and select the required amount of out-of-band attenuation in response to the detection of an interfering signal.

[0040] Further examples of the present invention are described below: 1. Configurable microacoustic RF filter comprising: - a first gate (110) and a second gate (120); - a first filter section (140) comprising at least one series-connected microacoustic resonator and at least one shunt-connected microacoustic resonator, the first filter section (140) being coupled to the first port (110); - a switch (160) having a first terminal (161) connected to the first filter section (140), a second terminal (162) and a third terminal (163); - a second filter section (150) comprising at least one microacoustic resonator connected in series and at least one microacoustic resonator connected in shunt connection, wherein the second filter section (150) is coupled to the third terminal (163) of the switch and the second gate (120). 2. The configurable microacoustic RF filter of example 1, further comprising another switch (210) having a first terminal (211) coupled to the second port (120), a second terminal (212) coupled to the second terminal (162) of the switch (160), and a third terminal (213) coupled to the second filter subsection (150). 3. The configurable microacoustic RF filter of example 1, further comprising a third port (130) connected to the second terminal (162) of the switch (160). 4. The configurable microacoustic RF filter of any one of examples 1 to 3, further comprising a shunted inductor (810) coupled to the third terminal (163) of the switch (160). 5. The configurable microacoustic RF filter of example 4, wherein the inductance (810) is configured to compensate for a parasitic capacitance of the switch (160) or to improve the matching of the RF filter. 6. Configurable microacoustic RF filter according to example 4 or 5, wherein the inductance (810) has an inductance value L of L = 1 / (ω 2 * 2 Cp) or from L = 1 / (ω 2 * 2 Cp) ± 20%, where ω represents the angular frequency at which compensation is to be applied and / or the adaptation of the RF filter is achieved, and 2 Cp represents the capacitance value of the parasitic capacitance of the switch (160). 7. The configurable microacoustic RF filter of example 2, further comprising another shunt-connected inductor (820) coupled to the third terminal (213) of the other switch (210), the inductor (820) being configured to compensate for a parasitic capacitance of the other switch (210) relative to the ground potential. 8. The configurable microacoustic RF filter of any one of examples 1 to 7, wherein the first and second filter sections (140, 150) each have a first and a second terminal and are each symmetrical with respect to the first and second terminals. 9. The configurable microacoustic RF filter of any one of examples 1 to 8, wherein the first and second filter sections (140, 150) comprise a T-configuration comprising: - the series-connected microacoustic resonator (331) with one terminal; - the shunt-connected microacoustic resonator (333) coupled between the terminal of the series-connected microacoustic resonator and a ground potential terminal (334); and - another series-connected microacoustic resonator (332) connected to the terminal of the series-connected microacoustic resonator. 10. The configurable microacoustic RF filter of any one of examples 1 to 8, wherein the first and second filter sections (140, 150) comprise a PI configuration comprising: - the series-connected microacoustic resonator (531) having a first terminal and a second terminal; - the shunt-connected microacoustic resonator (532) coupled between the first terminal of the series-connected microacoustic resonator and a ground potential terminal (534); and - another shunt-connected microacoustic resonator (533) coupled between the second terminal of the series-connected microacoustic resonator and the ground potential terminal (534). 11. The configurable microacoustic RF filter of example 9, further comprising an impedance element (1211) connected between the shunt-connected microacoustic resonator (333) and the ground potential terminal (334). 12. The configurable microacoustic RF filter of example 10, further comprising an impedance element (1212) connected between the shunted microacoustic resonator (532) and the ground potential terminal (534), and a further impedance element (1213) connected between the further shunted microacoustic resonator (533) and the ground potential terminal (534). 13. The configurable microacoustic RF filter of example 10 with respect to example 2, wherein the shunted microacoustic resonator (532) and / or the other shunted microacoustic resonator (533) are configured with reduced capacitance to compensate for the parasitic capacitance of the switch (160) and / or the other switch (210). 14. The configurable microacoustic RF filter of example 2, further cascading one or more additional filter subsections (1030) between the other filter subsection (150) and the other switch (210) through one or more additional switches (1010, 1020). 15. The configurable microacoustic RF filter of example 2 or 14, further comprising a third switch (1010), a fourth switch (1020), and a third filter subsection (1030), wherein the third switch (1010) has a first terminal (1011) coupled to the second filter subsection (150), a second terminal (1012), and a third terminal (1013), wherein the third terminal (1013) is coupled to the third filter subsection (1030), wherein the fourth switch (1020) has a first terminal (1021) coupled to the third terminal (213) of the other switch (210), a second terminal (1022) coupled to the second terminal (1012) of the third switch (1010), and a third terminal (1023) coupled to the third filter subsection (1030). 16. A communication device comprising the configurable microacoustic RF filter according to any one of examples 1 to 15 and a detector configured to detect an interferer in a stopband range of the RF filter and configured to generate a detection signal indicative of one of the presence and absence of the interferer, wherein the switches (160, 210, 1010, 1020) of the RF filter are adjusted in dependence on the detection signal.

Claims

[1] Configurable microacoustic RF filter comprising: - a first gate (110) and a second gate (120); - a first filter section (140) comprising at least one series-connected microacoustic resonator and at least one shunt-connected microacoustic resonator, the first filter section (140) being coupled to the first port (110); - a switch (160) having a first terminal (161) connected to the first filter section (140), a second terminal (162) and a third terminal (163); - a second filter section (150) comprising at least one series-connected microacoustic resonator and at least one shunt-connected microacoustic resonator, wherein the second filter section (150) is coupled to the third terminal (163) of the switch and the second port (120); further comprising - another switch (210) having a first terminal (211) coupled to the second gate (120), a second terminal (212) coupled to the second terminal (162) of the switch (160), and a third terminal (213) coupled to the second filter section (150). [2] A configurable microacoustic RF filter according to claim 1, wherein the first and second filter sections (140, 150) each have a first and a second terminal and are each symmetrical with respect to the first and second terminals. [3] Configurable microacoustic RF filter according to one of claims 1 to 2, further comprising a shunt-connected inductor (810) coupled to the third terminal (163) of the switch (160). [4] Configurable microacoustic RF filter according to claim 3, wherein the inductance (810) is designed to compensate for a parasitic capacitance of the switch (160) or to improve the matching of the RF filter. [5] Configurable microacoustic RF filter according to claim 3 or 4, wherein the inductance (810) has an inductance value L of L = 1 / (ω 2 * 2 Cp) or from L = 1 / (ω 2 * 2 Cp) ±20%, where ω represents the angular frequency at which compensation is to be applied and / or the adaptation of the RF filter is achieved, and 2 Cp represents the capacitance value of the parasitic capacitance of the switch (160). [6] The configurable microacoustic RF filter of claim 2, further comprising another shunt-connected inductor (820) coupled to the third terminal (213) of the other switch (210), the inductor (820) being configured to compensate for a parasitic capacitance of the other switch (210) relative to the ground potential. [7] A configurable microacoustic RF filter according to any one of claims 1 to 6, wherein the first and second filter sections (140, 150) comprise a T-configuration comprising: - the series-connected microacoustic resonator (331) with one terminal; - the shunt-connected microacoustic resonator (333) coupled between the terminal of the series-connected microacoustic resonator and a ground potential terminal (334); and - another series-connected microacoustic resonator (332) connected to the terminal of the series-connected microacoustic resonator. [8] A configurable microacoustic RF filter according to any one of claims 1 to 6, wherein the first and second filter sections (140, 150) comprise a PI configuration comprising: - the series-connected microacoustic resonator (531) having a first terminal and a second terminal; - the shunt-connected microacoustic resonator (532) coupled between the first terminal of the series-connected microacoustic resonator and a ground potential terminal (534); and - another shunt-connected microacoustic resonator (533) coupled between the second terminal of the series-connected microacoustic resonator and the ground potential terminal (534). [9] A configurable microacoustic RF filter according to claim 7, further comprising an impedance element (1211) connected between the shunt-connected microacoustic resonator (333) and the ground potential terminal (334). [10] Configurable microacoustic RF filter according to claim 8, further comprising an impedance element (1212) connected between the shunt-connected microacoustic resonator (532) and the ground potential terminal (534), and a further impedance element (1213) connected between the further shunt-connected microacoustic resonator (533) and the ground potential terminal (534). [11] A configurable microacoustic RF filter according to claim 8 with reference to claim 2, wherein the shunted microacoustic resonator (532) and / or the other shunted microacoustic resonator (533) are designed with reduced capacitance to compensate for the parasitic capacitance of the switch (160) and / or the other switch (210). [12] A configurable microacoustic RF filter according to claim 2, further cascading one or more additional filter subsections (1030) through one or more additional switches (1010, 1020) between the other filter subsection (150) and the other switch (210). [13] Configurable microacoustic RF filter according to claim 2 or 12, further comprising a third switch (1010), a fourth switch (1020) and a third filter subsection (1030), wherein the third switch (1010) has a first terminal (1011) coupled to the second filter subsection (150), a second terminal (1012) and a third terminal (1013), wherein the third terminal (1013) is coupled to the third filter subsection (1030), wherein the fourth switch (1020) has a first terminal (1021) coupled to the third terminal (213) of the other switch (210), a second terminal (1022) coupled to the second terminal (1012) of the third switch (1010) and a third terminal (1023) coupled to the third filter subsection (1030). [14] A communication device comprising the configurable microacoustic RF filter according to any one of claims 1 to 13 and a detector configured to detect an interferer in a stopband range of the RF filter and configured to generate a detection signal indicative of one of the presence and absence of the interferer, wherein the switches (160, 210, 1010, 1020) of the RF filter are adjusted in dependence on the detection signal.

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