Bandpass filtering circuit

Abstract

Bandpass filtering circuit This description relates to a bandpass filtering circuit (100) comprising, in series, a first high-pass filter (HPF110), a bandpass filter (BPF100) and a second high-pass filter (HPF120), in which the bandpass filter (BPF100) comprises: - first and second acoustic resonators (AWR101, AWR102) arranged in series between first and second nodes (N102, N103); - two first coils (LBPF101, LBF102) arranged in series with each other, and arranged in parallel with said first acoustic resonator (AWR101); - two second coils (LBPF103, LBF104) arranged in series with each other, and arranged in parallel with said second acoustic resonator (AWR102); - a third acoustic resonator (AWR103) arranged between a third node (N105) midway between the said first coils (LBPF101, LBF102) and a fourth node (GND100);and - a fourth acoustic resonator (AWR104) disposed between a fifth node (N106) midway between said second coils (LBPF103, LBF104) and said fourth node (GND100). Figure for the abbreviation: Fig. 1;

Description

Title of the invention: Bandpass filtering circuit technical field

[0001] This description relates generally to the processing and transmission of periodic signals such as radio frequency signals. More specifically, this description relates to the implementation of a filtering operation on a radio frequency signal. Previous technique

[0002] Periodic signals, such as radio frequency signals, are very frequently used to transmit information. Their processing is essential for good data transmission.

[0003] The use of filters of different types is part of the classic processing applied to periodic signals.

[0004] It would be desirable to be able to improve, at least in part, certain aspects of the periodic signal filtering circuits. Summary of the invention

[0005] There is a need for more efficient periodic signal filtering circuits.

[0006] There is a need for more efficient radio frequency signal filtering circuits.

[0007] There is a need for more efficient radio frequency signal bandpass filtering circuits.

[0008] There is a need for bandpass filtering circuits for radio frequency signals that can filter signals having a frequency within a wider frequency band.

[0009] There is a need for a filtering process having these same advantages.

[0010] There is a need for a transmission chain using such a filtering circuit.

[0011] There is a need for a method of transmitting signals exhibiting these same benefits.

[0012] An embodiment overcomes all or part of the drawbacks of known filtering circuits.

[0013] An embodiment overcomes all or part of the drawbacks of known signal filtering methods.

[0014] One embodiment overcomes all or part of the drawbacks of known transmission chains.

[0015] An embodiment overcomes all or part of the drawbacks of known transmission methods.

[0016] One embodiment provides a bandpass filtering circuit comprising, in series, a first high-pass filter, a bandpass filter and a second high-pass filter, in which the bandpass filter comprises: - a first acoustic resonator and a second acoustic resonator arranged in series between a first node and a second node; - at least two first coils arranged in series with each other, and arranged in parallel with said first acoustic resonator; - at least two second coils arranged in series with each other, and arranged in parallel with said second acoustic resonator; - at least one third acoustic resonator arranged between a third midpoint between said first coils and a fourth reference node; and - at least one fourth acoustic resonator arranged between a fifth mid-node between said second coils and said fourth reference node.

[0017] Another embodiment provides a method for filtering a radio frequency signal using a bandpass filtering circuit comprising, in series, a first high-pass filter, a bandpass filter and a second high-pass filter, in which the bandpass filter comprises: - a first acoustic resonator and a second acoustic resonator arranged in series between a first node and a second node; - at least two first coils arranged in series with each other, and arranged in parallel with said first acoustic resonator; - at least two second coils arranged in series with each other, and arranged in parallel with said second acoustic resonator; - at least one third acoustic resonator arranged between a third midpoint between said first coils and a fourth reference node; and - at least one fourth acoustic resonator arranged between a fifth mid-node between said second coils and said fourth reference node.

[0018] According to one embodiment, the first and second acoustic resonators are identical, in which the first coils are identical to the second coils, and the third and fourth acoustic resonators are identical.

[0019] According to one embodiment, the first acoustic resonator may comprise at least two fifth acoustic resonators arranged in series.

[0020] According to one embodiment, the second acoustic resonator may comprise at least two sixth acoustic resonators arranged in series.

[0021] According to one embodiment, the first high-pass filter comprises: - two initial capacitors arranged in series between a sixth node and said first node; and - a second capacitor and a third coil arranged in series between a seventh midpoint between said first capacitors and said fourth reference node.

[0022] According to one embodiment, the second high-pass filter comprises: - two third capacitors arranged in series between said second node and an eighth node; and - a fourth capacitor and a fourth coil arranged in series between a ninth midpoint between said second capacitors and said fourth reference node.

[0023] According to one embodiment, the first and second high-pass filters are symmetrical with respect to said band-pass filter.

[0024] According to one embodiment, said filtering circuit further comprises a fifth coil arranged in series between said sixth node and said fourth reference node.

[0025] According to one embodiment, said filtering circuit further comprises a sixth coil arranged in series between said seventh node and said fourth reference node.

[0026] Another embodiment provides for a transmission chain comprising a filtering circuit described above.

[0027] Another embodiment provides a method for transmitting a signal using the filtering method described above. Brief description of the drawings

[0028] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0029] [Fig.1] represents a diagram illustrating a first embodiment of a bandpass filtering circuit;

[0030] [Fig.2] includes graphics illustrating the operation of the embodiment of [Fig.1];

[0031] [Fig.3] includes a graph illustrating the operation of the embodiment of [Fig.1];

[0032] [Fig.4] represents a diagram illustrating a second embodiment of a bandpass filtering circuit;

[0033] [Fig.5] includes graphics illustrating the operation of the embodiment of [Fig.4];

[0034] [Fig. 6] includes a graph illustrating the operation of the embodiment of [Fig. 4]; and

[0035] [Fig.7] represents a top view of a practical implementation of the embodiments of figures 1 and 4. Description of the implementation methods

[0036] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0037] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0038] Unless otherwise specified, when referring to two elements connected together, this means directly connected without intermediate elements other than conductors, and when referring to two elements coupled together, this means that these two elements can be connected or linked through one or more other elements.

[0039] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0040] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0041] The embodiments described below relate to the filtering of periodic signals, and more particularly to the filtering of radio frequency signals, i.e., signals with frequencies between 3 kHz and 300 GHz. More precisely, the embodiments described below are bandpass filtering circuits whose isolation and rejection characteristics have been improved for use in communications using sets of wireless communication protocols, such as Wi-Fi communication protocols. To this end, these filtering circuits are designed to allow the passage of signals with frequencies between 6 GHz and 7.2 GHz, more particularly between 6.105 GHz and 7.125 GHz, and to reject signals with frequencies in the range of 5 GHz. These embodiments are described in detail with reference to Figures 1 to 7.These embodiments are particularly well-suited for use in information and / or data transmission chains.

[0042] Furthermore, the embodiments described above are particularly suitable for use in any type of industrial market where filtering periodic signals is useful. More specifically, such a bandpass filtering circuit can be used to: - the automotive industry, for example in the field of automotive electrification and automotive telematics or in the field of advanced driver assistance systems (ADAS); - the industrial industry, for example in the field of green energy, in the field of infrastructure electrification, the Internet of Things (IoT) and Smart Homes, where electricity and energy consumption and data exchange are key elements; - the personal electronics industry, for example in the field of mobile telephony and the Internet of Things (IoT), as well as in the field of broadband interfaces; and - the communications equipment, computer and peripherals industry, for example in the field of infrastructure and data centers, and in the field of low Earth Orbit (LEO) satellites.

[0043] Fig. 1 represents an electrical diagram of a first embodiment of a 100 bandpass filtering circuit.

[0044] Circuit 100 includes an input node IN 100 and an output node OUT100. The input node IN100 is designed to receive periodic signals for filtering. The output node OUT100 is designed to provide filtered periodic signals. Circuit 100 is also referenced to a reference node GND100, which receives a reference potential, such as ground.

[0045] The circuit 100 further includes, optionally, a first coil L101 for protection against electrostatic discharge. A first terminal of the coil L101 is connected, preferably connected, to the input node IN100, and a second terminal of the coil L101 is connected, preferably connected, to the reference node GND100.

[0046] The circuit 100 further includes, optionally, a second coil L102 for protection against electrostatic discharge. A first terminal of the coil L102 is connected, preferably connected, to the output node OUT100, and a second terminal of the coil L102 is connected, preferably connected, to the reference node GND100.

[0047] According to one embodiment, the circuit 100 further comprises a first high-pass filter HPF110 including an input node connected, preferably connected, to the input node IN100, and an output node N102. In one example, the HPF110 filter includes three capacitors CHPF111, CHPF112 and CHPF113, and one coil LHPF111.

[0048] According to one example, the capacitors CHPF111 and CHPF112 are arranged in series between the nodes IN100 and N102. More specifically, a first terminal of the capacitor CHPF111 is connected, preferably connected, to the node IN100, and a second terminal of the capacitor CHPF111 is connected, preferably connected, to a node N101. A first terminal of the capacitor CHPF112 is connected, preferably connected, to the node N101, and a second terminal of the capacitor CHPF111 is connected, preferably connected, to the node N102.

[0049] According to one example, the capacitor CHPF113 and the coil LHPF111 are arranged in series between nodes N101 and GND100. More specifically, a first terminal of the capacitor CHPF113 is connected, preferably connected, to node N101, and a second terminal of the capacitor CHPF113 is connected, preferably connected, to a first terminal of the coil LHPF111. A second terminal of the coil LHPF111 is connected, preferably connected, to node GND100.

[0050] The HPF110 filter described herein is a first-order high-pass filter. According to one variant of In practice, the HPF110 filter could be a higher order high-pass filter.

[0051] According to one embodiment, the circuit further comprises a bandpass filter BPF100 including an input node connected, preferably connected, to the output node N102 of the high-pass filter HPF110, and an output node N103. In one example, the filter BPF110 comprises four acoustic resonators AWR101, AWR102, AWR103, and AWR104, and four inductors LBPF101, LBPF102, LBPF103, and LBPF104. Here, an acoustic resonator is defined as a mechanical and electronic component using, for example, a piezoelectric material that resonates between two conductive plates, such as metal plates.

[0052] According to one embodiment, the resonators AWR101 and AWR102 are arranged in series between the nodes N102 and N103. More particularly, a first terminal of the resonator AWR101 is connected, preferably connected, to the node N102, and a second terminal of the resonator AWR101 is connected, preferably connected, to a node N104. A first terminal of the resonator AWR102 is connected, preferably connected, to the node N104, and a second terminal of the resonator AWR102 is connected, preferably connected, to the node N103.

[0053] According to one embodiment, each AWR101, AWR102 resonator can be replaced by a series arrangement of at least two acoustic resonators. This can have the advantage of increasing the surface area of ​​the acoustic resonators while maintaining the total capacitance of the circuit, thus simplifying manufacturing and improving power handling.

[0054] According to one embodiment, the coils LBPF101 and LBPF102 are arranged in series between nodes N102 and N104. In other words, the coils LBPF101 and LBPF102 are arranged in series with each other and in parallel with the acoustic resonator AWR101. More specifically, a first terminal of the coil LBPF101 is connected, preferably connected, to node N102, and a second terminal of the coil LBPF101 is connected, preferably connected, to node N105. A first terminal of the coil LBPF102 is connected, preferably connected, to node N105, and a second terminal of the coil LBPF102 is connected, preferably connected, to node N104.

[0055] According to one embodiment, the coils LBPF103 and LBPF104 are arranged in series between nodes N104 and N103. In other words, the coils LBPF103 and LBPF104 are arranged in series with each other and in parallel with the acoustic resonator AWR102. More specifically, a first terminal of the coil LBPF103 is connected, preferably connected, to node N104, and a second terminal of the coil LBPF103 is connected, preferably connected, to node N106. A first terminal of the coil LBPF104 is connected, preferably connected, to node N106, and a second terminal of the coil LBPF104 is connected, preferably connected, to node N103.

[0056] According to one embodiment, the AWR103 resonator connects the N105 node to the reference node GND100. In other words, a first terminal of the AWR103 resonator is connected, preferably connected, to the N105 node, and a second terminal of the AWR103 resonator is connected, preferably connected, to the GND100 node.

[0057] According to one embodiment, the AWR104 resonator connects the N106 node to the reference node GND100. In other words, a first terminal of the AWR104 resonator is connected, preferably connected, to the N106 node, and a second terminal of the AWR104 resonator is connected, preferably connected, to the GND100 node.

[0058] According to one embodiment, each AWR103, AWR104 resonator can be replaced by a series arrangement of at least two acoustic resonators. This can have the advantage of increasing the surface area of ​​the acoustic resonators while maintaining the total capacitance of the circuit, thus simplifying manufacturing and improving power handling.

[0059] According to one embodiment, the circuit further comprises a second high-pass filter HPF120 including an input node connected, preferably connected, to the output node N103 of the band-pass filter BPF100, and an output node connected, preferably connected, to the output node OUT100. According to one example, the HPF120 filter includes three capacitors CHPF121, CHPF122 and CHPF123, and an inductor LHPF121.

[0060] According to one example, the capacitors CHPF121 and CHPF122 are arranged in series between nodes N103 and OUT100. More specifically, a first terminal of the Capacitor CHPF121 is connected, preferably connected, to node N103, and a second terminal of capacitor CHPF121 is connected, preferably connected, to node N107. A first terminal of capacitor CHPF122 is connected, preferably connected, to node N107, and a second terminal of capacitor CHPF122 is connected, preferably connected, to node OUT100.

[0061] According to one example, the capacitor CHPF123 and the coil LHPF121 are arranged in series between nodes N107 and GND100. More specifically, a first terminal of the capacitor CHPF123 is connected, preferably connected, to node N107, and a second terminal of the capacitor CHPF123 is connected, preferably connected, to a first terminal of the coil LHPF121. A second terminal of the coil LHPF121 is connected, preferably connected, to node GND100.

[0062] The HPF120 filter described here is a first-order high-pass filter. According to an alternative embodiment, the HPF120 filter could be a higher-order high-pass filter.

[0063] According to a practical example of the invention, the components of the filter circuit 100 can have the following numerical values. It should be noted that other values ​​can be imagined and their determination is within the capabilities of a person skilled in the art.

[0064] In the HPF110 high-pass filter: - the CHPF1 capacitor links a capacitance between 0.1 and 5 pF, for example on the order of 0.53 pF; - the CHPF112 capacitor has a capacitance between 0.1 and 5 pF, for example on the order of 0.61 pF; - the CHPF113 capacitor has a capacitance between 0.1 and 5 pF, for example on the order of 1.53 pF; and - the LHPF1 coil links an inductance between 0.1 and 5 nH, for example on the order of 1.51 nH.

[0065] In the BPF100 bandpass filter: - the LHPF101 coil has an inductance between 0.1 and 5 nH, for example on the order of 1.61 nH; - the LHPF102 coil has an inductance between 0.1 and 5 nH, for example on the order of 1 nH; - the LHPF103 coil has an inductance between 0.1 and 5 nH, for example on the order of 1.4 nH; - the LHPF104 coil has an inductance between 0.1 and 5 nH, for example on the order of 0.93 nH; - the AWR101 acoustic resonator has a capacitance between 0.1 and 5 pF, for example on the order of 0.524 pF, has a resonance frequency between 5 and 10 GHz, for example on the order of 6.51 GHz, and has an anti-resonance frequency between 5 and 10 GHz, for example on the order of 7.02 GHz; - the AWR102 acoustic resonator has a capacitance between 0.1 and 5 pF, for example on the order of 0.314 pF, has a resonance frequency between 5 and 10 GHz, for example on the order of 6.46 GHz, and has an anti-resonance frequency between 5 and 10 GHz, for example on the order of 6.98 GHz; - the AWR103 acoustic resonator has a capacitance between 0.1 and 5 pF, for example on the order of 0.206 pF, a resonant frequency between 5 and 10 GHz, for example on the order of 6.09 GHz, and an anti-resonant frequency between 5 and 10 GHz, for example on the order of 6.57 GHz; and - The AWR104 acoustic resonator has a capacitance between 0.1 and 5 pF, for example on the order of 0.200 pF, has a resonance frequency between 5 and 10 GHz, for example on the order of 6.10 GHz, and has an anti-resonance frequency between 5 and 10 GHz, for example on the order of 6.57 GHz.

[0066] In the HPF120 high-pass filter: - the CHPF121 capacitor has a capacitance between 0.1 and 5 pF, for example on the order of 1.86 pF; - the CHPF122 capacitor has a capacitance between 0.1 and 5 pF, for example on the order of 1.75 pF; - the CHPF123 capacitor has a capacitance between 0.1 and 5 pF, for example on the order of 1 pF; and - the LHPF121 coil has an inductance between 0.1 and 5 nH, for example on the order of 1.76 nH.

[0067] The operation of the bandpass filtering circuit 100 is described in detail with reference to Figures 2 and 3.

[0068] A method for filtering a periodic signal, such as a radio frequency signal, using a filtering circuit of the type of filtering circuit 100 described here is also covered by this description.

[0069] Furthermore, the 100 bandpass filtering circuit can be used within an information and / or data transmission chain. A method for transmitting information and / or data using such a transmission chain is covered by this description.

[0070] [Fig.2] includes three graphs (A), (B) and (C) illustrating the operation of the three filters included in the filtering circuit 100 described in relation to [Fig.1].

[0071] In particular, graph (A) illustrates the operation of the HPF110 high-pass filter. Graph (B) illustrates the operation of the BPF100 band-pass filter. Graph (C) illustrates the operation of the HPF120 high-pass filter.

[0072] Each of the graphs (A), (B) and (C) includes two curves illustrating the performance in terms of matching and attenuation of the filter as a function of the frequency of the signal received by the filter. More specifically, a first curve The first curve represents the filter's matching, that is, the ratio of reflected power to incident power in decibels, also called Retum Loss. A second curve represents the filter's attenuation, that is, the relative decrease in the power of a signal being transmitted, which can be expressed as the ratio between the power of the input signal and that of the output signal (ratio measured in decibels).

[0073] In particular, graph (A) includes a curve 201 illustrating the matching of the HPF110 high-pass filter, and a curve 202 illustrating the attenuation of the HPF110 high-pass filter. For this simulation, an input signal applied at node IN100 and an output signal supplied by node N102 are considered. Curves 201 and 202 show that the HPF110 filter rejects any signal with a frequency below 5 GHz, and exhibits low insertion loss for signals with a frequency above 5 GHz.

[0074] Graph (B) includes a curve 203 illustrating the attenuation of the BPF100 bandpass filter, and a curve 204 illustrating the matching of the BPF100 bandpass filter. For this simulation, an input signal applied at node N102 and an output signal supplied by node N103 are considered. Curves 203 and 204 show that the BPF100 filter allows any signal with a frequency between approximately 6 GHz and 7.5 GHz to pass through, and exhibits attenuation for signals with a frequency between approximately 3 GHz and 6 GHz and above 7 GHz.

[0075] Graph (C) includes a curve 205 illustrating the attenuation of the HPF120 high-pass filter, and a curve 206 illustrating the matching of the HPF120 high-pass filter. For this simulation, an input signal applied at node N103 and an output signal provided by node OUT100 are considered. Curves 205 and 206 show that the HPF120 filter rejects any signal with a frequency below approximately 4 GHz, and exhibits low insertion loss for signals with a frequency above 4 GHz.

[0076] [Fig.3] is a graph illustrating the operation of the circuit 100 described in relation to [Fig.1].

[0077] In particular, the graph in [Fig.3] illustrates the operation of the filtering circuit 100, i.e. the association of the HPF110, BPF100 and HPF120 filters whose operation has been described previously.

[0078] Thus, like graphs (A), (B), and (C), the graph in [Fig. 3] comprises two curves illustrating the performance in terms of matching and attenuation of the filtering circuit as a function of the frequency of the signal received by the filter. More specifically, the first curve represents the matching of the filter, that is, the ratio of reflected power to incident power in decibels, also called Retum Loss. The second curve represents the attenuation of the filter, that is to say the relative decrease in the power of a signal being transmitted which can be expressed by the ratio between the power of the input signal and that of the output signal (ratio measured in decibels).

[0079] Thus, the graph in [Fig. 3] includes a curve 301 illustrating the attenuation of the bandpass filtering circuit 100, and a curve 302 illustrating the matching of the bandpass filtering circuit 100. To perform this simulation, an input signal applied at the IN 100 node and an output signal provided by the OUT 100 node are considered. Curves 301 and 302 show that the filtering circuit 100 rejects any signal having a frequency below 6 GHz and above approximately 7.2 GHz.

[0080] An advantage of the filtering circuit 100 of [Fig.1] is that it makes it possible to obtain an attenuation or rejection of less than -40 dB, on the order of -49 dB, for a signal having a frequency on the order of 5.895 GHz.

[0081] Fig. 4 represents an electrical diagram of a first embodiment of a 400 bandpass filtering circuit.

[0082] The bandpass filtering circuit 400 is similar to the bandpass filtering circuit 100 described in relation to [Fig. 1]. The elements common to circuits 100 and 400 are not described again in detail here. Only the differences between circuits 100 and 400 are highlighted.

[0083] The bandpass filtering circuit 400 comprises the same components as the bandpass filtering circuit 100, but also exhibits a symmetry in the characteristics of these components. More specifically, node N104 forms an axis of symmetry of the circuit 400.

[0084] In particular, the following components are identical in pairs: - the CHPF111 capacitor of the HPF110 filter and the CHPF122 capacitor of the HPF120 filter; - the CHPF112 capacitor of the HPF110 filter and the CHPF121 capacitor of the HPF120 filter; - the CHPF113 capacitor of the HPF110 filter and the CHPF123 capacitor of the HPF120 filter; - the LHPF111 coil of the HPF110 filter and the LHPF121 coil of the HPF120 filter; - the AWR101 and AWR102 resonators of the BPF100 filter; - the LBPF101 and LBPF104 coils of the BPF100 filter; - the LBPF102 and LBPF103 coils of the BPF100 filter; and - the AWR103 and AWR104 resonators of the BPF100 filter.

[0085] According to a practical example of the invention, the components of the filter circuit 400 can have the following numerical values. It should be noted that other values ​​can be imagined and their determination is within the capabilities of a person skilled in the art.

[0086] In the HPF410 high-pass filter: - the CHPF1 capacitor links a capacitance between 0.1 and 5 pF, for example on the order of 0.86 pF; - the CHPF112 capacitor has a capacitance between 0.1 and 5 pF, for example on the order of 0.93 pF; - the CHPF113 capacitor has a capacitance between 0.1 and 5 pF, for example, on the order of 0.84 pF; and - the coil LHPF1 links an inductance between 0.1 and 5 nH, for example on the order of 1.57 nH.

[0087] In the BPF400 bandpass filter: - the LHPF101 coil has an inductance between 0.1 and 5 nH, for example on the order of 0.74 nH; - the LHPF102 coil has an inductance between 0.1 and 5 nH, for example on the order of 0.74 nH; - the LHPF103 coil has an inductance between 0.1 and 5 nH, for example on the order of 0.51 nH; - the LHPF104 coil has an inductance between 0.1 and 5 nH, for example on the order of 0.51 nH; - the AWR101 acoustic resonator has a capacitance between 0.1 and 5 pF, for example on the order of 0.587 pF, has a resonance frequency between 5 and 10 GHz, for example on the order of 6.51 GHz, and has an anti-resonance frequency between 5 and 10 GHz, for example on the order of 7.03 GHz; - the AWR102 acoustic resonator has a capacitance between 0.1 and 5 pF, for example on the order of 0.587 pF, has a resonance frequency between 5 and 10 GHz, for example on the order of 6.51 GHz, and has an anti-resonance frequency between 5 and 10 GHz, for example on the order of 7.03 GHz; - the AWR103 acoustic resonator has a capacitance between 0.1 and 5 pF, for example on the order of 0.264 pF, has a resonance frequency between 5 and 10 GHz, for example on the order of 6.01 GHz, and has an anti-resonance frequency between 5 and 10 GHz, for example on the order of 6.51 GHz; - the AWR104 acoustic resonator has a capacitance between 0.1 and 5 pF, for example on the order of 0.264 pF, has a resonance frequency between 5 and 10 GHz, for example on the order of 6.01 GHz, and has an anti-resonance frequency between 5 and 10 GHz, for example on the order of 6.51 GHz;

[0088] In the HPF420 high-pass filter: - the CHPF121 capacitor has a capacitance between 0.1 and 5 pF, for example on the order of 0.86 pF; - the CHPF122 capacitor has a capacitance between 0.1 and 5 pF, for example on the order of 0.93 pF; - the CHPF123 capacitor has a capacitance between 0.1 and 5 pF, for example, on the order of 0.84 pF; and - the LHPF121 coil has an inductance between 0.1 and 5 nH, for example on the order of 1.57 nH.

[0089] Fig. 5 includes three graphs (A), (B) and (C) illustrating the operation of the three filters included in the filtering circuit 400 described in relation to Fig. 4.

[0090] In particular, graph (A) illustrates the operation of the HPF410 high-pass filter. Graph (B) illustrates the operation of the BPF400 band-pass filter. Graph (C) illustrates the operation of the HPF420 high-pass filter.

[0091] As described in relation to [Fig. 2], each of the graphs (A), (B), and (C) in [Fig. 4] comprises two curves illustrating the filter's matching and attenuation performance as a function of the frequency of the signal received by the filter. More specifically, the first curve represents the filter's matching, that is, the ratio of reflected power to incident power in decibels, also known as Retum Loss. The second curve represents the filter's attenuation, that is, the relative decrease in the power of a transmitted signal, which can be expressed as the ratio between the input signal power and the output signal power (ratio measured in decibels).

[0092] In particular, graph (A) includes a curve 501 illustrating the matching of the HPF410 high-pass filter, and a curve 502 illustrating the attenuation of the HPF410 high-pass filter. For this simulation, an input signal applied at node IN100 and an output signal supplied by node N102 are considered. Curves 501 and 502 show that the HPF410 filter rejects any signal with a frequency below 5 GHz, and exhibits low insertion loss for signals with a frequency above 5 GHz.

[0093] Graph (B) includes a curve 503 illustrating the attenuation of the BPF400 bandpass filter, and a curve 504 illustrating the matching of the BPF400 bandpass filter. For this simulation, an input signal applied at node N102 and an output signal supplied by node N103 are considered. Curves 503 and 504 show that the HPF400 filter allows any signal with a frequency below 4.5 GHz and between approximately 6 GHz and 7.5 GHz to pass through, and exhibits attenuation or rejection for signals with a frequency between approximately 4.5 GHz and 6 GHz and above 8 GHz.

[0094] Graph (C) includes a curve 505 illustrating the attenuation of the HPF420 high-pass filter, and a curve 506 illustrating the matching of the HPF420 high-pass filter. For this simulation, an input signal applied at node N103 and an output signal supplied by node OUT100 are considered. Curves 505 and 506 show that the HPF420 filter rejects any signal with a frequency lower than at approximately 5 GHz, and exhibits low insertion loss for signals with a frequency above 5 GHz.

[0095] Fig. 6 is a graph illustrating the operation of the circuit 400 described in relation to Fig. 4.

[0096] In particular, the graph in [Fig.6] illustrates the operation of the filtering circuit 400, i.e. the association of the HPF410, BPF400 and HPF420 filters whose operation has been described previously.

[0097] Thus, like graphs (A), (B), and (C), the graph in [Fig. 5] comprises two curves illustrating the performance in terms of matching and attenuation of the filtering circuit as a function of the frequency of the signal received by the filter. More specifically, the first curve represents the matching of the filter, that is, the ratio of reflected power to incident power in decibels, also called Retum Loss. The second curve represents the attenuation of the filter, that is, the relative decrease in the power of a signal being transmitted, which can be expressed as the ratio between the power of the input signal and that of the output signal (ratio measured in decibels).

[0098] Thus, the graph in [Fig. 6] includes a curve 601 illustrating the attenuation of the bandpass filtering circuit 400, and a curve 602 illustrating the matching of the bandpass filtering circuit 400. To perform this simulation, an input signal applied at the IN 100 node and an output signal provided by the OUT100 node are considered. Curves 601 and 602 show that the filtering circuit 400 rejects any signal having a frequency below 6 GHz and above approximately 8 GHz.

[0099] An advantage of the filtering circuit 100 of [Fig.1] is that it makes it possible to obtain a rejection gain of less than -40 dB, on the order of -38 dB, for a frequency on the order of 5.895 GHz.

[0100] Fig. 7 is a top view illustrating a practical implementation of a 700 circuit of the type of the 100 and 400 bandpass filtering circuits described in relation to Figures 1 and 4.

[0101] Fig. 7 shows the position of the different components of the 100 and 400 bandpass filtering circuits, and more particularly the positioning of the HPF110 high-pass filter, the BPF100 bandpass filter and the HPF120 high-pass filter.

[0102] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0103] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. Bandpass filtering circuit (100; 400) comprising, in series, a first high-pass filter (HPF110; HPF410), a bandpass filter (BPF100; BPF400) and a second high-pass filter (HPF120; HPF420), in which the bandpass filter (BPF100; BPF400) comprises: - a first acoustic resonator (AWR101) and a second acoustic resonator (AWR102) arranged in series between a first node (N 102) and a second node (N 103); - at least two first coils (LBPF101, LBF102) arranged in series with each other, and arranged in parallel with said first acoustic resonator (AWR101); - at least two second coils (LBPF103, LBF104) arranged in series with each other, and arranged in parallel with said second acoustic resonator (AWR102); - at least one third acoustic resonator (AWR103) arranged between a third node (N105) midway between said first coils (LBPF101, LBF102) and a fourth reference node (GND100);and - at least one fourth acoustic resonator (AWR104) disposed between a fifth node (N106) midway between said second coils (LBPF103, LBF104) and said fourth reference node (GND100).;

2. A method for filtering a radio frequency signal using a bandpass filtering circuit (100; 400) comprising, in series, a first high-pass filter (HPF110; HPF410), a bandpass filter (BPF100; BPF400) and a second high-pass filter (HPF120; HPF420), in which the bandpass filter (BPF100; BPF400) comprises: - a first acoustic resonator (AWR101) and a second acoustic resonator (AWR102) arranged in series between a first node (N 102) and a second node (N 103); - at least two first coils (LBPF101, LBF102) arranged in series with each other, and arranged in parallel with said first acoustic resonator (AWR101); - at least two second coils (LBPF103, LBF104) arranged in series with each other, and arranged in parallel with said second acoustic resonator (AWR102); - at least one third acoustic resonator (AWR103) arranged between a third node (N105) midway between said first coils (LBPF101, LBF102) and a fourth reference node (GND100); and - at least one fourth acoustic resonator (AWR104) arranged between a fifth node (N106) midway between said second coils (LBPF103, LBF104) and said fourth reference node (GND100).

3. Circuit according to claim 1, or method according to claim 2, wherein the first and second acoustic resonators (AWR101, AWR102) are identical, wherein the first coils (LBPF101, LBF102) are identical to the second coils (LBPF103, LBF104), and the third and fourth acoustic resonators (AWR103, AWR104) are identical.

4. Circuit according to claim 1 or 3, or method according to claim 2 or 3, wherein the first acoustic resonator (AWR101) may comprise at least two fifth acoustic resonators arranged in series.

5. Circuit according to any one of claims 1, 3 or 4, or method according to any one of claims 2 to 4, wherein the second acoustic resonator (AWR102) may comprise at least two sixth acoustic resonators arranged in series.

6. Circuit according to any one of claims 1, 3 to 5, or method according to any one of claims 2 to 5, wherein the first high-pass filter (HPF110; HPF410) comprises: - two first capacitors (CHPF111, CHPF112) arranged in series between a sixth node (IN 100) and said first node (N 102); and - a second capacitor (CHPF113) and a third coil (LHPF111) arranged in series between a seventh node (N101) midway between said first capacitors (CHPF111, CHPF112) and said fourth reference node (GND100).

7. Circuit according to any one of claims 1, 3 to 6, or method according to any one of claims 2 to 6, wherein the second high-pass filter (HPF120; HPF420) comprises: - two third capacitors (CHPF121, CHPF122) arranged in series between said second node (N103) and an eighth node (OUT100); and - a fourth capacitor (CHPF123) and a fourth inductor (LHPF121) arranged in series between a ninth node (N107) midway between said second capacitors (CHPF121, CHPF122) and said fourth reference node (GND100).

8. Circuit according to any one of claims 1, 3 to 7, or method according to any one of claims 2 to 7, wherein the first and second high-pass filter (HPF110; HPF410) are symmetric with respect to said band-pass filter (BPF100; BPF400).

9. Circuit according to any one of claims 1, 3 to 8, or method according to any one of claims 2 to 8, wherein said filtering circuit further comprises a fifth coil arranged in series between said sixth node (IN100) and said fourth reference node (GND100).

10. Circuit according to any one of claims 1, 3 to 9, or method according to any one of claims 2 to 9, wherein said filtering circuit further comprises a sixth coil arranged in series between said seventh node (OUT100) and said fourth reference node (GND100).

11. Transmission chain comprising a filtering circuit according to any one of claims 1, 3 to 10.

12. Method of transmitting a signal using the filtering method according to any one of claims 2 to 10.

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