A radio-frequency switchable filter

Abstract

The invention relates to a filter bank (10) comprising an input point (11 ) configured to receive a radio-frequency signal that has been amplified by an amplifier and that includes harmonic components generated by said amplifier, and an output point (12) to which the radio-frequency signal with suppressed harmonic components is transmitted. Accordingly, the novelty of the invention resides in comprising a plurality of low-pass filters (13) configured to suppress harmonic components in the radio frequency signal; a first switching unit (14) configured to route the radio-frequency signal received from the input point (11) to at least one of the low-pass filters (13); and a second switching unit (15) configured to route the radio-frequency signal, whose harmonic components have been suppressed by the low-pass filter (13), to the output point (12).

Description

[0001] A RADIO-FREQUENCY SWITCHABLE FILTER

[0002] TECHNICAL FIELD

[0003] The invention relates to a filter bank configured to suppress harmonic components present in a radio-frequency signal that has been amplified by an amplifier and contains harmonic components generated by said amplifier.

[0004] PRIOR ART

[0005] In radio-frequency (RF) systems, the generation of unwanted harmonic components during the amplification and transmission of signals is an inevitable phenomenon. While amplifiers boost the input signal, they also produce harmonic components of the fundamental frequency due to their nonlinear behavior. These harmonic components may cause interference in other systems operating at the target frequency, lead to spectral pollution, and result in performance degradation, particularly in sensitive applications such as communication and radar systems.

[0006] Various filtering techniques have been developed to suppress harmonic components. In general, band-pass or low-pass filters are employed to eliminate signal components outside a designated frequency range. However, the use of a single fixed filter limits the system’s ability to operate at different frequencies and fails to provide the needed flexibility. This presents a significant constraint for applications that must operate over a wide frequency range, such as multi-band communication systems.

[0007] Switching circuits that enable the selection of filters operating at different frequencies may be employed for suppressing harmonic components. In existing techniques, switching elements are typically designed in a single-stage structure, where a switching mechanism routes the signal to a specific filter. However, such architectures suffer from several disadvantages, including insufficient isolation at high frequencies, additional signal losses, and increased noise levels — particularly in high-power applications. These issues, in turn, lead to higher cost, complex circuit structures, and increased power consumption.One of the most critical problems encountered is the inability to achieve adequate isolation. Insufficient isolation between filter circuits can cause unwanted signal leakage, thereby degrading harmonic suppression performance. This issue adversely affects overall system efficiency and immunity to interference, especially in high-frequency applications.

[0008] Accordingly, there is a need for a filtering system that can effectively suppress harmonic components generated by amplifiers, can be adapted to different frequencies, provides high isolation to prevent undesired signal leakage, operates with low power consumption, and delivers high efficiency.

[0009] In the existing art, patent document CN110622415A relates to an amplifier. In the referenced amplifier, the charge on a capacitor is actively controlled through a switching structure including a calibration switch and a reset switch, thereby improving measurement accuracy. However, patent document CN110622415A does not disclose any filtering structure incorporating a switching architecture that provides suppression of harmonic components at radio frequencies and high isolation performance.

[0010] In conclusion, all of the aforementioned issues have made it necessary to introduce an innovation in the relevant technical field.

[0011] BRIEF DESCRIPTION OF THE INVENTION

[0012] The present invention relates to a filter bank intended to eliminate the disadvantages mentioned above and to provide new advantages in the relevant technical field.

[0013] An objective of the invention is to provide a filter bank that enables an increased isolation level.

[0014] Another objective of the invention is to provide a filter bank configured to suppress harmonic components in radio-frequency signals.

[0015] In order to achieve all of the objectives mentioned above and those that will become apparent from the detailed description below, the present invention provides a filter bank comprising an input point configured to receive a radio-frequency signal that has been amplified by an amplifier and that includes harmonic components generated bysaid amplifier, and an output point to which the radio-frequency signal with suppressed harmonic components is transmitted.

[0016] Accordingly, the filter bank comprises a plurality of low-pass filters configured to suppress the harmonic components in the radio-frequency signal; a first switching unit configured to route the radio-frequency signal received from the input point to at least one of the low-pass filters; and a second switching unit configured to route the radiofrequency signal, in which the harmonic components have been suppressed by the low-pass filter, to the output point. Thus, high isolation and suppression of harmonic components are provided.

[0017] A feature of a possible embodiment of the invention is that the first switching unit comprises a switching circuit.

[0018] A feature of another possible embodiment of the invention is that the second switching unit comprises a switching circuit.

[0019] A further feature of a possible embodiment of the invention is that the switching circuit comprises a first switching element and a second switching element connected in series. Thus, improved isolation is achieved during signal routing, thereby making the filtering of undesired harmonic components more efficient.

[0020] A feature of another possible embodiment of the invention is that the first switching element and the second switching element are PIN diodes.

[0021] BRIEF DESCRIPTION OF THE DRAWING

[0022] Figure 1 illustrates a representative view of the filter bank.

[0023] Figure 2 illustrates another representative view of the filter bank.

[0024] Figure 3 illustrates a representative view of the switching circuit.

[0025] DETAILED DESCRIPTION OF THE INVENTIONIn the detailed description that follows, the subject matter of the invention is explained solely through examples intended to facilitate understanding and is not to be construed as limiting in any way.

[0026] With reference to Figure 1, the invention relates to a filter bank (10) configured to suppress harmonic components in a radio-frequency signal amplified by an amplifier, said radio-frequency signal including harmonic components generated by the amplifier. As is well known in the art, a filter bank comprises a plurality of filters used to analyze or process a signal across different frequency bands. In this manner, undesired harmonic components are removed from the radio-frequency signal, thereby providing a cleaner and more stable transmission.

[0027] The filter bank (10) comprises an input point (11) configured to receive the radiofrequency signal amplified by the amplifier and including harmonic components, and an output point (12) to which the radio-frequency signal with suppressed harmonic components is transmitted. Accordingly, the radio-frequency signal is received at the input point (11), purified by removing undesired harmonic components, and the cleaned signal is delivered via the output point (12).

[0028] With reference to Figure 2, the filter bank (10) comprises a plurality of low-pass filters (13) configured to suppress harmonic components in the radio-frequency signal containing such harmonic components. In a possible embodiment of the invention, the filter bank (10) comprises six low-pass filters (13). The low-pass filters (13), which may have different cutoff frequencies, can perform harmonic suppression over a wide frequency range. In this manner, harmonic components of radio-frequency signals in the 30-512 MHz range can be suppressed.

[0029] In a possible embodiment of the invention, the filter bank (10) comprises a housing (100) that protects the filter bank (10) from external effects. The housing (100) may include a filter board (200). The filter board (200) comprises the plurality of low-pass filters (13). By accommodating all of the low-pass filters (13) within a single integrated structure, the filter board (200) enables the filter bank (10) to be compact, orderly, and easy to manage.Furthermore, the filter bank provides a customizable architecture for different applications, thereby offering flexible solutions to harmonic-suppression requirements across various frequency ranges. In this manner, system flexibility is increased, allowing the filter bank to be readily adapted to different radio-frequency applications.

[0030] In a possible embodiment of the invention, the housing (100) may further comprise a control board (300) and a power board (400). The control board (300) manages the operating parameters of the filter bank (10) to provide effective harmonic suppression within selected frequency ranges. The power board (400) provides the electrical supply required for stable operation of the filter bank (10), thereby ensuring proper operation of the filters.

[0031] In a possible embodiment of the invention, the filter board (200), the control board (300), and the power board (400) may be fixed within the housing (100) by means of fasteners (500). The boards may each be implemented as a respective printed circuit board (PCB).

[0032] In a possible embodiment of the invention, the housing (100) comprises covers (600). In this manner, the internal structures are protected against dust, humidity, and mechanical impacts, thereby enabling long-term and reliable operation of the filter bank (10). Accordingly, the housing (100) both simplifies the assembly process — allowing rapid system installation — and facilitates maintenance and replacement operations, thereby improving operational efficiency.

[0033] The filter bank (10) comprises a first switching unit (14) configured to route the radiofrequency signal containing harmonic components, received from the input point (11), to at least one of the low-pass filters (13). The first switching unit (14) enables the input signal to be directed to a selected low-pass filter (13), thereby allowing appropriate filtering for different frequency components. This structure increases system flexibility and assists the system in adapting to different operating conditions. In this manner, harmonic components are effectively suppressed, making it possible to obtain the desired output signal.

[0034] The filter bank (10) comprises a second switching unit (15) configured to route the radio-frequency signal, whose harmonic components have been suppressed by thelow-pass filter (13), to the output point (12). The second switching unit (15) directs the filtered signal to the output point (12), thereby enabling transmission of a clean signal free from undesired components.

[0035] In a possible embodiment of the invention, the first switching unit (14) and the second switching unit (15) comprise a switching circuit (16). In another possible embodiment, the switching circuit (16) comprises a first switching element (161) and a second switching element (168), wherein the first switching element (161) and the second switching element (168) are connected in series.

[0036] By connecting the first switching element (161) and the second switching element (168) in series, the propagation of the radio-frequency signal along the designated path is controlled more precisely, and suppression of undesired harmonic components is performed effectively. Furthermore, the series connection increases the isolation within the circuit, minimizing coupling between different signal paths and thereby providing more stable signal transmission.

[0037] The switching elements may be PIN diodes. PIN diodes, when used as switching elements in an RF signal path, enable the routing of the signal within a specified frequency range. This structure allows the system to selectively activate a particular low-pass filter (13). By permitting the input signal to be directed to the selected low-pass filter (13) via the switching elements, the frequency selectivity of the system is increased. Thus, the most suitable filtering path can be selected for different frequency components, making suppression of undesired signals more effective.

[0038] By virtue of the switching elements, the isolation between the filter channels (131) is increased. In particular, interference and crosstalk effects that may occur between signal paths are reduced, thereby improving system performance. For example, by using two diodes connected in series, the inter-channel isolation (131) can be increased from 20 dB to 40 dB. In this way, signal leakage between different filtering paths is minimized, providing cleaner and more reliable signal transmission. Accordingly, higher-accuracy signal processing is achieved in radio-frequency applications, thereby enhancing the performance and stability of communication systems.With reference to Figure 3, the switching circuit (16) comprises at least one first Deblocking capacitor (162), the first switching element (161), at least one first RF choke inductor (164), a first control resistor (165), and at least one second RF choke inductor (167).

[0039] The first DC-blocking capacitor (162) blocks the DC components of the radio-frequency signal containing harmonic components received from the input point (11), thereby allowing only the AC components to be transmitted and contributing to accurate routing of the RF signal. The first switching element (161) controls the signal flow, enabling the selected filtering path to be activated. The first RF choke inductor (164) provides a high impedance at high frequencies. The first control resistor (165) stabilizes the operating conditions of the switching element by limiting current in the circuit, thereby supporting reliable and stable operation.

[0040] The first RF choke inductor (164) and the first control resistor (165) are disposed between a first DC control voltage node (163) and the anode terminal of the first switching element (161), thereby preventing the DC control voltage from coupling into the RF signal path. The second RF choke inductor is disposed between a second DC control voltage node (166) and the cathode terminal of the first switching element (161). The RF choke inductors provide high impedance at high frequencies, preventing undesired RF components from being shunted to ground and ensuring that the signal remains on the designated transmission line.

[0041] Furthermore, the switching circuit (16) comprises a second switching element (168), at least one third RF choke inductor (172), at least one fourth RF choke inductor (174), and a second DC-blocking capacitor (170). The second switching element (168) provides a selective switching mechanism by routing the signal to the output point (12).

[0042] The third RF choke inductor (172) and the second control resistor (169) are disposed between a third DC control voltage node (171) and the anode terminal of the second switching element (168), thereby preventing the DC control voltage from coupling into the RF signal path. The fourth RF choke inductor (174) is disposed between a fourth DC control voltage node (175) and the cathode terminal of the second switching element (168). The second DC-blocking capacitor (170) is disposed between the second switching element (168) and the output point (12).The control voltages cause the switching elements to be driven into conduction or cutoff, thereby determining the path through which the RF signal will pass. By changing the operating states of the switching elements, the control voltages enable the signal to be routed to a specific low-pass filter (13) or blocked as required.

[0043] The first switching element (161) and the second switching element (168) are connected to each other in series via at least one third DC-blocking capacitor (173) configured to provide DC isolation therebetween. The third DC-blocking capacitor (173) blocks direct-current components in the circuit and allows only alternating-current components (the RF signal) to pass, thereby ensuring DC isolation between the switching elements. Accordingly, both switching elements can be controlled independently and the signal-routing process can be managed more flexibly.

[0044] As a result, the switching elements operating under different control voltages are electrically isolated from one another, thereby preventing undesired DC offsets within the system. Thus, the signal-routing operation is made more stable and the reliability of the RF signal-processing process is improved.

[0045] In a possible embodiment of the invention, a ground-referenced capacitor (176) is used to stabilize the control voltages and to prevent the radio-frequency signal from being diverted to ground through undesired paths. The ground-referenced capacitor (176) maintains the stability of the DC control voltages, thereby preserving the proper operating conditions of the switching elements and reducing noise effects that may occur in the circuit.

[0046] In addition, it helps suppress high-frequency interference that may arise on the RF signal path by shunting such interference to the ground line, thereby increasing the system’s immunity to interference. In this manner, stability of the control voltages is ensured, circuit reliability is improved, and undesired losses during RF signal transmission are prevented.

[0047] The scope of protection of the invention is defined in the claims provided in the annex and cannot in any way be limited to the exemplary embodiments described in this detailed description. It is evident that a person skilled in the art may devise similarembodiments in light of the foregoing without departing from the essential concept of the invention.REFERENCE NUMERALS SHOWN IN THE DRAWINGS

[0048] 10 Filter bank

[0049] 11 Input point

[0050] 12 Output point

[0051] 13 Low-pass filter

[0052] 131 Channel

[0053] 14 First switching unit

[0054] 15 Second switching unit

[0055] 16 Switching circuit

[0056] 161 First switching element

[0057] 162 First DC-blocking capacitor

[0058] 163 First DC control voltage node

[0059] 164 First RF choke inductor

[0060] 165 First control resistor

[0061] 166 Second DC control voltage node

[0062] 167 Second RF choke inductor

[0063] 168 Second switching element

[0064] 169 Second control resistor

[0065] 170 Second DC-blocking capacitor

[0066] 171 Third DC control voltage node

[0067] 172 Third RF choke inductor

[0068] 173 Third DC-blocking capacitor

[0069] 174 Fourth RF choke inductor

[0070] 175 Fourth DC control voltage node

[0071] 176 Ground-referenced capacitor

[0072] 100 Housing

[0073] 200 Filter board

[0074] 300 Control board

[0075] 400 Power boardFasteners Cover

Claims

CLAIMS1. The invention is a filter bank (10) comprising an input point (11 ) configured to receive a radio-frequency signal that has been amplified by an amplifier and that includes harmonic components generated by said amplifier, and an output point (12) to which the radio-frequency signal with suppressed harmonic components is transmitted characterized in that it comprises a plurality of low-pass filters (13) configured to suppress harmonic components in the radio-frequency signal; a first switching unit (14) configured to route the radio-frequency signal received from the input point (11) to at least one of the low-pass filters (13); and a second switching unit (15) configured to route the radio-frequency signal, whose harmonic components have been suppressed by the low-pass filter (13), to the output point (12).

2. A filter bank (10) according to Claim 1 , characterized in that the first switching unit (14) comprises a switching circuit (16).

3. A filter bank (10) according to Claim 1, characterized in that the second switching unit (15) comprises a switching circuit (16).

4. A filter bank (10) according to Claims 2 and 3, characterized in that the switching circuit (16) comprises a first switching element (161) and a second switching element (168) connected in series.

5. A filter bank (10) according to Claim 4, characterized in that the first switching element (161) and the second switching element (168) are PIN diodes.

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