An ultrawideband complex function filter based on lumped-distributed hybrid circuits

Abstract

This invention discloses an ultra-wideband complex function filter based on a lumped-distributed hybrid circuit, comprising: an ultra-wideband bandpass filter body, a cascaded low-pass filter, an input port, and an output port; the ultra-wideband bandpass filter body and the cascaded low-pass filter are cascaded together; the input port is connected to the ultra-wideband bandpass filter body; and the output port is connected to the cascaded low-pass filter. This invention can achieve an ultra-wideband response with high selectivity, high out-of-band rejection, and a wide stopband. Compared to filters of the same order, the use of a lumped-distributed hybrid circuit significantly reduces the filter size, making the structure simpler and more compact, while also pushing back higher harmonics.

Description

Technical Field

[0001] This invention relates to the field of filter technology, and in particular to an ultra-wideband complex function filter based on a lumped-distributed hybrid circuit. Background Technology

[0002] Ultra-wideband (UWB) systems are widely used in military radar and wireless communications due to their advantages such as strong anti-interference capability, high transmission speed, and large system capacity. Wideband filters, as key components in wideband systems, have always been a research hotspot. With the increasing integration of systems, filters not only need to be miniaturized in size but also need to simultaneously achieve wide bandwidth, low loss, and high selectivity. This often requires wideband filters to have higher orders and the ability to arbitrarily specify the number and location of transmission zeros—that is, to achieve a complex response function, which is particularly difficult for planar UWB filters.

[0003] Existing ultra-wideband filter designs struggle to arbitrarily specify the number and location of transmission zeros, especially in planar circuits. Existing literature describes methods for implementing broadband filters, including optimal short-circuit stub filters, high-pass / low-pass (band-pass / band-stop) cascades, and multimode resonators. To introduce zeros, optimal short-circuit stub filters introduce cross-coupling at the input and output ports, but the number and location of the introduced transmission zeros are limited. Multimode resonator-based broadband filters achieve broadband response by rationally controlling the distribution of multiple modes in the passband. However, the resonator structure is simple, harmonics are interconnected, making precise bandwidth control difficult and limiting the flexibility in controlling the number and location of zeros.

[0004] In addition, when the passband frequency of a bandpass filter is lower than the S-band, the resulting capacitance or inductance values ​​are often very large and difficult to achieve. Traditional high- and low-impedance line designs cannot achieve high capacitance or inductance values. Furthermore, the larger the filter bandwidth, the stronger the coupling between resonators, making planar structures difficult to implement. Often, multi-layer fabrication processes, such as LTCC technology and multi-layer LCP technology, are required to achieve strong coupling, resulting in high manufacturing costs and precision requirements.

[0005] Compared to the circuit implementations mentioned above, mixed-lumped / distributed element circuits (MLDs) offer many unique advantages and are widely used for miniaturization and harmonic suppression. However, in high-frequency and broadband applications, the presence of parasitic effects such as distributed effects, higher-order modes, edge effects, and discontinuities leads to complex equivalent circuits in the actual physical structure. This results in filter responses that deviate significantly from the ideal response, requiring substantial time and effort for optimization. This greatly limits the application of mixed-lumped / distributed element circuits.

[0006] Existing methods for implementing ultra-wideband filters include: optimal short-circuit stub filters, high-pass and low-pass (band-pass and band-stop) cascades, and multimode resonators.

[0007] Optimal short-circuit stub filter: The connecting lines between short-circuit stubs act as frequency-selective elements, thus exhibiting very steep sideband characteristics. However, the connecting lines have no redundancy. Cross-coupling can also be introduced at the input and output ports, introducing transmission zeros to further improve selectivity and stopband rejection. However, the number of transmission zeros is limited.

[0008] High-pass / low-pass / band-pass and band-stop cascading: This method allows for flexible implementation of ultra-wide bandwidth and wide stopband suppression, and the cascaded filters can be designed independently. However, this circuit configuration is large in size and has high insertion loss. Furthermore, the impedance matching issue needs to be considered after the low-pass and high-pass filters are cascaded, often requiring further optimization, which is time-consuming and labor-intensive.

[0009] Multimode resonators can be divided into degenerate multimode resonators and higher-order multimode resonators. By utilizing multiple resonant modes of a single resonant structure and distributing these modes reasonably within the passband, a broadband response can be achieved. They are easily miniaturized, but due to their simple structure, the harmonics are interconnected, making it difficult to simultaneously and flexibly control both the passband and stopband responses, and hindering precise bandwidth control and the achievement of complex function responses.

[0010] To improve the performance of broadband filters, fabrication processes that implement multi-layer topologies are often employed, such as multi-layer LCP technology and LTCC, to achieve strong coupling that is difficult to achieve with planar structures. This requires sophisticated fabrication processes and is therefore costly. Summary of the Invention

[0011] To address the technical problems of existing planar ultra-wideband filters, such as limited number and location of transmission zeros, large size, high requirements for manufacturing processes, and long design cycles, this invention provides an ultra-wideband complex function filter based on lumped-distributed hybrid circuits to solve the above-mentioned technical problems.

[0012] This invention discloses an ultra-wideband complex function filter based on a lumped-distributed hybrid circuit, which includes: an ultra-wideband bandpass filter body, a cascaded low-pass filter, an input port, and an output port;

[0013] The ultra-wideband bandpass filter body is cascaded with the cascaded low-pass filter; the input port is connected to the ultra-wideband bandpass filter body; and the output port is connected to the cascaded low-pass filter.

[0014] Furthermore, the ultra-wideband bandpass filter body, the cascaded low-pass filter, the input port, and the output port are all disposed on the dielectric substrate.

[0015] Furthermore, it also includes grounding holes and mounting holes;

[0016] The fixing holes are symmetrically and evenly distributed on both sides of the ultra-wideband complex function filter;

[0017] The grounding via is a metallized via, and the upper metal layer of the ultra-wideband complex function filter is connected to the back grounding metal layer, which are uniformly distributed on the dielectric substrate.

[0018] Furthermore, the input port and the output port are respectively connected to coaxial ports.

[0019] Furthermore, the main body of the ultra-wideband bandpass filter is composed of a series resonator, a stepped impedance resonator stub, an inductor stub containing a chip inductor, a resonator stub containing a chip inductor, and a resonator stub containing a chip inductor and a chip capacitor.

[0020] The series resonators are cascaded sequentially along the long side of the ultra-wideband complex function filter;

[0021] The stepped impedance resonator stub, the inductor stub containing a surface mount inductor, the resonator stub containing a surface mount inductor, and the resonator stub containing a surface mount inductor and a surface mount capacitor are connected in parallel with the series resonator and are located on both sides of the cascaded series resonator.

[0022] Furthermore, the series resonator includes a first microstrip high-impedance line, a first pad, and a first surface-mount capacitor; the first microstrip high-impedance line is symmetrically arranged on both sides of the first pad, and the first surface-mount capacitor is disposed on the first pad;

[0023] The inductor stub containing the surface mount inductor is composed of a second microstrip high-impedance line, a second pad, a first surface mount inductor, and a first ground via; wherein, the second microstrip high-impedance line is connected to the first surface mount inductor through the second pad, and the first ground via is used to ground the inductor stub containing the surface mount inductor.

[0024] Furthermore, the resonator stub containing the surface mount inductor is composed of a third microstrip high-impedance line, a third pad, a second surface mount capacitor, and an open-circuit microstrip low-impedance line; wherein, the third microstrip high-impedance line is connected to the second surface mount capacitor through the third pad, and the second surface mount capacitor is connected to the open-circuit microstrip low-impedance line.

[0025] Furthermore, the resonator stub containing the surface mount inductor and surface mount capacitor includes a fourth microstrip high impedance line, a second surface mount inductor, a third surface mount capacitor, a second ground via, and a fourth pad.

[0026] The fourth microstrip high-impedance line is connected to the second surface mount inductor via a pad; the second surface mount inductor is connected to the third surface mount capacitor via the fourth pad; the second ground via is used for grounding the resonator stub containing the surface mount inductor and the surface mount capacitor.

[0027] Furthermore, the stepped impedance resonator stub is composed of a fifth microstrip high impedance line and an open-circuit microstrip low impedance line connected to the fifth microstrip high impedance line.

[0028] Furthermore, the cascaded low-pass filter includes multiple segments of a sixth microstrip high-impedance line and multiple stepped impedance resonator stubs connected in parallel with the sixth microstrip high-impedance line;

[0029] The stepped impedance resonator stubs are used to achieve transmission zeros, suppress higher harmonics, and improve far-band suppression.

[0030] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0031] 1. A novel ultrawideband complex function filter circuit structure layout based on lumped-distributed hybrid circuit is presented, which can achieve high selectivity, high out-of-band rejection, and wide stopband broadband response. Compared with filters of the same order, the lumped-distributed hybrid circuit form greatly reduces the filter size, making the structure simpler and more compact, while also pushing away higher harmonics.

[0032] 2. A series of series resonators and series resonator stub modules based on lumped-distributed hybrid circuits are presented, realizing large capacitance and inductance in planar circuits with miniaturization. Simultaneously, a reserved length of high-impedance line can be used to control the zero-point position, giving the resonator stubs a certain degree of flexibility.

[0033] 3. Based on the resonator stub module described above, a modular filter implementation method can be used to decompose the filter into modules such as series resonators and parallel resonators, and parallel inductors. This allows for accurate broadband approximations of each module, enabling the rapid achievement of good initial values ​​for broadband bandpass filters and effectively shortening the design cycle. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0035] Figure 1 This is a schematic diagram of the overall structure of an ultrawideband complex function filter based on a lumped-distributed hybrid circuit according to an embodiment of the present invention.

[0036] Figure 2 This is a top view schematic diagram of an ultrawideband complex function filter based on a lumped-distributed hybrid circuit according to an embodiment of the present invention.

[0037] Figures 3(a) to 3(d) These are schematic diagrams of the structure of a series resonator, a series resonator, a resonator stub with a patch inductor, and a resonator stub with a patch inductor, respectively, according to embodiments of the present invention.

[0038] Figure 4 This is a schematic diagram of the main body of the ultra-wideband bandpass filter according to an embodiment of the present invention;

[0039] Figure 5 This is a simulation diagram of the S-parameters of the cascaded low-pass filter according to an embodiment of the present invention;

[0040] Figure 6 The image shows the S-parameter simulation diagram of the ultra-wideband complex function filter according to an embodiment of the present invention. Attached image description:

[0042] 1-Ultra-wideband bandpass filter body, 2-Cascaded low-pass filter, 3-Input port, 4-Output port, 5-Ground hole, 6-Fixing hole, 11-Series resonator, 111-First microstrip high-impedance line, 112-First pad, 113-First surface mount capacitor, 12-Stepped impedance resonator stub, 13-Inductor stub containing surface mount inductor, 131-Second microstrip high-impedance line, 132-Second pad, 133-The... 134 - First grounding via, 14 - Resonator stub containing the surface mount inductor, 141 - Third microstrip high impedance line, 142 - Third pad, 143 - Second surface mount capacitor, 144 - Open-circuit microstrip low impedance line, 15 - Resonator stub containing the surface mount capacitor, 151 - Fourth microstrip high impedance line, 152 - Pad, 153 - Second surface mount inductor, 154 - Third surface mount capacitor, 155 - Second grounding via. Detailed Implementation

[0043] The present invention will be further described in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.

[0044] See Figure 1 The present invention provides an embodiment of an ultra-wideband complex function filter based on a lumped-distributed hybrid circuit, which includes: an ultra-wideband bandpass filter body 1, a cascaded low-pass filter 2, an input port 3 and an output port 4;

[0045] The main body of the ultra-wideband bandpass filter 1 is cascaded with the cascaded low-pass filter 2; the input port is connected to the main body of the ultra-wideband bandpass filter; and the output port is connected to the cascaded low-pass filter.

[0046] In this embodiment, the ultra-wideband bandpass filter body 1, the cascaded low-pass filter 2, the input port 3, and the output port 4 are all disposed on the dielectric substrate.

[0047] In this embodiment, a grounding hole 5 and a fixing hole 6 are also included;

[0048] The fixed apertures are symmetrically and evenly distributed on both sides of the ultra-wideband complex function filter;

[0049] Grounding hole 5 is a metallized via. The upper metal layer of the ultra-wideband complex function filter is connected to the back grounding metal layer and is evenly distributed on the dielectric substrate.

[0050] In this embodiment, input port 3 and output port 4 are respectively connected to coaxial ports.

[0051] In this embodiment, the ultra-wideband bandpass filter body 1 is composed of a series resonator 11, a stepped impedance resonator stub 12, an inductor stub 13 containing a patch inductor, a resonator stub 14 containing a patch inductor, and a resonator stub 15 containing a patch inductor and a patch capacitor.

[0052] The series resonators 11 are cascaded sequentially along the long side of the ultra-wideband bandpass filter body 1;

[0053] Stepped impedance resonator stub 12, inductor stub 13 containing a chip inductor, resonator stub 14 containing a chip inductor, and resonator stub 15 containing a chip inductor and a chip capacitor are connected in parallel with series resonator 11 and are located on both sides of the cascaded series resonator 11.

[0054] In this embodiment, the series resonator 11 includes two symmetrical first microstrip high impedance lines 111, two first pads 112, and one first surface mount capacitor 113; the first microstrip high impedance lines 111 are symmetrically arranged on both sides of the first pads 112, and the first surface mount capacitor 113 is arranged on the first pads 112.

[0055] The inductor stub 13 containing the surface mount inductor is composed of a second microstrip high impedance line 131, a second pad 132, a first surface mount inductor 133, and a first ground via 134; wherein, the second microstrip high impedance line 131 is connected to the first surface mount inductor 133 through the second pad 132, and the first ground via 134 is used to ground the inductor stub 13 containing the surface mount inductor.

[0056] In this embodiment, the resonator stub 14 containing the surface mount inductor is composed of a third microstrip high impedance line 141, a third pad 142, a second surface mount capacitor 143, and an open-circuit microstrip low impedance line 144; wherein, the third microstrip high impedance line 141 is connected to the second surface mount capacitor 143 through the third pad 142, and the second surface mount capacitor 143 is connected to the open-circuit microstrip low impedance line 144.

[0057] In this embodiment, the resonator stub 15 containing a surface mount inductor and a surface mount capacitor includes a fourth microstrip high impedance line 151, a second surface mount inductor 153, a third surface mount capacitor 154, and a second ground via 155.

[0058] The fourth microstrip high-impedance line 151 is connected to the second surface mount inductor via a pad; the second surface mount inductor is connected to the third surface mount capacitor 154 via a pad 152; the second ground via is used to ground the resonator stub 15 containing the surface mount inductor and the surface mount capacitor.

[0059] In this embodiment, the stepped impedance resonator stub 12 is composed of a fifth microstrip high impedance line and an open-circuit microstrip low impedance line connected to the fifth microstrip high impedance line.

[0060] In this embodiment, the cascaded low-pass filter 2 includes multiple segments of the sixth microstrip high-impedance line and multiple stepped impedance resonator stubs 12 connected in parallel with the sixth microstrip high-impedance line.

[0061] Stepped impedance resonator stub 12 is used to achieve transmission zero, suppress higher harmonics, and improve far-band suppression.

[0062] For ease of understanding, the present invention provides a more specific embodiment:

[0063] Figure 1 This is a schematic diagram of the overall structure of the ultra-wideband bandpass filter according to Embodiment 1 of the present invention. The wideband bandpass filter adopts a microstrip structure, the dielectric substrate is Rogers 4003 (dielectric constant is 3.55), and the metal material is copper plating;

[0064] Figure 2 This is a top view of the broadband bandpass filter according to Embodiment 1 of the present invention. The broadband bandpass filter includes an ultra-wideband bandpass filter body 1, a cascaded low-pass filter 2, an input port 3 and an output port 4, a grounding hole 5, and a mounting hole 6.

[0065] The main body 1 of the ultra-wideband bandpass filter has one port connected to the output port 3, and another port cascaded with a cascaded low-pass filter 2. The other port of the cascaded low-pass filter 2 is connected to the output port 4, used to suppress higher harmonics and improve far-band suppression. Input port 3 and output port 4 are 50-ohm ports, connected to an external coaxial interface. Grounding hole 5 is a metallized via, with the upper metal layer of the microstrip connected to the back ground metal layer, uniformly distributed throughout the entire dielectric substrate, used to effectively improve filter grounding and suppress possible resonance caused by the dielectric substrate. Mounting hole 6 is a metallized via, uniformly distributed on both sides of the filter, used to fix the filter to the mounting position.

[0066] The main body 1 of the ultra-wideband bandpass filter consists of a lumped-distribution hybrid circuit series resonator 11, a stepped impedance resonator stub 12, an inductor stub 13 containing a surface-mount inductor, a resonator stub 14 containing a surface-mount inductor, and a resonator stub 15 containing both surface-mount inductors and surface-mount capacitors. In the main body 1 of the ultra-wideband bandpass filter, the lumped-distribution hybrid circuit series resonator 11 is cascaded sequentially along the y-axis. The stepped impedance resonator stub 12, the inductor stub 13 containing a surface-mount inductor, the resonator stub 14 containing a surface-mount inductor, and the resonator stub 15 containing both surface-mount inductors and surface-mount capacitors are connected in parallel with the lumped-distribution hybrid circuit series resonator 11, and arranged vertically along the x-axis with the series resonator 11 as the center. In Embodiment 1 of the present invention, the ultra-wideband bandpass filter body 1 is composed of a total of 9 lumped-distributed hybrid circuit series resonators 11, 3 stepped impedance resonator stubs 12, 3 inductor stubs 13 containing chip inductors, 1 resonator stub 14 containing chip inductors, and 1 resonator stub 15 containing chip inductors and chip capacitors.

[0067] One end of the cascaded low-pass filter 2 is cascaded with the main body of the ultra-wideband bandpass filter 1, and the other end is connected to the output port 4. The cascaded low-pass filter 2 includes 6 microstrip high-impedance lines and 5 centrally symmetrical stepped impedance resonator stubs 12. The stepped impedance resonator stubs 12 are used to achieve transmission zeros, suppress higher harmonics, and improve far-band suppression.

[0068] Figure 3 is a schematic diagram of a lumped-distributed hybrid circuit resonator, resonator stub, and inductor stub. In Figure 3(a), the lumped-distributed hybrid circuit series resonator 11 includes two symmetrical first microstrip high-impedance lines 111, two first pads 112, and one first surface-mount capacitor 113. In Figure 3(b), the inductor stub 13 with a surface-mount inductor consists of a second microstrip high-impedance line 131, two second pads 132, one first surface-mount inductor 133, and five first ground vias 134. In Figure 3(c), the resonator stub 14 with a surface-mount inductor consists of a third microstrip high-impedance line 141, a third pad 142, a second surface-mount capacitor 143, and an open-circuit microstrip low-impedance line 144. Figure 3(d) shows a resonator stub 15 containing surface-mount inductors and capacitors, comprising a fourth microstrip high-impedance line 151, three pads 152, a second surface-mount inductor 153, a third surface-mount capacitor 154, and a second ground via 155. The two pads between the second surface-mount inductor 153 and the third surface-mount capacitor 154 are cascaded into a single large pad. The stepped impedance resonator stub 12 consists of a fifth microstrip high-impedance line and an open-circuit microstrip low-impedance line. In Embodiment 1 of this invention, the surface-mount capacitors and inductors use a 0402 package, specifically the Murata GJM1555 and LQW15AN series, with pad dimensions meeting the 0402 component soldering standard.

[0069] Figure 4 This is a schematic diagram of the ultra-wideband bandpass filter body 1 in Embodiment 1 of the present invention, corresponding to the ultra-wideband bandpass filter body 1 described above. The schematic diagram consists of 9 series LC resonators, 5 parallel series LC resonators, and 3 parallel inductors. The transmission zeros of the 5 parallel resonators are 0.79GHz, 3.56GHz, 4.54GHz, 5.74GHz, and 7.41GHz, respectively.

[0070] Figure 5 This is a simulation diagram of the S-parameters of the cascaded low-pass filter 2 in Embodiment 1 of the present invention, where the horizontal axis represents the frequency range (GHz) and the vertical axis represents the S-parameter magnitude (dB). The S-parameters of the return loss and insertion loss in Embodiment 1 were simulated and calculated using the commercial simulation software HFSS_19.0. The cutoff frequency of the cascaded low-pass filter 2 is 6.5GHz, the return loss is greater than 20dB, and the out-of-band rejection ratio (OSB) in the 8-12GHz range is greater than 60dB. This effectively suppresses the high-order harmonics of the ultra-wideband bandpass filter body 1, achieving wide stopband characteristics for the entire filter.

[0071] Figure 6This is a simulation graph of the S-parameters of the ultra-wideband complex function filter in Embodiment 1 of the present invention. The horizontal axis represents the frequency range (GHz), and the vertical axis represents the magnitude of the S-parameters (dB). The S-parameters of the return loss and insertion loss of Embodiment 1 were simulated and calculated using the commercial simulation software HFSS_19.0. Figure 6 It can be seen that the passband range of the ultra-wideband complex function filter is 0.9 GHz to 3 GHz, with a relative bandwidth greater than 100%, while also exhibiting good passband selectivity, near-band rejection greater than 40 dB, and out-of-band rejection greater than 80 dB (S) within the 5 GHz to 12 GHz range. 21 The result (less than -80dB) indicates that the ultra-wideband bandpass filter in this invention has both high out-of-band rejection and wide stopband, achieving an ultra-wideband complex function response.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A lumped distributed hybrid circuit based ultra-wideband complex function filter, characterized by, The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter.

2. The lumped distributed hybrid circuit based ultra-wideband complex function filter according to claim 1, characterized in that, The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter.

3. The lumped-distributed hybrid circuit-based ultra-wideband complex function filter of claim 1, wherein, The application relates to an ultra-wideband complex function filter.

4. The lumped-distributed hybrid circuit-based ultra-wideband complex function filter of claim 1, wherein, The application relates to an ultra-wideband complex function filter.

5. The lumped-distributed hybrid circuit-based ultra-wideband complex function filter of claim 1, wherein, The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter.

6. The lumped-distributed hybrid circuit-based ultra-wideband complex function filter of claim 1, wherein, The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. 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The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband complex function filter. The application relates to an ultra-wideband

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