A low-pass filter with wide stopband IPD

Abstract

This invention relates to an IPD low-pass filter with a wide stopband, comprising inductors L1, L2, and L3. Inductor L1 is connected to the input terminal, and inductor L3 is connected to the output terminal. A grounding capacitor C1 is connected between inductors L1 and L2, a grounding capacitor C2 is connected between inductors L2 and L3, and a grounding capacitor C3 is connected between inductor L3 and the output terminal. This invention introduces a transmission zero through the mutual inductance between the two inductors on the main path, avoiding the increase in circuit complexity and losses caused by introducing more capacitors or inductors, and also avoiding the introduction of additional resonance near the passband. A pair of notch filter resonators is added at both the input and output terminals. The introduction of these notch filter resonators suppresses higher-frequency high-order modes, ultimately achieving a wide stopband.

Description

Technical Field

[0001] This utility model relates to the field of filters, and in particular to an IPD low-pass filter with a wide stopband. Background Technology

[0002] A low-pass filter is a device that allows low-frequency signals to pass through while attenuating or suppressing high-frequency signals. It plays a crucial role in communication systems, including suppressing high-frequency noise, optimizing bandwidth, and protecting sensitive components. Therefore, low-pass filters are an indispensable and essential component in communication system design, effectively ensuring system stability and reliability. With the development of communication technology, miniaturization of communication systems has become a significant trend. This requires filters to achieve miniaturization while also possessing high-performance characteristics such as low loss, high suppression levels, and wide stopband. IPD (Integrated Passive Device) filters, as a technology that integrates passive filters onto semiconductors, can achieve chip-scale filtering devices. Compared with traditional filters, IPD technology has two significant advantages: First, it builds filters using capacitors and inductors, overcoming the limitations of electrical length; second, thanks to the low loss and high Q-value characteristics of thin-film inductors and capacitors, IPD filters can maintain excellent performance while achieving miniaturization. Based on these advantages, IPD technology is very suitable for designing low-pass filters that combine miniaturization and high performance.

[0003] Currently, numerous low-pass filters based on IPD technology have been proposed, offering advantages such as chip-scale size, low loss, and high selectivity. However, to achieve high selectivity, these filters typically require quasi-elliptic response circuits, i.e., parallel capacitors across the inductor in the main path or parallel inductors across the capacitors in the branches, to introduce transmission zeros. While this design improves selectivity, it inevitably introduces the following problems: first, the circuit structure becomes more complex; second, it increases insertion loss; and finally, it introduces additional resonance, resulting in limited stopband width. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an IPD low-pass filter with a wide stopband, thus solving the deficiencies of the prior art.

[0005] The purpose of this utility model is achieved through the following technical solution: an IPD low-pass filter with a wide stopband, which includes inductors L1, L2 and L3, inductor L1 connected to the input terminal and inductor L3 connected to the output terminal; a grounding capacitor C1 is connected between inductors L1 and L2, a grounding capacitor C2 is connected between inductors L2 and L3, and a grounding capacitor C3 is connected between inductor L3 and the output terminal.

[0006] A pair of harmonic suppression resonators are added between the input terminal and inductor L1, and a pair of harmonic suppression resonators are added between the output terminal and inductor L3.

[0007] The harmonic suppression resonator is composed of an inductor L11 and a capacitor L1 connected in series, with the other end of the capacitor L1 grounded. Each harmonic suppression resonator is connected in parallel between the input terminal and the inductor L1 or between the output terminal and the inductor L3.

[0008] This invention offers the following advantages: An IPD low-pass filter with a wide stopband introduces a transmission zero through the mutual inductance between two inductors on the main path. This avoids increasing circuit complexity and introducing more losses by adding more capacitors or inductors, and also prevents the introduction of additional resonance near the passband. A pair of notch filter resonators is added at both the input and output terminals. The introduction of these notch filter resonators suppresses higher-frequency, higher-order modes, ultimately achieving a very wide stopband. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of the present invention. Figure 1 ;

[0010] Figure 2 This is a schematic diagram of the structure of the present invention. Figure 2 . Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is not intended to limit the scope of protection of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The present invention will be further described below with reference to the accompanying drawings.

[0012] like Figure 1As shown, this utility model specifically relates to an IPD low-pass filter with a wide stopband. It has three inductors L1, L2, and L3 on the main path, a grounding capacitor C1 between L1 and L2, a grounding capacitor C2 between L2 and L3, and a grounding capacitor C3 between L3 and the output terminal. Since inductor L2 has mutual inductance with both inductors L1 and L3, it is divided into two parts in the circuit diagram, both represented as L2 / 2.

[0013] To improve the selectivity of the proposed low-pass filter, mutual inductance is introduced between two adjacent inductors on the main path, ultimately introducing two transmission zeros and achieving high selectivity. No additional capacitors are introduced on the main path, nor are any additional inductors introduced in the branches, thus avoiding additional resonance near the passband. This circuit also offers the advantage of a wide stopband.

[0014] To further improve the stopband width of the proposed low-pass filter, a pair of notch suppression resonators was added at both the input and output ends, ultimately resulting in the following: Figure 2 The final equivalent circuit is shown. A single notch filter resonator is constructed from a series LC resonant circuit consisting of inductor ll1 and capacitor cc1. This structure can suppress higher frequency resonances, ultimately achieving a wider stopband. Finally, this low-pass filter generates two transmission zeros on the right side of the passband through the mutual inductance of the inductors, and achieves a wider stopband through the suppression resonator. This gives the proposed low-pass filter the advantages of low loss, high selectivity, and a wide stopband.

[0015] The above description is merely a preferred embodiment of this utility model. It should be understood that this utility model is not limited to the form disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and improvements, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this utility model should be protected within the scope of the appended claims.

Claims

1. An IPD low-pass filter with wide stopband, characterized by: It includes inductors L1, L2, and L3. Inductor L1 is connected to the input terminal, and inductor L3 is connected to the output terminal. A grounding capacitor C1 is connected between inductors L1 and L2, a grounding capacitor C2 is connected between inductors L2 and L3, and a grounding capacitor C3 is connected between inductor L3 and the output terminal.

2. The IPD low-pass filter with wide stopband according to claim 1, characterized in that: A pair of harmonic suppression resonators are added between the input terminal and inductor L1, and a pair of harmonic suppression resonators are added between the output terminal and inductor L3.

3. The IPD low-pass filter with wide stopband according to claim 2, characterized in that: The harmonic suppression resonator is composed of an inductor L11 and a capacitor L1 connected in series, with the other end of the capacitor L1 grounded. Each harmonic suppression resonator is connected in parallel between the input terminal and the inductor L1 or between the output terminal and the inductor L3.

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