CN111478677A

CN111478677A - 670MHz low-pass filter based on L TCC and design method

Info

Publication number: CN111478677A
Application number: CN201910063723.9A
Authority: CN
Inventors: 张奇; 巩德阳; 梁婷婷; 吴树辉
Original assignee: Xi'an Borui Jixin Electronic Technology Co ltd
Current assignee: Xi'an Borui Jixin Electronic Technology Co ltd
Priority date: 2019-01-23
Filing date: 2019-01-23
Publication date: 2020-07-31

Abstract

The invention discloses a design method of a 670MHz low-pass filter based on L TCC, which comprises the following steps of S1, determining the circuit structure of the low-pass filter, S2, selecting an inductance element and a capacitance element, and utilizing the inductance element and the capacitance element to construct a L C circuit with the operating frequency of 670MHz, and S3, carrying out structural layout and modeling on the low-pass filter, wherein the inductance element and the capacitance element are embedded in L TCC media, the inductance element is arranged at a position far away from a L medium bottom grounding layer, and the capacitance element is arranged at a position close to an L TCC medium bottom grounding layer.

Description

670MHz low-pass filter based on L TCC and design method

Technical Field

The invention relates to a low-pass filter, in particular to a 670MHz low-pass filter based on L TCC and a design method thereof.

Background

With the continuous progress of mobile communication technology, the technical requirements of filters are moving toward low cost and miniaturization, and although microstrip filters, SAW filters, dielectric filters, etc. exist in the prior art, the inherent disadvantages of these filters are difficult to overcome. Particularly, in the current UV band rf circuit, please refer to fig. 1, the filter generally adopts the conventional inductor-capacitor surface mount scheme, which is disadvantageous in terms of higher insertion loss, larger volume and smaller power capacity, and in order to overcome the short board of the existing similar device, some substitute products, such as the similar band series low-pass filter produced by Mini Circuits, are appeared in the market, but these products still have the defects of long transition band, general rectangular coefficient, and the like, and are difficult to meet the application requirements.

Disclosure of Invention

The invention aims to solve the technical problem of providing a 670MHz low-pass filter and a design method thereof, which adopt L TCC technology to realize multilayer line superposition so as to reduce the volume of devices and reduce insertion loss, aiming at the defects of the prior art.

In order to solve the technical problems, the invention adopts the following technical scheme.

A670 MHz low pass filter based on L TCC comprises L TCC medium and a L C circuit consisting of an inductance element and a capacitance element, wherein the working frequency of the L C circuit is 670MHz, the bottom of the L TCC medium is provided with a grounding layer, the inductance element is far away from the grounding layer at the bottom of the L TCC medium, and the capacitance element is close to the grounding layer at the bottom of the L TCC medium.

Preferably, the capacitor element includes a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4, the inductor element includes an inductor L1, an inductor L2 and an inductor L03, the inductor L11, the inductor L22 and the inductor L33 are connected in series in sequence, a front end of the inductor L1 is used as an input end P1 of the L C circuit, a rear end of the inductor L3 is used as an output end P2 of the L C circuit, the capacitor C1 is connected between the front end of the inductor L1 and a ground layer, the capacitor C2 is connected between the rear end of the inductor L1 and the ground layer, the capacitor C3 is connected between the rear end of the inductor L2 and the ground layer, and the capacitor C4 is connected between the rear end of the inductor L3 and the ground layer.

Preferably, the capacitance element is a VIC capacitance or a MIM capacitance.

Preferably, the inductance element is a planar structure, a stacked structure, a displacement structure, or a three-dimensional spiral structure.

Preferably, the capacitor C1 and the capacitor C4 are both 9.7pF capacitors, the capacitor C2 and the capacitor C3 are both 5.23pF capacitors, the inductor L1 and the inductor L3 are both 16.7nH inductors, and the inductor L2 is a 19.12nH inductor.

A design method of a 670MHz low-pass filter based on L TCC comprises the following steps of S1 determining a circuit structure of the low-pass filter, S2 selecting an inductance element and a capacitance element and using the inductance element and the capacitance element to build a L C circuit with the working frequency of 670MHz, and S3 performing structural layout and modeling on the low-pass filter, wherein the inductance element and the capacitance element are embedded in L TCC media, the inductance element is arranged at a position far away from a bottom grounding layer of L TCC media, and the capacitance element is arranged at a position close to the bottom grounding layer of L TCC media.

Preferably, in step S1, the circuit structure of the low-pass filter is selected as any one of an elliptic function low-pass filter, a chebyshev low-pass filter and a butterworth low-pass filter.

Preferably, in step S2, the capacitance value of the selected capacitive element is calculated according to the plate capacitance formula:

wherein the content of the first and second substances,_rthe relative dielectric constant of L TCC media, S the area of the capacitor plates, and d the capacitor plate spacing.

Preferably, in step S2, the capacitive element is a VIC capacitor or a MIM capacitor, and the inductive element is a planar structure, a stacked structure, a displacement structure, or a three-dimensional spiral structure.

Preferably, in step S2, the parameters of the capacitive element and the inductive element are set such that the capacitor C1 and the capacitor C4 are both 9.7pF capacitors, the capacitor C2 and the capacitor C3 are both 5.23pF capacitors, the inductor L1 and the inductor L3 are both 16.7nH inductors, and the inductor L2 is 19.12nH inductor.

In the L TCC-based 670MHz low-pass filter disclosed by the invention, a circuit schematic diagram is designed firstly, then a capacitor and an inductor element are selected, a L C circuit with the working frequency of 670MHz is constructed, then a whole simulation model is laid out and established, the low-pass filter designed by the process is composed of lumped elements, various parasitic capacitors are utilized, and meanwhile, the influence of various parasitic effects on the performance of the filter is avoided as much as possible.

Drawings

Fig. 1 is an internal structural view of a conventional low-pass filter;

FIG. 2 is an internal structural view of the low pass filter of the present invention;

FIG. 3 is a schematic diagram of the L C circuit;

FIG. 4 is a schematic diagram of four inductor configurations;

FIG. 5 is a diagram of a U-shaped spiral inductor simulation model;

FIG. 6 is a graph of a simulation of an inductive element;

FIG. 7 is a schematic diagram of a MIM capacitor structure;

FIG. 8 is a schematic diagram of a VIC capacitor structure;

FIG. 9 is a schematic diagram of a VIC capacitance simulation model;

FIG. 10 is a graph of a simulation of a capacitive element;

FIG. 11 is a graph of the attenuation characteristics of an elliptic function, Chebyshev and Butterworth low pass filter;

FIG. 12 is a graph of L TCC filter simulations at 670 MHz.

Detailed Description

The invention is described in more detail below with reference to the figures and examples.

The invention discloses a 670MHz low pass filter based on L TCC, please refer to FIG. 2, which includes L TCC medium 1 and L C circuit composed of inductance element 2 and capacitance element 3, the working frequency of the L C circuit is 670MHz, the bottom of L TCC medium 1 is provided with a ground layer, the inductance element 2 is far away from the ground layer at the bottom of L TCC medium 1, and the capacitance element 3 is near the ground layer at the bottom of L TCC medium 1.

In the structure of the low-pass filter, a circuit schematic diagram is designed firstly, then capacitance and inductance elements are selected, an L C circuit with the working frequency of 670MHz is constructed, then a whole simulation model is laid out and established, the low-pass filter designed by the process is composed of lumped elements, various parasitic capacitances are utilized, meanwhile, the influence of various parasitic effects on the performance of the filter is avoided as much as possible, in addition, in the design process of the inductance, the inductance is far away as possible to reduce the parasitic capacitance, so that the Q value and the self-resonant frequency are improved.

Referring to fig. 3, in this embodiment, the capacitor element 3 includes a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4, the inductor element 2 includes an inductor L1, an inductor L and an inductor L, the inductor L, the inductor L and the inductor L are sequentially connected in series, a front end of the inductor L serves as an input end P1 of the L C circuit, a rear end of the inductor L serves as an output end P2 of the L C circuit, the capacitor C1 is connected between a front end of the inductor L1 and a ground layer, the capacitor C2 is connected between a rear end of the inductor L1 and the ground layer, the capacitor C3 is connected between a rear end of the inductor L2 and the ground layer, and the capacitor C4 is connected between a rear end of the inductor L and the ground layer.

Regarding the parameter setting of the L C circuit, in this embodiment, the capacitor C1 and the capacitor C4 are both 9.7pF capacitors, the capacitor C2 and the capacitor C3 are both 5.23pF capacitors, the inductor L1 and the inductor L3 are both 16.7nH inductors, and the inductor L2 is a 19.12nH inductor.

As for the selection of the capacitor, as shown in fig. 7 to 10, the capacitor element 3 is a VIC capacitor or a MIM capacitor.

As for the selection of the inductance, as shown in fig. 4 to 6, the inductance element 2 is a planar structure, a stacked structure, a displacement structure, or a three-dimensional spiral structure.

The invention has fully utilized L TCC technological characteristics, about low temperature co-fired ceramic, this technology is the new material technology developed in the company of hous in 1952, make low temperature sintering ceramic powder into the accurate and compact green porcelain tape of thickness, utilize processes such as laser drilling, micropore slip casting, accurate conductor paste printing to make the circuit figure needed on the green porcelain tape, and bury a plurality of passive components (such as low-capacitance value capacitor, resistance, wave filter, impedance converter, coupler, etc.) in the multilayer ceramic base plate, then laminate together, the internal and external electrode can use metals such as silver, copper, gold, etc., sinter under 900 duC, make the three-dimensional space noninterference high density circuit, can also make the three-dimensional circuit base plate to embed passive component, can paste IC and active device on its surface, make the passive/active integrated functional module, can further miniaturize the circuit and high density, especially suitable for the assembly for high frequency communication, the wide application in the single electronic system combat system, aerospace field, the whole machine system becomes the high-performance of the circuit, the high-integrated technology of high-degree, the high-stability is more and more reliable and the advantage is obtained because of its L advantages.

In order to better describe the technical scheme of the invention, the invention also discloses a 670MHz low pass filter design method based on L TCC, which is shown in fig. 2 and fig. 3, and comprises the following steps:

step S1, determining a low-pass filter circuit configuration;

step S2, selecting an inductance element 2 and a capacitance element 3, and using the inductance element 2 and the capacitance element 3 to build a L C circuit with the working frequency of 670 MHz;

in step S3, the low pass filter is structurally laid out and modeled by embedding an inductive element 2 and a capacitive element 3 in L TCC medium 1, disposing the inductive element 2 at a position away from the bottom ground plane of L TCC medium 1, and disposing the capacitive element 3 at a position close to the bottom ground plane of L TCC medium 1.

In the method, as a L TCC technology can embed capacitors, inductors and resistors in the filter, the filter is designed based on the principle, the volume of a module is greatly reduced by embedding passive components in a substrate, and the L TCC medium has higher reliability and can be more flexibly designed.

On the basis, compared with the traditional capacitance and inductance surface-mounted scheme, the invention adopts L TCC technology, can realize multilayer circuit superposition, is beneficial to three-dimensional integration of a circuit structure, realizes integration of microwave devices on a multilayer three-dimensional substrate, can enable the types of integrated devices to be more and the parameter range to be wider, can fully utilize interlayer interconnection to reduce the occupied area on the premise of ensuring the performance, can reduce the area by nearly 50% through measurement, and has obvious advantages.

As a preferred mode, referring to fig. 11, the S parameters of the Butterworth (Butterworth) low-pass filter, the Chebyshev (Chebyshev) low-pass filter, and the Elliptic function (eliptic) low-pass filter under the same order and the same cut-off frequency are simulated by using the ADS software, so that the attenuation characteristics of different types of filters can be obtained. In addition, in step S1, the circuit configuration of the low-pass filter is selected as any one of an elliptic function low-pass filter, a chebyshev low-pass filter, and a butterworth low-pass filter. The rectangle degree from the pass band of the elliptic function low-pass filter to the stop band is the highest, high attenuation can be achieved through a narrow transition band outside the cut-off frequency, a transmission zero point is arranged in the stop band, and far-end suppression is smooth; the attenuation rate of the Chebyshev low-pass filter is between the elliptic function low-pass filter and the Butterworth low-pass filter; the Butterworth low-pass filter has better ripple waves in a pass band, but the squareness is not ideal. The butterworth low pass filter is similar to the chebyshev low pass filter in that all transmission zeros are located at infinity. And in the design process, a proper filter structure can be selected according to specific index requirements.

In the process of designing the L C element in step S2, the filter design based on L TCC may be implemented by selecting distributed parameters and lumped parameters, and in this embodiment, the system operating frequency band is low, and the filter design may be implemented by using lumped parameters, where the inductor implementation of the L C L TCC filter is provided by a transmission line, and includes a meander inductor and a spiral inductor, and the capacitor is formed by more than two layers of flat plate structures, such as a VIC capacitor and an MIM capacitor, and the L TCC filter of L C lumped structure is formed by these forms of inductor and capacitor, and its resonance is also implemented by an inductor and capacitor circuit.

In practical applications, L TCC embedded inductors are implemented in many ways, and in the current L TCC embedded rectangular inductor component, please refer to fig. 4, there are mainly four structures, which are planar (planar), stacked (stack), shifted (offset), and three-dimensional spiral (3D helical), respectively.

Please refer to fig. 5, fig. 5 is a model of an inductor, fig. 6 is a simulation result thereof, wherein the inductor has 8 layers in total and has an area of 2mm × 2mm 2.

In this embodiment, the design process of L TCC embedded capacitor includes that in L TCC dielectric, the capacitor is similar to the traditional parallel plate capacitor, and is realized by coupling between two metal plates, and the capacitance value can be calculated by using a parallel plate capacitor calculation formula, specifically, in step S2, the capacitance value of the selected capacitor element 3 is calculated according to a plate capacitor formula:

wherein the content of the first and second substances,_rthe relative dielectric constant of L TCC medium 1, S the area of the capacitor plates, and d the capacitor plate spacing.

Referring to fig. 7 and 8, L TCC embedded Capacitor elements are mainly designed in MIM (metal-Insulator-metal) and VIC (vertical-Capacitor) structures, and the comparison of the L TCC capacitance parameters of MIM and VIC structures is shown in the following table:

please refer to fig. 9 and 10, which show a preferred capacitance simulation model and simulation results, wherein the total capacitance is 11 layers, and the area is 2 × 2 mm.

Based on the above principle, the following alternatives can be selected in the present embodiment: in step S2, the capacitive element 3 may be a VIC capacitor or a MIM capacitor, and the inductive element 2 may be a planar structure, a stacked structure, a displacement structure, or a three-dimensional spiral structure.

Regarding the overall layout and modeling in step S3, in this embodiment, the overall component layout needs to take into consideration the circuit performance, the area occupied by each component and the number of design layers, taking the last stage of the low-pass filter with a filter cutoff frequency of 670MHz as an example, the structure adopts the chebyshev form, and totally 7 components, and 7L C components are divided into three rows for layout connection, wherein 4 grounded capacitors are placed at the bottom layer near the "ground", and 3 inductors are placed at the top layer far from the "ground".

The invention relates to a lumped parameter low-pass filter design based on L TCC multilayer process, which comprises two end bonding pads and an intermediate grounding bonding pad, wherein the interior of the filter is composed of 4 capacitors and 3 inductors, the filter adopts a Chebyshev response function, and due to the symmetry of the filter, a capacitor C1 is the same as a capacitor C4, a capacitor C2 is the same as a capacitor C3, an inductor L1 is the same as an inductor L3, 4 capacitors occupy the lower 6 layers, and 3 inductors occupy the upper 8 layers, and the effective values of the inductors are respectively modeled and extracted, wherein the parameters of the capacitor element 3 and the inductor element 2 are set as that the capacitor C1 and the capacitor C4 are both 9.7pF capacitors, the capacitor C2 and the capacitor C3 are both 5.23pF capacitors, the inductor L1 and the inductor L3 are both 16.7nH inductors, and the inductor L2 is 19.12nH inductors.

The invention discloses an L TCC-based 670MHz low-pass filter and a design method thereof, wherein the filter is composed of lumped elements, various parasitic capacitances are utilized, and the influence of various parasitic effects on the performance of the filter is avoided as much as possible.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, therefore, all equivalent substitutions made under the spirit of the present invention should be included in the scope of the present invention.

Claims

1. A670 MHz low pass filter based on L TCC, characterized by that, including L TCC medium (1) and L C circuit that comprises inductance element (2) and capacitive element (3), the operating frequency of L C circuit is 670MHz, the bottom of L TCC medium (1) is equipped with the ground plane, inductance element (2) is far away from the ground plane of L TCC medium (1) bottom, capacitive element (3) is close to the ground plane of L TCC medium (1) bottom.

2. The L TCC-based 670MHz low pass filter according to claim 1, wherein the capacitive element (3) comprises a capacitor C1, a capacitor C2, a capacitor C3 and a capacitor C4, the inductive element (2) comprises an inductor L1, an inductor L02 and an inductor L13, the inductor L21, an inductor L32 and an inductor L43 are sequentially connected in series, a front end of the inductor L1 serves as an input terminal P1 of the L C circuit, a rear end of the inductor L3 serves as an output terminal P2 of the L C circuit, the capacitor C1 is connected between a front end of the inductor L1 and a ground plane, the capacitor C2 is connected between a rear end of the inductor L1 and the ground plane, the capacitor C3 is connected between a rear end of the inductor L2 and the ground plane, and the capacitor C4 is connected between a rear end of the inductor L3 and the ground plane.

3. The L TCC-based 670MHz low pass filter of claim 1, wherein said capacitive element (3) is a VIC capacitor or a MIM capacitor.

4. The L TCC-based 670MHz low pass filter of claim 1, wherein the inductive element (2) is a planar structure, a stacked structure, a displaced structure, or a three-dimensional spiral structure.

5. The L TCC-based 670MHz low pass filter of claim 1, wherein the capacitor C1 and the capacitor C4 are both 9.7pF capacitors, the capacitor C2 and the capacitor C3 are both 5.23pF capacitors, the inductor L1 and the inductor L3 are both 16.7nH inductors, and the inductor L2 is a 19.12nH inductor.

6. A670 MHz low pass filter design method based on L TCC is characterized by comprising the following steps:

step S1, determining a low-pass filter circuit configuration;

step S2, selecting an inductance element (2) and a capacitance element (3), and constructing a L C circuit with the working frequency of 670MHz by using the inductance element (2) and the capacitance element (3);

and step S3, carrying out structural layout and modeling on the low-pass filter, namely embedding an inductance element (2) and a capacitance element (3) in a L TCC medium (1), arranging the inductance element (2) at a position far away from the bottom grounding layer of the L TCC medium (1), and arranging the capacitance element (3) at a position close to the bottom grounding layer of the L TCC medium (1).

7. The method of designing a 670MHz low pass filter based on L TCC of claim 6, wherein in step S1, the circuit structure of the low pass filter is selected as any one of an elliptic function low pass filter, a Chebyshev low pass filter and a Butterworth low pass filter.

8. The method of designing a 670MHz low pass filter based on L TCC of claim 6, wherein in step S2, the capacitance value of the selected capacitive element (3) is calculated according to the plate capacitance formula:

wherein the content of the first and second substances,_rthe relative dielectric constant of L TCC medium (1), S the area of the capacitor plates, and d the capacitor plate spacing.

9. The design method of L TCC-based 670MHz low-pass filter according to claim 6, wherein in step S2, the capacitive element (3) is selected from a VIC capacitor or a MIM capacitor, and the inductive element (2) is selected from a planar structure, a stacked structure, a displacement structure or a three-dimensional spiral structure.

10. The design method of L TCC-based 670MHz low pass filter according to claim 6, wherein in step S2, the parameters of said capacitive element (3) and said inductive element (2) are set such that said capacitor C1 and said capacitor C4 are both 9.7pF capacitors, said capacitor C2 and said capacitor C3 are both 5.23pF capacitors, said inductor L1 and said inductor L3 are both 16.7nH inductors, and said inductor L2 is 19.12nH inductor.