A reflectionless high-pass filter based on ltcc

Abstract

The application discloses a non-reflection high-pass filter based on LTCC, which is composed of three inductors, three capacitors and two built-in resistors. The microwave device based on LTCC has good high-temperature resistance and can bear a large current. The LTCC process can manufacture dozens of layers of substrates, embed passive devices, improve the integration degree, and reduce the interference of other assembled elements. Inductors and resistors are connected to the input port and the output port respectively to form a circuit branch to absorb the reflected signals of the low-pass frequency band, and capacitors are connected to the input port and the output port to transmit high-frequency signals. On the premise that the passband and the stopband have extremely low reflection loss, the element has the characteristics of small size, simple structure, good stability, high reliability, high-temperature resistance and good material consistency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of microwave technology, in particular to a non-reflection high-pass filter based on LTCC. BACKGROUND

[0002] The filter has the function of screening fixed frequency signals, and is widely used in communication and radio frequency systems. According to the processing method of the filter stop band signal, it can be divided into reflection type filter and non-reflection type filter, wherein the stop band signal of the reflection type filter is reflected back to the signal input end, and the non-reflection type filter absorbs and consumes the reflected signal through a certain circuit structure. Compared with the mature research and design of the traditional reflection type filter, the research of the non-reflection filter is still very little, and there is a lack of related research and design in China.

[0003] In many practical applications, such as mixers are very sensitive to all out-of-band signal changes; the stability of high-gain amplifiers is affected by out-of-band signal feedback in the packaging environment; the reliability and stability of high-power transmitters are limited by out-of-band reflected signals. Therefore, a non-reflection high-pass filter based on LTCC is needed. LTCC, which stands for low temperature co-fired ceramic, is a thick film technology with high stability, high quality factor and high integration. Compared with other materials, ceramic materials have high stability and large dielectric constant range, which are suitable for the manufacture of microwave devices.

[0004] There are two types of existing non-reflection filter designs: one type uses a single-terminal prototype filter as an absorbing load to form a different filter with complementary admittance curves in a duplexer or multiplexer mode to achieve the matching of passband and stopband; the other type uses a reflection filter and two 3dB directional couplers to combine the reflected energy in the stopband to cancel each other out. The two types of filters have many components, complex design process and large component size.

[0005] The existing non-reflection design scheme has the following shortcomings: (1) The non-reflection high-pass filter is designed by using a duplexer or a multiplexer structure, which requires high-low path pairs and complementary phase frequency curves. The design and debugging are difficult, and the components are large in size; (2) The non-reflection high-pass filter is designed by using a reflection filter and two 3dB directional couplers, which has many components, large size and large insertion loss; (3) The symmetric circuit design based on IPD technology has low stability and heat dissipation. SUMMARY

[0006] In view of the above technical problems in the prior art, the present application provides a non-reflection high-pass filter based on LTCC.

[0007] The application discloses a reflection-free high-pass filter based on LTCC, which comprises a first isolation resistor R1, a second isolation resistor R2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first inductor L1, a second inductor L2 and a third inductor L3, one end of the first capacitor C1 is connected with an input port P1, and the other end is electrically connected with the first isolation resistor R1, the second isolation resistor R2, the third inductor L3 and one end of the second capacitor C2 respectively; the other end of the first isolation resistor R1 is electrically connected with the first inductor L1 and the third capacitor C3 respectively; the first inductor L1 is connected with the input port P1; the other end of the third capacitor C3 is connected with the other end of the second isolation resistor R2 and the second inductor L2 respectively; the second inductor L2 and the second capacitor C2 are connected with an output port P3 respectively; the third inductor L3 is connected with the middle part of a shielding layer SH; and the two ends of the shielding layer SH are connected with a first grounding port P2 and a second grounding port P4 respectively.

[0008] Preferably, the first inductor L1 and the second inductor L2 are arranged left-right symmetrically, the first capacitor C1 and the second capacitor C2 are arranged left-right symmetrically, the first isolation resistor R1 and the second isolation resistor R2 are arranged left-right symmetrically, and the third inductor L3 and the third capacitor C3 are located at the middle position.

[0009] Preferably, the symmetric arrangement has a common symmetry plane, and the third inductor L3 and the third capacitor C3 are arranged symmetrically on the left and right sides of the symmetry plane.

[0010] Preferably, the input port P1 and the output port P3 are distributed left and right, and the first grounding port P2 and the second grounding port P4 are distributed front and back.

[0011] The first inductor L1 is arranged on the upper side of the first capacitor C1, and the second inductor L2 is arranged on the upper side of the second capacitor C2.

[0012] The lower side of the first isolation resistor R1 and the second isolation resistor R2 is the third inductor L3, and the upper side is the third capacitor C3.

[0013] The third inductor L3 is arranged on the upper side of the shielding layer SH, and forms a laminated structure.

[0014] Preferably, the first inductor is a first spiral inductor L1, and the second inductor is a second spiral inductor L2.

[0015] The first spiral inductor L1 has six layers, and the layers are connected through a through-hole connecting column, the first layer is connected with the input port P1, and the sixth layer is connected with a first connecting line Li n1.

[0016] The second spiral inductor L2 has six layers, and the layers are connected through a through-hole connecting column, the first layer is connected with the output port P3, and the sixth layer is connected with a fifth connecting line Li n5.

[0017] The third spiral inductor L3 has three layers, and the layers are connected by a through-hole connecting column. The first layer is connected with the second transmission line T2, and the third layer is connected with the upper end of the fifth connecting column H5.

[0018] The first capacitor C1 has three layers. The first layer and the third layer are connected with the input port P1, and the second layer is connected with the first transmission line T1.

[0019] The second capacitor C2 has three layers. The first layer and the third layer are connected with the output port P3, and the second layer is connected with the third transmission line T3.

[0020] The third capacitor C3 has two layers. The first layer is connected with the second connecting line Lin2, and the second layer is connected with the sixth connecting line Lin6.

[0021] One end of the first isolation resistor R1 is connected with the first connecting line Lin1, and the other end is connected with the third connecting line Lin3.

[0022] One end of the second isolation resistor R2 is connected with the fifth connecting line Lin5, and the other end is connected with the seventh connecting line Lin7.

[0023] One end of the shielding layer SH is connected with the first ground port P2, and the other end is connected with the second ground port P4.

[0024] The first connecting line Lin1 and the second connecting line Lin2 are connected by the first connecting column H1, the third connecting line Lin3 and the fourth connecting line Lin4 are connected by the second connecting column H2, the fifth connecting line Lin5 and the sixth connecting line Lin6 are connected by the third connecting column H3, and the seventh connecting line Lin7 and the eighth connecting line Lin8 are connected by the fourth connecting column H4. The second layer of the first capacitor C1 is connected with one end of the first transmission line T1, the other end of the first transmission line T1 is connected with one end of the fourth connecting line Lin4, the other end of the fourth connecting line Lin4 is connected with one end of the second transmission line T2, the other end of the second transmission line T2 is connected with the eighth connecting line Lin8, and the other end of the eighth connecting line Lin8 is connected with the second layer of the second capacitor C2. The midpoint of the second transmission line T2 is connected with the first layer of the third spiral inductor L3, the third layer of the third spiral inductor L3 is connected with the upper end of the fifth connecting column H5, and the lower end of the fifth connecting column H5 is connected with the middle part of the shielding layer SH.

[0025] Preferably, the second layer of the third capacitor C3 is electrically connected with the first connecting column H1. The first layer of the third capacitor C3 is provided with a first through-hole, and the first connecting column H1 passes through the first through-hole and is electrically connected with the third connecting line Lin3.

[0026] Preferably, the input port P1 and the output port P3 are both 50-ohm impedance ports.

[0027] Preferably, the input port P1, the first ground port P2, the output port P3 and the second ground port P4 are external package pins.

[0028] Preferably, the first isolation resistor R1 and the second isolation resistor R2 are in a buried structure, and the first isolation resistor R1 and the second isolation resistor R2 have an impedance of 50 ohms.

[0029] Preferably, the reflection-free high-pass filter is a low-temperature co-fired ceramic piece.

[0030] Compared with the prior art, the microwave device based on LTCC has good high-temperature resistance and can bear a large current, the LTCC process can make a substrate with dozens of layers, the passive device is buried, the integration degree is improved, and the interference of other assembled elements is reduced; the inductance and the resistance are connected to the input port and the output port respectively to form a circuit branch to absorb reflected signals in a low-pass frequency band, and the capacitance is connected to the input port and the output port to transmit high-frequency signals; on the premise that the passband and the stopband have extremely low reflection loss, the element has the characteristics of small size, simple structure, good stability, high reliability, high-temperature resistance, and good material consistency. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a structure diagram of a reflection-free high-pass filter based on LTCC of the present application;

[0032] Figure 2 is a top view of the reflection-free high-pass filter;

[0033] Figure 3 is a side view of the present application;

[0034] Figure 4 is a curve diagram of insertion loss and return loss of performance test;

[0035] Figure 5 is a curve diagram of standing wave ratio of performance test.

[0036] Marking in the figure:

[0037] Input port P1, first ground port P2, output port P3, second ground port P4;

[0038] First transmission line T1, second transmission line T2, third transmission line T3, first connection line Lin1, second connection line Lin2, third connection line Lin3, fourth connection line Lin4, fifth connection line Lin5, sixth connection line Lin6, seventh connection line Lin7, eighth connection line Lin8, first connecting column H1, second connecting column H2, third connecting column H3, fourth connecting column H4, fifth connecting column H5, shielding layer SH;

[0039] The first inductor L1, the second inductor L2, the third inductor L3, the first capacitor C1, the second capacitor C2, the third capacitor C3, the first isolation resistor R1 and the second isolation resistor R2. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0041] The present application will be further described in detail below in conjunction with the drawings:

[0042] A LTCC-based reflectionless high-pass filter, as shown in Figures 1-3 includes a first isolation resistor R1, a second isolation resistor R2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a first inductor L1, a second inductor L2 and a third inductor L3. One end of the first capacitor C1 is connected to an input port P1, and the other end is respectively electrically connected to the first isolation resistor R1, the second isolation resistor R2, the third inductor L3 and one end of the second capacitor C2. The other end of the first isolation resistor R1 is respectively electrically connected to the first inductor L1 and the third capacitor C3. The first inductor L1 is connected to the input port P1. The other end of the third capacitor C3 is respectively connected to the other end of the second isolation resistor R2 and the second inductor L2. The second inductor L2 and the second capacitor C2 are respectively connected to an output port P3. The third inductor L3 is connected to the middle part of a shielding layer SH. The two ends of the shielding layer SH are respectively connected to a first ground port P2 and a second ground port P4.

[0043] The LTCC-based microwave device has good high-temperature resistance and can bear a large current. The LTCC process can make dozens of layers of substrates, embed passive devices inside, improve the integration level, and reduce the interference of other assembled elements. An inductor and a resistor are respectively connected to the input port and the output port to form a circuit branch to absorb reflected signals in the low-pass frequency band, and a capacitor is connected to the input port and the output port for high-frequency signal transmission. On the premise of having extremely low reflection loss in the passband and the stopband, the device has the characteristics of small size, simple structure, good stability, high reliability, high-temperature resistance and good material consistency. The circuit structure is simple, and by adjusting the combination of inductors and capacitors, a reflectionless filter with arbitrary frequency and stopband requirements can be realized.

[0044] The reflectionless high-pass filter can be widely applied to 5G mobile communication, phased array radar, Beidou navigation system satellite communication and other systems and equipment with high requirements of electrical performance, material consistency, thermal mechanical property, temperature stability, processability and anti-interference.

[0045] The first inductor L1 and the second inductor L2 are arranged symmetrically on the left and right, the first capacitor C1 and the second capacitor C2 are arranged symmetrically on the left and right, the first isolation resistor R1 and the second isolation resistor R2 are arranged symmetrically on the left and right, and the third inductor L3 and the third capacitor C3 are located in the middle position. The above-mentioned symmetric arrangement has a common symmetry plane, and the third inductor L3 and the third capacitor C3 are symmetrically arranged on the left and right sides of the symmetry plane. The symmetric design is simple and symmetrical in circuit structure, and is convenient for design and development.

[0046] The input port P1 and the output port P3 are distributed on the left and right, and the first ground port P2 and the second ground port P4 are distributed in front and back; the first inductor L1 is arranged on the upper side of the first capacitor C1, and the second inductor L2 is arranged on the upper side of the second capacitor C2; the lower side of the first isolation resistor R1 and the second isolation resistor R2 is the third inductor L3, and the upper side is the third capacitor C3; the third inductor L3 is arranged on the upper side of the shielding layer SH to form a laminated structure.

[0047] The first inductor can adopt a first spiral inductor L1, and the second inductor can adopt a second spiral inductor L2.

[0048] The connection lines of each component can also be optimized: the first spiral inductor L1 has six layers, and the layers are connected through a through-hole connecting column, the first layer is connected with the input port P1, and the sixth layer is connected with the first connection line Lin1;

[0049] The second spiral inductor L2 has six layers, and the layers are connected through a through-hole connecting column, the first layer is connected with the output port P3, and the sixth layer is connected with the fifth connection line Lin5;

[0050] The third spiral inductor L3 has three layers, and the layers are connected through a through-hole connecting column, the first layer is connected with the second transmission line T2, and the third layer is connected with the upper end of the fifth connecting column H5;

[0051] The first capacitor C1 has three layers, and the first layer and the third layer are respectively connected with the input port P1, and the second layer is connected with the first transmission line T1;

[0052] The second capacitor C2 has three layers, and the first layer and the third layer are respectively connected with the output port P3, and the second layer is connected with the third transmission line T3;

[0053] The third capacitor C3 has two layers; the first layer is connected with the second connection line Lin2, and the second layer is connected with the sixth connection line Lin6;

[0054] One end of the first isolation resistor R1 is connected with the first connection line Lin1, and the other end is connected with the third connection line Lin3.

[0055] One end of the second isolation resistor R2 is connected with the fifth connection line Lin5, and the other end is connected with the seventh connection line Lin7.

[0056] One end of the shielding layer SH is connected with the first ground port P2, and the other end is connected with the second ground port P4.

[0057] The first connection line Lin1 and the second connection line Lin2 are connected through the first connection column H1, the third connection line Lin3 and the fourth connection line Lin4 are connected through the second connection column H2, the fifth connection line Lin5 and the sixth connection line Lin6 are connected through the third connection column H3, and the seventh connection line Lin7 and the eighth connection line Lin8 are connected through the fourth connection column H4; the second layer of the first capacitor C1 is connected with one end of the first transmission line T1, the other end of the first transmission line T1 is connected with one end of the fourth connection line Lin4, the other end of the fourth connection line Lin4 is connected with one end of the second transmission line T2, the other end of the second transmission line T2 is connected with the eighth connection line Lin8, and the other end of the eighth connection line Lin8 is connected with the second layer of the second capacitor C2; the midpoint of the second transmission line T2 is connected with the first layer of the third spiral inductor L3, the third layer of the third spiral inductor L3 is connected with the upper end of the fifth connection column H5, and the lower end of the fifth connection column H5 is connected with the middle part of the shielding layer SH.

[0058] The connection column realizes the connection between different levels, and is realized by punching; the connection column, the connection line and the transmission line are realized by different processes; the transmission line realizes the connection between different elements in the same level; and the connection line is used for reliable connection between the connection column and the transmission line.

[0059] As shown in Figure 3 The second layer of the third capacitor C3 is electrically connected with the first connection column H1; the first layer of the third capacitor C3 is provided with a first through hole, and the first connection column H1 passes through the first through hole and is electrically connected with the third connection line Lin3.

[0060] In one specific embodiment, the input port P1 and the output port P3 are both 50-ohm impedance ports, and the input port P1, the first ground port P2, the output port P3 and the second ground port P4 are external package pins; the first isolation resistor R1 and the second isolation resistor R2 are in an embedded structure, and the impedance of the first isolation resistor R1 and the second isolation resistor R2 is 50 ohm; the reflectionless high-pass filter is a low-temperature co-fired ceramic (LTCC) piece, that is, an LTCC process is used to manufacture a reflectionless high-pass filter with a size of 2.5mmx1.25mmx0.94mm, and detection is performed, as shown in Figure 4 and Figure 5 . Figure 4The horizontal coordinate is frequency, and the vertical coordinate is decibel ratio; Figure 5 The horizontal coordinate is frequency, and the vertical coordinate is standing wave ratio. It is concluded from the detection data and the graph that the passband distribution is 2.5GHz-9GHz, the insertion loss in the frequency range is better than -2dB, the attenuation in the stopband range DC-1.9GHz is less than -16dB; in the frequency range DC-9GHz, the return loss of the incident port is less than -10dB, and the standing wave ratio is better than 2.

[0061] The application is composed of three symmetrical inductors, three capacitors and two built-in resistors, the connection line of two series capacitors is adjusted, the position of the built-in resistor and the parallel inductor is optimized, so that a small high-pass filter with superior performance is obtained. The design principle of the application is: an RLC single-terminal high-pass prototype filter and its dual filter are adopted, the open point (disconnection point) and the grounding point (shorting point) are replaced and simplified by passive elements, so that a high-pass filter with no reflection characteristic is realized.

[0062] The above only is the preferred embodiment of the present application, and is not used to limit the present application, for the person skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A reflectionless high-pass filter based on LTCC, characterized in that The first isolation resistor (R1), the second isolation resistor (R2), the first capacitor (C1), the second capacitor (C2), the third capacitor (C3), the first inductor (L1), the second inductor (L2) and the third inductor (L3) are arranged in a symmetrical manner. One end of the first capacitor (C1) is connected with the input port (P1), and the other end is electrically connected with the first isolation resistor (R1), the second isolation resistor (R2), the third inductor (L3) and one end of the second capacitor (C2) respectively. The other end of the first isolation resistor (R1) is electrically connected with the first inductor (L1) and the third capacitor (C3) respectively. The first inductor (L1) is connected with the input port (P1). The other end of the third capacitor (C3) is connected with the other end of the second isolation resistor (R2) and the second inductor (L2) respectively. The second inductor (L2) and the second capacitor (C2) are connected with the output port (P3) respectively. The third inductor (L3) is connected with the middle part of the shielding layer (SH), and the two ends of the shielding layer (SH) are connected with the first grounding port (P2) and the second grounding port (P4) respectively.

2. The reflectionless high-pass filter of claim 1, wherein The first inductor (L1) and the second inductor (L2) are arranged in a left-right symmetrical manner, the first capacitor (C1) and the second capacitor (C2) are arranged in a left-right symmetrical manner, the first isolation resistor (R1) and the second isolation resistor (R2) are arranged in a left-right symmetrical manner, and the third inductor (L3) and the third capacitor (C3) are located in the middle position.

3. The reflectionless high-pass filter of claim 2, wherein The symmetrical arrangement has a common symmetry plane, and the third inductor (L3) and the third capacitor (C3) are arranged symmetrically on the left and right sides of the symmetry plane.

4. The reflectionless high-pass filter of claim 2, wherein The input port (P1) and the output port (P3) are distributed left and right, and the first grounding port (P2) and the second grounding port (P4) are distributed front and back. The first inductor (L1) is arranged on the upper side of the first capacitor (C1), and the second inductor (L2) is arranged on the upper side of the second capacitor (C2). The lower side of the first isolation resistor (R1) and the second isolation resistor (R2) is the third inductor (L3), and the upper side is the third capacitor (C3). The third inductor (L3) is arranged on the upper side of the shielding layer (SH) to form a laminated structure.

5. The reflectionless high-pass filter according to any one of claims 1-4, characterized in that, The first inductor is a first spiral inductor (L1), and the second inductor is a second spiral inductor (L2). The first spiral inductor (L1) has six layers, and the layers are connected through a through-hole connecting column. The first layer is connected with the input port (P1), and the sixth layer is connected with the first connecting line (Lin1). The second spiral inductor (L2) has six layers, and the layers are connected through a through-hole connecting column. The first layer is connected with the output port (P3), and the sixth layer is connected with the fifth connecting line (Lin5). The third spiral inductor (L3) has three layers, and the layers are connected through a through-hole connecting column. The first layer is connected with the second transmission line (T2), and the third layer is connected with the upper end of the fifth connecting column (H5). The first capacitor (C1) has three layers, and the first layer and the third layer are connected with the input port (P1) respectively. The second layer is connected with the first transmission line (T1). The second capacitor (C2) has three layers, and the first layer and the third layer are connected with the output port (P3) respectively. The second layer is connected with the third transmission line (T3). The first capacitor (C1) has three layers, and the first layer and the third layer are connected with the input port (P1) respectively. The second layer is connected with the first transmission line (T1). The second capacitor (C2) has three layers, and the first layer and the third layer are connected with the output port (P3) respectively. The second layer is connected with the third transmission line (T3). The third capacitor (C3) has two layers, the first layer is connected with the second connection line (Lin2), and the second layer is connected with the sixth connection line (Lin6); One end of the first isolation resistor (R1) is connected with the first connection line (Lin1), and the other end is connected with the third connection line (Lin3); One end of the second isolation resistor (R2) is connected with the fifth connection line (Lin5), and the other end is connected with the seventh connection line (Lin7); One end of the shielding layer (SH) is connected with the first ground port (P2), and the other end is connected with the second ground port (P4); The first connection line (Lin1) and the second connection line (Lin2) are connected through the first connection column (H1), the third connection line (Lin3) and the fourth connection line (Lin4) are connected through the second connection column (H2), the fifth connection line (Lin5) and the sixth connection line (Lin6) are connected through the third connection column (H3), and the seventh connection line (Lin7) and the eighth connection line (Lin8) are connected through the fourth connection column (H4); the second layer of the first capacitor (C1) is connected with one end of the first transmission line (T1), the other end of the first transmission line (T1) is connected with one end of the fourth connection line (Lin4), the other end of the fourth connection line (Lin4) is connected with one end of the second transmission line (T2), the other end of the second transmission line (T2) is connected with the eighth connection line (Lin8), and the other end of the eighth connection line (Lin8) is connected with the second layer of the second capacitor (C2); the midpoint of the second transmission line (T2) is connected with the first layer of the third spiral inductor (L3), the third layer of the third spiral inductor (L3) is connected with the upper end of the fifth connection column (H5), and the lower end of the fifth connection column (H5) is connected with the middle part of the shielding layer (SH).

6. The reflectionless high-pass filter of claim 5, wherein, The input port (P1) and the output port (P3) are both 50-ohm impedance ports.

7. The reflectionless high-pass filter of claim 5, wherein, The input port (P1), the first ground port (P2), the output port (P3), and the second ground port (P4) are external package pins.

8. The reflectionless high-pass filter of claim 5, wherein, The first isolation resistor (R1) and the second isolation resistor (R2) are in an embedded structure, and the first isolation resistor (R1) and the second isolation resistor (R2) have an impedance of 50 ohms.

9. The reflectionless high-pass filter of claim 5, wherein, The reflectionless high-pass filter is a low-temperature co-fired ceramic piece.

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