Low-loss integrated passive device band-pass filter of 5G communication frequency band

Abstract

The utility model relates to a low-loss integrated passive device band-pass filter for a 5G communication frequency band, and aims to solve the problems of low Q value, insufficient roll-off capability and the like of the filter in 5G communication caused by the existing CMOS (Complementary Metal-Oxide-Semiconductor Transistor), LTCC (Low Temperature Co-Fired Ceramic) and other technologies. The low-loss integrated passive device band-pass filter comprises a first LC series resonance circuit, a second LC parallel resonance circuit, a third LC parallel resonance circuit and a fourth LC parallel resonance circuit, and two ends of the first LC series resonance circuit are respectively connected with a signal input end and a signal output end. The second LC parallel resonance circuit is connected in parallel to the two ends of the first LC series resonance circuit, the third LC parallel resonance circuit is connected in series between the signal input end and the ground, and the fourth LC parallel resonance circuit is connected in series between the signal output end and the ground. The three-order Chebyshev filter provided by the utility model has low and flat insertion loss in the whole passband, and an introduced zero pole obtains out-of-band rejection capability exceeding-20dB.

Description

Technical Field

[0001] The utility model relates to a low-loss integrated passive device bandpass filter for the 5G communication frequency band. Background Art

[0002] Filters are important frequency selection devices in the RF front end of wireless communication systems. Whether it is a base station or a mobile terminal, whether it is to suppress interference signals or suppress out-of-band signals, bandpass, bandstop and programmable filters have been widely studied.

[0003] Thin Film Integrated Passive Device (TFIPD) technology is becoming more and more popular in the RF front-end of 5G communication systems due to its tiny size, superior quality and small insertion loss, providing excellent functions at a lower cost while being compact and low power.

[0004] GaAs substrate has higher resistivity and dielectric constant than Si substrate of complementary metal oxide semiconductor (CMOS), which overcomes the problem that CMOS cannot produce high Q inductors and capacitors. Compared with low temperature co-fired ceramic (LTCC) technology, it avoids the challenging problems such as high mechanical precision, complex design, large volume and high cost. The filter proposed by TFIPD technology can effectively overcome the limitations mentioned above, thereby reducing size and power loss.

[0005] Thanks to the technical advantages of TFIPD, it can be seamlessly integrated with other chips on the same substrate at the system-in-package (SiP) system level. TFIPD bandpass filters can easily meet the high-density, miniature and high-performance requirements of RF front-end systems. Especially in the context of 5G communications, this is a key component of integrated and miniaturized wireless and mobile communication systems. Utility Model Content

[0006] The purpose of the utility model is to solve the problems of low Q value and insufficient roll-off capability of filters in 5G communications caused by existing technologies such as CMOS and LTCC, and to provide a low-loss integrated passive device bandpass filter for the 5G communication frequency band.

[0007] The utility model provides a low-loss integrated passive device bandpass filter for the 5G communication frequency band, comprising a first LC series resonant circuit, a second LC parallel resonant circuit, a third LC parallel resonant circuit and a fourth LC parallel resonant circuit, wherein a signal input end is connected to an input end of the first LC series resonant circuit, a signal output end is connected to an output end of the first LC series resonant circuit, a second LC parallel resonant circuit is connected in parallel to both ends of the first LC series resonant circuit, a third LC parallel resonant circuit is connected in series between the signal input end and the ground, and a fourth LC parallel resonant circuit is connected in series between the signal output end and the ground;

[0008] The first LC series resonant circuit is composed of inductor L1, capacitor C1 and inductor L2 in series; the second LC parallel resonant circuit is composed of capacitor C2 and inductor L3 in parallel; the third LC parallel resonant circuit is composed of capacitor C3 and inductor L4 in parallel; the fourth LC parallel resonant circuit is composed of capacitor C4 and inductor L5 in parallel.

[0009] The utility model discloses a low-loss integrated passive device bandpass filter which is a GaAs-based TFIPD bandpass filter suitable for the N77 frequency band.

[0010] The utility model provides a low-loss integrated passive device bandpass filter for the 5G communication frequency band, comprising a No. 1 LC series resonant circuit, a No. 2 LC parallel resonant circuit, a No. 3 LC parallel resonant circuit and a No. 4 LC series-parallel resonant circuit, wherein the signal input end is connected to the input end of the No. 1 LC series resonant circuit, the signal output end is connected to the output end of the No. 1 LC series resonant circuit, the No. 2 LC parallel resonant circuit is connected in parallel to both ends of the No. 1 LC series resonant circuit, the No. 3 LC parallel resonant circuit is connected in series between the signal input end and the ground, and the No. 4 LC series-parallel resonant circuit is connected in series between the signal output end and the ground;

[0011] The first LC series resonant circuit is composed of inductor L1, capacitor C1 and inductor L2 in series; the second LC parallel resonant circuit is composed of capacitor C2 and inductor L3 in parallel; the third LC parallel resonant circuit is composed of capacitor C3 and inductor L4 in parallel; the fourth LC series-parallel resonant circuit is composed of capacitor C4 and inductor L5 in parallel and then in series with inductor L6.

[0012] The utility model discloses a low-loss integrated passive device bandpass filter which is a GaAs-based TFIPD bandpass filter suitable for the N78 frequency band.

[0013] The GaAs-based TFIPD filter described in the utility model is based on the Chebyshev prototype filter. Compared with the elliptic function filter, its design is relatively simpler, and compared with the Butterworth filter, the transition band is steeper. The third-order Chebyshev filter meets the low insertion loss requirements, but its problems are wide transition zone, low rectangular coefficient, and insufficient roll-off capability.

[0014] In the above-mentioned GaAs-based TFIPD filter of the utility model, the filter constructs poles and zeros to introduce a notch structure. Thereby improving the steep drop performance of the filter. The rectangular coefficient is improved, and the poles and zeros are achieved by adding capacitors and inductors to the resonant circuit, thereby enhancing the roll-off capability of the working sideband of the BPF and adjusting the passband width. The zeros can be achieved by a grounded series resonant branch or a parallel resonant circuit, and the poles can be achieved by a grounded parallel resonant branch or a series resonant circuit. When designing the filter and calculating the zeros and poles, a capacitor or inductor having an opposite reactance characteristic to the connected resonant circuit is used to realize a notch structure near the zeros, thereby improving the passband width and steep drop performance of the filter.

[0015] In the above-mentioned GaAs-based TFIPD filter, the substrate is a 100μm thick GaAs substrate, and the inductor component in the TFIPD adopts a spiral inductor based on an air bridge structure to minimize the influence of parasitic effects, while a metal-insulator-metal (MIM) capacitor is incorporated into the capacitor component to simplify the structure. Both the interdigital capacitor and the MIM capacitor are integral components of the basic structure of the TFIPD capacitor. Compared with the interdigital capacitor, the MIM capacitor exhibits superior precision and density.

[0016] The utility model has the advantages that the third-order Chebyshev filter has low and flat insertion loss in the entire passband, and the introduced zero pole obtains an out-of-band suppression capability of more than -20dB. In particular, a grounded inductor is connected in series in the parallel resonant circuit to achieve the generation of a transmission zero in the right stopband. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the structure of a low-loss integrated passive device bandpass filter for the 5G communication frequency band described in the first specific implementation mode;

[0018] Figure 2 This is a schematic diagram of the structure of a low-loss integrated passive device bandpass filter for the 5G communication frequency band described in the fourth specific implementation mode;

[0019] Figure 3 It is the S parameter simulation and test result of the low loss integrated passive device bandpass filter of N77 frequency band in the embodiment;

[0020] Figure 4 This is a physical picture of the chip of the low-loss integrated passive device bandpass filter operating in the N77 frequency band in the first embodiment;

[0021] Figure 5 This is a physical picture of the chip of the low-loss integrated passive device bandpass filter operating in the N78 frequency band in the second embodiment;

[0022] Figure 6It is a topological principle diagram of LC calculation in the low-loss integrated passive device bandpass filter in the embodiment. DETAILED DESCRIPTION

[0023] Specific implementation method 1: In this implementation method, the low-loss integrated passive device bandpass filter of the 5G communication frequency band includes a first LC series resonant circuit, a second LC parallel resonant circuit, a third LC parallel resonant circuit and a fourth LC parallel resonant circuit, the signal input end is connected to the input end of the first LC series resonant circuit, the signal output end is connected to the output end of the first LC series resonant circuit, the second LC parallel resonant circuit is connected in parallel at both ends of the first LC series resonant circuit, the third LC parallel resonant circuit is connected in series between the signal input end and the ground, and the fourth LC parallel resonant circuit is connected in series between the signal output end and the ground;

[0024] The first LC series resonant circuit is composed of inductor L1, capacitor C1 and inductor L2 in series; the second LC parallel resonant circuit is composed of capacitor C2 and inductor L3 in parallel; the third LC parallel resonant circuit is composed of capacitor C3 and inductor L4 in parallel; the fourth LC parallel resonant circuit is composed of capacitor C4 and inductor L5 in parallel.

[0025] Specific implementation mode 2: The difference between this implementation mode and specific implementation mode 1 is that capacitors C1, C2, C3 and C4 are all parallel plate capacitors.

[0026] Specific implementation method three: This implementation method is different from specific implementation method one or two in that the inductor L1 , the inductor L2 , the inductor L3 , the inductor L4 and the inductor L5 are all planar spiral inductors.

[0027] Specific implementation method four: In this implementation method, the low-loss integrated passive device bandpass filter of the 5G communication frequency band includes a No. 1 LC series resonant circuit, a No. 2 LC parallel resonant circuit, a No. 3 LC parallel resonant circuit and a No. 4 LC series-parallel resonant circuit, the signal input end is connected to the input end of the No. 1 LC series resonant circuit, the signal output end is connected to the output end of the No. 1 LC series resonant circuit, the No. 2 LC parallel resonant circuit is connected in parallel to both ends of the No. 1 LC series resonant circuit, the No. 3 LC parallel resonant circuit is connected in series between the signal input end and the ground, and the No. 4 LC series-parallel resonant circuit is connected in series between the signal output end and the ground;

[0028] The first LC series resonant circuit is composed of inductor L1, capacitor C1 and inductor L2 in series; the second LC parallel resonant circuit is composed of capacitor C2 and inductor L3 in parallel; the third LC parallel resonant circuit is composed of capacitor C3 and inductor L4 in parallel; the fourth LC series-parallel resonant circuit is composed of capacitor C4 and inductor L5 in parallel and then in series with inductor L6.

[0029] Specific implementation mode 5: This implementation mode is different from the specific implementation mode 4 in that the capacitors C1 , C2 , C3 and C4 are all parallel plate capacitors.

[0030] Specific implementation example six: This implementation example is different from specific implementation example four or five in that the inductor L1 , the inductor L2 , the inductor L3 , the inductor L4 , the inductor L5 and the inductor L6 are all planar spiral inductors.

[0031] Embodiment 1: The low-loss integrated passive device bandpass filter of this embodiment working in the N77 frequency band includes a first LC series resonant circuit, a second LC parallel resonant circuit, a third LC parallel resonant circuit and a fourth LC parallel resonant circuit, the signal input end is connected to the input end of the first LC series resonant circuit, the signal output end is connected to the output end of the first LC series resonant circuit, the second LC parallel resonant circuit is connected in parallel to both ends of the first LC series resonant circuit, the third LC parallel resonant circuit is connected in series between the signal input end and the ground, and the fourth LC parallel resonant circuit is connected in series between the signal output end and the ground;

[0032] The first LC series resonant circuit is composed of inductor L1, capacitor C1 and inductor L2 in series; the second LC parallel resonant circuit is composed of capacitor C2 and inductor L3 in parallel; the third LC parallel resonant circuit is composed of capacitor C3 and inductor L4 in parallel; the fourth LC parallel resonant circuit is composed of capacitor C4 and inductor L5 in parallel.

[0033] The BPF of this embodiment works in the N77 frequency band, introduces transmission zeros at 2.867 GHz and 5.083 GHz, has a minimum insertion loss of 0.755 dB, a maximum insertion loss of 1.237 dB, a return loss of 30.716 dB, and has a 1.51×1.33 mm 2 The compact physical size makes the N77BPF compatible with other microwave devices at the package system (SiP) level. Based on the third-order Chebyshev filter, by connecting capacitors and inductors in parallel in a series resonant tank, a transmission zero can be generated in each of the left and right stop bands, thereby obtaining a filter with excellent steep drop performance.

[0034] The S parameter simulation and test results of this embodiment are as follows Figure 1 As shown, the introduced zero pole obtains an out-of-band suppression capability of more than -20dB. In particular, a grounded inductor is connected in series in the parallel resonant circuit to achieve a transmission zero in the right stopband.

[0035] Embodiment 2: The low-loss integrated passive device bandpass filter of this embodiment working in the N78 frequency band includes a No. 1 LC series resonant circuit, a No. 2 LC parallel resonant circuit, a No. 3 LC parallel resonant circuit and a No. 4 LC series-parallel resonant circuit, the signal input end is connected to the input end of the No. 1 LC series resonant circuit, the signal output end is connected to the output end of the No. 1 LC series resonant circuit, the No. 2 LC parallel resonant circuit is connected in parallel to both ends of the No. 1 LC series resonant circuit, the No. 3 LC parallel resonant circuit is connected in series between the signal input end and the ground, and the No. 4 LC series-parallel resonant circuit is connected in series between the signal output end and the ground;

[0036] The first LC series resonant circuit is composed of inductor L1, capacitor C1 and inductor L2 in series; the second LC parallel resonant circuit is composed of capacitor C2 and inductor L3 in parallel; the third LC parallel resonant circuit is composed of capacitor C3 and inductor L4 in parallel; the fourth LC series-parallel resonant circuit is composed of capacitor C4 and inductor L5 in parallel and then in series with inductor L6.

[0037] The BPF working in the N78 frequency band described in this embodiment introduces transmission zeros at 3.017 GHz and 4.448 GHz, with a minimum insertion loss of 0.824 dB, a maximum insertion loss of 1.215 dB, a maximum in-band return loss of 27.439 dB, and a minimum of 18.145 dB. By connecting a grounded inductor in series in the parallel resonant circuit, a transmission zero can be generated in the right stop band, thereby obtaining a Chebyshev BPF with three zeros in the N78 band with a smaller bandwidth.

[0038] The capacitor and inductor are designed based on Figure 6 In the circuit shown, equations (1)-(4) are used to determine the impedance characteristics to identify the specific components that produce zero points. The impedance of the first resonance is represented by B1, while the impedance of the second resonance is represented by X2, and the other resonant circuits are represented by X3 and X4. The transfer function is calculated by H(jω), as shown in equation (5). After selecting the zero point near the sideband, the value of the capacitor and inductor can be preliminarily calculated by the transfer function. The out-of-band steep drop performance is optimized by the location of the transmission zero point. In this way, the corresponding principle in Example 1 is calculated Figure 6 The values ​​of components are: C1=2.9pF, C2=0.4pF, C3=2.9pF, C4=1.5pF, L1=0.69nH, L2=5.41nH, L3=0.69nH, L4=0.67nH.

[0039]

[0040] The capacitor and inductor are designed by taking into account the influence of high-frequency parasitic parameters and determining the impedance value of each component through moment method simulation optimization.

[0041] The specific method of introducing zero poles in this embodiment is as follows: In order to introduce a zero point in the high-frequency stop band, the third-order Chebyshev filter can connect a series inductor in a parallel resonant circuit, or a parallel capacitor in a series resonant circuit. Doubly, in order to introduce a zero in the low-frequency stop band, a series capacitor can be connected in a parallel resonant circuit, or a parallel inductor can be connected in a series resonant circuit. The number of zeros introduced depends on the number of inductors or capacitors added. By optimizing the filter structure and its layout, the final design introduces zero points in the high-frequency and low-frequency stop bands by connecting parallel inductors and capacitors to the series resonant circuit to reduce the bandwidth of the transition band, and the out-of-band suppression effect is good.

[0042] The TFIPD integrated passive components can be manufactured on different substrates for different product applications, and the substrates can be selected from alumina ceramic substrates, silicon wafers, GaAs substrates and glass substrates.

Claims

Low-loss integrated passive device bandpass filter for 1.5G communication frequency band, characterized by The low-loss integrated passive device bandpass filter of the 5G communication frequency band includes a first LC series resonant circuit, a second LC parallel resonant circuit, a third LC parallel resonant circuit and a fourth LC parallel resonant circuit, the signal input end is connected to the input end of the first LC series resonant circuit, the signal output end is connected to the output end of the first LC series resonant circuit, the second LC parallel resonant circuit is connected in parallel to both ends of the first LC series resonant circuit, the third LC parallel resonant circuit is connected in series between the signal input end and the ground, and the fourth LC parallel resonant circuit is connected in series between the signal output end and the ground; The first LC series resonant circuit is composed of inductor L1, capacitor C1 and inductor L2 in series; the second LC parallel resonant circuit is composed of capacitor C2 and inductor L3 in parallel; the third LC parallel resonant circuit is composed of capacitor C3 and inductor L4 in parallel; the fourth LC parallel resonant circuit is composed of capacitor C4 and inductor L5 in parallel.

2. The low-loss integrated passive device bandpass filter for the 5G communication frequency band according to claim 1, characterized in that The capacitor C1, the capacitor C2, the capacitor C3 and the capacitor C4 are all parallel plate capacitors.

3. The low-loss integrated passive device bandpass filter for the 5G communication frequency band according to claim 1, characterized in that The inductor L1 , the inductor L2 , the inductor L3 , the inductor L4 and the inductor L5 are all planar spiral inductors. Low-loss integrated passive device bandpass filter for 4.5G communication frequency band, characterized by The low-loss integrated passive device bandpass filter of the 5G communication frequency band includes a No. 1 LC series resonant circuit, a No. 2 LC parallel resonant circuit, a No. 3 LC parallel resonant circuit and a No. 4 LC series-parallel resonant circuit, the signal input end is connected to the input end of the No. 1 LC series resonant circuit, the signal output end is connected to the output end of the No. 1 LC series resonant circuit, the No. 2 LC parallel resonant circuit is connected in parallel to both ends of the No. 1 LC series resonant circuit, the No. 3 LC parallel resonant circuit is connected in series between the signal input end and the ground, and the No. 4 LC series-parallel resonant circuit is connected in series between the signal output end and the ground; The first LC series resonant circuit is composed of inductor L1, capacitor C1 and inductor L2 in series; the second LC parallel resonant circuit is composed of capacitor C2 and inductor L3 in parallel; the third LC parallel resonant circuit is composed of capacitor C3 and inductor L4 in parallel; the fourth LC series-parallel resonant circuit is composed of capacitor C4 and inductor L5 in parallel and then in series with inductor L6.

5. The low-loss integrated passive device bandpass filter for the 5G communication frequency band according to claim 4, characterized in that The capacitor C1, the capacitor C2, the capacitor C3 and the capacitor C4 are all parallel plate capacitors.

6. The low-loss integrated passive device bandpass filter for the 5G communication frequency band according to claim 4, characterized in that Inductor L1 , inductor L2 , inductor L3 , inductor L4 , inductor L5 and inductor L6 are all planar spiral inductors.

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