Miniaturized high-selectivity ipd band-pass filter and radio frequency front end

Abstract

The application discloses a miniaturized high-selectivity IPD band-pass filter and a radio frequency front end, which comprises four resonators formed by lumped capacitances and lumped inductances, coupling is formed between adjacent resonators through the lumped capacitances, the four resonators are a first resonator, a second resonator, a third resonator and a fourth resonator, wherein the first resonator, the third resonator and the fourth resonator are formed by the parallel connection of the lumped capacitances and the lumped inductances, and a single zero point is formed on both sides of a passband, the second resonator comprises a Π type network, two parallel resonant networks and a lumped inductance, two branches of the Π type network are connected with the two parallel resonant networks respectively, and then grounded through the same lumped inductance, and three zero points are formed on both sides of the passband. The application guarantees the high selectivity and wide stopband of the circuit, and can well meet the index requirement of a filter device for a 5G communication radio frequency front end module.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a miniaturized, highly selective IPD bandpass filter and radio frequency front end. Background Technology

[0002] With the development of modern wireless communication technology, RF front-end modules face higher demands for miniaturization and integration. As a crucial component in RF front-end modules for signal screening and interference suppression, the performance of filters directly impacts the overall system performance. Achieving miniaturization, high selectivity, and high integration of filters has always been a key research focus for professionals in the RF filter field.

[0003] Traditional bandpass filters suffer from large area and low integration, hindering their application in RF front-ends. Integrated Passive Device (IPD) technology offers a solution to these problems. IPD technology boasts advantages such as small size and high precision, reducing filter size while facilitating integration with other components.

[0004] While IPD technology offers new possibilities for filter design, it also presents some pressing issues. Due to limitations in semiconductor manufacturing processes, miniaturization of filters based on IPD technology often results in lower Q values ​​and higher losses. How to effectively utilize IPD technology to design miniaturized, highly selective filters that meet the needs of modern communication systems while maintaining low losses remains a significant challenge. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this invention is to provide a miniaturized high-selectivity IPD bandpass filter and RF front end.

[0006] This invention employs IPD (Integrated Product Design) technology in its design, with the filter circuit composed of lumped capacitors and inductors. The lumped inductors include three different forms: planar spiral inductors, 3D inductors, and grounded copper pillars. The lumped capacitors utilize a parallel-plate capacitor structure. This hybrid use of inductor structures effectively utilizes space and reduces the filter's size while ensuring filter performance. Furthermore, the resonant structure formed by the lumped capacitors and inductors introduces multiple transmission zeros on both the upper and lower sides of the passband, ensuring high selectivity and a wide stopband for the filter.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A miniaturized, highly selective IPD bandpass filter includes four resonators composed of lumped capacitors and lumped inductors. Adjacent resonators are coupled through lumped capacitors. The four resonators are designated as a first resonator, a second resonator, a third resonator, and a fourth resonator. The first, third, and fourth resonators are composed of lumped capacitors and lumped inductors connected in parallel, forming a single zero on each side of the passband. The second resonator includes a Π-type network, two parallel resonant networks, and a lumped inductor. The two branches of the Π-type network are connected to the two parallel resonant networks respectively, and then grounded through the same lumped inductor, forming three zeros on both sides of the passband.

[0009] Furthermore, it includes the total inductance of the first set, the total inductance of the second set, the total inductance of the third set, the total inductance of the fourth set, the total inductance of the fifth set, the total inductance of the sixth set, the total capacitance of the first set, the total capacitance of the second set, the total capacitance of the third set, the total capacitance of the fourth set, the total capacitance of the fifth set, the total capacitance of the sixth set, the total capacitance of the seventh set, the total capacitance of the eighth set, the total capacitance of the ninth set, the total capacitance of the tenth set, the total capacitance of the eleventh set, and the total capacitance of the twelfth set;

[0010] The first resonator includes a first lumped inductor and a second lumped capacitor connected in parallel;

[0011] The third resonator includes a fourth lumped inductor and a tenth lumped capacitor connected in parallel.

[0012] The fourth resonator includes a fifth lumped inductor and a twelfth lumped capacitor connected in parallel;

[0013] The second resonator includes a second lumped inductor, a third lumped inductor, a sixth lumped inductor, a fourth lumped capacitor, a fifth lumped capacitor, a sixth lumped capacitor, a seventh lumped capacitor, and an eighth lumped capacitor. The second lumped inductor and the fifth lumped capacitor are connected in parallel, with one end connected in series with the fourth lumped capacitor and the other end connected in series with the sixth lumped inductor. The third lumped inductor and the eighth lumped capacitor are connected in parallel, with one end connected in series with the seventh lumped capacitor and the other end connected in series with the sixth lumped inductor. The two ends of the sixth lumped capacitor are respectively connected to the fourth lumped capacitor and the seventh lumped capacitor. The sixth lumped inductor is connected to the second ground port. The second resonator forms three zeros on both sides of the passband.

[0014] One end of the first lumped capacitor is connected to the signal input port and one end of the first resonator, respectively. The other end of the first lumped capacitor is connected to the first ground port. The first resonator is connected to the second resonator through the third lumped capacitor. The second resonator is connected to the third resonator through the ninth lumped capacitor. The third resonator is connected to one end of the fourth resonator through the eleventh lumped capacitor. The other end of the fourth resonator is connected to the signal output port.

[0015] Furthermore, the lumped inductor is based on IPD technology and is implemented in three different forms: planar spiral structure, 3D solid structure, and grounding copper pillar.

[0016] Furthermore, the first and fourth lumped inductors adopt a 3D three-dimensional structure, and the third lumped inductor adopts a 3D layered structure.

[0017] Furthermore, the second and fifth lumped inductors adopt a planar spiral structure.

[0018] Furthermore, the sixth total inductor adopts a grounded copper pillar structure.

[0019] Furthermore, the lumped capacitor adopts a parallel plate capacitor structure.

[0020] Furthermore, it also includes a four-layer dielectric substrate and a three-layer metal layer;

[0021] The four dielectric substrates, arranged from top to bottom, are a first dielectric substrate, a second dielectric substrate, a third dielectric substrate, and a fourth dielectric substrate;

[0022] The three metal layers are a first metal layer, a second metal layer, and a third metal layer. The first metal layer is deposited in a first dielectric substrate, the second metal layer is deposited in a third dielectric substrate, and the third metal layer is deposited in a fourth dielectric substrate. The first metal layer and the second metal layer are connected through a tapered metal via, and the second metal layer and the third metal layer are connected through a cylindrical metal via. The first metal layer and the third metal layer are not directly connected.

[0023] Furthermore, the first dielectric substrate, the third dielectric substrate, and the fourth dielectric substrate are passivation protective layers, and the second dielectric substrate is a glass substrate layer.

[0024] An RF front end includes the aforementioned miniaturized high-selectivity IPD bandpass filter.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] This invention uses IPD technology, combining 3D inductors, planar spiral inductors, and grounded copper pillars to effectively improve filter integration and reduce circuit size without affecting filter passband performance. Multiple transmission zeros are introduced on both sides of the filter passband, providing efficient suppression of adjacent frequency bands beside the passband, ensuring high selectivity and wide stopband of the circuit, and well meeting the performance requirements of 5G communication RF front-end modules for filter components. Attached Figure Description

[0027] Figure 1 This is a chip process structure diagram of the present invention;

[0028] Figure 2 This is the circuit schematic diagram of the present invention;

[0029] Figure 3 This is a 3D model diagram of the circuit structure of the present invention;

[0030] Figure 4 This is the electromagnetic simulation S-parameter curve of the present invention;

[0031] Figure 5 This is a graph of the S-parameters of the passband portion of this invention;

[0032] Figure 6 This is a graph showing the S-parameters of the present invention in the range of 0.7-2 GHz;

[0033] Figure 7 This is a graph showing the S-parameters of the present invention in the 2.4-2.7 GHz range;

[0034] Figure 8 This is a graph showing the S-parameters of the present invention at 5-6 GHz;

[0035] Figure 9 This is a graph showing the S-parameters of the present invention in the second harmonic frequency band;

[0036] Figure 10 This is a graph showing the S-parameters of the present invention at 9-10 GHz. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0038] like Figure 1 As shown, a miniaturized, high-selectivity IPD bandpass filter comprises four dielectric substrates and three metal layers. The four dielectric substrates, from top to bottom, are a first dielectric substrate 101, a second dielectric substrate 102, a third dielectric substrate 103, and a fourth dielectric substrate 104. The first dielectric substrate 101, the third dielectric substrate 103, and the fourth dielectric substrate 104 are passivation protective layers made of polyimide (PI). The second dielectric substrate 102 is a glass substrate layer.

[0039] The three metal layers, from top to bottom, are a first metal layer 201, a second metal layer 202, and a third metal layer 203. The first metal layer 201 is deposited in the first dielectric substrate 101, the second metal layer 202 is deposited in the third dielectric substrate 103, and the third metal layer 203 is deposited in the fourth dielectric substrate 104. The first metal layer 201 and the second metal layer 202 are connected through a tapered metal via, and the second metal layer 202 and the third metal layer 203 are connected through a cylindrical metal via. The first metal layer 201 and the third metal layer 203 are not directly connected.

[0040] like Figure 2 As shown, a miniaturized high-selectivity IPD bandpass filter includes four resonators composed of lumped capacitors and lumped inductors. Adjacent resonators are coupled through lumped capacitors. The four resonators are a first resonator, a second resonator, a third resonator, and a fourth resonator. The first, third, and fourth resonators are composed of lumped capacitors and lumped inductors connected in parallel, forming a single zero on both sides of the passband. The second resonator includes a Π-type network, two parallel resonant networks, and a lumped inductor. The two branches of the Π-type network are connected to the two parallel resonant networks respectively, and then grounded through the same lumped inductor, forming three zeros on both sides of the passband.

[0041] Its specific circuit includes the first lumped inductor L1, the second lumped inductor L2, the third lumped inductor L3, the fourth lumped inductor L4, the fifth lumped inductor L5, the sixth lumped inductor L6, the first lumped capacitor C1, the second lumped capacitor C2, the third lumped capacitor C3, the fourth lumped capacitor C4, the fifth lumped capacitor C5, the sixth lumped capacitor C6, the seventh lumped capacitor C7, the eighth lumped capacitor C8, the ninth lumped capacitor C9, the tenth lumped capacitor C10, the eleventh lumped capacitor C11, and the twelfth lumped capacitor C12.

[0042] The first resonator includes the first lumped inductor L1 and the second lumped capacitor C2 as described above; the second resonator includes the second lumped inductor L2, the third lumped inductor L3, the sixth lumped inductor L6, the fourth lumped capacitor C4, the fifth lumped capacitor C5, the sixth lumped capacitor C6, the seventh lumped capacitor C7, and the eighth lumped capacitor C8 as described above; the third resonator includes the fourth lumped inductor C4 and the tenth lumped capacitor C10 as described above; and the fourth resonator includes the fifth lumped inductor L5 and the twelfth lumped capacitor C12 as described above.

[0043] In the first resonator, the first lumped inductor L1 is connected in parallel with the second lumped capacitor C2; in the third resonator, the fourth lumped inductor L4 is connected in parallel with the tenth lumped capacitor C10; in the fourth resonator, the fifth lumped inductor L5 is connected in parallel with the twelfth lumped capacitor C12. The first, third, and fourth resonators each form a single zero on both sides of the passband.

[0044] In the second resonator, the second lumped inductor L2 is connected in parallel with the fifth lumped capacitor C5, and one end is connected in series with the fourth lumped capacitor C4, while the other end is connected in series with the sixth lumped inductor L6. The third lumped inductor L3 is connected in parallel with the eighth lumped capacitor C8, and one end is connected in series with the seventh lumped capacitor C7, while the other end is also connected in series with the sixth lumped inductor L6. The sixth lumped capacitor C6 is connected to the fourth lumped capacitor C4 and the seventh lumped capacitor C7 on its left and right sides. The second resonator forms three zeros on both sides of the passband.

[0045] The specific connection method is as follows:

[0046] Signal input port 301 is connected to one end of the first capacitor C1, the first inductor L1, and the second capacitor C2. The other end of the first capacitor C1 is connected to the first ground port 303. The other ends of the first inductor L1 and the second capacitor C2 are connected to one end of the third capacitor C3. The other end of the third capacitor C3 is connected to one end of the fourth capacitor C4 and the sixth capacitor C6. The other end of the fourth capacitor C4 is connected to one end of the fifth capacitor C5 and the second inductor L2. The other end of the fifth capacitor C5 and the second inductor L2 is connected to one end of the sixth inductor L6. The other end of the sixth capacitor C6 is connected to one end of the seventh capacitor C7 and the ninth capacitor C9. The other end of capacitor C7 is connected to one end of the eighth capacitor C8 and the third inductor L3. The other end of the eighth capacitor C8 and the third inductor L3 is connected to one end of the sixth inductor L6. The other end of the sixth inductor L6 is connected to the second grounding port 304. The other end of the ninth capacitor C9 is connected to one end of the tenth capacitor C10 and the fourth inductor L4. The other end of the tenth capacitor C10 and the fourth inductor L4 is connected to one end of the eleventh capacitor C11. The other end of the eleventh capacitor C11 is connected to one end of the fifth inductor L5 and the twelfth capacitor C12. The other end of the fifth inductor L5 and the twelfth capacitor C12 is connected to the signal output port 302.

[0047] The first, second, third, and fourth resonators mentioned above achieve a total of six transmission zeros on the left and right sides of the passband, ensuring high selectivity and wide stopband of the circuit.

[0048] like Figure 3 As shown, in this embodiment, the first lumped inductor L1 and the fourth lumped inductor L4 adopt a 3D three-dimensional structure, and the lumped inductor is transferred to the first metal layer wiring, which is far from the ground, through vias; the third lumped inductor L3 adopts a 3D stacked structure, and the parallel traces of the first metal layer and the second metal layer are alternately connected through vias; the second lumped inductor L2 and the fifth lumped inductor L5 adopt a planar spiral structure; the sixth lumped inductor L6 is realized through the connection from the bottom of the chip to the PCB board; by combining the three different structures, the volume is effectively utilized and the filter size is reduced.

[0049] In this embodiment, the first lumped capacitor C1, the second lumped capacitor C2, the third lumped capacitor C3, the fourth lumped capacitor C4, the fifth lumped capacitor C5, the sixth lumped capacitor C6, the seventh lumped capacitor C7, the eighth lumped capacitor C8, the ninth lumped capacitor C9, the tenth lumped capacitor C10, the eleventh lumped capacitor C11, and the twelfth lumped capacitor C12 all adopt a MIM parallel plate structure.

[0050] Reference Figure 3As shown, signal input port 301 is connected to one end of the first lumped capacitor C1, the first lumped inductor L1, and the second lumped capacitor C2. The other end of the first lumped capacitor C1 is connected to the first ground port 303. The other ends of the first lumped inductor L1 and the second lumped capacitor C2 are connected to one end of the third lumped capacitor C3. The other end of the third lumped capacitor C3 is connected to one end of the fourth lumped capacitor C4 and the sixth lumped capacitor C6. The other end of the fourth lumped capacitor C4 is connected to one end of the fifth lumped capacitor C5 and the second lumped inductor L2. The other end of the fifth lumped capacitor C5 and the second lumped inductor L2 is connected to one end of the sixth lumped inductor L6. The other end of the sixth lumped capacitor C6 is connected to one end of the seventh lumped capacitor C7 and the ninth lumped capacitor C9. The other end of the seventh collective capacitor C7 is connected to one end of the eighth collective capacitor C8 and the third collective inductor L3. The other end of the eighth collective capacitor C8 and the third collective inductor L3 is connected to one end of the sixth collective inductor L6. The other end of the sixth collective inductor L6 is connected to the second grounding port 304. The other end of the ninth collective capacitor C9 is connected to one end of the tenth collective capacitor C10 and the fourth collective inductor L4. The other end of the tenth collective capacitor C10 and the fourth collective inductor L4 is connected to one end of the eleventh collective capacitor C11. The other end of the eleventh collective capacitor C11 is connected to one end of the fifth collective inductor L5 and the twelfth collective capacitor C12. The other end of the fifth collective inductor L5 and the twelfth collective capacitor C12 is connected to the signal output port 302.

[0051] The first and fourth lumped inductors both employ a 3D structure, with vias transferring the inductance to the first metal layer, which is farther from ground. The third inductor uses a 3D stacked structure, with vias alternately connecting the parallel traces of the first and second metal layers. The second and fifth lumped inductors use a planar spiral structure. The sixth lumped inductor is implemented through a connection from the bottom of the chip to the PCB board. By combining these three structures, the volume is effectively utilized and the filter size is reduced, achieving filter miniaturization.

[0052] Reference Figure 3 As shown, the miniaturized high-selectivity IPD bandpass filter proposed in this application embodiment has a size of 1250um × 600um;

[0053] Reference Figure 4The figure shows the S-parameter curves from electromagnetic simulation provided in this embodiment. The filter's passband is located between 3.3 and 4.2 GHz, and its return loss within the passband is better than -14 dB. To achieve high selectivity, the S-parameter curves show six transmission zeros on both sides of the passband. There are two transmission zeros on the low-frequency side, located at 1.9 GHz and 2.5 GHz respectively, and four transmission zeros on the high-frequency side, located at 5.2 GHz, 5.6 GHz, 7.3 GHz, and 9.9 GHz respectively. Thanks to the presence of these multiple transmission zeros, the filter achieves high out-of-band rejection and a wide stopband.

[0054] Reference Figure 5 The figure shown is a passband S-parameter curve provided in this embodiment. Within the passband, the filter insertion loss is less than 1.4 dB, and the insertion loss at the passband center frequency (3.75 GHz) is less than 1.2 dB.

[0055] Reference Figure 6 The figure shown is an S-parameter diagram for 0.7-2GHz provided in an embodiment of this application. It can be seen that there is a transmission zero point located between 0.7-2GHz, and the out-of-band suppression is better than 30dB throughout the entire frequency band.

[0056] Reference Figure 7 The diagram shown is a detailed S-parameter diagram for the 2.4-2.7GHz band provided in this embodiment. It can be seen that there is a transmission null point between 2.4-2.7GHz, and within the 2.4-2.5GHz band, out-of-band suppression is better than 30dB, ensuring good isolation from the 2.4GHz WiFi band.

[0057] Reference Figure 8 The diagram shown is a detailed S-parameter diagram for the 5-6GHz band provided in this embodiment. It can be seen that there is a transmission null point near 5.15GHz and another near 5.85GHz. These two points work together to ensure that out-of-band rejection is greater than 39dB in the 5.15-5.85GHz band, thus ensuring good isolation from the 5GHz WiFi band.

[0058] Reference Figure 9 The figure shows the S-parameter diagram of the second harmonic provided in this embodiment. It can be seen that there is a transmission zero located within the second harmonic. Within the second harmonic, the out-of-band rejection is greater than 35dB.

[0059] Reference Figure 10 The figure shown is an S-parameter diagram for the 9-10 GHz band provided in this embodiment. It can be seen that there is a transmission zero point located between 9 and 10 GHz. Below 10 GHz, the out-of-band rejection is greater than 30 dB.

[0060] In summary, the miniaturized, highly selective IPD bandpass filter proposed in this embodiment, by introducing a transmission zero, effectively achieves high out-of-band rejection in the stopband while ensuring low insertion loss in the passband. It achieves out-of-band rejection exceeding 30dB for frequencies below 2GHz, 2.4-2.5GHz, 5.15-5.85GHz, harmonics, and below 10GHz; specifically, for the 5.15-5.85GHz band, the out-of-band rejection is better than 39dB, achieving excellent isolation. This meets the industry's requirements for miniaturized, highly integrated, and highly selective RF filters.

[0061] This invention provides an RF front-end, including the miniaturized high-selectivity IPD bandpass filter described in this embodiment.

[0062] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A miniaturized, highly selective IPD bandpass filter, characterized in that, The device includes four resonators composed of lumped capacitors and lumped inductors. Adjacent resonators are coupled through lumped capacitors. The four resonators are designated as the first resonator, the second resonator, the third resonator, and the fourth resonator. The first, third, and fourth resonators are composed of lumped capacitors and lumped inductors connected in parallel, forming a single zero on both sides of the passband. The second resonator includes a Π-type network, two parallel resonant networks, and a lumped inductor. The two branches of the Π-type network are connected to the two parallel resonant networks respectively, and then grounded through the same lumped inductor, forming three zeros on both sides of the passband. The first resonator includes a first lumped inductor and a second lumped capacitor connected in parallel; The third resonator includes a fourth lumped inductor and a tenth lumped capacitor connected in parallel. The fourth resonator includes a fifth lumped inductor and a twelfth lumped capacitor connected in parallel; The second resonator includes a second lumped inductor, a third lumped inductor, a sixth lumped inductor, a fourth lumped capacitor, a fifth lumped capacitor, a sixth lumped capacitor, a seventh lumped capacitor, and an eighth lumped capacitor. One end of the second lumped inductor and the fifth lumped capacitor connected in parallel is connected in series with one end of the fourth lumped capacitor. One end of the third lumped inductor and the eighth lumped capacitor connected in parallel is connected in series with one end of the seventh lumped capacitor. The other end of the second lumped inductor and the fifth lumped capacitor connected in parallel is connected to the other end of the third lumped inductor and the eighth lumped capacitor connected in parallel at a connection point. One end of the sixth lumped inductor is connected to the connection point, and its other end is connected to the second ground port. The second resonator forms three zeros on both sides of the passband. The miniaturized high-selectivity IPD bandpass filter also includes a first lumped capacitor, a third lumped capacitor, a ninth lumped capacitor, and an eleventh lumped capacitor. One end of the first lumped capacitor is connected to the signal input port and one end of the first resonator, respectively. The other end of the first lumped capacitor is connected to the first ground port. The other end of the first resonator is connected to the connection point of the fourth and sixth lumped capacitors in the second resonator through the third lumped capacitor. The connection point of the sixth and seventh lumped capacitors in the second resonator is connected to the third resonator through the ninth lumped capacitor. The third resonator is connected to one end of the fourth resonator through the eleventh lumped capacitor. The other end of the fourth resonator is connected to the signal output port. The first and fourth sets of total inductance adopt a 3D stereo structure, and the third set of total inductance adopts a 3D layered structure. The second and fifth sets of total inductance adopt a planar spiral structure; The sixth set of total inductors adopts a grounded copper pillar structure; The first to twelfth sets of total capacitors adopt a parallel plate capacitor structure; The miniaturized high-selectivity IPD bandpass filter has a structure comprising four dielectric substrate layers and three metal layers. The four dielectric substrates, from top to bottom, are a first dielectric substrate, a second dielectric substrate, a third dielectric substrate, and a fourth dielectric substrate; The three metal layers are a first metal layer, a second metal layer, and a third metal layer. The first metal layer is deposited in a first dielectric substrate, the second metal layer is deposited in a third dielectric substrate, and the third metal layer is deposited in a fourth dielectric substrate. The first metal layer and the second metal layer are connected through a tapered metal via, and the second metal layer and the third metal layer are connected through a cylindrical metal via. The first metal layer and the third metal layer are not directly connected.

2. The miniaturized high-selectivity IPD bandpass filter according to claim 1, characterized in that, The first dielectric substrate, the third dielectric substrate, and the fourth dielectric substrate are passivation protective layers, and the second dielectric substrate is a glass substrate layer.

3. A radio frequency front end, characterized in that, Including the miniaturized high-selectivity IPD bandpass filter as described in any one of claims 1-2.

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