Low-insertion-loss band-pass filter based on IPD technology

Abstract

A low-insertion-loss band-pass filter based on IPD technology, which mainly consists of a circuit layer (1), a grounding member (2) surrounding the circuit layer (1), and a dielectric layer (3). The circuit layer (1) comprises a first capacitor (51), a second capacitor (52), a third capacitor (53), a fourth capacitor (54), a fifth capacitor (55), a sixth capacitor (56), a seventh capacitor (57), an eighth capacitor (58), a first inductor (61), a second inductor (62), and a third inductor (63). By using a novel circuit topological structure, the low-insertion-loss performance is realized. Three zero points are generated outside a high frequency band by using two LC series-parallel units, and a grounding capacitor is introduced between the two LC series-parallel units, so that a zero point can also be generated outside a low frequency band; in addition, an additional zero point is generated outside the low frequency band by using an LC series structure, and finally, the matching performance is improved by means of the grounding capacitor between the two LC series-parallel units, thereby implementing the low-insertion-loss band-pass filter.

Description

Low insertion loss bandpass filter based on IPD technology Technical Field

[0001] The present invention belongs to the field of radio frequency / microwave / communication technology, and in particular relates to a low insertion loss bandpass filter based on IPD technology. Background Art

[0002] Bandpass filters play a very important role in the fields of radio frequency, microwave, and communication technology by transmitting signals of specific frequencies and blocking signals of other frequencies. At the same time, a bandpass filter with a flat passband and high out-of-band rejection performance, that is, a bandpass filter with superior performance, can greatly improve the performance of the entire system.

[0003] Current bandpass filter designs face the following challenges: 1. Microstrip and waveguide-based bandpass filters are large, failing to meet the miniaturization requirements of RF front-ends. 2. LTCC-based bandpass filters, while offering low insertion loss, are large and thus fail to meet miniaturization requirements. 3. SAW and BAW filters, while capable of achieving low insertion loss and high out-of-band rejection, are significantly affected by temperature and are costly. 4. IPD filters, while capable of miniaturization, suffer from a low squareness factor, meaning the slope is not sufficiently steep, making it difficult to achieve a balanced balance between insertion loss and out-of-band rejection.

[0004] Therefore, in order to solve the problem of low insertion loss, the present invention introduces a new topology structure, proposes a new topology structure based on the principle, and constructs a low insertion loss bandpass filter based on the integrated passive device (IPD) technology. Summary of the Invention

[0005] The present invention aims to address the high insertion loss and large size of bandpass filters implemented using traditional processes by providing a low-insertion-loss bandpass filter based on IPD technology. By adopting the IPD process, the filter is miniaturized. Low insertion-loss performance is achieved by proposing a novel circuit topology. Two LC series-parallel units are used to generate a zero outside the high-frequency band, thereby widening the bandpass filter's stopband and improving the filter's selectivity. Furthermore, an LC series resonant unit is introduced to generate a zero outside the low-frequency band. Bandpass filters constructed based on this novel topology can meet current demands in the fields of radio frequency, microwave, and communication technologies.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A low insertion loss bandpass filter based on IPD technology, comprising:

[0008] Circuit layer (1);

[0009] A ground ring (2) is arranged around the circuit layer (1);

[0010] dielectric layer (3);

[0011] The circuit layer (1) includes a first pad (4-1), a second pad (4-2), a third pad (4-3), a first capacitor (51), a second capacitor (52), a third capacitor (53), a fourth capacitor (54), a fifth capacitor (55), a sixth capacitor (56), a seventh capacitor (57), an eighth capacitor (58), a first inductor (61), a second inductor (62), and a third inductor (63); the first pad (4-1) is a signal input terminal, the second pad (4-2) is a signal output terminal, and the third pad (4-3) is connected to the ground ring (2);

[0012] One end of the first capacitor (51), one end of the first inductor (61), and one end of the second inductor (62) are respectively connected to the first pad (4-1); the other end of the first inductor (61) is connected to one end of the seventh capacitor (57), and the other end of the seventh capacitor (57) is connected to the ground ring (2); the other end of the first capacitor (51) is connected to one end of the second capacitor (52), the other end of the second capacitor (52) is connected to one end of the third capacitor (53), one end of the fourth capacitor (54), and one end of the third inductor (63), and then connected to one end of the eighth capacitor (58), the other end of the third capacitor (52) is connected to the other end of the second inductor (62), and the other end of the eighth capacitor (58) is connected to the ground ring (2); the other end of the fourth capacitor (54) is connected to one end of the fifth capacitor (55), the other end of the third inductor (63) is connected to one end of the sixth capacitor (56), and the other end of the fifth capacitor (55) is connected to the other end of the sixth capacitor (56), and then connected to the second pad (4-2);

[0013] The first capacitor (51), the second capacitor (52), the third capacitor (53), the second inductor (62), the fourth capacitor (54), the fifth capacitor (55), the sixth capacitor (56), and the third inductor (63) constitute two LC series-parallel resonant units, thereby achieving the regulation of the high-frequency out-of-band zero point.

[0014] The seventh capacitor (57) and the first inductor (61) form an LC series resonance to achieve control of the low-frequency out-of-band zero point.

[0015] Preferably, the first inductor (61), the second inductor (62), and the third inductor (63) are spiral inductors, the line width of the spiral inductors gradually increases or decreases as the number of inductor turns increases, and the shape is not limited to polygons such as circles, ellipses, rectangles, hexagons, and octagons;

[0016] Preferably, the first capacitor (51), the second capacitor (52), the third capacitor (53), the fourth capacitor (54), the fifth capacitor (55), the sixth capacitor (56), the seventh capacitor (57), and the eighth capacitor (58) are planar capacitors, and their structures are not limited to parallel plate structures, interdigitated structures, and fractal structures.

[0017] Preferably, the dielectric layer (3) is made of a semiconductor such as GaAs, Si or glass.

[0018] Two LC series-parallel resonant units are formed by the first capacitor (51), the second capacitor (52), the second inductor (62), the third capacitor (53), the fourth capacitor (54), the fifth capacitor (55), the third inductor (63), and the sixth capacitor (56), which can generate three zero points outside the high-frequency band; then, an LC series resonator is formed by the first inductor (61) and the seventh capacitor (57) to generate a zero point outside the low-frequency band; finally, an eighth capacitor (58) is connected between the two LC series-parallel units to improve the matching performance of the filter, and at the same time, a zero point can be generated outside the low-frequency band. The low-frequency zero point is mainly controlled by the first inductor (61) and the seventh capacitor (57). As the first inductor (61) and the seventh capacitor (57) increase, the low-frequency zero point will move to a lower frequency.

[0019] The beneficial effects of the present invention are:

[0020] (1) The present invention adopts the IPD process, which can achieve the miniaturization of the filter while saving costs, so it can be mass-produced; in addition, the present invention can still achieve a low insertion loss of 0.8 dB while maintaining the advantage of a small size.

[0021] (2) The present invention utilizes a novel topological structure that uses two LC series-parallel resonant units to generate zero points at high frequencies, and then combines this with an LC series resonator to generate zero points at low frequencies. This can significantly reduce the insertion loss of the filter while broadening the high-frequency stopband. The present invention adds zero points outside the high-frequency band by introducing two LC series-parallel resonant structures, and then introduces an LC series resonant unit to introduce zero points at low frequencies. That is, the introduction of multiple zero points can improve the selectivity and flexibility of the bandpass filter, making it applicable to different frequency bands from 0 to 10G, and can also improve the out-of-band suppression performance.

[0022] (3) The present invention adopts an octagonal inductor, which reduces the area while improving the flexibility of the design layout. The four sides of the octagonal inductor are all scalable, simplifying the parameter adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a topological structure diagram of a bandpass filter;

[0024] Figure 2 is a schematic diagram of the overall model of the bandpass filter;

[0025] FIG3 is a schematic diagram of the structures of the bandpass filter;

[0026] FIG4 is a graph showing the S-parameter results of the bandpass filter implementation example.

[0027] In the figure: 1, circuit layer; 2, ground ring; 3, dielectric layer; 4-1, first pad; 4-2, second pad; 4-3, third pad; 51, first capacitor; 52, second capacitor; 53, third capacitor; 54, fourth capacitor; 55, fifth capacitor; 56, sixth capacitor; 57, seventh capacitor; 58, eighth capacitor; 61, first inductor; 62, second inductor; 63, third inductor. Implementation Method

[0028] In order to more clearly illustrate the problems solved by the present invention, the technical solutions adopted and the beneficial effects, the specific implementation methods of the present invention are illustrated below with reference to figures. The preferred embodiments described here are only used to illustrate and explain the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be within the scope of protection of the present invention. Example

[0029] As shown in Figure 2-3, the low insertion loss out-of-band rejection filter based on IPD technology includes: a circuit layer 1; a ground ring 2 surrounding the circuit layer 1; and a dielectric layer 3.

[0030] The circuit layer 1 includes a first pad 4-1, a second pad 4-2, and a third pad 4-3. The first pad 4-1 is a signal input terminal, the second pad 4-2 is a signal output terminal, and the third pad 4-3 is connected to the ground ring 2.

[0031] One end of the first capacitor 51, one end of the first inductor 61, and one end of the second inductor 62 are respectively connected to the first pad 4-1; the other end of the first inductor 61 is connected to one end of the seventh capacitor 57, and the other end of the seventh capacitor 57 is connected to the ground ring 2; the other end of the first capacitor 51 is connected to one end of the second capacitor 52, the other end of the second capacitor 52 is connected to one end of the third capacitor 53, one end of the fourth capacitor 54, and one end of the third inductor 63, and then connected to one end of the eighth capacitor 58, the other end of the third capacitor 52 is connected to the other end of the second inductor 62, and the other end of the eighth capacitor 58 is connected to the ground ring 2; the other end of the fourth capacitor 54 is connected to one end of the fifth capacitor 55, the other end of the third inductor 63 is connected to one end of the sixth capacitor 56, the other end of the fifth capacitor 55 is connected to the other end of the sixth capacitor 56, and then connected to the second pad 4-2;

[0032] The first capacitor 51, the second capacitor 52, the third capacitor 53, the second inductor 62 and the fourth capacitor 54, the fifth capacitor 55, the sixth capacitor 56, and the third inductor 63 constitute two LC series-parallel resonant units to achieve the regulation of the high-frequency out-of-band zero point.

[0033] The seventh capacitor 57 and the first inductor 61 form an LC series resonance to achieve control of the low-frequency out-of-band zero point.

[0034] Figure 1 is an equivalent circuit diagram of the structure shown in Figure 3; the first capacitor 51 in Figure 3 is equivalent to the capacitor C1 in Figure 1, the second capacitor 52 is equivalent to the capacitor C2, the third capacitor 53 is equivalent to the capacitor C3, the fourth capacitor 54 is equivalent to the capacitor C4, the fifth capacitor 55 is equivalent to the capacitor C5, the sixth capacitor 56 is equivalent to the capacitor C6, the seventh capacitor 57 is equivalent to the capacitor C7, and the eighth capacitor 58 is equivalent to the capacitor C8; the first inductor 61 is equivalent to the inductor L1, the second inductor 62 is equivalent to the inductor L2, and the third inductor 63 is equivalent to the inductor L3.

[0035] As shown in Figure 1, the working principle of the circuit is: the first capacitor 51, the second capacitor 52, the third capacitor 53, the second inductor 62 and the fourth capacitor 54, the fifth capacitor 55, the sixth capacitor 56, and the third inductor 63 constitute two LC series-parallel resonance units, which can introduce three zero points outside the high-frequency band; the seventh capacitor 57 and the first inductor 61 form an LC series resonance to achieve control of the zero point outside the low-frequency band.

[0036] As shown in FIG4 , the insertion loss of the present invention is very small, about 0.74 dB; the return loss in the passband is about -20.5 dB; and three zero points are generated outside the high-frequency band, widening the high-frequency stopband; and two zero points are generated outside the low-frequency band, improving the selectivity of the filter.

[0037] The above embodiments are not limitations of the present invention, and the present invention is not limited to the above embodiments. As long as the requirements of the present invention are met, they belong to the protection scope of the present invention.

Claims

1. Low insertion loss bandpass filter based on IPD technology, including: Circuit layer (1); A ground ring (2) surrounding the circuit layer (1); Dielectric layer (3); The circuit layer (1) comprises a first pad (4-1), a second pad (4-2), a third pad (4-3), a first capacitor (51), a second capacitor (52), a third capacitor (53), a fourth capacitor (54), a fifth capacitor (55), a sixth capacitor (56), a seventh capacitor (57), an eighth capacitor (58), a first inductor (61), a second inductor (62), and a third inductor (63); the first pad (4-1) is a signal input terminal, the second pad (4-2) is a signal output terminal, and the third pad (4-3) is connected to a ground ring (2); One end of the first capacitor (51), one end of the first inductor (61), and one end of the second inductor (62) are respectively connected to the first pad (4-1); the other end of the first inductor (61) is connected to one end of the seventh capacitor (57), and the other end of the seventh capacitor (57) is connected to the ground ring (2); the other end of the first capacitor (51) is connected to one end of the second capacitor (52), the other end of the second capacitor (52) is connected to one end of the third capacitor (53), one end of the fourth capacitor (54), and one end of the third inductor (63), and then connected to one end of the eighth capacitor (58); the other end of the third capacitor (52) is connected to the other end of the second inductor (62), and the other end of the eighth capacitor (58) is connected to the ground ring (2); the other end of the fourth capacitor (54) is connected to one end of the fifth capacitor (55), the other end of the third inductor (63) is connected to one end of the sixth capacitor (56), and the other end of the fifth capacitor (55) is connected to the other end of the sixth capacitor (56), and then connected to the second pad (4-2); The first capacitor (51), the second capacitor (52), the third capacitor (53), the second inductor (62), the fourth capacitor (54), the fifth capacitor (55), the sixth capacitor (56), and the third inductor (63) form two LC series-parallel resonance units, thereby achieving regulation of the high-frequency out-of-band zero point; The seventh capacitor (57) and the first inductor (61) form an LC series resonance to achieve control of the zero point outside the low-frequency band.

2. According to claim 1, the low insertion loss bandpass filter based on IPD technology is characterized in that: Two LC series-parallel units are formed by a first capacitor (51), a second capacitor (52), a second inductor (62) and a third capacitor (53) as well as a fourth capacitor (54), a fifth capacitor (55), a third inductor (63) and a sixth capacitor (56), which can generate three zero points outside the high-frequency band; an LC series resonator is formed by the first inductor (61) and the seventh capacitor (57) to generate a zero point outside the low-frequency band; and finally, an eighth capacitor (58) is connected between the two LC series-parallel units to improve the matching performance of the filter, and at the same time, a zero point can be generated outside the low-frequency band.

3. According to claim 2, the low insertion loss bandpass filter based on IPD technology is characterized in that: The low-frequency zero point is mainly controlled by the first inductor (61) and the seventh capacitor (57). As the first inductor (61) and the seventh capacitor (57) increase, the low-frequency zero point will move to a lower frequency.

4. According to claim 2, the low insertion loss bandpass filter based on IPD technology is characterized in that: The two LC series-parallel units formed by the first capacitor (51), the second capacitor (52), the second inductor (62) and the third capacitor (53) and the fourth capacitor (54), the fifth capacitor (55), the third inductor (63) and the sixth capacitor (56) can generate three zero points outside the high frequency band.

5. The low insertion loss bandpass filter based on IPD technology according to claim 2, characterized in that: The first inductor (61), the second inductor (62), and the third inductor (63) are spiral inductors, the line width of which gradually increases or gradually decreases or remains unchanged as the number of inductor turns increases.

6. The low insertion loss bandpass filter based on IPD technology according to claim 5, characterized in that: The shape of the spiral inductor is circular, oval, rectangular, hexagonal or octagonal.

7. The low insertion loss bandpass filter based on IPD technology according to claim 5, characterized in that: The first capacitor (51), the second capacitor (52), the third capacitor (53), the fourth capacitor (54), the fifth capacitor (55), the sixth capacitor (56), the seventh capacitor (57), and the eighth capacitor (58) are planar capacitors or chip capacitors.

8. The low insertion loss bandpass filter based on IPD technology according to claim 7, characterized in that: The structure of the planar capacitor adopts a parallel plate structure, an interdigital structure or a fractal structure.

9. The low insertion loss bandpass filter based on IPD technology according to claim 7, characterized in that: The dielectric layer (3) is made using GaAs technology, Si technology or semiconductor technology.

10. The low insertion loss bandpass filter based on IPD technology according to claim 7, characterized in that: It can be transplanted to other working frequency bands through frequency.

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