Low insertion loss high out-of-band rejection filter based on ipd technology

Abstract

The application discloses a low-insertion-loss high-band-out-suppression filter based on an IPD technology. The application mainly comprises a circuit layer, a ground ring surrounding the circuit layer and a dielectric layer. The circuit layer comprises a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor, a first inductor, a second inductor, a third inductor and a fourth inductor. By adopting an optimized circuit structure, higher high-frequency band-out suppression is achieved, and the filter performance is improved. By adopting a T-shaped circuit to add a controllable zero point, low-frequency band-out suppression is improved. By adopting a line-width-gradually-changing inductor design, the Q value of the inductor is improved, and the insertion loss of the filter is reduced.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency / microwave / communication technology, specifically relating to a low insertion loss and high out-of-band rejection filter based on IPD technology. Background Technology

[0002] Filters play a crucial role in wireless communication systems, and for this reason, the design of high-performance, miniaturized filters has always been a hot research topic in the electronics industry. A bandpass filter is a device that allows waves of a specific frequency band to pass through while blocking other frequency bands. An ideal bandpass filter should have a perfectly flat passband, meaning there is no attenuation within the passband, and all frequencies outside the passband are completely attenuated. Furthermore, the out-of-passband switching should occur within a very small frequency range.

[0003] Current bandpass filter designs mainly suffer from the following problems: As frequency increases, parasitic effects arise, introducing harmonics into the passband, which affects the filter's passband performance; planar bandpass filters based on microstrip lines, while small in size, typically have high insertion loss; bandpass filters based on waveguide structures, while offering good performance, are usually large in size and have low integration density, failing to meet the miniaturization requirements of RF front-ends; high-dielectric-constant ceramic bandpass filters, while exhibiting good out-of-band rejection and stable temperature coefficients, require sophisticated manufacturing processes, resulting in high costs. Adding zeros is an effective method to improve out-of-band rejection, typically done directly during synthesis in the filter design process; however, adjusting the zeros in this method also affects the overall filter performance. Summary of the Invention

[0004] The purpose of this invention is to address the problems of high insertion loss, poor out-of-band rejection, and large size of bandpass filters implemented using traditional processes, as mentioned in the background art. It proposes a low insertion loss, high out-of-band rejection integrated passive device (IPD) bandpass filter. By employing IPD technology, the filter achieves miniaturization; through an optimized circuit topology, high out-of-band rejection is achieved; and by using a tapered spiral inductor, low insertion loss performance is achieved. The addition of a T-shaped zero-point control circuit enables effective zero-point control, meeting the current needs of the RF / microwave / communication technology field.

[0005] The technical solution adopted in this invention is as follows:

[0006] Low insertion loss out-of-band rejection filters based on IPD technology include:

[0007] Circuit layer (1);

[0008] A grounding ring (2) surrounds the circuit layer (1);

[0009] Dielectric layer (3).

[0010] The circuit layer (1) includes a first pad (4-1), a second pad (4-2), a third pad (4-3), a fourth pad (4-4), a fifth pad (4-5), a sixth pad (4-6), a seventh pad (4-7), an eighth pad (4-8), a ninth pad (4-9), 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), a third inductor (63), and a fourth inductor (64).

[0011] The first pad (4-1), the third pad (4-3), the fourth pad (4-4), the fifth pad (4-5), the sixth pad (4-6), the eighth pad (4-8), and the ninth pad (4-9) are connected to the grounding ring (2); the second pad (4-2) and the seventh pad (4-7) serve as the input and output ports of the circuit.

[0012] One end of the first capacitor (51) is connected to the second pad (4-2), and the other end of the first capacitor (42) is connected to one end of the first inductor (61) and one end of the third capacitor (53), respectively. The other end of the first inductor (61) is connected to one end of the second capacitor (52), and the other end of the second capacitor (52) is connected to the grounding ring (2). The other end of the third capacitor (53) is connected to one end of the fourth capacitor (54), and the other end of the fourth capacitor (54) is connected to one end of the second inductor (62). The other end of the second inductor (62) is connected to the fifth capacitor (53). One end of the fifth capacitor (55) is connected to the grounding ring (2), and the other end of the sixth capacitor (55) is connected to one end of the third inductor (63) and one end of the sixth capacitor (56). The other end of the third inductor (63) is connected to the grounding ring (2), and the other end of the sixth capacitor (56) is connected to one end of the seventh capacitor (57) and one end of the eighth capacitor (58). The other end of the seventh capacitor (57) is connected to the grounding ring (2), and the other end of the eighth capacitor (58) is connected to one end of the fourth inductor (64). The other end of the fourth inductor (64) is connected to the seventh pad (4-7).

[0013] The first capacitor (51), the second capacitor (52), the third capacitor (53), the fourth capacitor (54) and the first inductor (61) form a T-shaped zero-point control circuit to control the zero point.

[0014] As a preferred embodiment, the first inductor (61), the second inductor (62), the third inductor (63), and the fourth inductor (64) are spiral inductors with gradually varying line widths. The line width of the spiral inductor gradually increases or decreases as the number of turns of the inductor increases, and its shape is not limited to polygons such as circles, ellipses, rectangles, hexagons, and octagons.

[0015] 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 types, or fractal structures.

[0016] Preferably, the dielectric layer (3) is implemented using semiconductor processes such as GaAs, Si, or glass.

[0017] Preferably, a bandpass filter is constructed from a fifth capacitor (55), a sixth capacitor (56), a seventh capacitor (57), an eighth capacitor (58), a second inductor (62), a third inductor (63), and a fourth inductor (64). The bandpass filter itself has a high-frequency zero at high frequencies. By introducing a T-shaped zero-point control circuit into the bandpass filter, a low-frequency zero is generated at low frequencies. The low-frequency zero is controlled by the second capacitor (52). As the second capacitor (52) increases, the low-frequency zero will move to a lower frequency.

[0018] The beneficial effects of this invention are as follows:

[0019] (1) The design adopts IPD process, and uses spiral inductor and planar capacitor structure to replace the traditional discrete component structure of capacitor and inductor. It can improve the filter performance while achieving miniaturization, and has the advantages of low cost and high integration, making it suitable for mass production.

[0020] (2) An optimized circuit structure is adopted to achieve higher high-frequency out-of-band suppression and improve filter performance.

[0021] (3) By adopting an inductor design with gradually varying linewidth, the Q value of the inductor is improved, and the insertion loss of the filter is reduced. (4) By adding a zero-point control circuit, the low-frequency zero point of the filter can be effectively controlled, thereby improving the out-of-band rejection of the filter. Attached Figure Description

[0022] Figure 1 This is the circuit schematic of the filter;

[0023] Figure 2 This is a schematic diagram of the overall filter structure;

[0024] Figure 3 Here are schematic diagrams of the various structures of the filter;

[0025] Figure 4 (a) and (b) are schematic diagrams of a standard spiral inductor and a gradient spiral inductor, respectively.

[0026] Figure 5 A comparison chart of the Q values ​​of a standard spiral inductor and a tapered spiral inductor;

[0027] Figure 6 This is a diagram showing the effect of capacitor C7 on the zero-point control of the filter.

[0028] Figure 7 The graph shows the return loss and insertion loss results for the filter. Detailed Implementation

[0029] To more clearly illustrate the problems solved by the present invention, the technical solutions adopted, and the beneficial effects, the specific embodiments of the present invention are described below in conjunction with the figures. The preferred embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention. All modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be within the protection scope of the present invention.

[0030] Example 1

[0031] like Figure 2-3 As shown, the low insertion loss out-of-band rejection filter based on IPD technology includes: a circuit layer 1; a grounding ring 2 surrounding the circuit layer 1; and a dielectric layer 3.

[0032] The circuit layer 1 includes a first pad 4-1, a second pad 4-2, a third pad 4-3, a fourth pad 4-4, a fifth pad 4-5, a sixth pad 4-6, a seventh pad 4-7, an eighth pad 4-8, and a ninth pad 4-9. The first pad 4-1, third pad 4-3, fourth pad 4-4, fifth pad 4-5, sixth pad 4-6, eighth pad 4-8, and ninth pad 4-9 are connected to the grounding ring 2; the second pad 4-2 and the seventh pad 4-7 serve as input / output ports for the circuit.

[0033] 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, a third inductor 63, and a fourth inductor 64. One end of the first capacitor 42 is connected to the second pad 4-2. The other end of the first capacitor 51 is connected to one end of the first inductor 61 and one end of the third capacitor 53, respectively. The other end of the first inductor 61 is connected to one end of the second capacitor 52, and the other end of the second capacitor 52 is connected to the grounding ring 2. The other end of the third capacitor 53 is connected to one end of the fourth capacitor 54, and the other end of the fourth capacitor 54 is connected to one end of the second inductor 62. The other end of the second inductor 62 is connected to one end of the fifth capacitor 55. The other end of the fifth capacitor 55 is connected to one end of the third inductor 63 and the sixth capacitor 56, respectively. The other end of the third inductor 63 is connected to the grounding ring 2. The other end of the sixth capacitor 56 is connected to one end of the seventh capacitor 57 and the eighth capacitor 58, respectively. The other end of the seventh capacitor 57 is connected to the grounding ring 2. The other end of the eighth capacitor 58 is connected to one end of the fourth inductor 64. The other end of the fourth inductor 64 is connected to the seventh pad 4-7.

[0034] The first capacitor 51, the second capacitor 52, the third capacitor 53, the fourth capacitor 54 and the first inductor 61 form a T-shaped circuit to achieve zero-point control.

[0035] Figure 1 for Figure 3 The equivalent circuit diagram of the structure shown is as follows: the first capacitor 51 is equivalent to capacitor C1, the second capacitor 52 is equivalent to capacitor C7, the third capacitor 53 is equivalent to capacitor C2, the fourth capacitor 54 is equivalent to capacitor C3, the fifth capacitor 55 is equivalent to capacitor C4, the sixth capacitor 56 is equivalent to capacitor C5, the seventh capacitor 57 is equivalent to capacitor C8, and the eighth capacitor 58 is equivalent to capacitor C6; the first inductor 61 is equivalent to inductance L1, the second inductor 62 is equivalent to inductance L2, the third inductor 63 is equivalent to inductance L3, and the fourth inductor 64 is equivalent to inductance L4.

[0036] like Figure 1 As shown, the working principle of this circuit is as follows: A T-shaped zero-point control circuit is formed by capacitors C1, C2, C3, and C7, and inductor L1. The remaining components constitute a basic bandpass filter. This filter itself has a zero at high frequencies. By adding the T-shaped zero-point control circuit, a zero is generated at low frequencies. This zero can be freely controlled by C7 and has virtually no impact on the filter's passband. Figure 6 As shown.

[0037] like Figure 4 As shown, Figure 4 (a) is a traditional spiral inductor design, where the linewidth of the spiral inductor is fixed. Figure 4(b) shows the gradient spiral inductor design used in this design. The linewidth of this spiral inductor gradually increases with the number of inductor turns. This design effectively improves the Q value of the spiral inductor, thereby reducing the filter loss, such as... Figure 5 As shown.

[0038] like Figure 6 As shown, the low-frequency zero point in this embodiment can be effectively controlled by capacitor C7. As C7 increases, the low-frequency zero point will move to a lower frequency.

[0039] like Figure 7 As shown, the insertion loss in this embodiment is relatively small, about 1.5dB; the return loss in the passband is about -15dB; and a zero is formed at both the high and low frequencies of the passband, which effectively improves the out-of-band rejection level of the filter.

[0040] The above embodiments are not intended to limit the present invention, and the present invention is not limited to the above embodiments. Any embodiment that meets the requirements of the present invention is within the protection scope of the present invention.

Claims

1. Low insertion loss and high out-of-band rejection filters based on IPD technology, including: Circuit layer (1); A grounding ring (2) surrounds the circuit layer (1); Dielectric layer (3); The circuit layer (1) is characterized in that it includes a first pad (4-1), a second pad (4-2), a third pad (4-3), a fourth pad (4-4), a fifth pad (4-5), a sixth pad (4-6), a seventh pad (4-7), an eighth pad (4-8), a ninth pad (4-9), 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), a third inductor (63), and a fourth inductor (64). The first pad (4-1), the third pad (4-3), the fourth pad (4-4), the fifth pad (4-5), the sixth pad (4-6), the eighth pad (4-8), and the ninth pad (4-9) are connected to the grounding ring (2); the second pad (4-2) and the seventh pad (4-7) serve as the input and output ports of the circuit; One end of the first capacitor (51) is connected to the second pad (4-2), and the other end of the first capacitor (51) is connected to one end of the first inductor (61) and one end of the third capacitor (53), respectively. The other end of the first inductor (61) is connected to one end of the second capacitor (52), and the other end of the second capacitor (52) is connected to the grounding ring (2). The other end of the third capacitor (53) is connected to one end of the fourth capacitor (54), and the other end of the fourth capacitor (54) is connected to one end of the second inductor (62). The other end of the second inductor (62) is connected to the fifth capacitor (53). One end of the fifth capacitor (55) is connected to the other end of the third inductor (63) and the sixth capacitor (56), respectively. The other end of the third inductor (63) is connected to the grounding ring (2). The other end of the sixth capacitor (56) is connected to one end of the seventh capacitor (57) and the eighth capacitor (58), respectively. The other end of the seventh capacitor (57) is connected to the grounding ring (2). The other end of the eighth capacitor (58) is connected to one end of the fourth inductor (64), and the other end of the fourth inductor (64) is connected to the seventh pad (4-7). The first capacitor (51), the second capacitor (52), the third capacitor (53), the fourth capacitor (54) and the first inductor (61) form a T-shaped zero-point control circuit to realize the control of the zero point.

2. The low insertion loss, high out-of-band rejection filter based on IPD technology according to claim 1, characterized in that, A bandpass filter is formed by the fifth capacitor (55), the sixth capacitor (56), the seventh capacitor (57), the eighth capacitor (58), the second inductor (62), the third inductor (63), and the fourth inductor (64). The bandpass filter itself has a high-frequency zero at high frequencies. By introducing a T-shaped zero-point control circuit into the bandpass filter, a low-frequency zero is generated at low frequencies.

3. The low insertion loss, high out-of-band rejection filter based on IPD technology according to claim 2, characterized in that, The low-frequency zero point is controlled by the second capacitor (52). As the second capacitor (52) increases, the low-frequency zero point will move to a lower frequency.

4. The low insertion loss, high out-of-band rejection filter based on IPD technology according to claim 2, characterized in that, The first inductor (61), the second inductor (62), the third inductor (63), and the fourth inductor (64) are either planar spiral inductors or surface mount inductors.

5. The low insertion loss, high out-of-band rejection filter based on IPD technology according to claim 2, characterized in that, The first inductor (61), the second inductor (62), the third inductor (63), and the fourth inductor (64) are spiral inductors, and their line width gradually increases, decreases, or remains unchanged as the number of inductor turns increases.

6. The low insertion loss, high out-of-band rejection filter based on IPD technology according to claim 5, characterized in that, Spiral inductors can be circular, elliptical, rectangular, hexagonal, or octagonal in shape.

7. The low insertion loss, high out-of-band rejection 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 either planar capacitors or surface-mount capacitors.

8. The low insertion loss, high out-of-band rejection filter based on IPD technology according to claim 7, characterized in that, The planar capacitor can be constructed using a parallel plate structure, an interdigitated structure, or a fractal structure.

9. The low insertion loss, high out-of-band rejection filter based on IPD technology according to claim 7, characterized in that, The dielectric layer (3) is produced using GaAs or Si processes.

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