CN114335942B - TSV-based asymmetric serial cross-coupled filter - Google Patents

Abstract

The invention discloses an asymmetric serial cross-coupling filter based on TSV (through silicon vias), which comprises an upper RDL and a lower RDL which are arranged in parallel along the horizontal direction, wherein a silicon-based substrate is arranged between the upper RDL and the lower RDL, six resonant cavities formed by the TSV are distributed on the silicon-based substrate, and the six resonant cavities are respectively matched with the upper RDL and the lower RDL to form cross coupling combining positive coupling and negative coupling. The invention can realize the filtering function under the terahertz frequency band.

Description

TSV-based asymmetric serial cross-coupling filter

Technical Field

The invention belongs to the technical field of filters, and relates to an asymmetric serial cross-coupled filter based on TSV.

Background

In recent years, due to rapid development of wireless communication and scarcity of spectrum resources, frequency intervals of various wireless communication systems are very close, a device with high selective frequency is required to avoid mutual interference when various wireless communication systems operate, and with rapid development of fifth generation mobile communication technology, millimeter wave technology becomes one of key technologies for 5G communication because of realization of high-speed data transmission. The filter, as a key device of the communication system, plays an important role in frequency selection, and has a crucial influence on the transmission quality of the communication system. Microwave filters have attracted attention as one of the components capable of realizing high-performance rf filtering due to their advantages of high performance, low cost, small size, and the like. And the SIW structure which has the advantages of both high quality factor and low loss of the rectangular waveguide and small volume and easy integration of the microstrip line has very important significance for the development of microwave devices.

Through Silicon Vias (TSV) are vertical interconnection lines in a three-dimensional integrated circuit, and vertical interconnection between chips can be achieved. With the continuous fusion of the TSV technology and the mainstream technology of the chip, the technology is also applied to the field of passive devices, the stacking density of the chips in the three-dimensional direction can be maximized, the overall size is minimized under the condition that the process nodes are not reduced, and the filter based on the TSV has the advantages of small area, easiness in integration, good high-frequency characteristic and the like.

With the rise of communication frequency band of wireless communication system, the working frequency band of wireless system is gradually developing to high frequency band, the radio frequency device designed by using substrate integrated waveguide structure can realize working in terahertz wave band, has good in-band characteristic and is easy to integrate with other plane structure, so that research on the device is carried out.

Disclosure of Invention

The invention aims to provide an asymmetric serial cross-coupled filter based on TSV (through silicon vias), and the filter can realize a filtering function under a terahertz frequency band.

The technical scheme includes that the asymmetric serial cross-coupling filter based on the TSV comprises an upper layer RDL and a lower layer RDL which are arranged in parallel along the horizontal direction, a silicon-based substrate is arranged between the upper layer RDL and the lower layer RDL, six resonant cavities formed by the TSV are distributed on the silicon-based substrate, and the six resonant cavities are respectively matched with the upper layer RDL and the lower layer RDL to form cross coupling combining positive coupling and negative coupling.

The six resonant cavities are respectively: the first resonant cavity, the second resonant cavity, the third resonant cavity, the fourth resonant cavity, the fifth resonant cavity and the sixth resonant cavity;

the first resonant cavity is adjacent to the second resonant cavity and the fourth resonant cavity respectively, and the fourth resonant cavity is adjacent to the first resonant cavity and the fifth resonant cavity respectively.

The implementation mode of the cross coupling structure is as follows: a capacitance negative coupling structure is adopted between the first resonant cavity and the fourth resonant cavity; the positive coupling of the inductor is realized between the first resonant cavity and the second resonant cavity, between the second resonant cavity and the third resonant cavity, between the third resonant cavity and the fourth resonant cavity, between the fourth resonant cavity and the fifth resonant cavity, and between the fifth resonant cavity and the sixth resonant cavity in a windowing manner.

A window A is arranged between the first resonant cavity and the second resonant cavity, a window B is arranged between the second resonant cavity and the third resonant cavity, a window C is arranged between the third resonant cavity and the fourth resonant cavity, a window D is arranged between the fourth resonant cavity and the fifth resonant cavity, and a window E is arranged between the fifth resonant cavity and the sixth resonant cavity.

The first resonant cavity and the second resonant cavity are completely communicated, and the window A is a common side edge between the first resonant cavity and the second resonant cavity.

An S-shaped notch groove a is formed in the upper RDL layer; and the lower layer RDL is provided with an S-shaped notch groove b, the S-shaped notch groove a and the S-shaped notch groove b are corresponding in position and opposite in direction, and the S-shaped notch groove a and the S-shaped notch groove b are right positioned on the common side edge of the first resonant cavity and the fourth resonant cavity.

The invention has the following beneficial effects:

1. the terahertz filter adopts the silicon-based substrate, is compatible with common silicon process products, is easy to integrate with a mainstream CMOS circuit, has low production cost, adopts the silicon material as the substrate, has larger dielectric constant, and can realize the filtering function of the terahertz frequency band.

2. The feeder line in the invention adopts a mode of combining the microstrip line and the coplanar waveguide, so that a good feeding effect is realized with a small enough size.

3. The invention completes filtering by utilizing negative coupling realized by direct coupling and S-shaped cross structures.

Drawings

FIG. 1 is a three-dimensional view of a TSV based asymmetric tandem cross-coupled filter of the present invention;

FIG. 2 is a top view of the upper RDL, TSV and lower RDL connections in the TSV based asymmetric tandem cross-coupled filter of the present invention;

fig. 3 is a simulation graph of the asymmetric serial cross-coupled TSV-based filter in HFSS (High Frequency Structure Simulator).

In the figure, 1.tsv,2. Input RDL port, 3. Output RDL port, 4. Upper RDL,5. Lower RDL,6. First resonant cavity, 7. Second resonant cavity, 8. Third resonant cavity, 9. Fourth resonant cavity, 10. Fifth resonant cavity, 11. Sixth resonant cavity, 12.s-type notch a, and 13.s-type notch b.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The asymmetric serial cross-coupling filter based on TSV comprises an upper layer RDL4 and a lower layer RDL5 which are arranged in parallel as shown in figures 1 and 2 and respectively serve as high and low level areas of a filter circuit, and a silicon-based substrate is arranged between the upper layer RDL4 and the lower layer RDL 5; six resonant cavities formed by TSV are distributed in the center of the silicon substrate, the six resonant cavities, an upper layer RDL4 and a lower layer RDL5 achieve a cross-coupling topological function combining positive coupling and negative coupling, and two opposite sides of the upper layer RDL are respectively provided with an input RDL port 2 and an output RDL port 3.

The asymmetric serial cross-coupling filter based on the TSV is of six orders, namely, the filter is provided with six resonant cavities. The six resonant cavities are respectively a first resonant cavity 6, a second resonant cavity 7, a third resonant cavity 8, a fourth resonant cavity 9, a fifth resonant cavity 10 and a sixth resonant cavity 11;

the first resonant cavity 6 and the fourth resonant cavity 9 adopt a capacitance negative coupling structure. In addition, the other two adjacent resonant cavities sequentially pass through the window to realize inductive positive coupling.

The coupling structure between the input RDL port 2 and the first resonant cavity 6 is the same as the coupling structure between the output RDL port 3 and the sixth resonant cavity 11, and the feeding is realized by adopting a mode of combining a microstrip line and a coplanar waveguide.

The size of input RDL port 2 is: the length is 150 μm and the width is 220 μm. The dimensions of TSV1 are: diameter 10 μm and height 100. Mu.m.

The dimensions of the upper layer RDL4 are: 440 μm in width, 773.48 μm in length and 5 μm in thickness. In order to reduce unnecessary interference and reduce cost, the lower RDL5 is formed by connecting two metal plates; the upper layer RDL4 and the lower layer RDL5 are both L-shaped structures.

An S-shaped notch groove a12 is formed in the upper RDL 4; the lower layer RDL5 is provided with an S-shaped notch groove b13, the directions of the S-shaped notch groove a12 and the S-shaped notch groove b13 are opposite, and the S-shaped notch groove a12 and the S-shaped notch groove b13 are spliced together to form two complete circles.

Two coplanar waveguide notches are respectively formed in the joint of the upper RDL4 and the input RDL port 2 and the joint of the upper RDL4 and the output RDL port 3; the four coplanar waveguide slot notches have the same size and are 20 μm long and 5 μm wide.

A window a is arranged between the first resonant cavity 6 and the second resonant cavity 7, a window B is arranged between the second resonant cavity 7 and the third resonant cavity 8, a window C is arranged between the third resonant cavity 8 and the fourth resonant cavity 9, a window D is arranged between the fourth resonant cavity 9 and the fifth resonant cavity 10, and a window E is arranged between the fifth resonant cavity 10 and the sixth resonant cavity 11. In fig. 2, a, B, C, D, E are the positions of five windows, respectively.

The first resonant cavity 6 comprises two side edges which are respectively a region I, a region II and a region III, and the region II and the region III form one side edge of the first resonant cavity 6; the input RDL port 2 is located at one side of the first resonator 6;

region I includes a total of 10 TSVs 1 from left to right; region II includes 3 TSVs 1 from top to bottom; the area III comprises 3 TSV1 from top to bottom;

the second resonant cavity 7 comprises three side edges which are a region IV, a region V and a region VI respectively, wherein the region IV comprises 10 TSV1 in total from top to bottom; region V includes a total of 11 TSVs 1 from left to right; region VI includes a total of 2 TSVs 1 from top to bottom; window B is located in region VI; the window a is a common side of the first resonator 6 and the second resonator 7.

The third resonant cavity 8 comprises four side edges which are respectively a region VI, a region VII, a region IX and a region VIII;

region VII includes a total of 10 TSVs 1 from left to right; the area IX comprises 9 TSV1 in total from top to bottom; region VIII includes a total of 5 TSVs 1 from left to right; window C is located in region VIII.

The fourth resonant cavity 8 comprises four side edges, namely a region II, a region III, a region VIII, a region XI and a region X; the region II and the region III are added to form the same side edge of the fourth resonant cavity 8;

region X includes a total of 10 TSVs 1 from left to right; the area XI comprises 4 TSV1 in total from top to bottom, and the window D is located in the area XI;

the fifth cavity 10 includes four sides, namely region XI, region XIV, region XIII and region XII, region XIV including a total of 10 TSV1 from left to right; region XII includes a total of 10 TSVs 1 from left to right; the region XIII comprises a total of 2 TSVs 1 from top to bottom; the window E is located in the region XIII.

The sixth resonant cavity 11 includes three sides, which are a region XIII, a region XVI, and a region XV, respectively, and the output RDL port 3 is located at the fourth side of the sixth resonant cavity 11;

region XVI includes a total of 9 TSV1 from left to right; region XV includes a total of 9 TSVs 1 from left to right.

As shown in fig. 3, the filter realized by the present invention has stable and excellent return loss and insertion loss performance. The filter has a center frequency of 281GHz and an insertion loss (S) ₂₁ ) The passband frequency within 2dB is 262.3 GHz-300.7 GHz, the maximum insertion loss within the band is 1.38dB, and the maximum return loss within the band (S11) is 13.9dB. And at frequencies below 243.3GHz and above 333.5GHz the filter return loss is already above 25dB. In addition, the structure utilizes the TSV technology to realize excellent electrical characteristics, the center frequency of the structure is about 281GHz, the structure belongs to a terahertz wave band, and the structure can be applied to the application of the 5G technology and wireless systems such as communication, radar, electronic countermeasure and astronomical observation. The filter has the characteristics of stable performance, miniaturization, high efficiency, low loss and the like, and can be used as a radio frequency filter element for realizing good in-band characteristics and out-of-band characteristics in a terahertz frequency band.

Claims (1)

1. The TSV-based asymmetric serial cross-coupled filter is characterized in that: the silicon-based resonant cavity comprises an upper layer RDL and a lower layer RDL which are arranged in parallel along the horizontal direction, wherein a silicon-based substrate is arranged between the upper layer RDL and the lower layer RDL, six resonant cavities formed by TSV are distributed on the silicon-based substrate, and the six resonant cavities are respectively matched with the upper layer RDL and the lower layer RDL to form cross coupling combining positive coupling and negative coupling;

the six resonant cavities are sequentially arranged according to the direction of an input signal: the first resonant cavity, the second resonant cavity, the third resonant cavity, the fourth resonant cavity, the fifth resonant cavity and the sixth resonant cavity;

the first resonant cavity is respectively adjacent to the second resonant cavity and the fourth resonant cavity, the fourth resonant cavity is respectively adjacent to the first resonant cavity and the fifth resonant cavity, and the sixth resonant cavity is only adjacent to the fifth resonant cavity;

the implementation mode of the cross coupling structure is as follows: a capacitance negative coupling structure is adopted between the first resonant cavity and the fourth resonant cavity; the positive inductive coupling is realized between the first resonant cavity and the second resonant cavity, between the second resonant cavity and the third resonant cavity, between the third resonant cavity and the fourth resonant cavity, between the fourth resonant cavity and the fifth resonant cavity, and between the fifth resonant cavity and the sixth resonant cavity in a windowing way;

a window A is arranged between the first resonant cavity and the second resonant cavity, a window B is arranged between the second resonant cavity and the third resonant cavity, a window C is arranged between the third resonant cavity and the fourth resonant cavity, a window D is arranged between the fourth resonant cavity and the fifth resonant cavity, and a window E is arranged between the fifth resonant cavity and the sixth resonant cavity;

the first resonant cavity and the second resonant cavity are completely communicated, and the window A is a common side edge between the first resonant cavity and the second resonant cavity;

an S-shaped notch groove a is formed in the upper RDL layer; and the lower layer RDL is provided with an S-shaped notch groove b, the S-shaped notch groove a and the S-shaped notch groove b are corresponding in position and opposite in direction, and the S-shaped notch groove a and the S-shaped notch groove b are right positioned on the common side edge of the first resonant cavity and the fourth resonant cavity.

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