Three-dimensional integrated all-symmetrical transformer balun applied to millimeter wave band

Abstract

The application discloses a three-dimensional integrated full-symmetry transformer balun applied to a millimeter wave band, which comprises two layers of silicon dioxide isolation layers arranged from top to bottom, a top layer RDL metal wiring loop A and a top layer RDL metal wiring loop B are distributed on the silicon dioxide isolation layer at the upper layer, and a group of bottom layer RDL metal wiring loops are distributed on the silicon dioxide isolation layer at the lower layer, the bottom layer RDL metal wiring loops are located between the top layer RDL metal wiring loop A and the top layer RDL metal wiring loop B, and the top layer RDL metal wiring loop A, the top layer RDL metal wiring loop B and the bottom layer RDL metal wiring loops are connected through TSV cylinders. The balun structure designed by the application can effectively reduce the volume of the balun and improve the balance of the transformer balun.

Description

Technical Field

[0001] This invention belongs to the field of passive device technology and relates to a three-dimensional integrated fully symmetrical transformer balun applied in the millimeter-wave band. Background Technology

[0002] Baluns are widely used in differential circuit design, such as power amplifiers, balanced mixers, and antenna feed networks. As a key component providing differential signals in a circuit, the balun converts an unbalanced single-ended signal into two balanced signal components with the same amplitude and a 180° phase difference. Baluns are generally classified as active or passive. Passive baluns offer advantages such as high phase balance, amplitude equalization, small size, and wide bandwidth, and can be implemented in various ways. Transformer baluns are among the most popular passive baluns because they are unaffected by wavelength coupling length.

[0003] TSV technology, as a crucial component of 3D integrated circuits, acts as a "bridge" between layers in 3D-ICs, enabling information exchange and transmission between them. In planar integrated circuits, chips are connected via metal wires, while in vertical interconnects, all different chips and systems can be stacked together. This significantly improves transmission efficiency, reduces power consumption, and saves costs, freeing integrated circuit design from the constraints of a two-dimensional plane and granting greater freedom. Furthermore, it exhibits excellent reliability in terms of mechanical strength, thermal stress, and heat dissipation, making it one of the best solutions for overcoming the size limitations of two-dimensional integrated circuits. Summary of the Invention

[0004] The purpose of this invention is to provide a three-dimensional integrated fully symmetrical transformer balun for millimeter-wave bands. This balun structure can effectively reduce the volume of the balun while improving the balance of the transformer balun.

[0005] The technical solution adopted in this invention is a three-dimensional integrated fully symmetrical transformer balun applied to the millimeter-wave band, comprising two layers of silicon dioxide isolation layers arranged from top to bottom. Top RDL metal cloth coil A and top RDL metal cloth coil B are distributed on the upper silicon dioxide isolation layer, and a set of bottom RDL metal cloth coils are distributed on the lower silicon dioxide isolation layer. The bottom RDL metal cloth coils are located between the top RDL metal cloth coils A and B, and the top RDL metal cloth coils A and B are connected to the bottom RDL metal cloth coils via TSV cylinders.

[0006] The invention is further characterized by:

[0007] The top layer RDL metal cloth coil A, the top layer RDL metal cloth coil B, and the bottom layer RDL metal cloth coil all have two layers of turns.

[0008] The outer layers of the top RDL metal cloth coil A and the top RDL metal cloth coil B are both input circuits, and the inner layers of the top RDL metal cloth coil A and the top RDL metal cloth coil B are both output circuits; the outer layer of the bottom RDL metal cloth coil is an output circuit, and the inner layer of the bottom RDL metal cloth coil is an input circuit.

[0009] The outer layers of both the top RDL metal cloth coil A and the top RDL metal cloth coil B are connected to the inner layers of the bottom RDL metal cloth coil via TSV cylinders.

[0010] The outer interface of the top layer RDL metal cloth coil A is connected to the input tap and the input GND tap respectively, and the inner interface of the top layer RDL metal cloth coil A is connected to the center tap; the inner interface of the top layer RDL metal cloth coil B is connected to the output tap I and the output tap II respectively.

[0011] The beneficial effects of this invention are that it provides a fully symmetrical and compact transformer balun based on TSV. It reduces the balun area while achieving higher integration density and improving balun balance. Utilizing the excellent electrical characteristics of TSV technology, the signal transmission path is shortened, and the upper and lower layer output ports can be flexibly configured. Compared to ordinary baluns, this balun implemented using TSV exhibits better symmetry and balance, better out-of-band rejection characteristics, a compact structure, and simple design. Furthermore, it can interconnect with other circuits using the RDL on the substrate, improving three-dimensional integrated packaging and enabling wide application in various RF circuits. Attached Figure Description

[0012] Figure 1 This is an axonometric view of the three-dimensional integrated fully symmetrical transformer balun applied to the millimeter-wave band of this invention;

[0013] Figure 2 This is a top view of the three-dimensional integrated fully symmetrical transformer balun of the present invention applied to the millimeter-wave band;

[0014] Figure 3 This is a cross-sectional view of the three-dimensional integrated fully symmetrical transformer balun applied to the millimeter-wave band according to the present invention.

[0015] In the diagram, 1. Input tap, 2. Center tap, 3. Input GND tap, 4. RDL metal routing layer I, 5. RDL metal routing layer II, 6. TSV cylinder I, 7. TSV cylinder II, 8. RDL metal routing layer III, 9. RDL metal routing layer IV, 10. TSV cylinder III, 11. TSV cylinder IV, 12. RDL metal routing layer V, 13. RDL metal routing layer VI, 14. Output tap I, 15. 16. Output tap II, 17. Silicon substrate, 18. TSV cylinder V, 19. TSV cylinder VI, 20. Silicon dioxide isolation layer, 21. RDL metal wiring layer VII, 22. TSV cylinder VII, 23. TSV cylinder VIII, 24. RDL metal wiring layer VIII, 25. TSV cylinder IX, 26. TSV cylinder X, 27. RDL metal wiring layer X, 28. Silicon dioxide insulating layer. Detailed Implementation

[0016] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0017] This invention applies to a three-dimensional integrated fully symmetrical transformer balun in the millimeter-wave band, with the structure as follows: Figure 1 As shown, the input loop path is as follows: the input signal enters from input tap 1, passes through RDL metal wiring layer X27, passes through TSV cylinder IX25 to reach the bottom RDL metal wiring layer VIII23, the bottom RDL metal wiring layer VIII23 passes through TSV cylinder VIII22 to reach the top RDL metal wiring layer V12, the top RDL metal wiring layer V12 passes through TSV cylinder III10 to reach the bottom RDL metal wiring layer IV9, then passes through TSV cylinder II7 to reach the top RDL metal wiring layer II5, and finally goes from input GND tap 3 to GND.

[0018] The output is connected to GND at one end of the center tap 2 port and to the top RDL metal routing layer I4 at the other end. It then passes through TSV cylinder X26 to the bottom RDL metal routing layer IX24, through TSV cylinder I6 to the bottom RDL metal routing layer III8, and then through TSV cylinders VII21 and IV11 to the top RDL metal routing layer VII20 and RDL metal routing layer VI13. Finally, it passes through TSV cylinders VI18 and V17 to the parallel output taps I14 and II15.

[0019] The transformer balun is coupled by the inner and outer RDL line sidewalls, such as Figure 2As shown, the inner RDL metalline diameter is 80µm, the RDL metalline width is 10µm, and the RDL metalline thickness is 3µm; the input tap metalline length is 20µm, and the output tap metalline length is 35µm. The RDL layer includes the RDL wiring layer, which is disposed within a silicon dioxide isolation layer, as shown below. Figure 3 As shown in the example, the upper end of TSV cylinder I6 is connected to RDL metal wiring layer I4, the lower end of TSV cylinder I6 is connected to RDL metal wiring layer III8, the upper end of TSV cylinder X26 is connected to RDL metal wiring layer I4, and the lower end of TSV cylinder X26 is connected to RDL metal wiring layer IX24. RDL metal wiring layer I4 and RDL metal wiring layer IX24 are both disposed in silicon dioxide isolation layer 19. The outer walls of TSV cylinder I6 and TSV cylinder X26 are wrapped with silicon dioxide insulating layer 28. TSV cylinder I6 and TSV cylinder X26 are located in silicon substrate 16.

[0020] This invention relates to a three-dimensional integrated fully symmetrical transformer balun in the millimeter-wave band. It consists of a center-tapped transformer coupling, with the physical and electrical centers of the output circuit defined by the center tap, which is grounded. The other two ports are the output terminals. The top and bottom RDL metal cloth coils are connected by a TSV cylinder, and both are surrounded by a silicon dioxide insulating layer. The outer layer of the top RDL metal cloth coil is the input circuit, and the inner layer is the output circuit; similarly, the outer layer of the bottom RDL metal cloth coil is the output circuit, and the inner layer is the input circuit. The transformer balun uses copper for the top RDL, bottom RDL, and GND, all with a thickness of 3µm and a linewidth of 10µm. The silicon dioxide insulating layer of the RDL is 6µm thick. The height of the TSV cylinder connecting to the RDL is 1µm, the TSV cylinder height is 100µm, the diameter of the TSV metal cylinder is 10µm, and the thickness of the outer silicon dioxide insulating layer of the TSV is 1µm.

[0021] This invention features a dual-layer transformer balun design. This design effectively reduces parasitic capacitance between RDLs and allows for flexible adjustment of coupling circuits and input / output ports to achieve a smaller footprint and improve the independence of the transformer balun. Compared to traditional transformer baluns, it makes more efficient use of space within a limited area; it significantly improves the phase and amplitude balance of the balun, while effectively suppressing common-mode noise, increasing output power, and enhancing anti-interference capabilities. The transformer balun of this invention has an insertion loss of less than 1.3dB, a return loss greater than 10dB, a phase balance of less than 5°, and an amplitude balance of less than 1dB. It features a compact design, simple structure, and easy integration with other silicon-based devices.

Claims

1. A three-dimensional integrated fully symmetrical transformer balun applied to the millimeter-wave band, characterized in that: It includes two layers of silica isolation layer (19) arranged from top to bottom. Top RDL metal cloth coil A and top RDL metal cloth coil B are distributed on the upper silica isolation layer (19), and a set of bottom RDL metal cloth coils are distributed on the lower silica isolation layer (19). The bottom RDL metal cloth coils are located between the top RDL metal cloth coil A and the top RDL metal cloth coil B, and the top RDL metal cloth coil A and the top RDL metal cloth coil B are connected to the bottom RDL metal cloth coils through TSV cylinders.

2. The three-dimensional integrated fully symmetrical transformer balun applied to the millimeter-wave band according to claim 1, characterized in that: The top layer RDL metal cloth coil A, the top layer RDL metal cloth coil B, and the bottom layer RDL metal cloth coil all have two layers of turns.

3. The three-dimensional integrated fully symmetrical transformer balun applied to the millimeter-wave band according to claim 2, characterized in that: The outer layers of the top-layer RDL metal cloth coil A and the top-layer RDL metal cloth coil B are both input circuits, and the inner layers of the top-layer RDL metal cloth coil A and the top-layer RDL metal cloth coil B are both output circuits; the outer layer of the bottom-layer RDL metal cloth coil is an output circuit, and the inner layer of the bottom-layer RDL metal cloth coil is an input circuit.

4. The three-dimensional integrated fully symmetrical transformer balun applied to the millimeter-wave band according to claim 3, characterized in that: The outer layers of both the top-layer RDL metal cloth coil A and the top-layer RDL metal cloth coil B are connected to the inner layer of the bottom-layer RDL metal cloth coil via TSV cylinders.

5. The three-dimensional integrated fully symmetrical transformer balun applied to the millimeter-wave band according to claim 4, characterized in that: The outer interface of the top layer RDL metal cloth coil A is connected to the input tap (1) and the input GND tap (3) respectively, and the inner interface of the top layer RDL metal cloth coil A is connected to the center tap (2); the inner interface of the top layer RDL metal cloth coil B is connected to the output tap I (14) and the output tap II (15) respectively.

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