A terahertz radiation source based on a dielectric lens package with an air cavity

Abstract

The present invention discloses a terahertz radiation source based on a package with an air cavity dielectric lens, and relates to the field of terahertz radio frequency technology. The radiation source comprises: a dielectric lens with an air cavity, a terahertz radiation source chip, an FR4 circuit board, and a bonding gold wire. The terahertz radiation source chip is connected to the FR4 circuit board via a bonding gold wire, and the FR4 circuit board provides the terahertz radiation source chip with an operating voltage and a DC filter circuit. The core component of the terahertz radiation source adopts a resonant tunneling diode, which utilizes the negative resistance characteristics of the resonant tunneling diode and the equivalent inductance of the radiating antenna to form an LC oscillation to generate a terahertz radiation signal, which is radiated into free space through the dielectric lens with an air cavity. The present invention adopts a dielectric lens with an air cavity to package the terahertz radiation source, thereby improving the effective radiation power of the terahertz radiation source, having the advantages of high directivity and easy integration, and having important application value in long-distance terahertz communication and high-precision terahertz detection.

Description

Technical Field

[0001] The present invention relates to the field of terahertz radio frequency technology, and in particular to a terahertz radiation source based on a dielectric lens package with an air cavity. Background Art

[0002] Terahertz (THz) waves are electromagnetic waves between microwaves and infrared, with frequencies ranging from 0.1 to 10 THz. They bridge the gap between microwaves and infrared light and are considered a transitional stage between macroscopic electronics and microscopic optoelectronics. The practical application of THz technology is inseparable from the development of THz sources. As indispensable devices in systems such as THz communications, THz radar, and THz high-precision imaging, THz sources transmit signals and provide local oscillator signals within these systems. As a crucial component of the RF front-end, THz source power, efficiency, and stability are key performance indicators and represent bottlenecks hindering the practical application of current THz systems.

[0003] To realize an efficient, high-power terahertz radiation source, it is necessary to integrate a high-performance antenna with an oscillator circuit and couple the generated terahertz radiation into free space, thus achieving on-chip integrated terahertz radiation technology. To radiate most of the RF power in a specific direction and provide a greater coverage distance, an antenna with high gain and directivity is ideal. Integrating a high-performance antenna with an oscillator circuit ensures that most of the generated RF power is radiated into free space.

[0004] Antennas designed on high-dielectric-constant substrates radiate most of their energy into or through the substrate. Furthermore, any radiation incident on the substrate at angles greater than the critical angle is completely internally reflected at the top and bottom surfaces, confining the energy within the substrate. As long as the edge is continuous, the radiated energy is confined within the substrate and not released into free space, degrading antenna performance. A common solution is to use a hemispherical lens on the back side to collect power from the substrate's bottom surface. This approach achieves collimated radiation with a narrow half-power beamwidth. This narrow beamwidth is highly advantageous for point-to-point communication scenarios. However, the commonly used lens-to-chip connection is an "inverted lens" structure. This structure uses back-radiation, with the silicon lens bonded to the bottom of the chip. A tight fit between the lens and chip is difficult to achieve, and gaps are difficult to avoid. These small air gaps can cause multiple reflections and resonances at the lens edge, degrading output matching and radiation characteristics. This effect is particularly pronounced with high-dielectric-constant dielectric lenses. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned shortcomings and propose a terahertz radiation source based on a dielectric lens package with an air cavity. The dielectric lens with an air cavity is used to improve the effective radiation power and other performance of the terahertz radiation source chip, protect the terahertz radiation source chip, promote the compact design and lightweight of the RF front end, and has broad application prospects in the fields of long-distance terahertz communication and high-precision terahertz detection.

[0006] In order to achieve the above invention, the present invention provides the following technical solutions:

[0007] A terahertz radiation source based on a dielectric lens package with an air cavity, comprising a dielectric lens, a bonding gold wire, a terahertz radiation source chip, and an FR4 circuit board;

[0008] The dielectric lens is used to achieve high-gain forward radiation, and the terahertz radiation source chip is located in the air cavity of the dielectric lens to achieve protection and packaging of the terahertz radiation source chip;

[0009] The terahertz radiation source chip is used to generate and radiate a terahertz oscillation signal;

[0010] The FR4 circuit board is used to feed the DC signal of the terahertz radiation source chip and implement the DC filtering circuit;

[0011] The bonding gold wire is used to connect the power supply end of the terahertz radiation source chip and the FR4 circuit board.

[0012] Furthermore, the dielectric lens is arranged on the upper surface of the FR4 circuit board, and the bottom of the dielectric lens is concave and forms the air cavity with the FR4 circuit; the terahertz radiation source chips are all located in the air cavity, and the terahertz radiation source chips are installed on the top of the FR4 circuit, and the power supply end of the terahertz radiation source chip is connected to the FR4 circuit board through a bonding wire.

[0013] Furthermore, the dielectric lens is realized by using high-resistance silicon, nylon, glass fiber, plastic or photosensitive resin dielectric material.

[0014] Furthermore, the dielectric lens is realized by micromachining, laser processing, ultra-precision cutting, molding or 3D printing.

[0015] Furthermore, the terahertz radiation source chip is a terahertz patch antenna or a terahertz slot antenna.

[0016] Furthermore, the dielectric layer of the radiation antenna of the terahertz radiation source chip is made of any one or a combination of several of SU-8, polyimide, benzocyclobutene and silicon nitride.

[0017] Furthermore, the core component of the terahertz radiation source chip is a resonant tunneling diode, which forms a terahertz frequency band LC oscillation circuit with the equivalent inductance of the radiation antenna to generate a terahertz signal.

[0018] Furthermore, the semiconductor substrate material used in the terahertz radiation source chip is any one of indium phosphide, gallium arsenide and silicon, or a combination of several of them.

[0019] Furthermore, the main body of the dielectric lens is a hemispherical lens; the plane of the hemispherical lens extends outward; the optimal extension length of the hemispherical lens is L0, which is expressed as: ;

[0020] Among them, the radius of the hemispherical lens is R, and the dielectric constant of the lens material is ɛ L .

[0021] Furthermore, the optimal length of the air cavity is obtained as follows:

[0022] Step 1: The extension length of the hemispherical lens is the initial value L1, which is the sum of the optimal extension length L0 and the margin b; the step is performed according to the actual processing progress, changing from 0 to L1, and the step value is c;

[0023] Step 2: For a specific extension length L2, use the ray tracing method to calculate the focal length F corresponding to the current extension length, and the air cavity height a0=F-L2, where L2 is nc, n is the number of steps, and 0≤L2≤L1;

[0024] Step 3: Based on the obtained dielectric lens values, a simulation model of the lens antenna is established in the simulation software FECO. The simulated air cavity height range is: a0±0.2×a0, and the S parameters of the lens antenna are obtained.

[0025] Step 4: Repeat steps 2 and 3 to obtain the S parameters under different extension lengths L2. Import each S parameter into the simulation software ADS and perform a joint simulation analysis with the resonant tunneling diode device. By comparing the results, the optimal air cavity height and radiation power values ​​are obtained.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] 1. The terahertz radiation source with air cavity dielectric lens package provided by the present invention can realize forward radiation of the radiation source and improve the radiation efficiency of the radiation source.

[0028] 2. The terahertz radiation source with air cavity dielectric lens packaging provided by the present invention adopts the method of air cavity dielectric lens to realize the packaging design of terahertz radiation source chip, which reduces the volume and weight of the lens, protects the chip placed therein, improves the radiation performance of the radiation source, and promotes the compactness and lightweight of the radiation source. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure is a schematic structural diagram of a terahertz radiation source based on a dielectric lens package with an air cavity according to the present invention.

[0030] Figure 2 Schematic diagram of the dielectric lens structure with an air cavity.

[0031] Figure 3 Schematic diagram of the terahertz radiation source chip.

[0032] Figure 4 This is the A-A' cross-sectional view of the terahertz radiation source chip.

[0033] Figure 5 This is the BB' cross-sectional view of the terahertz radiation source chip. DETAILED DESCRIPTION

[0034] The following describes the technical solutions of exemplary embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, and not all of them. The described embodiments are intended for illustration only and are not intended to limit the scope of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0035] like Figure 1 As shown, the terahertz radiation source structure provided in the embodiment includes a dielectric lens 1 with an air cavity 1-2, a bonding gold wire 5, a terahertz radiation source chip 4, and an FR4 circuit board 3, wherein the main components of the terahertz radiation source chip 4 include a radiation antenna 4-2 and a resonant tunneling diode 4-1.

[0036] The DC signal passes through the feed and filter network of the FR4 circuit board 3 and, via the gold bonding wire 5, supplies DC power to the resonant tunneling diode 4-1. This biases the resonant tunneling diode 4-1 to its negative resistance state, creating a terahertz oscillation with the equivalent inductance of the radiating antenna 4-2, generating a terahertz signal. The generated terahertz signal passes through the dielectric lens 1 with the air cavity 1-2, enhancing the performance of the radiated signal, and is then radiated into free space.

[0037] Reference Figure 2, where R is the radius of the lens hemisphere, L is the extended length of the lens with air cavity 1-2, a is the height of air cavity 1-2, and b is the width of air cavity 1-2. For the optimal extended length L0 of the traditional extended hemispherical lens, it is related to the dielectric constant of the lens material (ɛ L ) is related to the radius R and can be expressed as:

[0038] .

[0039] Theoretically, the maximum directivity coefficient can be achieved by satisfying L + a equal to the focal length F for the lens with air cavity 1-2. However, considering the actual physical dimensions of the lens and chip, the lengths of L and a will vary. Therefore, the extended length of dielectric lens 1 with air cavity 1-2 and the dimensions of air cavity 1-2 require further optimization using electromagnetic simulation algorithms. The optimization process is as follows:

[0040] Step 1: Use the extended length of the traditional extended hemispherical lens as the initial value L1. The length of L1 is generally slightly larger than L0. It is stepped according to the actual processing progress, changing from 0 to L1.

[0041] Step 2: For a specific extension length L2, the corresponding focal length is calculated using the ray tracing method to obtain the initial air cavity 1-2 height a0; L2 is the total step length, that is, the product of the step value and the number of steps.

[0042] Step 3: Based on the obtained values ​​of dielectric lens 1, a simulation model of the lens antenna is established in the simulation software FECO. The height range of the simulated air cavity 1-2 is: a0±0.2×a0, and the S parameters of the lens antenna are obtained.

[0043] Step 4. Repeat steps 2 and 3 to obtain the S parameters under different extension lengths L2. Import each S parameter into the simulation software ADS and perform joint simulation analysis with the resonant tunneling diode 4-1 device. By comparing the results, the optimal air cavity 1-2 height and radiation power value are obtained.

[0044] Reference Figure 3 The terahertz radiation source includes a resonant tunneling diode 4-1, a radiating antenna 4-2, a feed line 4-3, a capacitor 4-4, a resistor 4-5, a ground 4-6, a substrate 4-7, a dielectric layer a4-8, a dielectric layer b4-9, and a metallized via 4-10.

[0045] The resonant tunneling diode 4 - 1 operates in a negative resistance region and is used to generate a terahertz signal together with the radiating antenna 4 - 2 .

[0046] The radiation antenna 4-2 is mainly used to form terahertz oscillation with the resonant tunneling diode 4-1 and radiate the generated terahertz signal. By changing the size of the radiation antenna 4-2, a terahertz radiation source with different oscillation frequencies can be realized.

[0047] The feed line 4 - 3 is mainly used to supply power to the resonant tunneling diode 4 - 1 via an external DC signal.

[0048] The capacitor 4-4 is mainly used to short-circuit the radio frequency signal to the ground 4-6 during transmission, thereby reducing radio frequency signal loss.

[0049] The resistors 4-5 are mainly used to suppress low-frequency oscillation and improve the stability of the radiation source.

[0050] The grounds 4-6 are mainly used for grounding the entire radiation source.

[0051] In order to realize the forward radiation of the terahertz radiation source, the radiation antenna 4-2 of the terahertz radiation source based on the resonant tunneling diode 4-1 is designed with low dielectric constant materials, such as Figure 4 shown.

[0052] The dielectric layer A is mainly used to realize the feed line 4 - 3 , thereby reducing the impact of feeding through the radiating antenna 4 - 2 on the entire radiation source.

[0053] The dielectric layer B is mainly used to realize the dielectric layer of the radiating antenna 4-2. By optimizing the thickness of the dielectric layer B and different dielectric materials, the radiating antenna 4-2 with the best performance is obtained, thereby improving the radiation performance of the radiation source.

[0054] The present embodiment proposes a terahertz radiation source based on a dielectric lens 1 packaged with an air cavity 1-2, which can realize forward radiation of the radiation source. The packaging design of the terahertz radiation source chip 4 is realized by using a dielectric lens 1 with an air cavity 1-2, which reduces the volume and weight of the lens, protects the chip placed therein, improves the radiation performance of the radiation source, and promotes the compactness and lightweight of the radiation source.

[0055] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the optimal embodiment of the present invention and does not limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

[0056] It should be understood that the above description of the specific implementation methods of this patent is merely an exemplary description listed to facilitate ordinary technicians in this field to understand the patent solution, and does not imply that the scope of protection of this patent is limited to these individual examples. Ordinary technicians in this field can fully understand the technical solution of this patent and, without any creative work, obtain more specific implementation methods by combining technical features, replacing some technical features, adding more technical features, etc. to the examples listed in this patent. All these specific implementation methods are within the scope of the claims of this patent. Therefore, these new specific implementation methods should also be within the scope of protection of this patent.

Claims

1. A terahertz radiation source based on a dielectric lens package with an air cavity, characterized in that: It comprises a dielectric lens (1), a bonding gold wire (5), a terahertz radiation source chip (4) and an FR4 circuit board (3); The dielectric lens (1) is used to achieve high-gain forward radiation, and the terahertz radiation source chip (4) is located in the air cavity (1-2) of the dielectric lens (1) to achieve protection and packaging of the terahertz radiation source chip (4); The terahertz radiation source chip (4) is used to realize the generation and radiation of a terahertz oscillation signal; The FR4 circuit board (3) is used to feed the DC signal of the terahertz radiation source chip (4) and implement a DC filter circuit; The bonding gold wire (5) is used to connect the power supply end of the terahertz radiation source chip (4) and the FR4 circuit board (3); The dielectric lens (1) is arranged on the upper surface of the FR4 circuit board (3), and the bottom of the dielectric lens (1) is concave and forms the air cavity (1-2) with the FR4 circuit board (3); the terahertz radiation source chip (4) is located in the air cavity (1-2), and the terahertz radiation source chip (4) is mounted on the top of the FR4 circuit board (3), and the power supply end of the terahertz radiation source chip (4) is connected to the FR4 circuit board (3) via a bonding wire (5); The main body of the dielectric lens (1) is a hemispherical lens; the plane of the hemispherical lens extends outward; the optimal extension length of the hemispherical lens is L0, which is expressed as: ; Among them, the radius of the hemispherical lens is R, and the dielectric constant of the lens material is ɛ L ; The optimal length of the air cavity (1-2) is obtained as follows: Step 1: The extension length of the hemispherical lens is the initial value L1, which is the sum of the optimal extension length L0 and the margin b; the step value is changed from 0 to L1 according to the actual processing progress, and the step value is c; Step 2: For a specific extension length L2, use the ray tracing method to calculate the focal length F corresponding to the current extension length, and the height of the air cavity (1-2) a0=F-L2, where L2 is nc, n is the number of steps, and 0≤L2≤L1; Step 3, based on the obtained dielectric lens (1) value, establish a simulation model of the lens antenna in the simulation software FECO, simulate the air cavity (1-2) height range: a0±0.2×a0, and obtain the S parameters of the lens antenna. Step 4: Repeat steps 2 and 3 to obtain the S parameters under different extension lengths L2. Import each S parameter into the simulation software ADS and perform a joint simulation analysis with the resonant tunneling diode (4-1) device. By comparing the results, the optimal air cavity (1-2) height and radiation power value are obtained.

2. The terahertz radiation source based on a dielectric lens package with an air cavity according to claim 1, characterized in that: The dielectric lens (1) is realized by using high-resistance silicon, nylon, glass fiber, plastic or photosensitive resin dielectric materials.

3. The terahertz radiation source based on a dielectric lens package with an air cavity according to claim 1, characterized in that: The dielectric lens (1) is manufactured by micro-machining, laser processing, ultra-precision cutting, moulding or 3D printing.

4. The terahertz radiation source based on a dielectric lens package with an air cavity according to claim 1, characterized in that: The terahertz radiation source chip (4) is a terahertz patch antenna or a terahertz slot antenna.

5. The terahertz radiation source based on a dielectric lens package with an air cavity according to claim 1, characterized in that: The dielectric layer of the radiation antenna (4-2) of the terahertz radiation source chip (4) is made of any one of SU-8, polyimide, benzocyclobutene and silicon nitride, or a combination of several of them.

6. The terahertz radiation source based on a dielectric lens package with an air cavity according to claim 1, characterized in that: The core component of the terahertz radiation source chip (4) is a resonant tunneling diode (4-1), which forms a terahertz frequency band LC oscillation circuit with the equivalent inductance of the radiation antenna (4-2) to generate a terahertz signal.

7. The terahertz radiation source based on a dielectric lens package with an air cavity according to claim 1, characterized in that: The semiconductor substrate material used in the terahertz radiation source chip (4) is any one of indium phosphide, gallium arsenide and silicon, or a combination of several of them.

Images