A broadband, high power, 1 dB attenuator circuit

Abstract

The application provides a broadband, high-power, 1dB attenuator circuit, which comprises an input circuit, an attenuation circuit and an output circuit, wherein the attenuation circuit comprises an input resistance film circuit, a T-shaped junction circuit, a ground resistance film circuit and an output resistance film circuit, and the input circuit and the output circuit have the same structure; the resistance values of the input resistance film circuit and the output resistance film circuit are both 2.88 ohms, the impedances are both 33 ohms, the length of the input resistance film circuit is 0.4576 times the width, and the length of the output resistance film circuit is 0.4576 times the width; the ground resistance value of the ground resistance film circuit is 433.34 ohms, the impedance value of the first section impedance transformation circuit in the ground resistance film circuit is 120 ohms, the resistance film length of the first section impedance transformation circuit is 7.66 times the width, the impedance value of the second section impedance transformation circuit in the ground resistance film circuit is 73 ohms, and the resistance film length of the second section impedance transformation circuit is 1 times the width. The circuit is simple, the flatness of the attenuation value is optimized, and the standing wave ratio is reduced.

Description

Technical Field

[0001] This invention relates to the field of electronic information technology, and in particular to a broadband, high-power 1dB attenuator circuit. Background Technology

[0002] A power attenuator, or simply attenuator, is an energy-dissipating microwave component containing resistive material. It is widely used in various applications requiring power level adjustment and improved circuit impedance matching. Microwave attenuators primarily have two structures: T-shaped and π-shaped. Other attenuators are derived from or combined with these two shapes. Current design experience suggests that the T-shaped attenuator is more suitable for attenuators with smaller attenuation values.

[0003] A 1dB attenuator is a low-attenuation attenuator that absorbs a small portion of the incident power while allowing a relatively large amount of power to pass through. With the development of technologies such as radar and communications, there is an urgent need for high-frequency, high-power, and well-performing low-attenuation attenuators with good VSWR. Low-attenuation attenuators form the basis for combining high-power matching loads and attenuators. Series combinations of some low-attenuation attenuators with other attenuation values ​​and matching loads can achieve matching load designs with a power handling capacity of over 500W and a VSWR within 1.05 at DC-18GHz, or attenuators with a power handling capacity of over 500W and excellent performance specifications.

[0004] The current mainstream design for 1dB attenuators is a T-shaped attenuator consisting of three single resistive films connected by an internal "lossless" circuit. A small amount of matching design is carried out in the external circuits such as the "lossless" connection circuit. As a result, the broadband matching circuit is complex, the attenuation value flatness is poor, and the maximum operating frequency and other indicators are significantly reduced. Summary of the Invention

[0005] The present invention aims to solve the technical problems of poor impedance matching, low power handling capacity, and large in-band ripple in broadband, high-power circuits with a capacity of 1dB.

[0006] Therefore, the purpose of this invention is to propose a broadband, high-power 1dB attenuator circuit. This attenuator circuit is simple, optimizes the flatness of the attenuation value, and reduces the standing wave ratio (SWR). The achievable SWR is within 1.05, and the power it can withstand is much greater than 100 watts. This lays the foundation for designing matching loads and attenuators with greater power handling capacity.

[0007] To achieve the above objectives, this invention proposes a broadband, high-power, 1dB attenuator circuit. The attenuator circuit utilizes a grounded coplanar waveguide circuit, located on the top copper layer and resistive film layer of a circuit board. The sheet resistance of the resistive film layer circuit is 50 ohms. The attenuator circuit includes an input circuit, an attenuation circuit, and an output circuit. The attenuation circuit consists of an input resistive film circuit, a T-junction circuit, a ground-to-resistive film circuit, and an output resistive film circuit. One end of the input circuit serves as the input terminal of the attenuator circuit. The other end of the input circuit is connected to one end of the input resistive film circuit. The other end of the input resistive film circuit is connected to the first end of the T-junction circuit. The second end of the T-junction circuit is connected to one end of the ground-to-resistive film circuit. The other end of the ground-to-resistive film circuit is connected to the bottom ground circuit of the circuit board through multiple copper vias. The third end of the T-junction circuit is connected to one end of the output resistive film circuit. The other end of the output resistive film circuit... The circuit is connected to one end of the output circuit, and the other end of the output circuit serves as the output terminal of the attenuator circuit. The input circuit has the same structure as the output circuit. The resistance values ​​of both the input and output resistive film circuits are 2.88 ohms, and their impedances are both 33 ohms. The length of the input resistive film circuit is 0.4576 times its width, and the length of the output resistive film circuit is also 0.4576 times its width. The resistance to ground of the resistive film circuit is 433.34 ohms. The impedance of the first impedance transformation circuit in the resistive film circuit is 120 ohms, and the length of the resistive film in the first impedance transformation circuit is 7.66 times its width. The impedance of the second impedance transformation circuit in the resistive film circuit is 73 ohms, and the length of the resistive film in the second impedance transformation circuit is 1 time its width.

[0008] The broadband, high-power, 1dB attenuator circuit of this invention utilizes a grounded coplanar waveguide circuit located on the top copper layer and resistive film layer of the circuit board. The sheet resistance of the resistive film layer circuit is 50 ohms. The attenuator circuit includes an input circuit, an attenuation circuit, and an output circuit. The attenuation circuit consists of an input resistive film circuit, a T-junction circuit, a ground-to-resistive film circuit, and an output resistive film circuit. One end of the input circuit serves as the input terminal of the attenuator circuit. The other end of the input circuit is connected to one end of the input resistive film circuit. The other end of the input resistive film circuit is connected to the first end of the T-junction circuit. The second end of the T-junction circuit is connected to one end of the ground-to-resistive film circuit. The other end of the ground-to-resistive film circuit is connected to the bottom ground circuit of the circuit board through multiple copper vias. The third end of the T-junction circuit is connected to one end of the output resistive film circuit. The other end of the output resistive film circuit is connected to the first end of the output circuit. The output circuit is connected at one end, and the other end serves as the output terminal of the attenuator circuit. The input circuit has the same structure as the output circuit. Both the input and output resistive film circuits have a resistance of 2.88 ohms and an impedance of 33 ohms. The length of the input resistive film circuit is 0.4576 times its width, and the length of the output resistive film circuit is also 0.4576 times its width. The ground resistance of the resistive film circuit is 433.34 ohms. The impedance of the first impedance transformation circuit in the ground resistive film circuit is 120 ohms, and the length of the resistive film in the first impedance transformation circuit is 7.66 times its width. The impedance of the second impedance transformation circuit in the ground resistive film circuit is 73 ohms, and the length of the resistive film in the second impedance transformation circuit is 1 time its width. Therefore, the attenuator circuit is simple, optimizes the flatness of the attenuation value, and reduces the standing wave ratio (SWR). The achievable SWR is within 1.05, and the power it can withstand is much greater than 100 watts. This lays the foundation for designing matching loads and attenuators with greater power handling capacity.

[0009] In addition, the broadband, high-power, 1dB attenuator circuit proposed in this invention can also have the following additional technical features:

[0010] According to one embodiment of the present invention, the circuit board structure, from top to bottom, comprises a top copper layer, a resistive film layer, a dielectric layer, and a bottom copper layer; wherein,

[0011] The thickness of the top copper clad layer is the same as the thickness of the bottom copper clad layer, and the copper foil thickness used in the top copper clad layer and the bottom copper clad layer is greater than or equal to 0.0178 mm.

[0012] The dielectric constant is less than 10, the loss tangent is less than 0.003 at 10 GHz, and the dielectric thickness is less than or equal to 1 mm.

[0013] The thickness of the resistive film layer is greater than or equal to 0.2 micrometers.

[0014] According to one embodiment of the present invention, the input circuit includes a two-layer structure comprising the top copper layer and the resistive film layer;

[0015] The input circuit consists of a first circuit section and a second circuit section. One end of the first circuit section serves as one end of the input circuit, and the other end of the first circuit section is connected to one end of the second circuit section. The other end of the second circuit section serves as the other end of the input circuit.

[0016] The first section of the circuit uses a grounded coplanar waveguide circuit. The input impedance and output impedance of the first section of the circuit are both 50 ohms, and the transmission line length of the first section of the circuit is greater than 1 mm.

[0017] The second circuit uses a tapered grounded coplanar waveguide circuit. The input impedance of the second circuit is 50 ohms, the output impedance of the second circuit is 33 ohms, and the transmission line length of the second circuit is less than 0.5mm.

[0018] According to one embodiment of the present invention, both the input resistive film circuit and the output resistive film circuit are composed of a resistive film layer on the top layer of the circuit board, and both the input resistive film circuit and the output resistive film circuit are circuits with series resistive films.

[0019] The input resistive film circuit and the output resistive film circuit bear different power values, and both the input resistive film circuit and the output resistive film circuit use grounded coplanar waveguide circuits.

[0020] According to one embodiment of the present invention, the T-junction circuit is composed of two layers: a copper-clad layer and a resistive film layer on the top layer of the circuit board. The T-junction circuit includes a T-junction, a first connection matching circuit, and a second connection matching circuit. A first end of the T-junction is connected to one end of the first connection matching circuit, the other end of the first connection matching circuit serves as the first end of the T-junction circuit, a second end of the T-junction serves as the second end of the T-junction circuit, and a third end of the T-junction is connected to one end of the second connection matching circuit, the other end of the second connection matching circuit serves as the third end of the T-junction circuit.

[0021] Both the first connection matching circuit and the second connection matching circuit are tapered grounded coplanar waveguide circuits;

[0022] The impedance of the first, second, and third ends of the T-junction is 120 ohms.

[0023] According to one embodiment of the present invention, the ground resistive film circuit is composed of the resistive film layer;

[0024] The ground resistance film circuit has two impedance transformation circuits. The input impedance of the first impedance transformation circuit is the ground resistance value of the second end of the corresponding T-junction, which is 433.34 ohms.

[0025] According to one embodiment of the present invention, the output circuit includes a two-layer structure of a copper-clad layer and a resistive film layer on the top layer of the circuit board;

[0026] The output circuit consists of a third circuit and a fourth circuit. One end of the third circuit serves as one end of the output circuit, and the other end of the third circuit is connected to one end of the fourth circuit. The other end of the fourth circuit serves as the other end of the output circuit.

[0027] The third circuit section uses a tapered grounded coplanar waveguide circuit, the input impedance of the third circuit section is 33 ohms, the output impedance of the third circuit section is 50 ohms, and the transmission line length of the third circuit section is less than 0.5mm.

[0028] The fourth circuit uses a coplanar waveguide circuit, and both its input and output impedances are 50 ohms. The transmission line length of the fourth circuit is greater than 1 mm.

[0029] According to one embodiment of the present invention, the ground terminal of the attenuator circuit is connected to a grounding circuit; wherein,

[0030] The grounding circuit is a connection circuit in which the resistive film layer on the top layer of the circuit board passes through multiple copper vias through the dielectric layer of the circuit board and connects to the copper cladding layer on the bottom layer of the circuit board. The resistance value of the connection circuit is less than 0.1 ohms.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0033] Figure 1 This is a schematic diagram of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0034] Figure 2 This is a structural principle block diagram of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention;

[0035] Figure 3 This is a simulation circuit diagram of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0036] Figure 4 This is a simulation circuit board diagram of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0037] Figure 5 This is a schematic diagram of the attenuation value of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0038] Figure 6 This is a schematic diagram of the resistance values ​​of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0039] Figure 7 This is a port voltage standing wave ratio diagram of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0040] Figure 8 This is a schematic diagram of the output power value of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention. Detailed Implementation

[0041] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0042] The following description, with reference to the accompanying drawings, describes a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0043] Figure 1 This is a schematic diagram of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0044] It should be noted that the broadband, high-power, 1dB attenuator circuit of this embodiment of the invention uses a grounded coplanar waveguide circuit located on the top copper layer and resistive film layer of the circuit board, and the sheet resistance of the resistive film layer circuit is 50 ohms.

[0045] like Figure 1 As shown, the broadband, high-power, 1dB attenuator circuit of this embodiment includes: an input circuit, an attenuation circuit, and an output circuit.

[0046] The attenuation circuit consists of an input resistive film circuit, a T-junction circuit, a ground resistive film circuit, and an output resistive film circuit. One end of the input circuit serves as the input terminal of the attenuator circuit. The other end of the input circuit is connected to one end of the input resistive film circuit, which in turn is connected to the first end of the T-junction circuit. The second end of the T-junction circuit is connected to one end of the ground resistive film circuit, which is connected to the bottom-layer grounding circuit of the circuit board via multiple copper vias. The third end of the T-junction circuit is connected to one end of the output resistive film circuit, and the other end of the output resistive film circuit is connected to one end of the output circuit. The other end of the output circuit serves as the output terminal of the attenuator circuit. The input and output circuits have the same structure. The resistance of the output resistive film circuit is 2.88 ohms. The impedance of both the input and output resistive film circuits is 33 ohms. The length of the input resistive film circuit is 0.4576 times its width, and the length of the output resistive film circuit is 0.4576 times its width. The resistance to ground of the resistive film circuit is 433.34 ohms. The impedance of the first impedance transformation circuit in the ground resistive film circuit is 120 ohms, and the length of the resistive film in the first impedance transformation circuit is 7.66 times its width. The impedance of the second impedance transformation circuit in the ground resistive film circuit is 73 ohms, and the length of the resistive film in the second impedance transformation circuit is 1 time its width.

[0047] The broadband, high-power, 1dB attenuator of this invention is an electrical device used to absorb a small portion of incident power while allowing a relatively large amount of power to pass through. The broadband, high-power, 1dB attenuator of this invention achieves an operating frequency of DC-18GHz, an attenuation value of 1±0.1dB, a power handling capacity of 1 watt, and a VSWR of less than 1.1.

[0048] In this embodiment of the invention, the circuit board structure consists of a top copper clad layer, a resistive film layer, a dielectric layer, and a bottom copper clad layer, from top to bottom. The thickness of the top copper clad layer and the bottom copper clad layer are the same, and the copper foil used in the top and bottom copper clad layers has a thickness greater than or equal to 0.0178 mm. The circuit board uses a substrate with a dielectric constant less than 10, a loss tangent less than 0.003 at 10 GHz, and a dielectric thickness less than or equal to 1 mm. The thickness of the resistive film layer is greater than or equal to 0.2 micrometers.

[0049] For example, the circuit board is a polytetrafluoroethylene glass cloth ceramic copper-clad board RA300A294; εr 2.94; tgδ 0.0015@10GHz; K 0.6W / mK; the thickness of the upper copper foil is 0.018mm; the thickness of the nickel-chromium resistor film is 0.2um, the sheet resistance RS is 50 ohms; the dielectric thickness is 0.762mm; the thickness of the lower copper foil is 0.018mm; and the coefficient of thermal expansion (CTE) is 8 / 8 / 20ppm / ℃.

[0050] Figure 2 This is a structural principle block diagram of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention.

[0051] like Figure 2 As shown, the input circuit comprises a two-layer structure: a copper-clad layer on the top of the circuit board and a resistive film layer. The input circuit consists of a first section and a second section. One end of the first section serves as one end of the input circuit, and the other end of the first section is connected to one end of the second section, which in turn serves as the other end of the input circuit. The first section uses a grounded coplanar waveguide circuit, with both its input and output impedances at 50 ohms. The transmission line length of the first section is greater than 1 mm, for example, within the range of 3-5 mm or longer. The second section uses a tapered grounded coplanar waveguide circuit, with an input impedance of 50 ohms, an output impedance of 33 ohms, and a transmission line length of less than 0.5 mm.

[0052] like Figure 2 As shown, both the input and output resistive film circuits are composed of a resistive film layer on the top layer of the circuit board. Both circuits are series-connected resistive film circuits. The resistance value of both circuits is 2.88 ohms, where the series resistance is L × Rsheet resistance / W. Here, L is the length of the resistive film, W is the width, and Rsheet resistance is a fixed 50 ohms or another given value. The transmission impedance of both circuits is 33 ohms. The input and output resistive film circuits have the same resistance value and the same length-to-width ratio. Since the power handled by the input and output resistive film circuits differs, the length and width of the resistive film can be designed differently. Both circuits utilize grounded coplanar waveguide circuits.

[0053] like Figure 2As shown, the T-junction circuit consists of two layers: a copper-clad layer and a resistive film layer on the top of the circuit board. The T-junction circuit includes a T-junction, a first connection matching circuit, and a second connection matching circuit. The first end of the T-junction is connected to one end of the first connection matching circuit, and the other end of the first connection matching circuit serves as the first end of the T-junction circuit. The second end of the T-junction serves as the second end of the T-junction circuit. The third end of the T-junction is connected to one end of the second connection matching circuit, and the other end of the second connection matching circuit serves as the third end of the T-junction circuit. Both the first and second connection matching circuits are tapered grounded coplanar waveguide circuits. The impedance of the first, second, and third ends of the T-junction is 120 ohms.

[0054] like Figure 2 As shown, the ground resistance film circuit is composed of the resistive film layer on the top layer of the circuit board; there are two impedance transformation circuits on the ground resistance film circuit. The input impedance of the first impedance transformation circuit is the ground resistance value of the second end of the corresponding T-junction, which is 433.34 ohms.

[0055] like Figure 2 As shown, the output circuit comprises a two-layer structure: a copper-clad layer and a resistive film layer on the top of the circuit board. The output circuit consists of a third section and a fourth section. One end of the third section serves as one end of the output circuit, and the other end of the third section is connected to one end of the fourth section, which in turn serves as the other end of the output circuit. The third section uses a tapered grounded coplanar waveguide circuit, with an input impedance of 33 ohms, an output impedance of 50 ohms, and a transmission line length of less than 0.5 mm. The fourth section uses a coplanar waveguide circuit, with both its input and output impedances at 50 ohms, and a transmission line length greater than 1 mm, ideally within the range of 3-5 mm or even longer.

[0056] like Figure 2 As shown, the grounding terminal of the broadband, high-power, 1dB attenuator circuit is connected to the grounding circuit; wherein, the grounding circuit is a connection circuit in which the resistive film layer on the top layer of the circuit board passes through multiple copper vias through the dielectric layer of the circuit board and connects to the copper layer on the bottom layer of the circuit board, wherein the resistance value of the connection circuit is less than 0.1 ohms.

[0057] Figure 3 This is a simulation circuit diagram of an attenuator circuit according to an embodiment of the present invention.

[0058] It should be noted that the circuit board parameters of the broadband, high-power, 1dB attenuator in this embodiment of the invention are as follows: εr 2.94; tgδ 0.0015 @ 10GHz; upper copper foil thickness 0.018mm; nickel-chromium resistor film thickness 0.2um, sheet resistance RS: 50 ohms; dielectric thickness 0.762mm; lower copper foil thickness 0.018mm;

[0059] like Figure 3 As shown, the input port is P1, and Z = 50 ohms.

[0060] The input circuit includes: a microstrip line (MLIN) connected to the input port and a microstrip stepped circuit (MSTEP) connected to the microstrip line; wherein, the microstrip line (MLIN) connected to the input port has ID=TL1, a width W of 1.95mm, and a length L=3mm; the microstrip stepped circuit (MSTEP) connected to the microstrip line has ID=TL5, a width W1 of 1.95mm, and a width W2 of 3.54mm.

[0061] Input resistive film circuit: TFR connected to the input circuit, ID=TL3, width W is 3.54mm, length is 0.203mm;

[0062] The T-junction circuit includes: a first connection matching circuit connected to the input resistive film circuit, which is a tapered circuit (MTAPER) with ID = MTL1, W1 = 3.54mm, W2 = 0.3mm, and length L = 0.55mm; a T-junction with W1 = 0.3mm, W2 = 0.3mm, and W3 = 0.28mm; and a second connection matching circuit connected to the input resistive film circuit, which is a tapered circuit (MTAPER) with ID = MTL2, W1 = 3.54mm, W2 = 0.3mm, and length L = 0.55mm.

[0063] The ground resistance film circuit includes two TFR sections; the first TFR section has ID=TL5, a width W1 of 0.28mm, and a length L=2.14mm; the second TFR section has ID=TL7, a width W1 of 1mm, and a length L=1mm.

[0064] The grounding circuit includes two VIAs, each with a hole diameter of 0.8mm.

[0065] Output resistive film circuit: TFR connected to the output circuit: ID=TL4, width W is 3.54mm, length is 0.203mm.

[0066] Output circuit: a microstrip stepped circuit (MSTEP) connected to the microstrip line and a microstrip line (MLIN) connected to the input port; wherein, the microstrip stepped circuit (MSTEP) connected to the microstrip line has ID=TL9, width W1 is 1.95mm, and width W2 is 3.54mm; the microstrip stepped circuit (MSTEP) connected to the microstrip line (MLIN) has ID=TL2, width W is 1.95mm, and length L=3mm.

[0067] Figure 4 This is a simulation circuit board diagram of an attenuator circuit according to an embodiment of the present invention. Figure 1, Figure 2 , Figure 3 All revolves around Figure 4 Explanations from different perspectives.

[0068] Figure 5 This is a schematic diagram of the attenuation value of an attenuator circuit according to an embodiment of the present invention; Figure 5 yes Figure 4 The simulation results, such as Figure 5 As shown, the attenuation value varies within the frequency range of 0–18 GHz. Specifically, at a frequency of 6 GHz, the attenuation value of the broadband, high-power, 1 dB attenuator circuit of this invention is 1.01719 dB; at a frequency of 13 GHz, the attenuation value of the 1 dB attenuator circuit is 1.0317 dB; and at a frequency of 18 GHz, the attenuation value of the broadband, high-power, 1 dB attenuator circuit of this invention is 1.06 dB.

[0069] Figure 6 This is a schematic diagram of the resistance values ​​of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention. Figure 6 yes Figure 4 The simulation results, such as Figure 6 As shown, the resistance value changes as follows within the frequency range of 0–18 GHz: at a frequency of 14.92 GHz, the resistance of the broadband, high-power, 1 dB attenuator circuit of this invention is 51.64 ohms, which is the maximum value; at a frequency of 6.335 GHz, the resistance of the broadband, high-power, 1 dB attenuator circuit of this invention is 48.27 ohms, which is the minimum value. Therefore, the resistance range of the broadband, high-power, 1 dB attenuator circuit of this invention is ±3 ohms.

[0070] Figure 7 This is a port voltage standing wave ratio diagram of a broadband, high-power, 1dB attenuator circuit according to an embodiment of the present invention. Figure 7 yes Figure 4 The simulation results, such as Figure 7 As shown, within the frequency range of 0–18 GHz, the VSWR is less than 1.05, with the maximum VSWR value occurring at the highest frequency. Within a larger frequency range, the VSWR is less than 1.043.

[0071] The feasibility of the proposed broadband, high-power 1dB attenuator circuit has been verified in theory, circuit simulation, and physical samples.

[0072] It should be noted that if the circuit board of the present invention is replaced with an AL2O3 ceramic substrate (er10, K: 30W / mK) with better thermal conductivity, the calculated power handling capacity will be close to 10W; if the circuit board of the present invention is replaced with a BeO ceramic substrate (er6, K: 240W / mK) with better thermal conductivity, the calculated power handling capacity will be greater than 100W.

[0073] In summary, the broadband, high-power, 1dB attenuator circuit of this invention utilizes a grounded coplanar waveguide circuit located on the top copper layer and resistive film layer of the circuit board. The sheet resistance of the resistive film layer circuit is 50 ohms. The attenuator circuit includes an input circuit, an attenuation circuit, and an output circuit. The attenuation circuit consists of an input resistive film circuit, a T-junction circuit, a ground-to-resistive film circuit, and an output resistive film circuit. One end of the input circuit serves as the input terminal of the attenuator circuit. The other end of the input circuit is connected to one end of the input resistive film circuit. The other end of the input resistive film circuit is connected to the first end of the T-junction circuit. The second end of the T-junction circuit is connected to one end of the ground-to-resistive film circuit. The other end of the ground-to-resistive film circuit is connected to the bottom ground circuit of the circuit board through multiple copper vias. The third end of the T-junction circuit is connected to one end of the output resistive film circuit. The other end of the output resistive film circuit is connected to the output circuit. One end of the circuit is connected, and the other end of the output circuit serves as the output terminal of the attenuator circuit. The input circuit and the output circuit have the same structure. The resistance values ​​of both the input and output resistive film circuits are 2.88 ohms, and their impedances are both 33 ohms. The length of the input resistive film circuit is 0.4576 times its width, and the length of the output resistive film circuit is also 0.4576 times its width. The resistance to ground of the resistive film circuit is 433.34 ohms. The impedance of the first impedance transformation circuit in the resistive film circuit is 120 ohms, and the length of the resistive film in the first impedance transformation circuit is 7.66 times its width. The impedance of the second impedance transformation circuit in the resistive film circuit is 73 ohms, and the length of the resistive film in the second impedance transformation circuit is 1 time its width. Therefore, the attenuator circuit provided by this invention uses a T-shaped structure, which increases the thin film size of the resistor. It mainly focuses on attenuation, matching, and heat dissipation design while using a lossy resistor film, supplemented by a small number of lossless connection circuit matching designs. This solves the problems of poor broadband impedance matching, reduced power handling at high frequencies, and large fluctuations in attenuation value in related technologies. The attenuator circuit is simple, optimizes the flatness of the attenuation value, and reduces the standing wave ratio (VSWR). The achievable VSWR is within 1.05, and the power handling is far greater than 100 watts. This lays the foundation for designing matching loads and attenuators with greater power handling.

[0074] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0075] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A broadband, high-power, 1dB attenuator circuit, characterized in that, The attenuator circuit uses a grounded coplanar waveguide circuit, located on the top copper layer and resistive film layer of the circuit board. The sheet resistance of the resistive film layer circuit is 50 ohms. The attenuator circuit includes: an input circuit, an attenuation circuit, and an output circuit. The attenuation circuit consists of an input resistive film circuit, a T-junction circuit, a ground-to-ground resistive film circuit, and an output resistive film circuit. One end of the input circuit serves as the input terminal of the attenuator circuit. The other end of the input circuit is connected to one end of the input resistive film circuit. The other end of the input resistive film circuit is connected to the first end of the T-junction circuit. The second end of the T-junction circuit is connected to one end of the ground-to-resistive film circuit. The other end of the ground-to-resistive film circuit is connected to the bottom ground circuit of the circuit board through multiple copper vias. The third end of the T-junction circuit is connected to one end of the output resistive film circuit. The other end of the output resistive film circuit is connected to one end of the output circuit. The other end of the output circuit serves as the output terminal of the attenuator circuit. The input circuit and the output circuit have the same structure. The resistance value of both the input resistive film circuit and the output resistive film circuit is 2.88 ohms, and the impedance of both is 33 ohms. The length of the input resistive film circuit is 0.4576 times the width of the input resistive film circuit, and the length of the output resistive film circuit is 0.4576 times the width of the output resistive film circuit. The ground resistance of the ground-to-ground film circuit is 433.34 ohms. The impedance of the first impedance transformation circuit in the ground-to-ground film circuit is 120 ohms. The length of the resistive film in the first impedance transformation circuit is 7.66 times the width of the resistive film in the first impedance transformation circuit. The impedance of the second impedance transformation circuit in the ground-to-ground film circuit is 73 ohms. The length of the resistive film in the second impedance transformation circuit is 1 time the width of the resistive film in the second impedance transformation circuit.

2. The broadband, high-power, 1dB attenuator circuit according to claim 1, characterized in that, The circuit board structure, from top to bottom, consists of a top copper layer, a resistive film layer, a dielectric layer, and a bottom copper layer; wherein... The thickness of the top copper clad layer is the same as the thickness of the bottom copper clad layer, and the copper foil thickness used in the top copper clad layer and the bottom copper clad layer is greater than or equal to 0.0178 mm. Dielectric constant less than 10, loss tangent less than 0.003 at 10GHz, dielectric thickness less than or equal to 1 mm; The thickness of the resistive film layer is greater than or equal to 0.2 micrometers.

3. The broadband, high-power, 1dB attenuator circuit according to claim 1, characterized in that, The input circuit comprises a two-layer structure: the top copper layer and the resistive film layer. The input circuit consists of a first circuit section and a second circuit section. One end of the first circuit section serves as one end of the input circuit, and the other end of the first circuit section is connected to one end of the second circuit section. The other end of the second circuit section serves as the other end of the input circuit. The first section of the circuit uses a grounded coplanar waveguide circuit. The input impedance and output impedance of the first section of the circuit are both 50 ohms, and the transmission line length of the first section of the circuit is greater than 1 mm. The second circuit uses a tapered grounded coplanar waveguide circuit. The input impedance of the second circuit is 50 ohms, the output impedance of the second circuit is 33 ohms, and the transmission line length of the second circuit is less than 0.5mm.

4. The broadband, high-power, 1dB attenuator circuit according to claim 1, characterized in that, Both the input resistive film circuit and the output resistive film circuit are composed of the resistive film layer on the top layer of the circuit board, and both the input resistive film circuit and the output resistive film circuit are circuits with series resistive films. The input resistive film circuit and the output resistive film circuit bear different power values, and both the input resistive film circuit and the output resistive film circuit use grounded coplanar waveguide circuits.

5. The broadband, high-power, 1dB attenuator circuit according to claim 1, characterized in that, The T-junction circuit consists of two layers: a copper-clad layer and a resistive film layer on the top layer of the circuit board. The T-junction circuit includes a T-junction, a first connection matching circuit, and a second connection matching circuit. The first end of the T-junction is connected to one end of the first connection matching circuit, and the other end of the first connection matching circuit serves as the first end of the T-junction circuit. The second end of the T-junction serves as the second end of the T-junction circuit. The third end of the T-junction is connected to one end of the second connection matching circuit, and the other end of the second connection matching circuit serves as the third end of the T-junction circuit. Both the first connection matching circuit and the second connection matching circuit are tapered grounded coplanar waveguide circuits; The impedance of the first, second, and third ends of the T-junction is 120 ohms.

6. The broadband, high-power, 1dB attenuator circuit according to claim 1, characterized in that, The ground resistive film circuit is composed of the resistive film layer; The ground resistance film circuit has two impedance transformation circuits. The input impedance of the first impedance transformation circuit is the ground resistance value of the second end of the corresponding T-junction, which is 433.34 ohms.

7. The broadband, high-power, 1dB attenuator circuit according to claim 1, characterized in that, The output circuit comprises a two-layer structure: a copper-clad layer and a resistive film layer on the top layer of the circuit board. The output circuit consists of a third circuit and a fourth circuit. One end of the third circuit serves as one end of the output circuit, and the other end of the third circuit is connected to one end of the fourth circuit. The other end of the fourth circuit serves as the other end of the output circuit. The third circuit section uses a tapered grounded coplanar waveguide circuit, the input impedance of the third circuit section is 33 ohms, the output impedance of the third circuit section is 50 ohms, and the transmission line length of the third circuit section is less than 0.5mm. The fourth circuit uses a coplanar waveguide circuit, and both its input and output impedances are 50 ohms. The transmission line length of the fourth circuit is greater than 1 mm.

8. The broadband, high-power, 1dB attenuator circuit according to claim 1, characterized in that, The ground terminal of the attenuator circuit is connected to the grounding circuit; wherein, The grounding circuit is a connection circuit in which the resistive film layer on the top layer of the circuit board passes through multiple copper vias through the dielectric layer of the circuit board and connects to the copper cladding layer on the bottom layer of the circuit board. The resistance value of the connection circuit is less than 0.1 ohms.

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