A self-detection multi-stage limiter based on micro-assembly and a preparation method thereof

Abstract

The disclosure provides a self-detection multi-stage limiter based on micro-assembly and a preparation method thereof. The limiter comprises a ceramic tube shell, a substrate, and a front-stage power detection processing circuit and a rear-stage leakage power processing circuit fixed on one side surface of the substrate based on a micro-assembly process. The rear-stage leakage power processing circuit is a monolithic microwave integrated circuit, and the monolithic microwave integrated circuit is integrated with M series limiting units in series. Each limiting unit comprises two element strings in reverse parallel connection, and each element string comprises a plurality of gallium nitride Schottky diodes in series connection. The self-detection limiter based on the micro-assembly process can realize a fast response time, clamp the leakage peak power leaked after the front-stage processing by using the rear-stage leakage power processing circuit, and realize flexible adjustment of the amplitude threshold and the leakage level by adjusting the number of limiting unit stages or the number of GaN SBDs in series connection in the limiting unit, so as to facilitate matching of the signal power range and the protection requirements of different use scenarios.

Description

Technical Field

[0001] This disclosure relates to the field of electromagnetic protection technology, and in particular to a micro-assembly-based self-testing multi-level limiter and its fabrication method. Background Technology

[0002] Limiters are important microwave control devices widely used in various microwave signal receiving systems. New requirements for electromagnetic protection necessitate a limiter that comprehensively balances key performance indicators such as low insertion loss, nanosecond-level fast response, high power handling capacity, and intelligent adjustability. However, traditional PiN limiters, while pursuing extremely high power capacity, suffer from peak leakage due to the unique physical mechanism of PiN diodes. Furthermore, addressing the signal suppression requirements of different signal protection scenarios necessitates multiple additional limiter settings, leading to device waste and increased manufacturing costs. Summary of the Invention

[0003] The purpose of this disclosure is to provide a micro-assembly-based self-detector multi-level limiter and its fabrication method, in order to solve the problems existing in the prior art.

[0004] The embodiments of this disclosure adopt the following technical solution: a self-detector multi-stage limiter based on micro-assembly, comprising: a ceramic tube shell, a substrate disposed on a base of the ceramic tube shell, and a front-stage power detection and processing circuit and a back-stage leakage power processing circuit fixed on the surface of the substrate away from the base based on a micro-assembly process; wherein, the back-stage leakage power processing circuit is a monolithic microwave integrated circuit, and the monolithic microwave integrated circuit integrates M limiting units connected in series; wherein, each limiting unit includes two strings of components connected in anti-parallel, and each string of components includes multiple gallium nitride Schottky diodes connected in series.

[0005] In some embodiments, M is a positive integer less than or equal to 5.

[0006] In some embodiments, microstrip lines are connected in series between adjacent limiting units.

[0007] In some embodiments, the front-end power detection and processing circuit includes: a PiN diode and a detector diode connected in reverse parallel, and an RC parallel circuit; the RC parallel circuit is connected in parallel with the PiN diode and the detector diode.

[0008] In some embodiments, a first DC blocking capacitor is connected in series between the input terminal of the self-detector multi-stage limiter and the pre-stage power detection and processing circuit, a second DC blocking capacitor is connected in series between the pre-stage power detection and processing circuit and the post-stage leakage power processing circuit, and a third DC blocking capacitor is connected in series between the post-stage leakage power processing circuit and the output terminal of the self-detector multi-stage limiter.

[0009] In some embodiments, the pre-stage power detection and processing circuit, the post-stage leakage power processing circuit, and the DC blocking capacitor are all bonded together using gold wires.

[0010] In some embodiments, the bonding is a wedge bonding.

[0011] In some embodiments, all DC blocking capacitors are located on the substrate.

[0012] In some embodiments, the substrate is an aluminum nitride substrate.

[0013] This disclosure also provides a method for fabricating a self-detector multi-stage limiter as described above, comprising: providing a ceramic housing; bonding a substrate to a base of the ceramic housing using nano-silver paste; applying nano-silver paste to designated locations on the substrate using a dispensing machine; sequentially picking up and placing components constituting the pre-stage power detection and processing circuit and a monolithic microwave integrated circuit serving as the post-stage leakage power processing circuit onto the silver paste; placing the ceramic housing and all components it carries in a sintering furnace for heating and curing; and performing a bonding connection between the pre-stage power detection and processing circuit and the post-stage leakage power processing circuit.

[0014] The beneficial effects of the embodiments disclosed herein are as follows: the self-detector limiter using micro-assembly technology can achieve a fast response time, while the leakage power processing circuit of the subsequent stage clamps the peak power leaked after the processing of the previous stage, and the amplitude threshold and leakage level can be flexibly adjusted by adjusting the number of limiting unit stages or the number of GaN SBDs connected in series in the limiting unit, which is convenient for matching the signal power range and the protection requirements of different application scenarios. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in one or more embodiments of this specification or in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a circuit diagram of a micro-assembly-based self-detector multi-stage limiter in the first embodiment of this disclosure; Figure 2 This is a circuit schematic diagram of the subsequent leakage power processing circuit in the first embodiment of this disclosure; Figure 3 This is a flowchart illustrating the fabrication method of the self-testing multi-stage limiter based on micro-assembly in the second embodiment of this disclosure. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this specification, and not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this document.

[0018] To address the problems existing in the prior art, the first embodiment of this disclosure provides a self-detector multi-stage limiter based on micro-assembly, which mainly includes a ceramic tube shell, a substrate disposed on a base of the ceramic tube shell, and a front-stage power detection and processing circuit and a rear-stage leakage power processing circuit fixed on the surface of the substrate away from the base based on the micro-assembly process. Figure 1 The circuit diagram of the self-detector multi-stage limiter in this embodiment is shown. The front-stage power detection and processing circuit uses PiN transistors and detectors to detect the power of the input microwave signal and bear most of the power. The rear-stage leakage power processing circuit is mainly used to process the peak power after the front-stage processing and complete the microwave signal limiting.

[0019] like Figure 1 As shown, the front-end power detection and processing circuit mainly includes a PiN diode D1 and a detector diode D2 connected in reverse parallel. The detector diode is a gallium nitride Schottky diode (GaN SBD). It also includes an RC parallel circuit, formed by a resistor R and a capacitor C connected in parallel. This RC parallel circuit, along with the PiN diode D1 and the detector diode D2, forms the front-end power detection and processing circuit. Specifically, the negative terminal of the PiN diode D1 is grounded, while the positive terminal is connected to the main circuit of the front-end power detection and processing circuit. Utilizing the characteristic that the resistance of the PiN diode decreases as the forward bias increases, high power attenuation is achieved, thus providing protection for the subsequent stage. The negative terminal of the detector diode D2 is connected to the main circuit of the front-end power detection and processing circuit, while the positive terminal is grounded. The reverse-biased detector diode D2 performs the detection function.

[0020] The subsequent leakage power processing circuit is mounted on the substrate as a monolithic microwave integrated circuit (MMIC), and its circuit schematic is shown below. Figure 2 As shown, it integrates M series-connected limiting units 10, in Figure 2In this embodiment, M=2, and each limiting unit 10 includes two anti-parallel element strings, each of which includes multiple series-connected gallium nitride Schottky diodes D3. While the PiN diode D1 in the front stage can achieve high-power limiting, its switching speed limitation makes it prone to peak leakage. In this embodiment, the subsequent stage uses multiple series-connected limiting units to clamp leakage peaks. When the MMIC is not saturated, the more limiting units there are, the lower the leakage level. That is, each additional limiting unit adds another layer of leakage power clamping, resulting in a step-like decrease in residual leakage power. Once the number of stages reaches a certain level, the leakage level tends to stabilize. Further increasing the number of stages at this point offers limited improvement in leakage suppression and may even introduce additional insertion loss. Therefore, this embodiment typically limits the value of M to less than or equal to 5 to avoid introducing additional insertion loss while ensuring effective leakage level control. At the same time, increasing the number of stages not only reduces the leakage level, but also slightly lowers the limiting threshold. Conversely, decreasing the number of stages increases the limiting threshold and consequently raises the leakage level. Therefore, the specific number of stages of the limiting unit needs to be matched according to the actual signal power range.

[0021] It should be noted that the number of gallium nitride Schottky diodes D3 connected in series in the component strings of different limiting units 10 can be the same or different, such as... Figure 2 As shown, the component string of the limiting unit on the left has three D3 diodes connected in series, while the component string of the limiting unit on the right has two D3 diodes connected in series. The specific number of GaN SBDs connected in series in each limiting unit can be determined according to the application scenario of the limiter and the power of the microwave signal to be processed. In this embodiment, while ensuring the full-cycle clipping function, the limiting unit significantly optimizes the voltage withstand capability by using multiple diodes connected in series. The attenuation effect and stability of the peak leakage level are also improved accordingly. At the same time, the multiple GaN SBDs connected in series can also reduce the equivalent junction capacitance and reduce the insertion loss. Therefore, in application scenarios with high microwave signal power and high requirements for peak leakage clipping effect, the number of GaN SBDs connected in series can be increased to achieve a better limiting effect.

[0022] Further as Figure 2 As shown, a microstrip line TL is connected in series between adjacent limiting units, which can accurately achieve impedance matching between units to optimize the transmission efficiency of microwave signals and reduce reflection and loss.

[0023] In the actual design of self-testing limiters, such as Figure 1As shown, a first DC blocking capacitor C1 is connected in series between the input terminal IN of the self-diagnostic multi-stage limiter and the preceding power detection and processing circuit; a second DC blocking capacitor C2 is connected in series between the preceding power detection and processing circuit and the subsequent leakage power processing circuit; and a third DC blocking capacitor C3 is connected in series between the subsequent leakage power processing circuit and the output terminal OUT of the self-diagnostic multi-stage limiter. The core function of the DC blocking capacitors is to isolate DC components, conduct radio frequency signals, and ensure the independent and stable operation of each stage of the circuit. They are key components for avoiding DC crosstalk, protecting sensitive devices, and maintaining circuit performance.

[0024] In this embodiment, all components of the self-detector limiter are integrated on a substrate using a micro-assembly process. Specifically, the substrate can be an aluminum nitride (AlN) substrate. Each component, both front-end and back-end, is bonded to the substrate surface using nano-silver paste and finally connected by gold wire bonding. The bonding process used in this embodiment employs wedge bonding to form a well-defined arc-shaped line, ensuring microwave performance and mechanical reliability. It is important to note that the DC blocking capacitors in this embodiment are also directly mounted on the substrate as on-chip integrated units, assembled together with the front-end power detection and processing circuit and the back-end leakage power processing circuit, ensuring the uniformity of the overall circuit integration and assembly process of the limiter.

[0025] This embodiment employs a self-detector limiter with micro-assembly technology, which can achieve a fast response time. At the same time, it utilizes a subsequent leakage power processing circuit to clamp the peak power leaked after the previous stage processing. The amplitude threshold and leakage level can be flexibly adjusted by adjusting the number of limiting unit stages or the number of GaN SBDs connected in series in the limiting unit, which is convenient for matching the signal power range and the protection requirements of different application scenarios.

[0026] Based on the same inventive concept, the second embodiment of this disclosure provides a method for preparing the self-detector limiter of the first embodiment, the flowchart of which is shown below. Figure 3 As shown, the main steps include the following: S1 provides a ceramic tube shell; S2, the substrate is bonded and fixed to the base of the ceramic tube shell using nano silver paste; S3. Using a dispensing machine, nano silver paste is applied to the designated positions on the substrate. The components that make up the front-end power detection and processing circuit and the monolithic microwave integrated circuit that serves as the back-end leakage power processing circuit are picked up and placed onto the silver paste in sequence. S4, place the current ceramic tube shell and all the components it carries in a sintering furnace for heating and curing; for example, the entire component can be placed in a sintering furnace and cured at 150°C for 1 hour to form a connection with high mechanical strength and good thermal and electrical conductivity. S5 performs a bonding connection between the pre-stage power detection and processing circuit and the post-stage leakage power processing circuit.

[0027] The post-stage leakage power processing circuit in this embodiment is a monolithic microwave integrated circuit, which integrates M series-connected limiting units; wherein, each limiting unit includes two anti-parallel component strings, and each component string includes multiple series-connected gallium nitride Schottky diodes.

[0028] In this embodiment, the nano silver paste can be a two-component epoxy silver paste of model EPO-TEK H20E with a solid content of 100%; in terms of interconnection structure, the devices are interconnected using gold wires with a diameter of 25 micrometers.

[0029] The self-detector limiter formed based on the preparation process described in this embodiment can achieve a fast response time. At the same time, the leakage power processing circuit in the subsequent stage clamps the peak power leaked after the processing in the previous stage. The amplitude threshold and leakage level can be flexibly adjusted by adjusting the number of limiting unit stages or the number of GaN SBDs connected in series in the limiting unit, which is convenient for matching the signal power range and the protection requirements of different application scenarios.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit them. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A self-detector multi-stage limiter based on micro-assembly, characterized in that, include: A ceramic housing, a substrate mounted on a base of the ceramic housing, and a front-end power detection and processing circuit and a rear-end leakage power processing circuit fixed to the surface of the substrate away from the base using a micro-assembly process; wherein, The subsequent leakage power processing circuit is a monolithic microwave integrated circuit, which integrates M series-connected limiting units; wherein each limiting unit includes two anti-parallel element strings, and each element string includes multiple series-connected gallium nitride Schottky diodes.

2. The self-detector multi-stage limiter according to claim 1, characterized in that, M is a positive integer less than or equal to 5.

3. The self-detector multi-stage limiter according to claim 1, characterized in that, Microstrip lines are connected in series between adjacent limiting units.

4. The self-detector multi-stage limiter according to claim 1, characterized in that, The front-end power detection and processing circuit includes: a PiN diode and a detector diode connected in reverse parallel, and an RC parallel circuit; the RC parallel circuit is connected in parallel with the PiN diode and the detector diode.

5. The self-detector multi-stage limiter according to claim 1, characterized in that, A first DC blocking capacitor is connected in series between the input terminal of the self-detector multi-stage limiter and the pre-stage power detection and processing circuit; a second DC blocking capacitor is connected in series between the pre-stage power detection and processing circuit and the post-stage leakage power processing circuit; and a third DC blocking capacitor is connected in series between the post-stage leakage power processing circuit and the output terminal of the self-detector multi-stage limiter.

6. The self-detector multi-stage limiter according to claim 5, characterized in that, The pre-stage power detection and processing circuit, the post-stage leakage power processing circuit, and the DC blocking capacitor are all bonded together using gold wire.

7. The self-detector multi-stage limiter according to claim 6, characterized in that, The bonding is a wedge bonding.

8. The self-detector multi-stage limiter according to claim 5, characterized in that, All DC blocking capacitors are located on the substrate.

9. The self-detector multi-stage limiter according to any one of claims 1 to 8, characterized in that, The substrate is an aluminum nitride substrate.

10. A method for preparing a self-detecting multi-stage limiter as described in any one of claims 1 to 9, characterized in that, include: Provide a ceramic tube shell; The substrate is bonded and fixed to the base of the ceramic tube shell using nano silver paste; Nano silver paste is applied to designated locations on the substrate using a dispensing machine. Components that make up the front-end power detection and processing circuit and monolithic microwave integrated circuits that serve as the back-end leakage power processing circuit are then picked up and placed onto the silver paste. The current ceramic tube shell and all the components it supports are placed in a sintering furnace for heating and curing; Perform a bonding connection between the pre-stage power detection and processing circuit and the post-stage leakage power processing circuit.

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