Multistage microwave amplitude limiting circuit and passive amplitude limiter

Abstract

The invention discloses a multistage microwave amplitude limiting circuit and a passive amplitude limiter. The multi-stage microwave amplitude limiting circuit is a multi-stage microwave amplitude limiting circuit of a gallium nitride Schottky diode adopting Schottky contact metal with different work functions and comprises a multi-stage amplitude limiting structure formed by cascading a plurality of amplitude limiting structures, and each stage of amplitude limiting structure comprises the gallium nitride Schottky diode adopting Schottky contact metal with different work functions. In the multi-stage amplitude limiting structure, Schottky metals with different work functions are used for modulating the turn-on voltage, so that the turn-on voltage of a diode in each stage of amplitude limiting structure is decreased progressively, and the lower amplitude limiting power of a high-power input signal is decreased progressively step by step. According to the invention, gallium nitride Schottky diodes of Schottky metal with different work functions are used in different stages of the amplitude limiting circuit, so that the power capacity is improved, the insertion loss is reduced, the response time and the recovery time are reduced, and the amplitude limiter can effectively protect a post-stage circuit under high-power input.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor microwave limiting, and in particular to a multi-stage microwave limiting circuit and a passive limiter of a gallium nitride Schottky diode using Schottky contact metals with different work functions. Background Art

[0002] Microwave limiters are important components for electromagnetic protection and are widely used in the front-end systems of various microwave signal receivers, including radar, WLAN, satellite communication, wireless communication, etc. Their performance is crucial for the entire receiving system. However, there are many problems in the existing limiter technical solutions.

[0003] Traditional microwave limiters use PIN diodes or Schottky diodes based on silicon or gallium arsenide. Among them, for limiters using PIN diodes based on silicon and gallium arsenide, there will inevitably be spike leakage and a long recovery time. Excessive spike leakage power may cause damage to sensitive devices in the subsequent stage of the receiving system, such as low-noise amplifiers, and the long recovery time may lead to information loss. Moreover, limiters using Schottky diodes based on silicon or gallium arsenide have significant shortcomings in terms of power handling.

[0004] In summary, there is an urgent need for new limiter technical solutions to solve these problems. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies and defects of the prior art, and to provide a multi-stage microwave limiting circuit and a passive limiter of a gallium nitride Schottky diode using Schottky contact metals with different work functions. The multi-stage microwave limiting circuit can effectively improve the power handling of the limiter, reduce the insertion loss of the limiter, and increase the design freedom of the limiter by making the work function of the anode contact metal of the Schottky diode decrease gradually with the number of stages of the limiting structure.

[0006] An object of the present invention is to provide a multi-stage microwave limiting circuit, which is a multi-stage microwave limiting circuit of a gallium nitride Schottky diode using Schottky contact metals with different work functions, including a multi-stage limiting structure formed by cascading multiple limiting structures. Each stage of the limiting structure includes a gallium nitride Schottky diode using Schottky contact metals with different work functions. In the multi-stage limiting structure, the Schottky metals with different work functions are used to modulate the turn-on voltage, so that the turn-on voltage of the diode in each stage of the limiting structure decreases gradually, so that the limiting power decreases gradually for a high-power input signal.

[0007] Among them, the multi-stage limiting structure includes at least three limiting structures to form a three-stage microwave limiting circuit.

[0008] Among them, in the three-stage microwave limiting circuit, the gallium nitride Schottky diode of the first-stage limiting structure uses platinum as the Schottky contact metal of the anode, and the metal work function of platinum adopts the first metal work function; the gallium nitride Schottky diode in the intermediate-stage limiting structure uses nickel as the Schottky contact metal of the anode, and the metal work function of nickel adopts the second metal work function; the gallium nitride Schottky diode in the last-stage limiting structure uses titanium as the Schottky contact metal of the anode, and the metal work function of titanium adopts the third metal work function.

[0009] Among them, the first metal work function, the second metal work function, and the third metal work function decrease in sequence from large to small.

[0010] Among them, the first metal work function is 5.65 eV, the second metal work function is 5.12 eV, and the third metal work function is 4.33 eV.

[0011] Among them, the gallium nitride Schottky diode includes a quasi-vertical gallium nitride Schottky diode.

[0012] Among them, each stage of the limiting structure includes at least two gallium nitride Schottky diodes, and the two gallium nitride Schottky diodes are connected in reverse parallel to form one stage of the limiting structure.

[0013] Another object of the present invention is to provide a passive limiter, including the multi-stage microwave limiting circuit.

[0014] The present invention uses gallium nitride Schottky diodes with Schottky metals of different work functions in different stages of the limiting circuit, thereby improving the power capacity, reducing the insertion loss, reducing the response time and the recovery time, so that the limiter can effectively protect the subsequent circuit under high-power input.

[0015] The present invention uses gallium nitride Schottky diodes with Schottky contact metals of different work functions to replace PIN diodes or Schottky diodes based on silicon or gallium arsenide in different-stage limiting structures of the multi-stage limiting circuit, improving the integration degree and design freedom of the limiting circuit.

[0016] The present invention provides strong support for the microwave limiting circuit to achieve high power capacity, low turn-on level, low response time and low recovery time when only using gallium nitride Schottky diodes. Description of the Drawings

[0017] Figure 1 is a schematic diagram of a three-stage passive limiter provided by an embodiment of the present invention (taking a quasi-vertical gallium nitride Schottky diode as an example).

[0018] Figure 2 is a schematic diagram of a four-stage passive limiter provided by an embodiment of the present invention (taking a quasi-vertical gallium nitride Schottky diode as an example). Detailed implementation manners

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] In the limiting circuit of a gallium nitride Schottky diode using anode Schottky contact metals with different work functions according to an embodiment of the present invention, in a multi-stage limiting structure formed by cascading multiple limiting structures, Schottky metals with different work functions are used to modulate the turn-on voltage, so that the turn-on voltage of the diode in each stage of the limiting structure decreases step by step, so that the lower limiting power of the high-power input signal decreases step by step.

[0021] In some embodiments, the limiting circuit of the gallium nitride Schottky diode using anode Schottky contact metals with different work functions includes a multi-stage limiting structure, and each stage of the limiting structure includes a gallium nitride Schottky diode.

[0022] See Figure 1 as shown Figure 1 is a schematic diagram of a three-stage passive limiter provided by an embodiment of the present invention. Among them, the gallium nitride Schottky diode in the first-stage limiting structure uses platinum (Pt) as the Schottky contact metal of the anode, and the metal work function of platinum (Pt) adopts the first metal work function; the gallium nitride Schottky diode in the intermediate-stage limiting structure uses nickel (Ni) as the Schottky contact metal of the anode, and the metal work function of nickel (Ni) adopts the second metal work function; the gallium nitride Schottky diode in the last-stage limiting structure uses titanium (Ti) as the Schottky contact metal of the anode, and the metal work function of titanium (Ti) adopts the third metal work function. Among them, the first metal work function, the second metal work function, and the third metal work function decrease in order from large to small.

[0023] More preferably, the first metal work function is 5.65 eV, the second metal work function is 5.12 eV, and the third metal work function is 4.33 eV.

[0024] In the present invention, for example, in a three-stage microwave limiting circuit, the gallium nitride Schottky diode in the first-stage limiting structure uses platinum (Pt) as the Schottky contact metal of the anode, and the metal work function of platinum (Pt) is 5.65 eV. The higher metal work function results in a larger Schottky barrier height, which can achieve a higher turn-on voltage, lower reverse leakage current, and higher reverse breakdown voltage, thereby improving the power-bearing capacity of the first-stage limiting circuit, replacing the role of the PIN diode in the previous stage of the traditional limiter, and having significant advantages over the PIN diode in terms of response speed and recovery time.

[0025] In the present invention, in a three-stage microwave limiting circuit, for example, in the intermediate-stage limiting structure, a nickel (Ni) is used as the Schottky contact metal for the anode of the gallium nitride Schottky diode. The metal work function of nickel (Ni) is 5.12 eV, which can achieve a moderate turn-on voltage compared with the first stage and the last stage.

[0026] In the present invention, in a three-stage microwave limiting circuit, for example, in the last-stage limiting structure, a titanium (Ti) is used as the Schottky contact metal for the anode of the gallium nitride Schottky diode. The metal work function of titanium (Ti) is 4.33 eV. Due to the lower metal work function, a lower turn-on voltage can be achieved, which is beneficial to reducing the power consumption of the diode in the forward conduction state, thereby reducing the turn-on level and insertion loss of the limiter, and replacing the role of the gallium arsenide Schottky diode in the latter stage of the traditional limiter.

[0027] Each stage of the limiting structure in the present invention includes at least two gallium nitride Schottky diodes. The two gallium nitride Schottky diodes are connected in reverse parallel. Reverse parallel means that the two parallel branches are connected to the anode and cathode of the gallium nitride-based Schottky diode in the opposite direction. The upper parallel branch is connected to the cathode of the gallium nitride-based Schottky diode, and the lower parallel branch is connected to the anode of the gallium nitride-based Schottky diode, thus forming a stage of the limiting structure. As Figure 1 、 2 shown, the radio frequency signal RF enters from the left, and after being limited, it is output from the right. For a microwave limiter, the transmission of microwave signals and the connection between various components all use microwave transmission lines such as microstrip lines. Figure 1 、 2 All the connecting lines in

[0028] represent microwave transmission lines such as microstrip lines. In practice, the microstrip lines in the same microwave circuit may have different thicknesses. Specifically, each stage of the limiting structure consists of a central microstrip line and two parallel branches that connect the diodes and are grounded. The diodes on the two parallel branches are in opposite directions, and the specific number of diodes can be adjusted; the central microstrip lines of multiple-stage limiting structures are connected to form an overall limiter.

[0028] In the present invention, the gallium nitride Schottky diode can be a quasi-vertical gallium nitride Schottky diode or a PIN diode based on silicon or gallium arsenide, but not limited thereto. As Figure 1 shown, the quasi-vertical gallium nitride Schottky diode adopted includes a substrate, a GaN buffer layer, a GaN transmission layer, a GaN drift layer, and an anode arranged in sequence from bottom to top on the substrate. The cathode is in the same layer as the GaN drift layer. On the GaN transmission layer, the anode is platinum, nickel, or titanium in sequence from the first stage to the third stage.

[0029] The above is the description of the three-stage microwave limiting circuit. Figure 2Schematic diagram of a four-stage passive limiter provided by an embodiment of the present invention. The four metal work functions are submitted in descending order. The anode is platinum, nickel, nickel or titanium from the first stage to the third stage. The specific metal work function values can be optimized according to actual design requirements.

[0030] In summary, in the embodiment of the present invention, the turn-on voltage is modulated by using Schottky metals with different work functions, so that the turn-on voltage of the diode in each stage of the limiter structure decreases, ensuring that the lower limit power of the high-power input signal decreases stage by stage.

[0031] Another object of the present invention is to provide a passive limiter including the multi-stage microwave limiting circuit.

[0032] The above shows and describes the basic principles, main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0033] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0034] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A multi-stage microwave limiting circuit, characterized in that: The invention discloses a multi-stage microwave limiting circuit for gallium nitride Schottky diodes using Schottky contact metals with different work functions, including a multi-stage limiting structure formed by cascading multiple limiting structures, each stage of the limiting structure including gallium nitride Schottky diodes using Schottky contact metals with different work functions, and in the multi-stage limiting structure, the Schottky metals with different work functions are used to modulate the turn-on voltage, so that the turn-on voltage of the diode in each stage of the limiting structure decreases gradually, so that the limiting power under the high-power input signal decreases step by step.

2. The multi-stage microwave limiting circuit according to claim 1, characterized in that: The multi-stage limiting structure includes at least three limiting structures to form a three-stage microwave limiting circuit.

3. The multi-stage microwave limiting circuit according to claim 2, characterized in that: In the three-stage microwave limiting circuit, the gallium nitride Schottky diode in the first-stage limiting structure uses platinum as the Schottky contact metal of the anode, and the metal work function of platinum adopts the first metal work function; the gallium nitride Schottky diode in the intermediate-stage limiting structure uses nickel as the Schottky contact metal of the anode, and the metal work function of nickel adopts the second metal work function; the gallium nitride Schottky diode in the last-stage limiting structure uses titanium as the Schottky contact metal of the anode, and the metal work function of titanium adopts the third metal work function.

4. The multi-stage microwave limiting circuit according to claim 3, characterized in that: The first metal work function, the second metal work function and the third metal work function decrease in sequence from large to small.

5. The multi-stage microwave limiting circuit according to claim 4, characterized in that: The first metal work function is 5.65 eV, the second metal work function is 5.12 eV, and the third metal work function is 4.33 eV.

6. The multi-stage microwave limiting circuit according to claim 1, characterized in that: The gallium nitride Schottky diode comprises a quasi-vertical gallium nitride Schottky diode.

7. The multi-stage microwave limiting circuit according to claim 1, characterized in that: Each level of the limiting structure includes at least two gallium nitride Schottky diodes, and the two gallium nitride Schottky diodes are connected in reverse parallel to form a level of limiting structure.

8. A passive limiter, characterized in that it comprises the multi-stage microwave limiting circuit according to any one of claims 1 to 7.

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