Frequency tripler and power combiner with integrated Schottky diode

Abstract

The present application discloses a frequency tripler and power synthesis device integrated with Schottky diodes. The frequency tripler includes: a substrate; and a first microstrip circuit and a first Schottky diode array located on the substrate, wherein the first Schottky diode array includes at least one first Schottky diode connected in series in a forward direction between a first pad and a second pad, and at least one second Schottky diode connected in series in a reverse direction between the first pad and the second pad. The first microstrip circuit includes an input probe, an output probe, and a low-pass filter, the low-pass filter being connected to the input probe. The first pad and the second pad of the first Schottky diode array are respectively connected to the low-pass filter and the output probe, and are used to convert the input signal into a tripled frequency output signal. By directly extracting the tripled frequency harmonics using the on-chip Schottky diode array, the frequency multiplication coefficient of the frequency tripler is improved, as well as the design consistency and operating stability of the frequency multiplier.

Description

Technical Field

[0001] The present invention relates to the field of signal processing, and more particularly to a frequency tripler and a power synthesis device integrated with a Schottky diode. Background Art

[0002] With the rapid development of wireless communication technology, the range of communication frequency bands has gradually increased to obtain more available spectrum resources and higher bandwidth. For example, millimeter wave bands are already being used in 5G communications. The millimeter wave band has a frequency range of 30 GHz to 300 GHz, while the terahertz band has a frequency range of 300 GHz to 3 THz. Compared with the millimeter wave band, the terahertz band has a higher bandwidth and lower transmission loss. Therefore, it is the next generation technology in wireless communication for high-speed data transmission and wireless communication. Terahertz technology also has important application prospects in target detection and medical imaging.

[0003] The application of terahertz technology remains limited by wave sources. Terahertz wave sources include optical wave sources based on the optical nonlinear effects of optical components and semiconductor wave sources based on the semiconductor nonlinear effects of semiconductor devices. Because direct generation of terahertz electromagnetic waves is difficult, semiconductor wave sources that use frequency multipliers to multiply microwaves or millimeter waves to terahertz waves have become the primary source of terahertz waves. These wave sources offer advantages such as compact structure, light weight, high reliability, and low cost.

[0004] The semiconductor wave source includes a signal source and a frequency multiplier. The working principle of the frequency multiplier is to use the nonlinear characteristics of the Schottky diode to achieve frequency doubling. This method has been widely used due to its advantages such as low cost and small size. However, on the one hand, due to the input power limitation of the Schottky diode, the output power of the existing frequency multiplier is low and can only be applied to low-power scenarios in the terahertz band. On the other hand, due to the circuit design of the frequency multiplier, the existing frequency multiplier mainly generates a tripled harmonic signal. Therefore, the frequency multiplication coefficient of the existing frequency multiplier is low and it is mainly used in the low-frequency end of the terahertz band.

[0005] Furthermore, existing frequency multipliers include independent Schottky diodes and microstrip circuits. The Schottky diode is a separate discrete component. During the frequency multiplier assembly process, it is flip-chip mounted on the microstrip circuit using a gold ribbon. However, due to the mounting process, there is a certain discrepancy between the product characteristics of the frequency multiplier and the simulation results. Due to the mounting process, the Schottky diode itself does not have sufficient contact with the microstrip circuit. As a result, heat accumulates continuously during operation, preventing effective heat dissipation. This affects the frequency multiplication efficiency and service life of the Schottky diode.

[0006] Therefore, it is expected to further improve the design of the frequency multiplier to enhance the working stability of the frequency multiplier, as well as to increase the frequency multiplication coefficient and output power, thereby expanding the application scenarios of semiconductor wave sources. Summary of the Invention

[0007] In view of the above problems, the object of the present invention is to provide a frequency tripler and a power synthesis device integrated with Schottky diodes, wherein an on-chip Schottky diode array is used to directly extract the tripled harmonics to improve the frequency multiplication coefficient of the frequency multiplier, as well as the design consistency and operating stability of the frequency multiplier.

[0008] According to one aspect of the present invention, there is provided a frequency tripler, comprising: a substrate; and a first microstrip circuit and a first Schottky diode array located on the substrate, wherein the first Schottky diode array comprises at least one first Schottky diode connected in series in a forward direction between a first pad and a second pad, and at least one second Schottky diode connected in series in a reverse direction between the first pad and the second pad; the first microstrip circuit comprises an input probe, an output probe, and a low-pass filter, the low-pass filter being connected to the input probe; the first pad and the second pad of the first Schottky diode array being connected to the low-pass filter and the output probe, respectively, for converting an input signal into a frequency-tripled output signal.

[0009] Optionally, the system further includes: a second microstrip circuit and a second Schottky diode array located on the substrate, wherein the second microstrip circuit and the first microstrip circuit are located on the same straight line and form a symmetrical structure separated from each other.

[0010] Optionally, the method further includes: a dielectric layer located between the microstrip circuit and the substrate.

[0011] Optionally, the substrate is a semiconductor substrate, and the at least one first Schottky diode and the at least one second Schottky diode respectively include: a first epitaxial layer and a second epitaxial layer, which are stacked in sequence on the semiconductor substrate, the first epitaxial layer and the second epitaxial layer are respectively doped into N-type, and the first epitaxial layer is heavily doped relative to the second epitaxial layer; a Schottky metal and a cathode electrode, which are respectively located on the second epitaxial layer and the first epitaxial layer.

[0012] Optionally, the semiconductor substrate is an undoped GaAs substrate, and the first epitaxial layer and the second epitaxial layer are doped GaAs substrates respectively.

[0013] Optionally, a cavity is formed in the dielectric layer, and the at least one first Schottky diode and the at least one second Schottky diode respectively include: an air bridge located above the cavity, and the air bridge is used to connect the Schottky metal.

[0014] Optionally, the output signal is an electromagnetic wave in the millimeter wave band or the terahertz frequency band.

[0015] According to another aspect of the present invention, a power synthesis device is provided, comprising: an input waveguide and an output waveguide; and the above-mentioned tripler, wherein the tripler is coupled to the input waveguide to receive an output signal and is coupled to the output waveguide to provide an output signal, wherein the output waveguide performs power synthesis on at least two output signals to generate a synthesized signal.

[0016] Optionally, the frequency tripler includes a first microstrip circuit and a second microstrip circuit located on a substrate, wherein the second microstrip circuit and the first microstrip circuit are located on the same straight line and form a symmetrical structure separated from each other.

[0017] Optionally, the power synthesis device includes a single frequency tripler, the input waveguide includes a single output end, the single input end is located at the symmetric center of the symmetrical structure, and is coupled to the input probe of the first microstrip circuit and the input probe of the second microstrip circuit respectively.

[0018] Optionally, the power synthesis device includes a plurality of triplers, the input waveguide includes a plurality of output ends, each of the plurality of output ends is located at the symmetry center of the corresponding tripler among the plurality of triplers, and is respectively coupled to the input probe of the first microstrip circuit and the input probe of the second microstrip circuit.

[0019] Optionally, the output waveguide includes a first input end and a second input end, and the first input end and the second input end are coupled to output probes of the first microstrip circuit and the second microstrip circuit respectively.

[0020] The frequency tripler according to an embodiment of the present invention integrates an on-chip Schottky diode array onto the substrate of a microstrip circuit. Compared to existing designs that mount discrete Schottky diodes during assembly, this eliminates the need for external bonding to the discrete Schottky diodes, ensuring consistency between the product characteristics of the frequency tripler and simulation results from the design phase. Furthermore, the on-chip Schottky diodes utilize the entire substrate of the frequency tripler for heat dissipation, thereby ensuring the lifespan of the Schottky diodes and the operational stability of the frequency tripler.

[0021] According to the frequency tripler of an embodiment of the present invention, the Schottky diode array is connected between the low-pass filter and the output probe, that is, connected in series in the microstrip circuit, which not only excites the harmonic signal of the fundamental signal, but also cancels the even harmonic components, leaving only the odd harmonic components. Therefore, the tripled harmonics can be directly extracted, and the tripled output signal can be obtained without the need for an additional high-pass filter for frequency selection. This not only simplifies the circuit structure and is conducive to the miniaturization design of the device, but also improves the conversion efficiency of the frequency multiplier.

[0022] According to a preferred embodiment, a tripler includes a first microstrip circuit and a second microstrip circuit located on the same straight line and forming a symmetrical structure separated from each other. An input signal is fed through the center of symmetry of the symmetrical structure and then enters the first microstrip circuit and the second microstrip circuit, respectively. Therefore, the broadband frequency multiplier itself performs the power distribution function for the input signal, eliminating the need for power distribution design of at least one input waveguide stage. This reduces input signal loss during transmission and indirectly improves the frequency multiplication efficiency of the frequency multiplier. Furthermore, the symmetrical structure allows for simulation design of a single-sided microstrip circuit during the design phase, saving simulation design time and effectively improving simulation design efficiency.

[0023] According to a preferred embodiment of the power combining device, the input waveguide includes at least one power distribution structure and multiple output ends, and the output waveguide includes at least one power combining structure and multiple input ends. The multiple output ends of the input waveguide are respectively connected to the symmetrical centers of corresponding triplers. Multiple triplers are used to respectively bear the input power. In each tripler, symmetrical first and second microstrip circuits are used to respectively bear the input power. Thus, the combination of the input waveguide and tripler can achieve multi-stage power distribution. The multiple input ends of the output waveguide are respectively connected to the two ends of the corresponding tripler, thereby achieving multi-stage power combining. Therefore, while the parameter requirements of the Schottky diode remain unchanged, the power combining device can use a single or multiple triplers to increase the output power. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic top view of a power combiner according to a first embodiment of the present invention is shown.

[0025] Figure 2 and Figure 3 Shown separately Figure 1 Top view and cross-sectional view of the frequency tripler in the power combining device shown.

[0026] Figure 4 Show Figure 2 Schematic perspective view of the Schottky diode array in the frequency tripler shown.

[0027] Figure 5 Show Figure 2Equivalent circuit diagram of the Schottky diode array in the frequency tripler shown.

[0028] Figure 6 and Figure 7 Shown separately Figure 2 The input return loss curve and frequency doubling efficiency curve of the tripler are shown.

[0029] Figures 8a to 8f Show Figure 2 Cross-sectional views of different stages in the fabrication process of the Schottky diodes used in the frequency tripler shown.

[0030] Figure 9 A schematic perspective view showing a power combiner device according to a second embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following is a detailed description of the layout structure of the mixed-signal chip proposed by the present invention, with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention.

[0032] Figure 1 A schematic top view of a power combiner according to a first embodiment of the present invention is shown.

[0033] The power combining device 100 includes an input waveguide 110 , an output waveguide 160 , and a frequency tripler 120 located therebetween.

[0034] Input waveguide 110 and output waveguide 160 are, for example, rectangular metal pipes for transmitting high-frequency electromagnetic waves. In this embodiment, input waveguide 110 is a standard waveguide with a linear structure, having a single input end and a single output end, while output waveguide 160 is a Y-shaped waveguide with a branched structure, having multiple input ends and a single output end.

[0035] The frequency tripler 120 is used to convert an input signal into a tripled frequency output signal. In this embodiment, the frequency tripler 120 has a symmetrical circuit structure. The center of symmetry of the frequency tripler 120 is coupled to the output end of the input waveguide 110 to receive the input signal. The two ends of the frequency tripler 120 are respectively coupled to the two input ends of the output waveguide 160 to receive the output signal. The output waveguide 160 also functions as a power combiner, combining the output signals received from multiple input ends into a single composite signal.

[0036] See also Figure 2 and Figure 3Frequency tripler 120 includes a substrate 121, and a first microstrip circuit 101 and a second microstrip circuit 102 formed on substrate 121. First microstrip circuit 101 and second microstrip circuit 102 are located on the same straight line and form a symmetrical structure separated from each other. Taking first microstrip circuit 101 as an example, first microstrip circuit 101 includes an input probe 131, a low-pass filter 132, and an output probe 134.

[0037] In this embodiment, a dielectric layer 122 is formed on a substrate 121. The substrate 121 is composed, for example, of undoped GaAs. The dielectric layer 122 is composed, for example, of silicon oxide or silicon nitride. An input probe 131, a low-pass filter 132, and an output probe 134 are metal patterns formed on the dielectric layer 122. The output end of the input waveguide 110 includes a sidewall opening. The input probe 131 of the frequency tripler 120 is inserted through the opening into the sidewall opening of the input waveguide 110 to achieve coupling with the input waveguide 110. The input end of the output waveguide 160 also includes a sidewall opening. The output probe 134 of the frequency tripler 120 is inserted through the opening into the sidewall opening of the output waveguide 160 to achieve coupling with the output waveguide 160. Furthermore, the low-pass filter 132 is connected to the input probe 131. On the one hand, the low-pass filter 132 transmits the low-frequency input signal received by the input probe 131 to the Schottky diode array 10 , and on the other hand, the low-pass filter 132 prevents the high-frequency harmonic signal generated by the Schottky diode array 10 from transmitting in reverse and reaching the input probe 131 .

[0038] In this embodiment, the low-pass filter 132 is, for example, a third-order high-low impedance low-pass filter.

[0039] See also Figure 4 The Schottky diode array 10 includes a first pad 141, a second pad 142, and a plurality of Schottky diodes formed between the first pad 141 and the second pad 142. The first pad 141 of the Schottky diode array 10 is connected to the low-pass filter 132, and the second pad 142 is connected to the output probe 134.

[0040] Between the first pad 141 and the second pad 142, a plurality of first Schottky diodes 11 are connected in series in the forward direction, and a plurality of second Schottky diodes 12 are connected in series in the reverse direction. In this embodiment, the first Schottky diode 11 and the second Schottky diode 12 are, for example, semiconductor blocks formed on the substrate 121. As a preferred embodiment, the first Schottky diode 11 and the second Schottky diode 12 are formed in an air cavity 151 surrounded by a dielectric layer 122, and are isolated from each other by an air dielectric. Furthermore, an interconnect metal 127 is formed above the air cavity 151 for connecting the Schottky metal of the Schottky diode to the cathode electrode of an adjacent Schottky diode, or to the first pad 141 / second pad 142. By using an air bridge to achieve the anode connection of the Schottky diode, the parasitic capacitance of the Schottky diode at high frequencies can be reduced by using the air dielectric.

[0041] See also Figure 5 The equivalent circuit of Schottky diode array 10 is a first Schottky diode 11 and a second Schottky diode 12 connected in antiparallel. Signal source 13 provides a fundamental signal at a frequency of f1. The Schottky diode array 10, stimulated by the source signal, generates frequency-doubled signals, including a second harmonic signal at a frequency of 2*f1 and higher harmonic signals.

[0042] In this embodiment, the Schottky diode array 10 is connected in series in the loop of the radio frequency signal. Since the Schottky diode is a reverse balanced structure, the second harmonics generated by the excitation in the Schottky diode array 10 have the same amplitude and opposite phase. They eventually cancel each other out, leaving only the odd harmonic components. Furthermore, the fundamental signal with a frequency of f1 can be filtered out by utilizing the carrier frequency of the output waveguide. The output signal provided by the output waveguide is the third harmonic and higher harmonic components of the fundamental signal, wherein the amplitude of the higher harmonics higher than the third harmonic is very small and can be ignored. Therefore, the tripler of this embodiment can directly obtain a tripled frequency signal. No additional filtering circuit is required at the output end of the output waveguide for frequency selection.

[0043] Figure 6 and Figure 7 Shown separately Figure 2 The input return loss curve and frequency doubling efficiency curve of the tripler are shown in Figure 2. In order to directly compare the input signal and output signal, Figure 6 In the horizontal coordinate of the curve, the frequency of the input signal has been normalized to the frequency of the output signal. It can be understood that the frequency of the actual input signal is 1 / 3 of the frequency shown on the horizontal coordinate in the figure.

[0044] See also Figure 6According to the tripler of this embodiment, the S11 parameter is less than -10dB within the bandwidth of 70-110GHz. Furthermore, the input return loss of the tripler can be calculated based on the modulus of the S11 parameter. The input return loss of the tripler is the ratio between the input signal power and the reflected signal power. In this embodiment, the S11 parameter of the tripler is less than -10dB, which means that the input return loss is very low and the reflected power is very small. Therefore, according to the tripler of this embodiment, within the frequency range of 70GHz to 110GHz, the frequency multiplier has good matching performance, low input return loss, and small reflected power.

[0045] from Figure 6 As shown in the input return loss curve, the frequency tripler according to this embodiment has a wide bandwidth (40 GHz) and a low input return loss (less than -10 dB). The former facilitates the realization of a broadband frequency tripler, adapting to the needs of different signal sources within the bandwidth range. The latter helps reduce signal loss and interference, thereby improving system efficiency and matching performance with signal sources.

[0046] See also Figure 7 According to the tripler of this embodiment, the frequency doubling efficiency is greater than 7% within a bandwidth of 70-110 GHz. The frequency doubling efficiency is the ratio of the output power of the output signal of the frequency multiplier to the input power, and is expressed as a percentage of the energy conversion efficiency of the frequency multiplier. The theoretical frequency doubling efficiency of the tripler is 1 / 9. The level of frequency doubling efficiency is crucial to the performance of the frequency multiplier. Higher frequency doubling efficiency means less energy loss and higher output power, thereby improving the conversion efficiency of the system.

[0047] from Figure 7 As shown in the conversion efficiency curve, the frequency tripler according to this embodiment has a wide bandwidth (40 GHz) and high conversion efficiency (greater than 7%). The former facilitates the realization of a broadband frequency tripler, adapting to the needs of different signal sources within the bandwidth range. The latter helps reduce signal loss in the frequency tripler itself, thereby improving the system's conversion efficiency and output power.

[0048] Figures 8a to 8f Show Figure 2 Cross-sectional views of different stages in the fabrication process of the Schottky diodes used in the frequency tripler shown.

[0049] For clarity, in Figure 8a and 8bFIG. 1 shows only one first Schottky diode 11 in the Schottky diode array 10. However, it is understood that the Schottky diode array 10 includes not only the first Schottky diodes 11 connected in series in the forward direction but also the second Schottky diodes 12 connected in series in the reverse direction, and the number of the first Schottky diodes 11 and the second Schottky diodes 12 can be any number.

[0050] See also Figure 8a A first epitaxial layer 122 and a second epitaxial layer 123 are sequentially grown on the substrate 121. In the frequency tripler, the substrate 121 is a common substrate for the microstrip circuit and the Schottky diode.

[0051] In this embodiment, the substrate 121, the first epitaxial layer 122 and the second epitaxial layer 123 are respectively an undoped GaAs substrate, a heavily doped N-type GaAs epitaxial layer and a lightly doped N-type GaAs epitaxial layer. GaAs substrates have excellent electron transport properties and high electron saturation drift velocity, and GaAs substrates can be used for epitaxial growth of lattice-matched N-type GaAs epitaxial layers. Therefore, GaAs substrates are substrate materials that can take into account the power requirements and high-frequency characteristics of microstrip circuits and Schottky diodes of terahertz frequency multipliers. In an alternative embodiment, the substrate of the Schottky diode can be a GaN substrate similar to GaAs. In another alternative embodiment, the substrate of the Schottky diode can be an epitaxially grown silicon carbide substrate or a quartz substrate. In the case of using a quartz substrate, an additional buffer layer can be used to improve the lattice matching between the quartz substrate and the epitaxial layer.

[0052] The process of epitaxially growing an N-type GaAs epitaxial layer on an undoped GaAs substrate is known. For example, a GaAs epitaxial layer is formed using processes such as metal organic chemical vapor epitaxy (MOCVD) or molecular beam epitaxy (MBE). A silicon source compound (e.g., trimethylsilane, Si(CH3)3H) is introduced into the feed gas for epitaxial growth. The silicon source compound chemically reacts with the GaAs on the surface of the GaAs epitaxial layer, incorporating Si as an N-type dopant into the GaAs epitaxial layer to form an N-type GaAs epitaxial layer.

[0053] See also Figure 8b , the first epitaxial layer 122 and the second epitaxial layer 123 are etched into semiconductor blocks to form a device region of the Schottky diode.

[0054] In this embodiment, substrate 121 includes a first region and a second region, wherein the first region is used to form a microstrip circuit, and the second region is used to form a Schottky diode. For example, a photoresist mask is formed on substrate 121, shielding a portion of the surface of second epitaxial layer 123 in the second region of substrate 121 while completely exposing the surface of second epitaxial layer 123 in the first region of substrate 121. Anisotropic dry etching is then used to sequentially remove the exposed regions of second epitaxial layer 123 and first epitaxial layer 122. By controlling the etching time, the etching depth can be controlled, allowing complete removal of first epitaxial layer 122 and second epitaxial layer 123 in the first region. Consequently, a semiconductor block is formed only in the second region, which is used to form the Schottky diode. When substrate 121 itself is lightly etched, a mesa is formed on substrate 121 below the semiconductor block.

[0055] See also Figure 8c , a dielectric layer 124 is formed on the substrate 121 .

[0056] In this embodiment, dielectric layer 124 serves as an isolation layer between the metal pattern of the microstrip circuit and the pad of the Schottky diode. Dielectric layer 124 is composed, for example, of silicon oxide or silicon nitride. For example, physical vapor deposition (PVD) or chemical vapor deposition (CVD) is used to form the dielectric layer covering the exposed surface of substrate 121. After the deposition process, the dielectric layer covers the semiconductor block. Furthermore, chemical mechanical polishing (CMP) is used to remove a portion of the dielectric layer to obtain a smooth surface. During the chemical mechanical polishing process, the semiconductor block is used as a stop layer to re-expose the surface of the semiconductor block.

[0057] See also Figure 8d , a portion of the second epitaxial layer 123 is removed by etching to re-expose the surface of the first epitaxial layer 122 .

[0058] In this embodiment, a photoresist mask is formed on substrate 121 to block a portion of the surface of second epitaxial layer 123. Anisotropic dry etching is used to remove the exposed areas of second epitaxial layer 123. By controlling the etching time, the etching depth can be controlled, allowing the exposed areas of second epitaxial layer 123 to be completely removed. This etching step re-exposes the surface of first epitaxial layer 122. While first epitaxial layer 122 is slightly etched, it forms a mesa below second epitaxial layer 123.

[0059] See also Figure 8e Corresponding metal patterns are formed on the surfaces of the first epitaxial layer 122 , the second epitaxial layer 123 , and the dielectric layer 124 , respectively.

[0060] In this embodiment, the process for forming the metal pattern includes forming a metal layer using a deposition process such as evaporation or sputtering, and then etching the metal layer through a photoresist mask to form a metal pattern. Multiple deposition processes and etching processes can be used to form metal patterns in different regions. For example, the metal pattern formed on the surface of the second epitaxial layer 123 is a Schottky metal 125, the metal pattern formed on the surface of the first epitaxial layer 126 is a cathode electrode 126, and the metal pattern formed on the surface of the dielectric layer 124 is a pad 141, as well as an interconnecting metal 127 between the Schottky metal 125 and the cathode electrode 126. The Schottky metal 125 is, for example, composed of one of the following metals or alloys: nickel, platinum, gold, cobalt, palladium, molybdenum, chromium, rhodium, rhenium, platinum silicide, and nickel silicide. The cathode electrode 126, the pad 141, and the interconnecting metal 127 are, for example, composed of one of the following metals: gold, silver, copper, aluminum, platinum, and nickel.

[0061] See also Figure 8f The dielectric layer 124 around the semiconductor block is selectively removed by etching to form an air cavity 151 surrounding the semiconductor block.

[0062] In this embodiment, a photoresist mask is formed on the surface of the semiconductor structure, exposing only the peripheral portion of the semiconductor block. An anisotropic wet etch is then used to remove the exposed areas of dielectric layer 124. Due to the selectivity of the etchant, the exposed areas of dielectric layer 124 are selectively removed relative to the semiconductor block and the metal pattern of the dielectric layer. The etchant stops on the surface of substrate 121, thereby forming an air cavity 151 surrounding the semiconductor block. Above air cavity 151, the Schottky metal 125 and the interconnect metal 127 of the cathode electrode 126 are suspended, forming an air bridge.

[0063] In this embodiment, the metal pattern of the microstrip circuit is located on the surface of dielectric layer 124, similar to the pad 141 of the Schottky diode. By selecting a metal material that is compatible with both the microstrip circuit and the Schottky diode, the metal pattern of the microstrip circuit and the metal pattern of the Schottky diode can be formed in the same step. The frequency tripler of this embodiment not only reduces manufacturing costs through a shared process, but also precisely defines the dimensions of the pads interconnecting the Schottky diode and the microstrip circuit. This ensures that the product characteristics of the frequency doubler are consistent with the simulation results obtained during the design phase.

[0064] Figure 9 A schematic perspective view showing a power combiner device according to a second embodiment of the present invention.

[0065] The power combining device 200 includes an input waveguide 210 , an output waveguide 260 , and frequency triplers 221 and 222 located therebetween.

[0066] Input waveguide 210 and output waveguide 260 are, for example, rectangular metal pipes for transmitting high-frequency electromagnetic waves. In this embodiment, input waveguide 210 is a Y-shaped waveguide with a branched structure, having a single input end and two output ends, while output waveguide 260 is a Y-shaped waveguide with a multi-stage cascade structure, having multiple input ends and a single output end.

[0067] The internal structure of the frequency triplers 221 and 222 in the power combiner according to the second embodiment is substantially the same as that of the frequency tripler in the power combiner according to the first embodiment, and thus will not be described in detail herein.

[0068] Input waveguide 210 performs power distribution, splitting the input signal from the signal source into two input signals, each of which is provided to two output terminals. Triplers 221 and 222 are used to convert the corresponding input signals into tripled frequency output signals. In this embodiment, triplers 221 and 222 each have a symmetrical circuit structure. The symmetry centers of triplers 221 and 222 are respectively coupled to the two output terminals of input waveguide 210 to receive the input signal. The two ends of tripler 221 are respectively coupled to the two input terminals of output waveguide 260 to receive the output signal. The two ends of tripler 222 are respectively coupled to the two input terminals of output waveguide 260 to receive the output signal. The output waveguide 260 also functions as a power combiner, combining the output signals received from multiple input terminals into a single composite signal.

[0069] According to the power combiner device of the second embodiment, the multiple output ends of the input waveguide are respectively connected to the symmetrical centers of corresponding triplers. Multiple triplers are used to respectively bear the input power. In each tripler, symmetrical first and second microstrip circuits are used to respectively bear the input power. Therefore, the combination of the input waveguide and tripler can achieve multi-stage power distribution. The multiple input ends of the output waveguide are respectively connected to the two ends of the corresponding tripler, thus achieving multi-stage power combination. Therefore, under the condition that the parameter requirements of the Schottky diode remain unchanged, the power combiner device can use a single or multiple triplers to increase the output power.

[0070] In the above embodiments, a frequency tripler for the terahertz band is described in detail as an example. The frequency tripler according to the embodiments of the present invention has a higher multiplication factor than a frequency doubler and can eliminate the need for frequency selection filtering circuits. Therefore, the frequency tripler is particularly suitable for the mid- and high-frequency ends of the terahertz band. However, the present invention is not limited to this, and the principles of the frequency tripler can be applied to any frequency range within the millimeter wave band or the terahertz band. For the millimeter wave band, the use of a frequency tripler can also reduce the design parameter requirements and hardware costs of the wave source.

[0071] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A frequency tripler, comprising: substrate; as well as a first microstrip circuit and a first Schottky diode array located on the substrate, The first Schottky diode array includes at least one first Schottky diode connected in series between the first pad and the second pad in a forward direction and at least one second Schottky diode connected in series between the first pad and the second pad in a reverse direction. The first microstrip circuit includes an input probe, an output probe, and a low-pass filter, wherein the low-pass filter is connected to the input probe, and the first pad and the second pad of the first Schottky diode array are respectively connected to the low-pass filter and the output probe, for converting the input signal into a tripled frequency output signal. The substrate is a semiconductor substrate, and the at least one first Schottky diode and the at least one second Schottky diode respectively include: A first epitaxial layer and a second epitaxial layer are stacked sequentially on the semiconductor substrate, the first epitaxial layer and the second epitaxial layer are doped into N-type respectively, and the first epitaxial layer is heavily doped relative to the second epitaxial layer; The Schottky metal and the cathode electrode are respectively located on the second epitaxial layer and the first epitaxial layer.

2. The frequency tripler according to claim 1, further comprising: a second microstrip circuit and a second Schottky diode array located on the substrate, The second microstrip circuit and the first microstrip circuit are located on the same straight line and form a symmetrical structure separated from each other.

3. The frequency tripler according to claim 2, wherein: Also includes: A dielectric layer is located between the microstrip circuit and the substrate.

4. The frequency tripler according to claim 1, wherein: The semiconductor substrate is an undoped GaAs substrate, and the first epitaxial layer and the second epitaxial layer are doped GaAs substrates respectively.

5. The frequency tripler according to claim 1, wherein: A cavity is formed in the dielectric layer. The at least one first Schottky diode and the at least one second Schottky diode each include an air bridge located above the cavity. The air bridge is used to connect the Schottky metal.

6. The frequency tripler according to claim 1, wherein: The output signal is an electromagnetic wave in the millimeter wave frequency band or the terahertz frequency band.

7. A power combining device comprising: input waveguide and output waveguide; as well as The frequency tripler according to any one of claims 1 to 6, wherein the frequency tripler is coupled to the input waveguide to receive an output signal and is coupled to the output waveguide to provide an output signal. The output waveguide performs power synthesis on at least two output signals to generate a synthesized signal.

8. The power combining device according to claim 7, wherein: The frequency tripler includes a first microstrip circuit and a second microstrip circuit located on a substrate. The second microstrip circuit and the first microstrip circuit are located on the same straight line and form a symmetrical structure separated from each other.

9. The power combining device according to claim 8, wherein: The power combining device includes a single frequency tripler, the input waveguide includes a single output end, the single output end is located at the symmetric center of the symmetrical structure, and is coupled to the input probe of the first microstrip circuit and the input probe of the second microstrip circuit respectively.

10. The power combining device according to claim 8, wherein: The power synthesis device includes multiple triplers, and the input waveguide includes multiple output ends. Each of the multiple output ends is located at the symmetry center of a corresponding tripler among the multiple triplers, and is respectively coupled to the input probe of the first microstrip circuit and the input probe of the second microstrip circuit.

11. The power combining device according to claim 8, wherein: The output waveguide includes a first input end and a second input end, wherein the first input end and the second input end are coupled to output probes of the first microstrip circuit and the second microstrip circuit, respectively.

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