W-band single tube frequency doubler

Abstract

The application belongs to the technical field of millimeter wave, and particularly relates to a W-waveband single-tube double frequency multiplier, which comprises a fundamental wave input standard rectangular waveguide, a second harmonic output standard rectangular waveguide, a substrate, a microstrip transmission circuit and a metal shielding cavity; the microstrip transmission circuit comprises an input probe, a low-pass filter, a diode, a short-circuit matching branch and an output probe; the input probe is used for transmitting an input signal to the low-pass filter; the low-pass filter filters the input signal to obtain a fundamental wave signal; the diode is used for screening the fundamental wave signal to generate each harmonic; the short-circuit matching branch is used for heat dissipation of the diode and signal extraction of the harmonic to obtain a second harmonic signal; and the output probe is used for outputting the second harmonic signal; the W-waveband double frequency multiplier of the application adopts a Schottky varistor diode, reduces the design of a direct current bias structure and simplifies the circuit.

Description

Technical Field

[0001] This invention belongs to the field of millimeter wave technology, specifically relating to a W-band single-tube frequency doubler. Background Technology

[0002] With continuous research into wireless communication technology, the radio spectrum allocated to communication systems has been pushed to the terahertz band. The W band (75GHz-110GHz) is an important wireless communication band, suitable for high-speed data transmission and radar imaging applications. The frequency bands below the W band are already occupied by various wireless communication systems. Because this band possesses ultra-wideband, untapped frequency resources, it has become a highly valued research direction for researchers. Various millimeter-wave systems can be applied to this band. A frequency multiplier is a nonlinear frequency converter that utilizes the nonlinearity of the device to output multiple harmonic signals. The desired harmonic signal is then extracted by a frequency selection circuit. At the circuit design level, the main performance indicators for frequency multipliers include operating frequency, frequency multiplication efficiency, and output power. To achieve the desired design goals, different technologies and methods have been proposed to optimize the performance of frequency multipliers. Currently, the frequency multiplication efficiency and output power of domestic millimeter-wave frequency multipliers are relatively low, making them difficult to directly apply to millimeter-wave transceiver systems. Furthermore, the limited power capacity of diode chips restricts the output power of solid-state frequency multipliers. Therefore, rationally selecting a high-quality topology to improve the output power of frequency multipliers has become an important research topic.

[0003] Currently, Schottky varactor diodes are commonly used as key nonlinear components in frequency doubler technology. Varactor diodes are highly sensitive to signal changes. To improve frequency doubling efficiency, a DC voltage is used to adjust the bias state of the varactor diode. Therefore, the resulting frequency doublers are typically three-port, with complex structures and large device sizes. To obtain high-power frequency doublers, the input power of the frequency doubler is relatively high. In engineering applications, high power can lead to device heating, thereby reducing overall performance. Existing technologies often neglect the issue of diode heating in engineering applications. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes a W-band single-tube frequency doubler, comprising a fundamental input standard rectangular waveguide, a second harmonic output standard rectangular waveguide, a substrate, a microstrip line transmission circuit, and a metal shielding cavity; the fundamental input standard rectangular waveguide and the second harmonic output standard rectangular waveguide are transitionally connected to the microstrip line transmission circuit; the microstrip line transmission circuit is disposed on the substrate; the substrate is disposed inside the metal shielding cavity;

[0005] The microstrip line transmission circuit includes: an input probe, a low-pass filter, a diode, a short-circuit matching stub, and an output probe. The input probe transmits the input signal to the low-pass filter. The low-pass filter filters the input signal to obtain the fundamental signal and inputs the fundamental signal into the diode. The diode filters the fundamental signal to generate various harmonics. The short-circuit matching stub dissipates heat from the diode and extracts the harmonic signals to obtain the second harmonic signal. The output probe outputs the second harmonic signal.

[0006] Preferably, the substrate used is the Rogers RT / duroid 5880 substrate.

[0007] Preferably, the input probe is a U-band waveguide probe and the output probe is a W-band waveguide probe; wherein the input probe is used to transition the signal waveguide to the microstrip line; and the output probe is used to output the WR-10 standard rectangular waveguide.

[0008] Preferably, both the input probe and the output probe adopt an E-plane waveguide probe transition structure, that is, the probe plane normal is perpendicular to the waveguide transmission direction.

[0009] Preferably, the diode is a Schottky variable resistor diode MA4E1310.

[0010] Preferably, the low-pass filter is a 7th-order high-low impedance low-pass filter.

[0011] Preferably, the short-circuit matching stub includes: a high-low impedance matching stub, a widening substrate, and a copper layer. The high-low impedance matching stub is disposed on the widening substrate and is used to match and filter the screened signal. The widening substrate is disposed on the copper layer, and a number of metallized vias are provided at positions corresponding to the copper layer on the widening substrate for grounding, so that the circuit forms a DC loop and increases the heat dissipation area of ​​the diode.

[0012] The beneficial effects of this invention are:

[0013] The W-band frequency doubler of this invention uses a Schottky variable resistor diode, reducing the design of the DC bias structure and simplifying the circuit. The filter section of this invention employs a high-low impedance structure, resulting in more stable phase performance and a frequency doubling efficiency of up to 10% across the entire W-band. This invention proposes a ground matching stub with filtering function. This structure has a filtering passband across the entire W-band (75GHz-110GHz), and the metal wings and metallized vias on both sides form a ground loop, increasing heat dissipation for the diodes and resulting in higher efficiency for the frequency doubler under the same performance conditions. Attached Figure Description

[0014] Figure 1This is a planar structural diagram of the W-band single-tube frequency doubler of the present invention;

[0015] Figure 2 This is a three-dimensional structural diagram of the W-band single-tube frequency doubler of the present invention;

[0016] Figure 3 This is a layered diagram of the W-band single-tube frequency doubler of the present invention;

[0017] Figure 4 This is a simulation diagram of the W-band single-tube frequency doubler of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention improves upon the traditional frequency doubler circuit, proposing a W-band single-tube frequency doubler that simplifies the circuit by eliminating the DC bias and designing a ground matching stub with filtering function, which not only achieves high power output but also has good heat dissipation.

[0020] In this embodiment, to simplify the circuit, the core nonlinear device used in this invention is the Ma-com gallium arsenide Schottky barrier diode MA4E1310. This diode has low series resistance, high cutoff frequency, and is a variable resistance diode, insensitive to changes in the static operating point. Therefore, the second harmonic structure does not require a bias structure. Furthermore, to address the heat dissipation issue, a grounding matching stub with filtering function is designed. A metal section is added to both sides of the microstrip to contact the cavity sidewall, and a certain number of grounding vias are drilled.

[0021] A W-band single-tube frequency doubler, such as Figures 1-3 As shown, the device includes: a fundamental input standard rectangular waveguide, a second harmonic output standard rectangular waveguide, a substrate, a microstrip line transmission circuit, and a metal shielding cavity; the fundamental input standard rectangular waveguide and the second harmonic output standard rectangular waveguide are transitionally connected to the microstrip line transmission circuit; the microstrip line transmission circuit is disposed on the substrate; the substrate is disposed inside the metal shielding cavity.

[0022] The microstrip line transmission circuit includes: an input probe, a low-pass filter, a diode, a short-circuit matching stub, and an output probe. The input probe transmits the input signal to the low-pass filter. The low-pass filter filters the input signal to obtain the fundamental signal and inputs the fundamental signal into the diode. The diode filters the fundamental signal to generate various harmonics. The short-circuit matching stub dissipates heat from the diode and extracts the harmonic signals to obtain the second harmonic signal. The output probe outputs the second harmonic signal.

[0023] In this embodiment, the input probe is used to transition the signal from the waveguide to the microstrip line and transmit it to the low-pass filter through the microstrip line. The low-pass filter filters the waveguide signal to obtain the fundamental signal. The fundamental signal is input into a diode to generate various harmonics. The second harmonic signal is extracted by using a short-circuit matching stub. The second harmonic signal is transmitted to the output probe through the microstrip line and then transitioned to the WR-10 standard rectangular waveguide output through the output probe.

[0024] In this embodiment, the frequency doubler is a nonlinear frequency converter based on the Schottky variable resistor diode MA4E1310, and the overall circuit adopts a series single-transistor structure. Using a Rogers RT / duroid 5880 substrate with a thickness of 0.127 mm and a dielectric constant of 2.2 as the carrier, the signal passes through a U-band waveguide probe transition, a 0-55 GHz low-pass filter, input matching, a diode, output matching, a short-circuit matching stub, and a W-band waveguide probe transition. The microstrip line thickness is 17 μm.

[0025] like Figure 1 As shown, the signal is transferred from the waveguide to the 50-ohm microstrip line through the input probe, and the useful fundamental signal is extracted by the 0-55GHz low-pass filter. The fundamental signal generates harmonics through the diode, and the useful second harmonic signal is extracted by the output short-circuit matching stub. Finally, the signal is transferred to the WR-10 standard rectangular waveguide output through the probe.

[0026] In this embodiment, the short-circuit matching stub includes: a high-low impedance matching stub, a widening substrate, and a copper layer. The high-low impedance matching stub is disposed on the widening substrate and is used to match and filter the filtered signal. The widening substrate is disposed on the copper layer, and a number of metallized vias are provided at positions corresponding to the copper layer on the widening substrate for heat dissipation of the diode.

[0027] like Figure 3As shown, layer 1 is the Rogers RT / duroid 5880 dielectric substrate (0.127mm thick), layer 2 is the metal layer (17um thick), layer 3 is the metal cavity, and layer 4 is the diode. A certain number of metallized vias (0.1mm radius, 0.144mm height) are drilled at specific locations on the dielectric substrate and the copper metal, and the metallized vias directly contact the cavity wall of layer 3.

[0028] Preferably, the metal layer is made of copper.

[0029] In one embodiment of this invention, the input section employs a waveguide-microstrip probe transition structure. The probe plane normal is perpendicular to the waveguide transmission direction, effectively transmitting the input signal to a 50-ohm microstrip line. The input waveguide is a WR-19 standard rectangular waveguide (2.388mm*4.775mm). The input filter allows the fundamental signal (37.5-55GHz) to pass through while preventing second and higher harmonic signals from returning to the input circuit. Considering the need for efficient transmission of the fundamental signal, efficient suppression of higher harmonics, and impedance matching at the diode input, this invention uses a maximum smoothing high-low impedance filter. After the fundamental signal passes through the diode, the output frequency includes not only the fundamental component but also higher harmonic components such as the second and third harmonics. The frequency doubler designed in this paper only requires the second harmonic output; therefore, the output section also needs a filtering structure. This structure must filter out the fundamental signal and reflected higher harmonic signals while also providing grounding and diode heat dissipation. This paper employs the short-circuit matching stub structure shown in the figure. Metallized grounding vias are used in the substrate mounting slots on the waveguide sidewalls, and low-resistance wires are used in the branches. This not only satisfies the circuit grounding requirements but also effectively helps dissipate heat from the diodes. The output section operates on the same principle as the input section, using a WR-10 standard rectangular waveguide (1.27mm*2.54mm).

[0030] Specifically, this invention uses the Schottky variable resistor diode MA4E1310. This diode has low series resistance, high cutoff frequency, and is a variable resistor diode, insensitive to changes in the quiescent operating point. Therefore, the frequency doubling structure does not require a bias structure. Based on the traditional series single-transistor frequency doubler, the DC bias structure is reduced, simplifying the frequency doubling circuit from a traditional three-port structure to a two-port structure. At the diode output, in addition to the traditional matching structure, perforated grounding sections are added on both sides of the matching stub. This not only provides grounding but also effectively dissipates heat from the diode during operation. The design was completed through joint modeling and simulation using HFSS and ADS. Figure 4As shown, simulation results indicate that when the input signal is 37.5-55GHz and the excitation is 20dBm, the frequency multiplication output signal is 10±0.5dBm in the frequency range of 75-110GHz, and the frequency multiplication efficiency is about 10%. It has the advantages of wide bandwidth, high frequency multiplication efficiency, simple structure and good diode heat dissipation.

[0031] The above-described embodiments further illustrate the purpose, technical solution, and advantages of the present invention. It should be understood that the above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made to the present invention within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A W-band single-tube frequency doubler, characterized in that, include: The system includes a fundamental input standard rectangular waveguide, a second harmonic output standard rectangular waveguide, a substrate, a microstrip line transmission circuit, and a metal shielding cavity; the fundamental input standard rectangular waveguide and the second harmonic output standard rectangular waveguide are transitionally connected to the microstrip line transmission circuit. The microstrip line transmission circuit is mounted on the substrate; The substrate is placed inside the metal shielding cavity; The microstrip line transmission circuit includes: an input probe, a low-pass filter, a diode, a short-circuit matching stub, and an output probe. The input probe transmits the input signal to the low-pass filter. The low-pass filter filters the input signal to obtain the fundamental signal, and then inputs the fundamental signal into the diode. The diode filters the fundamental signal to generate various harmonics. The short-circuit matching stub dissipates heat from the diode and extracts the harmonic signals to obtain the second harmonic signal. The output probe outputs the second harmonic signal. The short-circuit matching stub includes: high and low impedance matching stubs, a widened substrate, and a copper layer. The high and low impedance matching stubs are disposed on the widened substrate and are used to match and filter the filtered signal. The widened substrate is disposed on the copper layer, and a number of metallized vias are provided at the corresponding positions of the widened substrate and the copper layer for grounding, so that the circuit forms a DC loop and increases the heat dissipation area of ​​the diode.

2. The W-band single-tube frequency doubler according to claim 1, characterized in that, The substrate used is the Rogers RT / duroid 5880 substrate.

3. The W-band single-tube frequency doubler according to claim 1, characterized in that, Both the input and output probes adopt an E-plane waveguide probe transition structure, meaning that the probe plane normal is perpendicular to the waveguide transmission direction.

4. A W-band single-tube frequency doubler according to claim 3, characterized in that, The E-plane waveguide probe transition structure of the input probe adopts a U-band waveguide probe, while the E-plane waveguide probe transition structure of the output probe adopts a W-band waveguide probe.

5. A W-band single-tube frequency doubler according to claim 1, characterized in that, The diode is a Schottky variable resistor diode MA4E1310.

6. A W-band single-tube frequency doubler according to claim 1, characterized in that, The low-pass filter is a 7th-order high-low impedance low-pass filter.

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