A frequency multiplier and signal generator based on waveguide-microstrip collaborative matching filtering

Abstract

A frequency multiplier and a signal generator based on waveguide-microstrip collaborative matching filtering disclosed by the present disclosure include an input waveguide, a frequency multiplication circuit, and an output waveguide; the input waveguide includes multiple first waveguide segments and protruding branch segments located between adjacent first waveguide segments; the frequency multiplication circuit includes an input probe, a matching filtering network, and a diode pair connected in sequence; the first waveguide segment at the end of the input waveguide is connected to the input probe, and the diode pair is connected to the output waveguide. By setting the protruding branch segments on the input waveguide, waveguide impedance matching is introduced, and the purpose of impedance matching is jointly achieved with the matching filtering network, shortening the length of the overall microstrip circuit to reduce the transmission loss of the frequency multiplication circuit; at the same time, the matching filtering network also has a filtering effect, which can suppress other sub-harmonics to a certain extent, enabling them to return to the diode to complete second-harmonic frequency multiplication, further improving the frequency multiplication efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of terahertz technology, and in particular to a frequency multiplier and a signal generator based on waveguide-microstrip cooperative matching filtering. Background Art

[0002] The statements in this section merely provide background technical information related to the present disclosure and do not necessarily constitute prior art.

[0003] With the continuous development of terahertz technology, the application frequency band of terahertz signal generation technology based on solid-state electronics has gradually increased to above 1 THz or even higher frequencies. Among them, the frequency band covered by the standard waveguide WR1.0 is 0.75 THz - 1.1 THz, and the main application fields being developed and potential are radar cross-section scaling tests of large warships and other equipment, space-air-ground integrated communication, near-field microscopy, mass spectrometry analysis, etc. In the solid-state electronics terahertz signal generation technology, the signal generation method based on cascaded frequency multiplication and amplification has been widely applied due to its advantages such as room-temperature operation, high frequency resolution, wide working bandwidth, frequency tunability, and compact volume.

[0004] As the last-stage core component in the 0.75 THz - 1.1 THz cascaded frequency multiplication and amplification link, the 0.75 THz - 1.1 THz frequency multiplier plays a decisive role in the output power and bandwidth of the entire signal generation link. Firstly, its frequency multiplication factor directly determines the difficulty of implementing the entire drive link. For example, when using second-order frequency multiplication, the highest frequency of the drive link reaches 550 GHz, and the implementation difficulty is relatively large. It is necessary to combine the domestic industrial foundation and select an appropriate frequency multiplication factor. Secondly, its frequency multiplication efficiency directly determines its final output power level, and high efficiency characteristics need to be maintained.

[0005] Traditional unbiased terahertz even-order frequency multipliers include an input waveguide, an output waveguide, and a frequency multiplication microstrip circuit. The impedance matching network in the frequency multiplication microstrip circuit is mainly composed of high and low impedance lines on the microstrip chip. In order to obtain good matching effects, the overall matching network has a long volume, resulting in large transmission losses and low frequency multiplication efficiency. Summary of the Invention

[0006] To solve the above problems, the present disclosure proposes a frequency multiplier and a signal generator based on waveguide-microstrip cooperative matching filtering. By setting a raised branch segment on the input waveguide to introduce waveguide impedance matching and jointly achieving impedance matching with the matching filtering network, the length of the overall microstrip circuit is shortened to reduce the transmission loss of the frequency multiplication circuit. At the same time, the matching filtering network also has a filtering effect, which can suppress other sub-harmonics to a certain extent, enabling them to return to the diode for second-order frequency multiplication and further improving the frequency multiplication efficiency.

[0007] To achieve the above object, the present disclosure adopts the following technical solutions:

[0008] In a first aspect, a frequency multiplier based on waveguide-microstrip cooperative matching filtering is proposed, which includes an input waveguide, a frequency multiplication circuit, and an output waveguide;

[0009] The input waveguide includes multiple first waveguide segments and protruding stub segments located between adjacent first waveguide segments; the frequency multiplication circuit includes an input probe, a matching filtering network, and a diode pair connected in sequence; the first waveguide segment at the end of the input waveguide is connected to the input probe, and the diode pair is connected to the output waveguide.

[0010] In a second aspect, a signal generator is proposed, which includes a frequency multiplier based on waveguide-microstrip cooperative matching filtering proposed in the first aspect.

[0011] Compared with the prior art, the beneficial effects of the present disclosure are as follows:

[0012] 1. The present disclosure adopts waveguide-microstrip cooperative matching, with high efficiency; the method of waveguide impedance matching is introduced, and combined with the cooperative design of the matching filtering network, the length of the microstrip circuit is greatly reduced, reducing the transmission loss, that is, improving the frequency multiplication efficiency; the adopted matching filtering network has low-pass characteristics to a certain extent, which can suppress the harmonic signals output by the diode and make them return to the diode to complete the second harmonic multiplication, further improving the frequency multiplication efficiency.

[0013] 2. The present disclosure is for quadruple frequency multiplication. Compared with traditional second and third harmonic multiplications, the required driving frequency is low and it is easier to implement; compared with higher-order fifth and sixth harmonic multiplications, the frequency multiplication efficiency is higher.

[0014] The advantages of the additional aspects of the present invention will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0015] The specification drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application.

[0016] Figure 1 It is a schematic diagram of the overall structure of the frequency multiplier disclosed in Embodiment 1 of the present disclosure;

[0017] Figure 2 It is a schematic diagram of a typical structure for odd-order frequency multiplication;

[0018] Figure 3 It is a schematic diagram of a typical structure for even-order frequency multiplication.

[0019] Wherein: 1. First waveguide segment, 2. Protruding stub segment, 3. Matching filtering network, 4. Diode pair, 5. Output waveguide, 6. High-impedance line, 7. Low-impedance line. Detailed implementation mode

[0020] The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further descriptions of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0022] It should be noted that the terms used herein are only for describing specific implementation modes and are not intended to limit the exemplary implementation modes according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] In the present disclosure, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only relational terms determined for the convenience of describing the structural relationship of each component or element of the present disclosure and do not specifically refer to any component or element in the present disclosure and should not be construed as a limitation to the present disclosure.

[0024] In the present disclosure, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be a fixed connection, an integral connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium. For those relevant scientific research or technical personnel in the field, the specific meanings of the above terms in the present disclosure can be determined according to specific circumstances and should not be construed as a limitation to the present disclosure.

[0025] Embodiment 1

[0026] In this embodiment, a frequency multiplier based on waveguide-microstrip collaborative matching filtering is disclosed, including an input waveguide, a frequency doubling circuit, and an output waveguide;

[0027] The input waveguide includes multiple first waveguide segments and protruding branch segments located between adjacent first wavebands; the frequency doubling circuit includes an input probe, a matching filtering network, and a diode pair connected in sequence; the first waveguide segment at the end of the input waveguide is connected to the input probe, and the diode pair is connected to the output waveguide.

[0028] Furthermore, the matching filtering network adopts a high-low impedance line low-pass filtering structure.

[0029] Furthermore, the high-low impedance line low-pass filtering structure and the protruding branch segment on the input waveguide are used for impedance matching.

[0030] Furthermore, the input probe impedance is matched with the diode operating impedance.

[0031] Furthermore, the diode pair in the frequency doubling circuit is a series-connected diode pair with the same direction.

[0032] Furthermore, the protruding stub segment is coaxially arranged with the first waveguide segment.

[0033] Furthermore, the narrow-side length of the protruding stub segment is greater than that of the first waveguide segment.

[0034] Furthermore, the output waveguide and the diode pair form a balun structure.

[0035] Furthermore, the number of protruding stub segments is one, two, or three.

[0036] A frequency doubler based on waveguide-microstrip cooperative matching filtering disclosed in this embodiment will be described in detail.

[0037] Terahertz frequency doublers are mainly divided into two types: externally biased and unbiased. This embodiment mainly relates to an unbiased frequency doubler. The typical structures of traditional unbiased terahertz even and odd frequency doublers are as Figure 2 , 3 shown. The main structure includes an input waveguide, an output waveguide, a frequency doubling microstrip circuit, etc. The frequency doubling microstrip circuit mainly includes a microstrip probe, a matching network, and a diode. The diode part generally adopts a reverse parallel or series-connected structure with the same direction. The input waveguide signal passes through structures such as the microstrip probe, the matching network structure, the diode, and the output microstrip probe to complete the waveguide output of the frequency doubled signal. Compared with other complex spatial waveguide structures, this structure is easy to implement and assemble. At the same time, the bandwidth is relatively wide, which is conducive to the development of high-frequency band frequency doublers. Therefore, this embodiment focuses on the even frequency doubling structure.

[0038] As Figure 3 shown, in the traditional even frequency doubler, the impedance matching network is mainly the high and low impedance lines on the microstrip. In order to obtain a good matching effect, the overall volume of the matching network is relatively long, resulting in large transmission loss and low frequency doubling efficiency.

[0039] In order to solve the problem of relatively low frequency doubling efficiency of the existing even frequency doublers, this embodiment introduces waveguide impedance matching technology and combines it with the filtering matching network in the microstrip to jointly achieve the purpose of impedance matching, shortening the length of the overall microstrip circuit to reduce the transmission loss of the frequency doubling circuit; at the same time, this waveguide-microstrip cooperative matching network also has a filtering effect, which can suppress other sub-harmonics to a certain extent, making them return to the diode to complete the second harmonic frequency doubling, and further improving the frequency doubling efficiency.

[0040] A 0.75 THz - 1.1 THz broadband high - efficiency frequency multiplier based on waveguide - microstrip collaborative matching filtering is used to elaborate on a frequency multiplier based on waveguide - microstrip collaborative matching filtering disclosed in this embodiment.

[0041] As Figure 1 shown, a frequency multiplier based on waveguide - microstrip collaborative matching filtering mainly includes an input waveguide, an output waveguide 5, and a frequency - doubling circuit.

[0042] Among them, the frequency - doubling circuit mainly includes an input probe, a matching filtering network 3, and a diode pair 4 connected in sequence.

[0043] The input waveguide includes multiple first waveguide segments 1 and protruding branch segments 2 located between adjacent first waveguide segments 1. The protruding branch segments 2 are co - axially arranged with the first waveguide segments 1, and the narrow - side length of the protruding branch segments 2 is greater than the narrow - side length of the first waveguide segments 1.

[0044] The first waveguide segment 1 at the end of the input waveguide is connected to the input probe in the frequency - doubling circuit, and the diode pair 4 of the frequency - doubling circuit is connected to the output waveguide 5.

[0045] Assume that the frequency band of the input waveguide is 187.5 GHz - 275 GHz. Appropriate numbers of protruding branches are set on the input waveguide according to impedance - matching requirements, and combined with the matching filtering network on the microstrip to jointly provide impedance matching and filtering functions for the diode pair, achieving the purpose of efficient operation of the frequency multiplier.

[0046] An output waveguide and the diode pair 4 form a balun structure to extract the fourth - harmonic signal output by the diode, thereby obtaining a signal in the 0.75 THz - 1.1 THz frequency band.

[0047] The matching filtering network in this embodiment adopts a high - low impedance line low - pass filtering structure, including multiple high - impedance lines 6 and low - impedance lines 7 arranged at intervals between the high - impedance lines. Since the matching filtering network adopts a high - low impedance line structure, it has a low - pass filtering function. The passband is the fundamental frequency of the frequency multiplier, and the stopband is mainly other high - order harmonics of the frequency multiplier. While passing the fundamental frequency, it blocks high - order harmonics from entering the input waveguide, causing them to return to the diode to complete second - order frequency doubling and thus improve efficiency; this high - low impedance line structure also takes into account the impedance - matching effect, matching the input impedance of the waveguide probe in the fundamental - frequency band with the working impedance of the diode, optimizing the input standing wave of the overall frequency multiplier, and improving the efficiency of feeding the fundamental wave into the diode.

[0048] In this embodiment, the first waveguide section on the input waveguide is a normal waveguide, which belongs to high impedance, and the protruding stub section is a low impedance section. An appropriate number of protruding stub sections 2 are added to the input waveguide, making the structure of the input waveguide similar to a high-low impedance matching filter structure, which has the function of low-pass filtering and impedance matching. At the same time, since the waveguide transmission structure uses air as the medium, the transmission loss in the high-frequency band is small, which shortens the length of the required microstrip filter structure to a certain extent, reduces the transmission loss from the overall input waveguide to the diode, and improves the efficiency of feeding the input signal power into the diode.

[0049] By adding the protruding stub section 2 on the input waveguide and combining it with the microstrip matching filter network structure, the overall filtering function is first realized. The passband is the fundamental frequency range of the frequency multiplier, and the stopband is the harmonic frequency range of the frequency multiplier. The number of protruding stub sections and the microstrip filter structure can be added according to actual needs to optimize and meet the overall low-pass filtering requirements. The number of protruding stub sections is generally 1 - 3, and the specific addition method needs to be determined according to the actual low-pass filtering characteristics and the impedance matching requirements of the tube; on the basis of realizing low-pass filtering, the length and width of the protruding stub and the length and width of the microstrip high-low impedance line are slightly optimized according to the parameters such as the frequency multiplication loss and input standing wave of the frequency multiplier. On the premise of having little impact on the filtering function, the overall frequency multiplier achieves a good impedance matching effect, enabling the input fundamental frequency band signal to be fed into the diode more efficiently, completing frequency multiplication and extracting the required fourth harmonic signal.

[0050] In this embodiment, the length of the narrow side of the input waveguide is changed, and the protruding stub is used for impedance matching, shortening the length of the required microstrip matching stub, and thus shortening the length of the entire microstrip frequency multiplication circuit; the high-low impedance line is used for matching and taking into account the low-pass filtering effect, which can pass the fundamental wave signal and suppress other high-order harmonic signals, making them return to the diode to complete the second frequency multiplication to improve the frequency multiplication efficiency.

[0051] This embodiment uses a 0.75THz - 1.1THz frequency signal generation link based on solid-state frequency multiplication amplification cascade to realize a frequency multiplier with a high frequency multiplication factor and an efficient characteristic in the 0.75THz - 1.1THz band. The required drive frequency is 187.5 - 275GHz, and a high frequency multiplication efficiency is maintained, which can meet the requirements of the signal generation link for the final-stage frequency multiplier in the 0.75THz - 1.1THz band.

[0052] This embodiment fully considers the feasibility and frequency doubling efficiency, adopts a four - stage frequency doubling structure, introduces the method of waveguide impedance matching, and combines it with the collaborative design of a microstrip filtering matching network. The length of the microstrip circuit is greatly reduced, the transmission loss is reduced, that is, the frequency doubling efficiency is improved. Secondly, the adopted matching filtering network has a low - pass characteristic to a certain extent, which can suppress the harmonic signals output by the diode and make them return to the diode to complete the second - stage frequency doubling, further improving the frequency doubling efficiency. Compared with the traditional even - order frequency doubler, the frequency doubling efficiency is higher.

[0053] Embodiment 2

[0054] In this embodiment, a signal generator is disclosed, which includes a frequency doubler based on waveguide - microstrip collaborative matching filtering disclosed in Embodiment 1.

[0055] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A frequency multiplier based on waveguide-microstrip collaborative matching filtering, characterized in that, it includes an input waveguide, a frequency multiplication circuit and an output waveguide; The input waveguide includes multiple first waveguide segments and protruding stub segments located between adjacent first waveguide segments. Among them, the number of the protruding stub segments is one, two or three; the narrow-side length of the protruding stub segment is greater than the narrow-side length of the first waveguide segment; the first waveguide segments on the input waveguide are normal waveguides, belonging to high impedance, and the protruding stub segments are low-impedance segments. Adding protruding stub segments to the input waveguide makes the structure of the input waveguide similar to a high-low impedance matching filtering structure, which has the function of impedance matching while having low-pass filtering; the frequency band of the input waveguide is 187.5 GHz - 275 GHz; The frequency multiplication circuit includes an input probe, a matching filtering network and a diode pair connected in sequence; the matching filtering network adopts a high-low impedance line low-pass filtering structure, and the high-low impedance line low-pass filtering structure and the protruding stub segments on the input waveguide are jointly used for impedance matching; the impedance of the input probe is matched with the working impedance of the diode; The first waveguide segment at the end of the input waveguide is connected to the input probe, and the diode pair is connected to the output waveguide. Among them, the output waveguide and the diode pair form a balun structure for extracting the fourth harmonic signal output by the diode and obtaining a signal in the frequency band of 0.75 THz - 1.1 THz.

2. The frequency multiplier based on waveguide-microstrip collaborative matching filtering according to claim 1, characterized in that, the diode pair in the frequency multiplication circuit is a series-connected diode pair with the same direction.

3. The frequency multiplier based on waveguide-microstrip collaborative matching filtering according to claim 1, characterized in that, the protruding stub segment and the first waveguide segment are coaxially arranged.

4. A signal generator, characterized in that, it includes the frequency multiplier based on waveguide-microstrip collaborative matching filtering according to any one of claims 1-3.

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