A planar millimeter-wave or terahertz broadband noise source and its design method

Abstract

This invention discloses a planar millimeter-wave or terahertz broadband noise source and its design method, comprising a low-pass filter, an input RF matching circuit, an avalanche noise diode, an output RF matching circuit, and a DC grounding circuit. The input terminal of the low-pass filter is biased to an external constant current source, and its output terminal is connected to the cathode of the avalanche noise diode through the input RF matching circuit. The anode of the avalanche noise diode is connected to the input terminal of the DC grounding circuit through the output RF matching circuit, and the output terminal of the DC grounding circuit outputs an RF signal. This invention achieves the output of a broadband high-frequency noise signal while greatly simplifying the design of the matching circuit. The overall circuit adopts a planar structure, and all components can be integrated on the same substrate, which not only facilitates integration with other circuits but also reduces the difficulty of fabrication and assembly, and reduces transmission losses.

Description

Technical Field

[0001] This invention relates to the field of broadband noise source technology, specifically to a planar millimeter-wave or terahertz broadband noise source and its design method. Background Technology

[0002] Noise figure measurement plays a crucial role in microwave, millimeter-wave, and terahertz measurement fields. In noise characteristic testing systems, the noise source is a vital component, and its over-noise ratio (UNR), stability, and other parameters significantly impact the system's noise figure. In some radar systems, the receiver's noise figure is critical to the system's performance, making real-time measurement and calibration of this parameter essential. High-performance broadband noise sources are one of the main research directions in millimeter-wave or terahertz technology.

[0003] Traditional noise sources typically generate white noise using a constant-current, reverse-biased noise diode. Reverse leakage of noise power is suppressed by adding a low-pass filter at the bias input port. Avalanche diode noise sources are a type of solid-state noise source. Theoretically, the avalanche diode used can generate high-frequency noise signals over a wide frequency range. A constant-current source is used to operate the avalanche diode in the reverse avalanche breakdown state to design the noise source. In the terahertz band, high-performance, high-cutoff-frequency Schottky diodes operating in the reverse breakdown region can also be used to design noise sources.

[0004] Currently, companies such as Noisecom and Elva have commercialized waveguide-structured solid-state noise sources based on avalanche diode designs, with a maximum operating frequency of 170 GHz. High-frequency noise sources are mainly implemented using on-chip CMOS technology (Maya, MC et al. “Extraction of an avalanche diode noise model for its application as anon‐wafer noise source.” Microwave and Optical Technology Letters 38 (2003):89-92) and microwave monolithic integration (S. Diebold, E. Weissbrodt, H. Massler, A. Leuther, A. Tessmann and I. Kallfass, "AW -Band Monolithic Integrated ActiveHot and Cold Noise Source," in IEEE Transactions on Microwave Theory and Techniques, vol. 62, no. 3, pp. 623-630, March 2014, doi: 10.1109 / TMTT.2014.2299770), which are costly. In the terahertz band, due to the lack of available avalanche diode devices, low-temperature blackbody noise sources are generally used, which are relatively large and not conducive to commercial applications.

[0005] Existing noise sources in the terahertz band are limited in implementation methods, choices, and costs, making commercialization difficult. There is a lack of compact, low-cost, and easily integrated noise sources.

[0006] The invention patent application with publication number CN112003570A discloses a high-frequency broadband millimeter-wave noise source and its preparation method. The application adopts a novel suspension matching circuit, which can extend the frequency range to 110GHz. The overall circuit adopts a planar structure, which reduces the difficulty of processing and assembly and reduces the loss during transmission. The microstrip to coaxial method is used to replace the traditional waveguide generation structure, which optimizes the standing wave ratio and improves the super noise ratio.

[0007] First, this application uses a microstrip-to-coaxial structure for output. This structure only uses a planar microstrip circuit to convert to a coaxial line at the final output. In reality, the entire noise source is a hybrid structure of multiple transmission lines, including waveguides, suspended microstrips, and microstrip lines. Using a coaxial output structure has frequency limitations, reaching a maximum of 110 GHz, and is not suitable for the terahertz band.

[0008] Secondly, although the application also claims to use a planar structure, it was designed for early bulk avalanche diodes. Due to the limitations of early diode technology, most diodes were three-dimensional structures. Therefore, the circuit in this application is also a three-dimensional structure and can generally only exist in the form of modules. Furthermore, it mounts the diode on a ceramic capacitor, which has lower reliability, larger installation errors, and is prone to mismatch.

[0009] Then, the use of ceramic capacitors at the input of the application will lead to a reduction in overall output noise power. Moreover, ceramic capacitors will have a large parasitic effect in the terahertz band, which cannot meet the usage conditions of the terahertz band.

[0010] Finally, this application employs an output attenuation matching circuit designed with thin-film resistors. The principle of thin-film resistor attenuation matching is to reduce return loss by attenuating the signal, thereby achieving a better standing wave ratio at the port. However, this method fails in the terahertz band due to high-frequency parasitic effects, and the attenuator loss reduces the over-noise ratio of the noise source. Therefore, thin-film resistors are not suitable when the frequency increases to the terahertz band. Summary of the Invention

[0011] The technical problem to be solved by this invention is to provide a planar broadband noise source and design method that is easy to integrate in the terahertz band and has a simple structure.

[0012] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0013] A planar millimeter-wave or terahertz broadband noise source includes a low-pass filter, an input RF matching circuit, an avalanche noise diode, an output RF matching circuit, and a DC grounding circuit.

[0014] The input terminal of the low-pass filter is connected to an external constant current source, and the output terminal is connected to the cathode of the avalanche noise diode through an input RF matching circuit; the anode of the avalanche noise diode is connected to the input terminal of the DC grounding circuit through an output RF matching circuit, and the output terminal of the DC grounding circuit outputs an RF signal.

[0015] The low-pass filter adopts a CMRC structure; the avalanche noise diode adopts a planar structure; the input RF matching circuit and the output RF matching circuit include at least one microstrip transmission line; the DC grounding circuit adopts a substrate integrated waveguide filter.

[0016] The low-pass filter, input RF matching circuit, avalanche noise diode, output RF matching circuit, and DC grounding circuit are all mounted on the same substrate.

[0017] Advantages: This invention achieves broadband high-frequency noise signal output. The DC grounding circuit at the output terminal uses a substrate-integrated waveguide filter, which can be directly connected to the output RF matching circuit, greatly simplifying the design of the matching circuit. Using both input and output RF matching circuits, maximum power RF noise signal output can be achieved, significantly improving the noise source's over-noise ratio. Furthermore, the overall circuit of this invention adopts a planar structure, allowing all components to be integrated onto the same substrate. This not only facilitates integration with other circuits but also reduces the difficulty of fabrication and assembly, while simultaneously minimizing transmission losses.

[0018] Preferably, the input RF matching circuit includes three microstrip transmission lines.

[0019] Preferably, the output RF matching circuit includes three microstrip transmission lines.

[0020] Preferably, this noise source can be packaged in waveguide or coaxial packaging.

[0021] Preferably, the avalanche noise diode is a noise diode with a planar beam lead structure or a terahertz Schottky planar diode.

[0022] This invention also discloses a design method for a planar millimeter-wave or terahertz broadband noise source. The signal generated by an external constant current source is input through an SMA interface. After passing through a low-pass filter and an input RF matching circuit, the signal is sent to the cathode of an avalanche noise diode. The signal is output from the anode of the avalanche noise diode and then output as an RF noise signal after passing through an output RF matching circuit and a DC grounding circuit. The RF noise signal can be output through waveguide or coaxial packaging to achieve isolation between the noise source circuit and subsequent devices.

[0023] The low-pass filter and input RF matching circuit provide a return path for the RF noise signal; the DC grounding circuit provides DC signal grounding, allowing RF noise of a specific frequency band to pass through, and together with the output RF matching circuit, achieves the maximum RF noise signal output.

[0024] Preferably, if the user requires application in the terahertz band, this noise source adopts a waveguide package form:

[0025] The radio frequency noise signal output from the DC grounding circuit of this noise source is input to the input terminal of the waveguide microstrip converter. The output terminal of the waveguide microstrip converter is connected to the input terminal of the terahertz isolator and output from the output terminal of the terahertz isolator.

[0026] In particular, the microstrip probe part of the waveguide microstrip conversion shares the same substrate with the noise source device.

[0027] Preferably, if the user requires application in the millimeter-wave band, this noise source adopts a coaxial package form:

[0028] The radio frequency noise signal output from the DC grounding circuit of this noise source is input to the input terminal of the microstrip coaxial converter, and the output terminal of the microstrip coaxial converter outputs the radio frequency noise signal.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] (1) The overall circuit of the present invention adopts a planar structure, and all components can be integrated on the same substrate. This not only facilitates integration with other circuits, but also reduces the difficulty of processing and assembly, while reducing the loss during transmission and improving the super-noise ratio.

[0031] (2) The low-pass filter of this invention adopts a CMRC filter, which, together with the input RF matching circuit, can realize the return of broadband RF noise signals, with higher RF signal suppression, wider bandwidth, higher operating frequency, higher reliability, and greater convenience. Thus, it meets the usage environment of the terahertz band.

[0032] (3) The DC grounding circuit of the present invention uses a substrate integrated waveguide filter, which can be directly connected to the output RF matching circuit, greatly simplifying the design of the matching circuit. At the same time, the substrate integrated waveguide filter can not only provide DC signal grounding, but also achieve better output matching in conjunction with the output RF matching circuit, realize noise signal output in a specific frequency band, and improve the super-noise ratio.

[0033] (4) The present invention uses a two-segment microstrip matching circuit for input and output, which can realize the maximum power radio frequency noise signal output and greatly improve the over-noise ratio of the noise source.

[0034] (5) The present invention adopts a device design form. How the device is packaged depends on how the user uses it. It can be packaged in a coaxial manner to suit the millimeter-wave band, or in a waveguide manner to suit the terahertz band. It has a higher degree of freedom and stronger applicability. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the noise source implementation proposed in this invention;

[0036] Figure 2 This is a schematic diagram of a planar broadband terahertz noise source device according to an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the S-parameter simulation results of the low-pass filter according to an embodiment of the present invention;

[0038] Figure 4 This is a schematic diagram of the S-parameter simulation results of the substrate integrated waveguide filter according to an embodiment of the present invention;

[0039] Figure 5This is a schematic diagram of a noise source packaged using a waveguide method according to an embodiment of the present invention;

[0040] Figure 6 This is a schematic diagram of a noise source packaged in a coaxial manner according to an embodiment of the present invention;

[0041] In the diagram: 1. Low-pass filter; 2. Input RF matching circuit; 3. Avalanche noise diode; 4. Output RF matching circuit; 5. DC grounding circuit; 6. Waveguide microstrip converter; 7. Terahertz isolator; 8. Microstrip coaxial converter. Detailed Implementation

[0042] To facilitate understanding of the technical solution of the present invention by those skilled in the art, the technical solution of the present invention will now be further described in conjunction with the accompanying drawings.

[0043] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0044] See Figure 1 and Figure 2 This embodiment discloses a planar millimeter-wave or terahertz broadband noise source, including a low-pass filter 1, an input RF matching circuit 2, an avalanche noise diode 3, an output RF matching circuit 4, and a DC grounding circuit 5.

[0045] This embodiment can achieve broadband noise signal output in the 170-260GHz range, thereby solving the problems of complex circuit structure conversion, difficult processing and assembly, and uncontrollable over-noise ratio and VSWR in existing circuits. It is also effective for designs in other frequency bands.

[0046] The input of the low-pass filter 1 is connected to an external constant current source, and the output is connected to the cathode of the avalanche noise diode 3 through the input RF matching circuit 2. The anode of the avalanche noise diode 3 is connected to the input of the DC grounding circuit 5 through the output RF matching circuit 4, and the output of the DC grounding circuit 5 outputs an RF signal.

[0047] Low-pass filter 1 adopts a CMRC structure. Its input is connected to an external constant current source to bias avalanche noise diode 3. Low-pass filter 1 can pass a DC bias signal while blocking RF noise signals generated by avalanche noise diode 33 and other irrelevant high-frequency signals. The design specifications for low-pass filter 1 are: suppression greater than 60dB at 170GHz.

[0048] The input RF matching circuit 2 can be composed of at least one microstrip transmission line segment. The fewer the microstrip transmission line segments in this structure, the simpler the circuit structure, but the worse the matching performance; the more segments, the better the matching performance, but the more complex the circuit structure. Considering both circuit complexity and performance, the input RF matching circuit 2 in practical design is usually composed of three microstrip transmission line segments connected in series and parallel, which ensures good matching performance while also simplifying the circuit structure.

[0049] In this embodiment, the low-pass filter 1 uses a CMRC filter, which, together with the input RF matching circuit 2, enables the return of broadband RF noise signals. This results in higher RF signal suppression, wider bandwidth, higher operating frequency, higher reliability, and greater convenience, thus meeting the requirements of the terahertz band operating environment.

[0050] The avalanche noise diode 3 adopts a planar structure. Specifically, in this embodiment, the avalanche noise diode 3 can be a noise diode with a planar beam-lead structure or a terahertz Schottky planar diode. The cathode pad of the avalanche noise diode 3 is connected to the microstrip transmission line of the input RF matching circuit 2, and the anode pad is connected to the microstrip transmission line of the output RF matching circuit 4. For ease of installation, an inverted soldering method can be used. The noise signal generated by the avalanche noise diode 3 is reflected back to the avalanche noise diode 3 through the low-pass filter 1 and the input RF matching circuit 2, and finally output through the output RF matching circuit 4 and the substrate integrated waveguide filter.

[0051] In this embodiment, the avalanche noise diode 3 is directly mounted on the microstrip, which simplifies assembly, makes it more practical, and facilitates integration with other circuits. Furthermore, the avalanche noise diode 3 employs a planar structure, which, compared to earlier three-dimensional diodes, offers greater reliability and adaptability.

[0052] The output RF matching circuit 4 also consists of at least one microstrip transmission line. The fewer the number of microstrip transmission line segments in this structure, the simpler the circuit structure, but the worse the matching performance; the more segments, the better the matching performance, but the more complex the circuit structure. Considering both circuit complexity and performance, the actual output RF matching circuit 4 is constructed by connecting three microstrip transmission lines in series and parallel, ensuring good matching performance while also simplifying the circuit structure.

[0053] Impedance matching of the RF signal can be achieved by adjusting the length and width of each segment of the microstrip transmission line in the input RF matching circuit 2 and the output RF matching circuit 4, thereby increasing the output RF noise signal power. Therefore, the dimensions of the microstrip transmission lines in the input RF matching circuit 2 and the output RF matching circuit 4 are optimized during the design process to obtain the maximum noise power output and improve the super-noise ratio.

[0054] Therefore, in order to obtain the maximum noise signal output, the dimensions of the input RF matching circuit 2 and the output RF matching circuit 4 in this structure can be optimized simultaneously.

[0055] The DC grounding circuit 5 can be implemented using a substrate-integrated waveguide filter or a microstrip grounding via structure that allows RF signals to pass through. This embodiment specifically describes the substrate-integrated waveguide filter. The substrate-integrated waveguide filter is implemented using an electrically coupled slotted design. This filter provides DC ground for the avalanche noise diode 3 and only allows RF noise signals in the 170-260GHz frequency band to pass through. When used in conjunction with the waveguide microstrip converter 6 and an isolator at the RF output port, it can achieve stable RF signal output, unaffected by the load connected to the output terminal, and protect the noise source from signals reflected back from the load, thereby extending the lifespan of the noise source. The design specifications of the substrate-integrated waveguide filter are: suppression greater than 60dB at 140GHz and suppression greater than 60dB at 300GHz.

[0056] The DC grounding circuit 5 not only provides grounding for the DC bias signal, allowing specific broadband high-frequency noise signals to pass through, but also enhances the heat dissipation performance of the device, ensuring a stable noise output from the avalanche noise diode 3. Simultaneously, connecting an isolator to the noise source output port can improve the noise source output port matching, increase the output noise power, and prevent signals reflected from the load end from burning out the avalanche noise diode 3. By selecting a suitable constant current bias and designing appropriate low-pass filter 1, input RF matching circuit 2, output RF matching circuit 4, and DC grounding circuit 5, the output noise power can be increased, thereby improving the noise source's over-noise ratio.

[0057] Therefore, the substrate-integrated waveguide filter in this embodiment serves to ground the DC signal and suppress irrelevant signal output. The grounding via of the substrate-integrated waveguide filter enhances the heat dissipation of the device, ensures the stability of the diode output noise, and prevents the high current at the load end from burning out the noise diode.

[0058] Meanwhile, the low-pass filter 1 adopts a CMRC structure, which is a compact microstrip resonator and is a planar structure; the input RF matching circuit 2 and the output RF matching circuit 4 are both microstrip transmission lines; the avalanche noise diode 3 is also a planar structure; and the substrate-integrated waveguide filter, which serves as the DC grounding circuit 5, is also a planar structure. Therefore, this embodiment can achieve a planar structure for the overall circuit, allowing all the above-mentioned devices to be designed on the same substrate, so that all devices are located on the same plane. This not only facilitates integration with other circuits but also reduces the difficulty of fabrication and assembly, while also reducing losses during transmission.

[0059] Figure 3The simulation results for low-pass filter 1 are shown, where curve 1 represents S(1,1) and curve 2 represents S(2,1). (From...) Figure 3 It can be seen that low-pass filter 1 has a suppression of more than 60dB at 170GHz. Therefore, it can be concluded that low-pass filter 1 in this embodiment meets the design requirements.

[0060] like Figure 4 The simulation results for the substrate-integrated waveguide filter are shown. Curve 3 represents S(1,1), and curve 4 represents S(2,1). Figure 4 It can be seen that the return loss in the passband is greater than 20dB, the insertion loss is less than 0.5dB, the suppression at 140GHz is greater than 60dB, and the suppression at 300GHz is greater than 60dB. Therefore, the substrate-integrated waveguide filter of this embodiment can meet the design requirements.

[0061] In the specific operation of this embodiment, the DC signal is input from an external constant current source, passes through a low-pass filter 1 and an input RF matching circuit 2, and is then delivered to the cathode of the avalanche noise diode 3. It is then output from the anode of the diode, passes through an output RF matching circuit 4, and is DC grounded via the grounding hole of the substrate integrated waveguide filter, providing DC bias for the avalanche noise diode 3. The low-pass filter 1 and the input RF matching circuit 2 provide a return path for the RF signal, reducing RF signal loss. The output RF matching circuit 4 allows the RF signal to pass through, further reducing RF signal loss. Because the substrate integrated waveguide filter can pass RF signals in a specific frequency band while suppressing DC signals and other irrelevant signal components, the signal outputs an RF noise signal at the output terminal of the substrate integrated waveguide filter. Furthermore, the RF noise signal can be output through waveguide or coaxial packaging.

[0062] In this embodiment, the entire noise source is designed as a device. The specific packaging can be customized according to user requirements; for example, it can use coaxial packaging or waveguide packaging, and is not limited to a single-module design. Specifically:

[0063] If the user's requirement is for application in the terahertz band, then adopt the following... Figure 5The packaging scheme shown employs a waveguide-microstrip probe converter structure. In this embodiment, the RF noise signal output from the DC grounding circuit 5 is passed through the waveguide-microstrip converter 6 and the terahertz isolator 7 before being output as an RF noise signal. The microstrip probe portion of the waveguide-microstrip converter 6 in this packaging scheme can share the same substrate as the aforementioned noise source device portion, resulting in a compact structure that can be located on the same plane, enabling RF noise signal output in the 170-260 GHz frequency range. Furthermore, the output terminal of the waveguide-microstrip converter 6 is connected to the terahertz isolator 7, which improves matching, achieves stable RF noise signal output, and protects the noise source from signals reflected back from the load. It should be noted that this packaging method is also applicable to other terahertz bands.

[0064] If the user's requirement is for application in the millimeter-wave band, then adopt the following... Figure 6 The packaging scheme shown employs a microstrip coaxial converter 8 structure. In this embodiment, the RF noise signal output from the DC grounding circuit 5 is converted to an RF noise signal after passing through the microstrip coaxial converter 8. This packaging scheme's microstrip coaxial converter 8 avoids complex and redundant output conversion methods, resulting in a simple structure and convenient installation. Depending on actual needs, noise output in the frequency band below 110 GHz can be achieved.

[0065] It should be noted that the above are only two specific design forms of this embodiment. Other different packaging methods can be made according to the user's needs.

[0066] Therefore, the overall structure of this embodiment is designed in the form of a device, which allows for greater freedom and wider applicability.

[0067] It should be noted that the present invention differs from the patent application (hereinafter referred to as the prior art) in the following ways:

[0068] (1) The design method of the noise source module given in the prior art is for early bulk avalanche diodes. Therefore, the circuit is a three-dimensional structure and can generally only exist in the form of modules. In fact, only the output terminal realizes a planar structure. However, the overall circuit of the present invention can realize a planar structure and can design all devices on the same substrate, which is a true planar circuit.

[0069] (2) The prior art is only a design method for a module. The present invention is a design method for a device. How the device is packaged according to the present invention depends on how the user uses it. That is, it can be packaged in a coaxial package for millimeter wave band or in a waveguide package for terahertz band.

[0070] (3) The prior art mounts the diode on the ceramic capacitor, which has lower reliability, larger installation error, and is prone to mismatch. The overall circuit of this application adopts a planar structure, which not only facilitates integration with other circuits, but also reduces the difficulty of processing and assembly, while reducing transmission loss and improving the super-noise ratio.

[0071] (4) The prior art is not applicable to the terahertz band. The microstrip to coaxial connector it uses can only reach up to 110 GHz. At the same time, the input terminal uses ceramic capacitors and the output attenuation matching circuit uses a thin film resistor design, which are not suitable for the terahertz band. In contrast, this application, through the design of devices such as low-pass filter 1, input RF matching circuit 2, avalanche noise diode 3, output RF matching circuit 4 and DC grounding circuit 5, can be well applied to the terahertz band. Furthermore, depending on the actual packaging form, it can also be applied to the millimeter-wave band.

[0072] (5) The output attenuation matching circuit designed with thin-film resistors in the prior art is not suitable when the frequency increases to the terahertz band. However, the DC grounding circuit 5 of this application uses a substrate integrated waveguide filter, which can be directly connected to the output RF matching circuit 4, greatly simplifying the design of the matching circuit. At the same time, the substrate integrated waveguide filter can not only provide DC signal grounding, but also achieve better output matching in conjunction with the output RF matching circuit 4, realize noise signal output in the terahertz band, and improve the super-noise ratio.

[0073] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0074] The above embodiments are merely examples of implementation methods of the invention. The scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A planar millimeter-wave or terahertz broadband noise source, characterized in that: It includes a low-pass filter (1), an input RF matching circuit (2), an avalanche noise diode (3), an output RF matching circuit (4), and a DC grounding circuit (5). The input of the low-pass filter (1) is connected to an external constant current source, and the output is connected to the cathode of the avalanche noise diode (3) through the input RF matching circuit (2); the anode of the avalanche noise diode (3) is connected to the input of the DC grounding circuit (5) through the output RF matching circuit (4), and the output of the DC grounding circuit (5) outputs an RF signal. The low-pass filter (1) adopts a CMRC structure; the avalanche noise diode (3) adopts a planar structure; the input RF matching circuit (2) and the output RF matching circuit (4) include at least one microstrip transmission line; the DC grounding circuit (5) adopts a substrate integrated waveguide filter; The low-pass filter (1), input RF matching circuit (2), avalanche noise diode (3), output RF matching circuit (4) and DC grounding circuit (5) are all placed on the same substrate; If the user's usage requirement is to be applicable to the terahertz band, this noise source adopts a waveguide package form: the radio frequency noise signal output by the DC grounding circuit (5) of this noise source is input to the input terminal of the waveguide microstrip converter (6), the output terminal of the waveguide microstrip converter (6) is connected to the input terminal of the terahertz isolator (7), and outputs from the output terminal of the terahertz isolator (7). Among them, the microstrip probe part of the waveguide microstrip converter (6) shares the same substrate with the noise source device; if the user's usage requirement is to be applicable to the millimeter wave band, this noise source adopts a coaxial package form: the radio frequency noise signal output by the DC grounding circuit (5) of this noise source is input to the input terminal of the microstrip coaxial converter (8), and the output terminal of the microstrip coaxial converter (8) outputs the radio frequency noise signal.

2. The planar millimeter-wave or terahertz broadband noise source according to claim 1, characterized in that: The input RF matching circuit (2) includes three microstrip transmission lines.

3. The planar millimeter-wave or terahertz broadband noise source according to claim 1, characterized in that: The output RF matching circuit (4) includes three microstrip transmission lines.

4. The planar millimeter-wave or terahertz broadband noise source according to claim 1, characterized in that: The avalanche noise diode (3) is a noise diode with a planar beam lead structure or a terahertz Schottky planar diode.

5. A design method for a planar millimeter-wave or terahertz broadband noise source according to any one of claims 1-4, characterized in that: The signal generated by the external constant current source is input through the SMA interface. After passing through the low-pass filter (1) and the input RF matching circuit (2), the signal is sent to the cathode of the avalanche noise diode (3). The signal is output from the anode of the avalanche noise diode (3). After passing through the output RF matching circuit (4) and the DC grounding circuit (5), the RF noise signal is output. The RF noise signal can be output through waveguide or coaxial packaging to achieve isolation between the noise source circuit and subsequent devices. Among them, the low-pass filter (1) and the input RF matching circuit (2) provide a return path for the RF noise signal; the DC grounding circuit (5) provides DC signal grounding, allowing RF noise of a specific frequency band to pass through, and together with the output RF matching circuit (4), achieves the maximum RF noise signal output.

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