An integrated ultra-wideband high-frequency combining noise source device

Abstract

The application provides a kind of integrated ultra-wideband high-frequency combining noise source device, it is related to noise source circuit field, comprising: bias circuit, combining structure, π attenuator and output port connected with each other in turn;Wherein, bias circuit is used to provide reverse bias voltage for zener diode in combining structure, also be used to adjust noise source super noise ratio ENR;Combining structure includes at least two reverse bias working zener diodes, and zener diode is integrated on microstrip transmission structure in horizontal mode, so that noise signal is always kept in the same plane transmission in combining structure, π attenuator and output port.The technical scheme of the application overcomes the problems of insufficient noise transmission continuity, limited high-frequency end noise power, bias mode affecting radio frequency path and insufficient noise output adjustment flexibility in the prior art.

Description

Technical Field

[0001] This invention relates to the field of noise source circuits, and more specifically to an integrated ultra-wideband high-frequency combining noise source device. Background Technology

[0002] In existing technologies, commonly used noise sources typically operate based on reverse-biased semiconductor devices, such as avalanche diodes or Zener diodes, which generate random carrier movement in a breakdown state, thereby outputting noise power. These noise sources have relatively simple structures and a mature application base in the microwave frequency band. However, as operating frequencies continue to expand to millimeter waves and even higher frequencies, existing noise source solutions are gradually revealing the following shortcomings.

[0003] (1) Traditional noise source structures lack continuity at high frequencies

[0004] In existing noise sources, noise diodes mostly adopt vertical structures or traditional packaging forms. Their electrode leads and external transmission lines usually need to be interconnected through wire bonding, 3D pins, or multi-stage transition structures. Under high-frequency conditions, this type of non-coplanar structure is prone to introducing parasitic inductance and parasitic capacitance, causing signal path discontinuity, which in turn leads to problems such as reflection, mode conversion, and increased high-frequency loss.

[0005] Especially in the high-frequency millimeter-wave band, the aforementioned structural discontinuities can easily lead to a decrease in noise output power and an increase in fluctuations in the over-noise ratio (ENR), thereby affecting the stability and availability of the noise source at the high-frequency end.

[0006] (2) The noise power of the single-noise diode scheme is limited at the high-frequency end.

[0007] In existing technologies, most noise sources use only a single noise diode as the noise generation unit, and its output noise power is mainly determined by the device characteristics and operating current. When the operating frequency increases, due to the influence of parasitic parameters and high-frequency transmission efficiency, a single noise diode often cannot provide sufficient effective noise power at the high-frequency end, resulting in a low ENR in the high-frequency range, which is difficult to meet the requirements of high-frequency testing and calibration.

[0008] To improve noise power, some solutions attempt to introduce active amplifier circuits or complex post-stage compensation structures. However, such solutions not only increase system complexity but may also introduce additional nonlinearity and stability issues, which is not conducive to achieving a simple and stable ultra-wideband noise source.

[0009] (3) The existing noise source bias and RF path have high coupling, which limits the realization of ultra-wideband.

[0010] In existing noise source designs, bias voltage is typically injected through the RF path. To prevent DC signals from entering the subsequent RF network, a DC blocking capacitor is often connected in series in the noise output path. However, such DC blocking capacitors are difficult to simultaneously achieve low-frequency and high-frequency performance over a wide bandwidth. They can easily introduce additional frequency response fluctuations and high-frequency parasitic effects under ultra-wideband conditions, thereby limiting the broadband continuity of the noise source.

[0011] Furthermore, in existing noise sources, noise output regulation usually relies on changing the bias voltage or adjusting the output attenuation network parameters. This not only makes the regulation method inflexible but also easily affects the output impedance matching and high-frequency characteristics.

[0012] (4) Existing solutions have limited integration, which is not conducive to high-frequency applications.

[0013] In millimeter-wave and higher frequency applications, noise sources place higher demands on structural integration, interconnection methods, and packaging. However, existing noise source solutions often employ discrete connections between noise diodes, bias circuits, and output matching networks, resulting in insufficient overall structural compactness and consistency, which is detrimental to low-loss transmission of high-frequency signals and system-level integration.

[0014] Therefore, there is a need for an integrated ultra-wideband high-frequency combiner noise source device that is stable in high-frequency applications and covers an ultra-wide bandwidth. Summary of the Invention

[0015] The main objective of this invention is to provide an integrated ultra-wideband high-frequency combining noise source device to solve the problems of insufficient noise transmission continuity, limited noise power at the high-frequency end, the influence of bias mode on the radio frequency path, and insufficient flexibility in noise output adjustment in the prior art.

[0016] To achieve the above objectives, the present invention provides an integrated ultra-wideband high-frequency combining noise source device, comprising: a bias circuit, a combining structure, a π-type attenuator, and an output port connected in sequence; wherein, the bias circuit is used to provide a reverse bias voltage for the Zener diodes in the combining structure, and is also used to adjust the noise source over-noise ratio (ENR); the combining structure includes at least two reverse-biased Zener diodes, which are horizontally integrated on the microstrip transmission structure, so that the noise signal is always transmitted in the same plane in the combining structure, the π-type attenuator, and the output port.

[0017] The bias circuit includes a bias voltage source, a choke inductor L1, and an adjusting resistor R. The combined structure includes a first Zener diode D1 and a second Zener diode D2. The π-type attenuator includes two first resistors R1 and one second resistor R2. One end of the two first resistors R1 is grounded, and the other end of the two first resistors R1 is connected to both ends of the second resistor R2. The device also includes a bias branch, which includes a first decoupling capacitor C1 and a second decoupling capacitor C2. One end of the choke inductor L1 is grounded, and the other end is connected to the first Zener diode D1. The positive terminals of diode D1 and second Zener diode D2, and the negative terminals of first Zener diode D1 and second Zener diode D2 are connected to one end of the regulating resistor R. The other end of the regulating resistor R is connected to the bias voltage source. One end of first decoupling capacitor C1 is grounded, and the other end is connected to the regulating resistor R and the negative terminal of first Zener diode D1. One end of second decoupling capacitor C2 is grounded, and the other end is connected to the regulating resistor R and the negative terminal of second Zener diode D2. The positive terminals of first Zener diode D1 and second Zener diode D2, second resistor R2, and output terminal are connected.

[0018] Furthermore, the combining structure is disposed on the substrate. The substrate, the first Zener diode D1, the second Zener diode D2, the first decoupling capacitor C1, and the second decoupling capacitor C2 are located on the same plane. The first Zener diode D1 and the second Zener diode D2 are symmetrically arranged along the central axis of the substrate, and the first decoupling capacitor C1 and the second decoupling capacitor C2 are symmetrically arranged along the central axis of the substrate. A microstrip transmission line is fabricated on the substrate. The positive terminals of the first Zener diode D1 and the second Zener diode D2 are bonded to the metal of the microstrip transmission line by pressure bonding. The negative terminals of the first Zener diode D1 and the second Zener diode D2 are bonded to the second decoupling capacitor C2 and the first decoupling capacitor C1, respectively, by pressure bonding. The choke inductor L1 is bonded to the microstrip transmission line on the substrate by pressure bonding. The coaxial inner conductor of the π-type attenuator is bonded to the substrate by a metal strip ring.

[0019] Furthermore, the substrate is made of microwave materials, including quartz, ceramic, and RO5880.

[0020] Furthermore, the dielectric constant of the quartz is 3.8, and the thickness is 0.127 mm.

[0021] Furthermore, the connection angle between the beam leads of the Zener diode and the microstrip transmission line is set to 30°–60°.

[0022] Furthermore, the connection angle between the beam leads of the Zener diode and the microstrip transmission line is set to 45°.

[0023] Furthermore, the first decoupling capacitor C1 and the second decoupling capacitor C2 are parallel plate capacitors. The lower electrode of the parallel plate capacitor is located on the same horizontal plane as the substrate. The bottom of the substrate and the lower electrode of the parallel plate capacitor share the same ground. The upper electrode of the parallel plate capacitor is connected to the regulating resistor R through a metal lead, which is used to decouple the bias voltage source.

[0024] Furthermore, the π-type attenuator in the device is replaced with a T-type attenuator, an L-type matching device, a resistive matching device, or a broadband absorption matching device.

[0025] Furthermore, the first decoupling capacitor C1 and the second decoupling capacitor C2 are surface-mount high-frequency capacitors, multilayer ceramic capacitors, or film capacitors.

[0026] The present invention has the following beneficial effects:

[0027] (1) Improve the continuity and stability of noise signal transmission under high frequency conditions.

[0028] This invention employs a Zener diode with a beam-type lead structure and integrates it horizontally onto a microstrip transmission structure. This ensures that noise signals are transmitted within the same plane throughout the generation, combining, and output processes, avoiding the parasitic inductance, parasitic capacitance, and structural discontinuities introduced by traditional vertical structures or three-dimensional interconnects under high-frequency conditions.

[0029] The above structure helps to reduce the reflection and additional loss of high-frequency noise signals, and improves the stability and consistency of noise output under high-frequency conditions. It is especially suitable for noise source applications in millimeter wave and higher frequency bands.

[0030] (2) Effectively improves thermal noise power and over-noise ratio (ENR) at high frequencies.

[0031] This invention achieves superimposed output of multiple noise power channels by combining at least two reverse-biased Zener diodes for noise, without introducing active amplification devices.

[0032] When noises are independent and impedance matching conditions are approximately met, the combined structure can effectively improve the thermal noise power at the output end, thereby increasing the ENR at the high-frequency end. This improves the problem of insufficient noise power in existing single-noise diode solutions under high-frequency conditions and meets the requirements of high-frequency testing and calibration for noise output levels.

[0033] (3) It is beneficial to achieve ultra-wideband continuous noise output and avoid the frequency limitation introduced by DC blocking capacitor.

[0034] This invention forms a closed current loop between the bias circuit and the combining structure, preventing the bias current from entering the subsequent RF path, thus eliminating the need for a series DC blocking capacitor in the main RF path.

[0035] This design avoids the problem that DC blocking capacitors cannot balance low-frequency and high-frequency performance under ultra-wideband conditions, reduces the impact of parasitic effects on frequency response, and is conducive to achieving continuous and flat noise output characteristics in the 10MHz-110GHz ultra-wideband range. It is particularly suitable for the engineering implementation of ultra-wideband noise sources.

[0036] (4) It enables convenient adjustment of the noise equivalent ratio, is simple to operate and has high stability.

[0037] This invention achieves the adjustment of the operating current of the aligned nanodiode by setting an adjustment resistor in the bias circuit, while keeping the bias voltage constant, thereby adjusting the noise output level and ENR.

[0038] Compared with existing methods that adjust the bias voltage or change the output attenuator parameters, the adjustment method of the present invention is simple in structure, easy to operate, and less likely to introduce RF matching changes. It is beneficial to maintain the stability and repeatability of the high-frequency performance of the noise source and improve the convenience of the noise source in actual testing and use.

[0039] (5) High structural integration, strong engineering feasibility and applicability.

[0040] This invention integrates functions such as noise generation, combining, bias injection, impedance matching, and single-port output through an integrated structure, and uses a mature 1 mm coaxial π-type attenuator as the output port for easy direct connection with existing high-frequency test systems.

[0041] The device provided by this invention has a compact overall structure and a clear implementation path, which helps to reduce system complexity, improve assembly consistency and reliability, and is suitable for widespread application in high-frequency and ultra-wideband noise source products. Attached Figure Description

[0042] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0043] Figure 1 The diagram shows the overall structure of an integrated ultra-wideband high-frequency combiner noise source device according to the present invention.

[0044] Figure 2 The circuit diagram of an integrated ultra-wideband high-frequency combiner noise source device of the present invention is shown.

[0045] Figure 3 An assembly diagram of the combining structure of the present invention is shown.

[0046] Figure 4 The relationship between the over-noise ratio and frequency of the device provided by the present invention is shown.

[0047] Figure 5 The relationship between the VSWR and frequency at the output port of the device provided by the present invention is shown. Detailed Implementation

[0048] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0049] Example 1

[0050] like Figure 1 An integrated ultra-wideband high-frequency combining noise source device is shown, comprising: a bias circuit, a combining structure, a π-type attenuator, and an output port connected in sequence; wherein, the bias circuit is used to provide a reverse bias voltage for the Zener diodes in the combining structure, and is also used to adjust the noise source's excess noise ratio (ENR); the combining structure includes at least two reverse-biased Zener diodes, which are horizontally integrated on the microstrip transmission structure, so that the noise signal is always transmitted in the same plane in the combining structure, the π-type attenuator, and the output port.

[0051] like Figure 1 As shown, the noise source circuit of the present invention includes, in sequence along the signal transmission direction, a bias circuit, a combining structure, a π-type attenuator, and an output port. The bias circuit and the combining structure together form a current closed loop, which is used to provide a stable bias for the noise generation unit and realize the combined output of the noise signal.

[0052] In this invention: the radio frequency transmission path of the noise signal is: combining structure → π-type attenuator → output port; the flow path of the bias current is: bias circuit → combining structure → bias circuit. The bias circuit adopts a forward bias voltage of 15V, and the current passes through the regulating resistor R, the first Zener diode D1 and the second Zener diode D2, and the choke inductor L1 in sequence, thereby forming a closed current loop between the bias circuit and the combining structure.

[0053] The above structural design prevents the bias current from entering the π-type attenuator and the output port, thereby avoiding the influence of DC on the RF path and facilitating the realization of ultra-wideband noise output.

[0054] Specifically, such as Figure 2As shown, the bias circuit includes: a bias voltage source, a choke inductor L1, and an adjusting resistor R. The combined structure includes: a first Zener diode D1 and a second Zener diode D2. The π-type attenuator includes: two first resistors R1 and one second resistor R2. One end of the two first resistors R1 is grounded, and the other end of the two first resistors R1 is connected to both ends of the second resistor R2. The device also includes: a bias branch, which includes: a first decoupling capacitor C1 and a second decoupling capacitor C2. One end of the choke inductor L1 is grounded, and the other end is connected to the first Zener diode D2. The positive terminals of diode D1 and the second Zener diode D2, and the negative terminals of the first Zener diode D1 and the second Zener diode D2 are connected to one end of the regulating resistor R. The other end of the regulating resistor R is connected to the bias voltage source. One end of the first decoupling capacitor C1 is grounded, and the other end is connected to the regulating resistor R and the negative terminal of the first Zener diode D1. One end of the second decoupling capacitor C2 is grounded, and the other end is connected to the regulating resistor R and the negative terminal of the second Zener diode D2. The positive terminals of the first Zener diode D1 and the second Zener diode D2, the second resistor R2, and the output terminal are connected.

[0055] The bias circuit is located on the input side of the noise source circuit and is used to provide a reverse bias voltage to the noise generation unit in the combining structure.

[0056] The bias circuit includes a bias voltage source, an adjusting resistor R, and a choke inductor L1. The bias voltage source is applied to the Zener diode in the combiner structure through the adjusting resistor to control its reverse breakdown operation. The choke inductor L1 exhibits low impedance under DC conditions and high impedance under RF conditions. It limits the leakage of RF noise signals towards the bias circuit and provides a return path for the bias current after the Zener diode conducts. The choke inductor L1 is an ultra-wideband inductor with an inductance of 2μH and a resistance of less than 2Ω, ensuring low impedance under DC conditions. Through the configuration of the above bias circuit, the bias current forms a closed loop between the bias circuit and the combiner structure, thereby preventing the bias current from flowing through the subsequent RF network.

[0057] This invention employs a voltage-regulated bias circuit. Under the condition of a constant bias voltage, by adjusting the regulating resistor R in the bias branch, the voltage division relationship and breakdown current across the first Zener diode D1 and the second Zener diode D2 are changed, thereby adjusting the noise output power and the over-noise ratio (ENR). Thus, the ENR adjustment method of this invention is achieved by adjusting the bias operating state of the core noise-generating device.

[0058] In addition to Zener diodes, the combining structure of this invention can also use avalanche diodes, avalanche noise diodes, or other semiconductor devices capable of generating broadband noise in reverse breakdown state as the core noise source device. This invention uses two Zener diodes for combining to achieve an ENR improvement of approximately 3 dB, but in other embodiments, three or more noise diodes can be used for multi-path combining to obtain higher output noise power; alternatively, a single noise diode can be used to achieve noise output in applications with lower output noise power requirements.

[0059] In this invention, the bias circuit is used not only to provide a reverse bias voltage for the Zener diode, but also to adjust the noise source over-noise ratio (ENR).

[0060] When a Zener diode enters the breakdown conduction state under reverse bias, its electrical characteristics can be equivalent to a dynamic resistor with a small resistance value. At this time, the equivalent dynamic resistance of the Zener diode and the adjustment resistor form a series relationship and participate in the voltage distribution process in the bias circuit.

[0061] With the bias voltage remaining constant, adjusting the resistance of the regulating resistor can change the voltage and current distributed across the Zener diode, thereby altering the operating current of the Zener diode in the breakdown state. Since the thermal noise power generated by the noise diode in the breakdown state is closely related to its operating current, changes in the operating current will directly lead to changes in the noise output power and the equivalent noise temperature, thus achieving adjustment of the over-noise ratio (ENR).

[0062] In this way, the present invention achieves continuous adjustment of the noise source ENR without changing the bias voltage or adjusting the parameters of the subsequent π-type attenuator; the adjustment resistor R in the bias branch is adjusted directly. This adjustment method is simple in structure, easy to operate, and does not introduce changes in RF matching conditions, which is beneficial for maintaining the performance stability of the noise source under high-frequency and ultra-wideband conditions.

[0063] In one specific embodiment, the first Zener diode D1 and the second Zener diode D2 are model NC407B. When the bias voltage is set to a fixed value of 15V, different over-noise ratio (ENR) output states can be achieved under high-frequency operating conditions by adjusting the resistance value of the regulating resistor, thereby meeting the noise output level requirements of different testing and calibration applications. For example, when the regulating resistor R is 600 Ω, the ENR measured at 110 GHz is approximately 8 dB; when the regulating resistor R is adjusted to 300 Ω, under the same bias voltage conditions, the ENR at 110 GHz is increased to approximately 11 dB.

[0064] Specifically, such as Figure 3As shown, the combining structure is disposed on the substrate. The substrate, the first Zener diode D1, the second Zener diode D2, the first decoupling capacitor C1, and the second decoupling capacitor C2 are located on the same plane. The first Zener diode D1 and the second Zener diode D2 are symmetrically arranged along the central axis of the substrate, and the first decoupling capacitor C1 and the second decoupling capacitor C2 are also symmetrically arranged along the central axis of the substrate. A microstrip transmission line is fabricated on the substrate. The positive terminals of the first Zener diode D1 and the second Zener diode D2 are bonded to the metal of the microstrip transmission line by pressure bonding. The negative terminals of the first Zener diode D1 and the second Zener diode D2 are bonded to the second decoupling capacitor C2 and the first decoupling capacitor C1, respectively, by pressure bonding. The choke inductor L1 is bonded to the microstrip transmission line on the substrate by pressure bonding. The coaxial inner conductor of the π-type attenuator is bonded to the substrate by a metal strip ring.

[0065] This invention employs a beam-type leaded horizontal Zener diode. In terms of interconnection, the diode, microstrip chip, and decoupling capacitor are all kept in the same horizontal plane and integrated horizontally on the microstrip transmission structure. This allows noise signals to propagate along a coplanar path during generation, combining, and output, thereby improving signal continuity under high-frequency conditions and reducing the impact of parasitic parameters introduced by the three-dimensional interconnect structure.

[0066] Without altering the principle of this invention, the choke inductor can be replaced with other broadband choke inductors or equivalent RF choke structures that meet the requirements of "low DC impedance and high RF impedance." Besides a single tapered wire-wound inductor, multi-stage inductors in series, RF choke lines (high-impedance transmission segments), radial stubs, λ / 4 high-impedance lines, ferrite beads, or other equivalent broadband choke structures can also be used to achieve RF isolation and DC conduction. This invention preferably achieves ENR adjustment by adjusting the resistor. Alternatively, the adjusting resistor can be a potentiometer, a digital potentiometer, a controllable resistor network, or a programmable current or voltage source composed of a DAC + operational amplifier or transistor to achieve controllable adjustment of the breakdown current. Any replacement that effectively changes the breakdown current of the noise diode and achieves ENR adjustment can be considered equivalent. The decoupling capacitor preferably uses a planar capacitor structure. Alternatively, chip high-frequency capacitors, multilayer ceramic capacitors (MLCCs), or film capacitors can be used, or a multi-capacitor parallel / distributed decoupling structure can be employed to achieve bias-end decoupling and stability.

[0067] In addition to microstrip combining, the combining structure can also adopt power divider / combiner structure (such as Wilkinson combining, T-type combining, resistive combining, coupled line combining, etc.) or other combining networks that can achieve the superposition of multiple noise power.

[0068] Microstrip transmission lines can be replaced by striplines, coplanar waveguides (CPW), grounded coplanar waveguides (GCPW), or other planar transmission line forms suitable for high-frequency broadband transmission, as long as they can achieve low parasitic interconnection with noise diodes and meet impedance design requirements.

[0069] The substrate can be made of quartz material with a thickness of 0.127 mm and a dielectric constant of approximately 3.8. Alternatively, other low-loss high-frequency substrate materials can be used, such as high-frequency ceramics, PTFE-based high-frequency plates, or other dielectric materials suitable for the millimeter-wave / terahertz frequency band; the substrate thickness, dielectric constant, and other parameters can also be adjusted according to the operating frequency band and impedance design.

[0070] The combined circuit structure includes at least two reverse-biased Zener diodes, which are high-frequency Zener diodes with beam lead structures.

[0071] Two Zener diodes operate in reverse-biased breakdown mode. During breakdown, each Zener diode generates random carrier motion, thus forming a thermal noise signal. The noise output terminals of the two Zener diodes are connected through a combiner structure, so that the noise power of the two paths is superimposed at the RF output terminal.

[0072] By employing the above-described combining method, the effective noise power at the output is increased without introducing active amplification devices, particularly improving the noise output level in the high-frequency range, which is beneficial for enhancing the excess noise ratio (ENR) at high frequencies. ENR is typically used to characterize the extent to which the output noise power of a noise source exceeds the noise power at a reference temperature. The conversion formula between ENR and noise power satisfies the following:

[0073] ;

[0074] in, This is the cold-state noise power. This represents the thermal noise power when the noise source is turned on.

[0075] In this invention, by combining the noise outputs of at least two reverse-biased Zener diodes, their thermal noise power is superimposed under the condition that the noises are independent and the matching condition is approximately met. Ideally, the combined thermal noise power is approximately twice that of a single noise diode, corresponding to an increase in the over-noise ratio in decibels. This translates to approximately 3dB, effectively improving the ENR level of high-frequency noise sources.

[0076] To achieve the above-mentioned combining function and ensure the continuity of noise signal transmission under high-frequency conditions, the combining structure is disposed on a high-frequency substrate made of quartz material with a thickness of 0.127 mm and a dielectric constant of approximately 3.8. A microstrip transmission line with a characteristic impedance of 50 ohms is formed on the substrate to serve as the main radio frequency path for the noise signal.

[0077] Two Zener diodes are horizontally arranged on the substrate. One end of their beam leads (the anode of the Zener diode) is bonded to the metal of the microstrip transmission line via bonding, while the other end (the cathode of the Zener diode) is bonded to a decoupling capacitor. This arrangement ensures that the Zener diodes, microstrip transmission line, and decoupling capacitor are in the same plane, guaranteeing a continuous transmission path for noise signals within the combining region and reducing parasitic inductance and capacitance introduced by structural steps or three-dimensional interconnects at high frequencies.

[0078] The connection angle between the beam leads of the Zener diode and the microstrip transmission line is set to approximately 45° to reduce high-frequency signal reflection at the transition point and improve the smoothness of impedance transition.

[0079] The decoupling capacitor is a parallel-plate capacitor with its lower electrode connected to the substrate ground plane and its upper electrode connected to the regulating resistor in the bias branch via metal leads. This is used to decouple the bias voltage. This structure structurally separates the bias branch from the main RF path while ensuring stable operation of the Zener diode under high-frequency conditions.

[0080] By combining the noise outputs of at least two reverse-biased Zener diodes, their thermal noise power is superimposed at the RF output, assuming the noise is independent and the matching condition is approximately met. Ideally, the combined thermal noise power is approximately twice that of a single noise diode, corresponding to an ENR increase of about 3 dB, thereby effectively improving the over-noise ratio performance of high-frequency noise sources.

[0081] Specifically, a metal strip ring (or gold mesh ring) transition interconnection structure is set between the output end of the combining structure (microstrip transmission line output end) and the inner conductor of the 1 mm coaxial π-type attenuator.

[0082] A π-type attenuator is placed after the combining structure to achieve output impedance matching and improve the output VSWR over an ultra-wideband range. In a specific embodiment of the invention, the π-type attenuator is implemented using a mature attenuator product with a 1mm coaxial structure, and its internal structure consists of a π-type resistor network composed of series and parallel resistors.

[0083] Since the 1 mm coaxial attenuator product itself has a coaxial input terminal and a coaxial output terminal, the π-type attenuator is not only used to achieve broadband matching, but its coaxial output terminal also directly constitutes the single-port output port of the noise source of this invention, thereby realizing the single-port coaxial output of the noise signal, which is convenient for connection with external noise figure testers, receivers or other RF test equipment.

[0084] To ensure a high-frequency, low-loss transition between the pre-stage planar microstrip structure and the subsequent coaxial attenuator structure, this invention incorporates a metal strip loop (or gold mesh loop) transition interconnection structure between the output of the combining structure (microstrip transmission line output) and the inner conductor of the 1 mm coaxial attenuator. Specifically, the metal conductor at the microstrip transmission line output is loop-connected via a metal strip / gold mesh, allowing the signal path of the planar transmission line to smoothly transition to the coaxial inner conductor. Simultaneously, this forms a stable transition structure with the ground reference, thereby reducing reflections and additional losses under high-frequency conditions and ensuring the transmission integrity and output stability of noise signals in the 90–110 GHz high-frequency band.

[0085] Furthermore, since the bias current forms a closed current loop through the bias circuit and the combining structure, the π-type attenuator (1mm coaxial attenuator) and its output terminal do not carry DC current. Therefore, there is no need to set a series DC blocking capacitor in the RF main path, which avoids the parasitic effect introduced by the DC blocking capacitor under ultra-wideband conditions and is conducive to achieving continuous noise output in a wide frequency range.

[0086] Through the above structural design, the noise signal is output from the combining structure via a 50-ohm microstrip transmission line on the quartz substrate, then connected to a 1 mm coaxial π-type attenuator through a metal strip ring-wrapped transition interconnect structure, and finally formed as a single-port output from the coaxial output terminal of the attenuator, realizing a continuous, low-loss, and easy-to-engineer ultra-wideband high-frequency noise source output structure.

[0087] Specifically, the substrate is a microwave material, including: quartz, ceramic and RO5880 and other high-frequency microwave substrates.

[0088] Specifically, the dielectric constant of the quartz is 3.8 and the thickness is 0.127 mm.

[0089] Specifically, the connection angle between the beam leads of the Zener diode and the microstrip transmission line is set to 30°–60°. Besides metal strip ring / gold mesh ring wrapping, the microstrip-to-coaxial transition interconnect can also employ welding transition, spring transition, coaxial probe transition, via fence transition, or tapered transition, as long as it achieves a low-reflection, low-loss, high-frequency transition.

[0090] Specifically, the connection angle between the beam leads of the Zener diode and the microstrip transmission line is set to 45°. Compared with the parallel device layout in the prior art, the present invention, through the 45° angle connection and symmetrical arrangement, makes the impedance transition between the device and the microstrip line smoother, which helps to reduce high-frequency reflection and transmission discontinuity effects, thereby further optimizing the impedance matching characteristics under high-frequency conditions.

[0091] Specifically, the first decoupling capacitor C1 and the second decoupling capacitor C2 are parallel plate capacitors. The lower electrode of the parallel plate capacitor is located on the same horizontal plane as the substrate. The bottom of the substrate and the lower electrode of the parallel plate capacitor share the same ground. The upper electrode of the parallel plate capacitor is connected to the regulating resistor R through a metal lead, which is used to decouple the bias voltage source.

[0092] Specifically, the π-type attenuator in the device is replaced with a T-type attenuator, L-type matching unit, resistive matching unit, or broadband absorptive matching unit. The π-type attenuator can be a mature attenuator product with a 1 mm coaxial structure. Alternatively, 1.85 mm, 2.4 mm, or other coaxial structure devices and interface forms that meet the target frequency range can also be used.

[0093] Specifically, the first decoupling capacitor C1 and the second decoupling capacitor C2 are surface-mount high-frequency capacitors, multilayer ceramic capacitors (MLCCs), or film capacitors.

[0094] The device of the present invention will now be described in detail with reference to its beneficial effects:

[0095] 1. A horizontally integrated noise generation structure based on beam-lead Zener diodes adopts a high-frequency Zener diode with a beam-lead structure and integrates it horizontally on a microstrip transmission structure. This ensures that the noise signal is transmitted in the same plane during generation, combining, and output, improving signal continuity under high-frequency conditions and reducing the impact of parasitic effects on high-frequency performance.

[0096] 2. High-frequency noise combining structure with dual Zener diodes reverse bias: By combining at least two reverse-biased Zener diodes, noise power is superimposed without introducing active amplification devices, thereby effectively improving the noise output power and ENR at the high-frequency end.

[0097] 3. DC-blocking-free design with bias circuit and combiner structure forming a closed current loop: Through the coordinated design of bias circuit and combiner structure, the bias current forms a closed loop between the two, preventing DC from entering the subsequent RF path. Therefore, no DC blocking capacitor is needed in series in the main RF path, which is beneficial for achieving ultra-wideband continuous noise output.

[0098] 4. The ENR regulation method based on the regulating resistor changes the breakdown current of the Zener diode by adjusting the regulating resistor in the bias branch under the condition that the bias voltage remains unchanged, thereby adjusting the noise output power and ENR. The regulation method is simple and stable and does not affect the RF matching conditions.

[0099] 5. The integrated high-frequency transition structure of the planar microstrip and coaxial π-type attenuator achieves a low-loss transition connection between the planar microstrip transmission line and the 1 mm coaxial π-type attenuator through metal strip ring or gold mesh ring wrapping. This allows the π-type attenuator to simultaneously perform impedance matching and single-port output functions, making it suitable for high-frequency and ultra-wideband engineering applications.

[0100] Example 2

[0101] like Figure 1 As shown, the noise source circuit in this embodiment includes, in sequence along the RF signal transmission direction, a bias circuit, a combining structure, and a π-type attenuator. The π-type attenuator uses a mature attenuator product with a 1 mm coaxial structure, and its coaxial output terminal is directly used as the single-port output port of the noise source in this embodiment.

[0102] In this embodiment, the bias circuit and the combining structure together form a closed current loop, preventing the bias current from entering the subsequent RF path. As a result, there is no need to set up a DC blocking capacitor in the main RF path, ensuring the continuous operation of the noise source in the ultra-wideband range.

[0103] like Figure 2 As shown, the bias circuit in this embodiment includes a bias voltage source, an adjusting resistor, and a choke inductor.

[0104] In this embodiment, the bias voltage source provides a fixed DC bias voltage; the choke inductor has an inductance of approximately 2 μH and a DC resistance of less than 2 Ω, and is used to provide a low-impedance path under DC conditions and a high-impedance isolation under RF conditions.

[0105] A bias voltage is applied to the noise diode via an adjustable resistor to control its reverse breakdown operating state. Once the noise diode enters the breakdown conduction state, it functions as a small dynamic resistor, participating in voltage distribution within the bias circuit along with the adjustable resistor. By adjusting the value of the adjustable resistor, the operating current of the noise diode can be changed, thereby adjusting the noise output power and the over-noise ratio (ENR).

[0106] Under a specific operating condition, when the bias voltage remains constant, different ENR output states can be achieved by changing the resistance value of the regulating resistor, thus meeting different noise testing and calibration requirements.

[0107] like Figure 3As shown, the combining structure in this embodiment includes two reverse-biased high-frequency noise diodes, and the noise diodes are Noisecom's NC407B beam-lead Zener diodes.

[0108] In this embodiment, the noise diode is mounted on a quartz substrate with a thickness of 0.127 mm and a dielectric constant of approximately 3.8. A microstrip transmission line with a characteristic impedance of 50 ohms is formed on the substrate to serve as the main radio frequency path for the noise signal.

[0109] Two noise diodes are arranged horizontally, with one end of their beam leads connected to the metal conductor of the microstrip transmission line via bonding, and the other end connected to the bias branch via a planar decoupling capacitor. The lower electrode of the decoupling capacitor is connected to the ground plane, and the upper electrode is connected to the regulating resistor via a metal lead.

[0110] In this embodiment, the connection angle between the beam lead of the noise diode and the microstrip transmission line is set to approximately 45° to improve impedance transition characteristics under high-frequency conditions. This structure enables the combined output of two noise signals within the microstrip structure.

[0111] In this embodiment, the output end of the microstrip transmission line is connected to the inner conductor of a 1mm coaxial π-type attenuator through a metal strip ring (or gold mesh ring) transition structure, thereby achieving a low-loss transition from a planar microstrip structure to a coaxial structure.

[0112] A 1 mm coaxial π-type attenuator is used to achieve broadband impedance matching, and its coaxial output terminal directly serves as the single-port output port of the noise source in this embodiment. Since the bias current has formed a closed loop between the bias circuit and the combining structure, the π-type attenuator and its output terminal do not carry DC current, thereby ensuring the stable output of the noise source in the ultra-wideband range.

[0113] Figure 4 and Figure 5 As shown, by adjusting the regulating resistor, different ENR output states can be achieved while keeping the bias voltage constant. Under high-frequency operating conditions, the dual-noise diode combining structure effectively improves the high-frequency noise output capability, verifying the feasibility and stability of the structure of this invention in high-frequency and ultra-wideband noise source applications.

[0114] like Figure 5 As shown, based on the noise source device provided by the present invention, the single-port VSWR is less than 2.5 across the entire frequency band from 10M to 110GHz, demonstrating that the noise source device provided by the present invention has high broadband impedance matching.

[0115] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An integrated ultra-wideband high-frequency combiner noise source device, characterized in that, include: The system consists of a bias circuit, a combiner structure, a π-type attenuator, and an output port, which are connected in sequence. The bias circuit provides a reverse bias voltage for the Zener diodes in the combiner structure and also adjusts the noise source's over-noise ratio (ENR). The combiner structure includes at least two reverse-biased Zener diodes, which are horizontally integrated on the microstrip transmission structure, ensuring that the noise signal is always transmitted in the same plane in the combiner structure, the π-type attenuator, and the output port. The bias circuit includes a bias voltage source, a choke inductor L1, and an adjusting resistor R. The combined structure includes a first Zener diode D1 and a second Zener diode D2. The π-type attenuator includes two first resistors R1 and one second resistor R2. One end of the two first resistors R1 is grounded, and the other end of the two first resistors R1 is connected to both ends of the second resistor R2. The device also includes a bias branch, which includes a first decoupling capacitor C1 and a second decoupling capacitor C2. One end of the choke inductor L1 is grounded, and the other end is connected to the first Zener diode D1. The positive terminals of diode D1 and second Zener diode D2, and the negative terminals of first Zener diode D1 and second Zener diode D2 are connected to one end of the regulating resistor R. The other end of the regulating resistor R is connected to the bias voltage source. One end of first decoupling capacitor C1 is grounded, and the other end is connected to the regulating resistor R and the negative terminal of first Zener diode D1. One end of second decoupling capacitor C2 is grounded, and the other end is connected to the regulating resistor R and the negative terminal of second Zener diode D2. The positive terminals of first Zener diode D1 and second Zener diode D2, second resistor R2, and output terminal are connected.

2. The integrated ultra-wideband high-frequency combiner noise source device according to claim 1, characterized in that, The circuit structure is disposed on the substrate. The substrate, the first Zener diode D1, the second Zener diode D2, the first decoupling capacitor C1, and the second decoupling capacitor C2 are located on the same plane. The first Zener diode D1 and the second Zener diode D2 are symmetrically arranged along the central axis of the substrate, and the first decoupling capacitor C1 and the second decoupling capacitor C2 are symmetrically arranged along the central axis of the substrate. A microstrip transmission line is fabricated on the substrate. The positive terminals of the first Zener diode D1 and the second Zener diode D2 are bonded to the metal of the microstrip transmission line by pressure bonding. The negative terminals of the first Zener diode D1 and the second Zener diode D2 are bonded to the second decoupling capacitor C2 and the first decoupling capacitor C1, respectively, by pressure bonding. The choke inductor L1 is bonded to the microstrip transmission line on the substrate by pressure bonding. The coaxial inner conductor of the π-type attenuator is bonded to the substrate by a metal strip ring.

3. The integrated ultra-wideband high-frequency combiner noise source device according to claim 2, characterized in that, The substrate is made of microwave materials, including quartz, ceramic and RO5880.

4. The integrated ultra-wideband high-frequency combiner noise source device according to claim 3, characterized in that, The dielectric constant of the quartz is 3.8 and the thickness is 0.127 mm.

5. The noise source device for an integrated ultra-wideband high-frequency combiner according to claim 2, characterized in that, The connection angle between the beam leads of the Zener diode and the microstrip transmission line is set to 30°–60°.

6. The noise source device for an integrated ultra-wideband high-frequency combiner according to claim 5, characterized in that, The connection angle between the beam leads of the Zener diode and the microstrip transmission line is set to 45°.

7. The integrated ultra-wideband high-frequency combiner noise source device according to claim 2, characterized in that, The first decoupling capacitor C1 and the second decoupling capacitor C2 are parallel plate capacitors. The lower electrode of the parallel plate capacitor is located on the same horizontal plane as the substrate. The bottom of the substrate and the lower electrode of the parallel plate capacitor are grounded together. The upper electrode of the parallel plate capacitor is connected to the regulating resistor R through a metal lead, which is used to decouple the bias voltage source.

8. The integrated ultra-wideband high-frequency combiner noise source device according to claim 1, characterized in that, The π-type attenuator in the device is replaced with a T-type attenuator, an L-type matching device, a resistive matching device, or a broadband absorption matching device.

9. The noise source device for an integrated ultra-wideband high-frequency combiner according to claim 1, characterized in that, The first decoupling capacitor C1 and the second decoupling capacitor C2 are surface-mount high-frequency capacitors, multilayer ceramic capacitors, or film capacitors.

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