An ultra-wideband zero-bias power detector

Abstract

The application discloses a kind of ultra-wideband zero-bias power detectors, including input port, shielded cavity, first dielectric substrate, second dielectric substrate, microstrip metal circuit and low-barrier schottky diode placed in shielded cavity;Microstrip metal circuit includes microstrip probe, suspended microstrip transmission line, low-pass filter, first microstrip metal line and second microstrip metal line;Second microstrip metal line is connected with SMA connector;Radio frequency signal is input by input port, and after frequency conversion and filtering by microstrip metal circuit into low-barrier schottky diode, direct current signal is generated, and direct current signal is output shielded cavity by gold wire and second microstrip metal line.The application adopts two sides symmetrical grounding structure, and integrates the grounding structure into matching network, increases the design dimension of matching network, effectively widens the working bandwidth of detection circuit;And low-barrier schottky diode is integrated with peripheral metal on dielectric substrate, realizes micron-level alignment accuracy.

Description

Technical Field

[0001] This invention relates to the field of microwave and millimeter-wave detection circuit technology, and in particular to an ultra-wideband zero-bias power detector. Background Technology

[0002] Detectors, as nonlinear circuits that convert signals into DC signals, play a crucial role in fields such as test instruments, power detection equipment, direct detection receivers, and power control, and are one of the key functional circuits in millimeter-wave and submillimeter-wave application systems. Detectors based on Schottky barrier diodes have significant advantages in the millimeter-wave and submillimeter-wave frequency bands due to their excellent high-frequency characteristics, room-temperature operation, and short response time. Zero-bias detectors, as one implementation of detection circuits, have wide applications due to their advantages such as not requiring bias circuits and simple structure.

[0003] In the field of millimeter-wave and submillimeter-wave technology, the detector, as a crucial front-end circuit of the receiver, directly impacts the sensitivity and dynamic range of the overall system. To improve overall system performance, detectors typically require wide operating bandwidth and high sensitivity; therefore, expanding the operating bandwidth of detector circuits has significant research and engineering value. Currently, zero-bias detectors based on Schottky barrier diodes usually employ a rectangular waveguide-stripline (finned line with shielded cavity, microstrip / suspended microstrip line) structure as the carrier circuit. Due to the presence of the shielded cavity, the dielectric substrate width of the carrier circuit is limited, restricting the design of the RF matching network and diode RF grounding loop, making ultra-wideband design of the detector circuit quite difficult. Currently, the operating bandwidth of existing detectors cannot effectively cover the dominant mode frequency of a standard rectangular waveguide. Summary of the Invention

[0004] Purpose of the invention: In order to solve the technical problems mentioned in the background, the present invention proposes an ultra-wideband zero-bias power detector with a double-sided symmetrical grounding structure. By integrating the grounding loop and the matching network design, the dimension of the matching network design is increased, which can effectively expand the operating bandwidth of the detector circuit.

[0005] Technical solution: The present invention is an ultrawideband zero-bias power detector, comprising: an input port, a shielded cavity, a first dielectric substrate, a second dielectric substrate placed in the shielded cavity, a microstrip metal circuit and a low-barrier Schottky diode disposed on the two dielectric substrates;

[0006] The microstrip metal circuit includes a microstrip probe, a suspended microstrip transmission line, a low-pass filter, a first microstrip metal line disposed on a first dielectric substrate, and a second microstrip metal line disposed on a second dielectric substrate.

[0007] The suspended microstrip transmission line includes an impedance transformation line, a first ground impedance transformation line, and a second ground impedance transformation line. The first ground impedance transformation line and the second ground impedance transformation line are respectively connected to the shielding cavity through gold strip / gold wire to form a grounding loop, and are symmetrically distributed on both sides of the impedance transformation line.

[0008] The impedance transformation line is connected to the microstrip probe;

[0009] The first microstrip metal line is connected to the second microstrip metal line via a gold wire;

[0010] The second microstrip metal wire is connected to the SMA connector;

[0011] The radio frequency signal is input through the input port, passes through the microstrip probe, enters the suspended microstrip transmission line, and then enters the low-barrier Schottky diode for frequency conversion. After being filtered by the low-pass filter, a DC signal is generated. Finally, through the gold wire and the second microstrip metal line, only the DC signal is output to the shielded cavity.

[0012] Furthermore, the input port includes a standard rectangular waveguide and a tapered waveguide. The radio frequency signal is input through the standard rectangular waveguide, passes through the tapered waveguide, and then transitions into the suspended microstrip transmission line via a microstrip probe.

[0013] Furthermore, the obliquely tapered waveguide is composed of rectangular waveguides with inconsistent widths at both ends, and gradually narrows in the middle, starting from the signal input port.

[0014] Furthermore, the impedance transformation line is composed of five microstrip lines with different widths and lengths, thus forming an impedance transformation.

[0015] Furthermore, the first grounding impedance transformation line and the second grounding impedance transformation line have the same shape. The first grounding impedance transformation line is composed of two microstrip metal segments with different widths and lengths. The width and length of the microstrip metal segment near the edge of the first dielectric substrate need to be greater than 50 μm.

[0016] Furthermore, the low-barrier Schottky diode is composed of a low-barrier Schottky junction formed by the contact between semiconductor material InGaAs and metal Ti, and a diode package.

[0017] Compared with the prior art, the significant advantages of this invention are as follows:

[0018] 1. This invention integrates the design of the grounding loop and the matching network, and adopts a double-sided symmetrical grounding structure. While realizing the diode RF grounding loop, it increases the dimension of the matching network design and effectively expands the working bandwidth of the detection circuit.

[0019] 2. This invention utilizes monolithic integration technology to integrate a low-barrier diode and a microstrip circuit onto a dielectric substrate, achieving micron-level alignment between the diode and the peripheral circuit. Furthermore, it employs a gold wire / gold strip process to precisely position the grounding metal, minimizing the impact of assembly errors on the detection circuit and improving circuit performance and consistency.

[0020] 3. In this invention, the nonlinear device uses a low-barrier Schottky diode formed by the contact between semiconductor InGaAs and metal Ti, which ensures the detection circuit can detect small signals. Attached Figure Description

[0021] Figure 1 This is a top view of the overall structure of the present invention;

[0022] Figure 2 This is a side view of the overall structure of the present invention;

[0023] Figure 3(a) is a schematic diagram of a power detector structure using radio frequency transition grounding.

[0024] Figure 3(b) is a schematic diagram of a power detector structure using single-sided grounding.

[0025] Figure 3(c) is a schematic diagram of a power detector with a double-sided symmetrical grounding structure;

[0026] Figure 4 This is a schematic diagram showing the comparison results of the voltage sensitivity curves of power detectors using RF transition grounding, single-sided grounding, and double-sided symmetrical grounding structures, respectively. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1As shown, the ultra-wideband zero-bias power detector of the present invention includes a shielded cavity 15, a first dielectric substrate 11 and a second dielectric substrate 14 placed in the cavity, and a microstrip metal circuit and a low-barrier Schottky diode 8 on the dielectric substrate. From left to right, they are: a standard rectangular waveguide 1, a tapered waveguide 2, a positioning metal sheet 3, a microstrip probe 4, an impedance transformation line 5, a first ground impedance transformation line 6, a second ground impedance transformation line 7, a low-barrier Schottky diode 8, a low-pass filter 9, a first microstrip metal line 10, a first dielectric substrate 11, a gold wire 12, a second microstrip metal line 13, a second dielectric substrate 14, and a shielded cavity 15. The microstrip metal circuit includes a microstrip probe 4, a suspended microstrip transmission line, a low-pass filter 9, and a first microstrip metal line 10 disposed on a first dielectric substrate 11, and a second microstrip metal line 13 disposed on a second dielectric substrate 14; the impedance transformation line 5, the first ground impedance transformation line 6, the second ground impedance transformation line 7, the low-pass filter 9, the first microstrip metal line 10, and the first dielectric substrate 11 constitute the suspended microstrip transmission line.

[0029] The standard rectangular waveguide 1 is the input port for radio frequency signals, and different sizes can be used depending on the operating frequency band. The obliquely tapered waveguide 2 is composed of rectangular waveguides with inconsistent widths at both ends (i.e., the width of the narrow side), and gradually tapes in the middle, starting from the signal input port. This can realize the impedance transformation of the rectangular waveguide to complete the circuit matching, allowing as many signals as possible to enter the detection circuit.

[0030] The positioning metal piece 3 consists of three pieces of metal with edges parallel to the inner wall of the rectangular waveguide, serving as the positioning point during circuit packaging; the microstrip probe 4 is inserted into the rectangular waveguide, forming a classic probe transition structure from waveguide to suspended microstrip line, transitioning the signal from the rectangular waveguide to the suspended microstrip line; the impedance transformation line 5 consists of five microstrip lines with different widths and lengths, forming an impedance transformation.

[0031] The first ground impedance transformation line 6 consists of two microstrip lines with different widths and lengths, connected to the shielding cavity 15 via gold strips / wires to form a ground. The second ground impedance transformation line 7 has the same shape as the first impedance transformation line 6, and the two are symmetrically distributed. The width and length of the microstrip lines near the edge of the first dielectric substrate 11 in both the first and second ground impedance transformation lines 6 and 7 are greater than 50 μm to ensure that the pressure points of the gold strips / wires are distributed on the grounding metal. The impedance transformation line 5, together with the first and second ground impedance transformation lines 6 and 7, constitute the radio frequency matching network of the detection circuit. By introducing the first and second ground impedance transformation lines 6 and 7, the radio frequency matching network achieves the integrated design of the matching network and the grounding loop, increases the adjustable dimension of the matching network (the dimension perpendicular to the signal transmission direction), and can achieve optimal impedance matching between the microstrip probe 4 and the low-barrier Schottky diode 8 in a wider frequency range, thus expanding the effective operating bandwidth of the detector.

[0032] The low-barrier Schottky diode 8 is a nonlinear device in the detector circuit, used to convert the input radio frequency signal into a DC signal. It consists of a die and two connecting pads. The low-barrier Schottky diode 8 is composed of a low-barrier Schottky junction formed by the contact between the semiconductor material InGaAs and the metal Ti, and a packaging structure. It has a very low turn-on voltage, ensuring the effective detection of small signals by the detector circuit. The low-barrier Schottky diode 8 is integrated with the peripheral circuit on a dielectric substrate using monolithic integration technology. Micron-level alignment of the diode and the matching network is achieved through photolithography. The low-barrier Schottky diode is connected to a low-pass filter 9 to extract the DC signal generated by the diode. The distance between the two controls the reflection phase of the radio frequency signal, adjusting the position of the operating frequency band of the detector circuit.

[0033] The low-pass filter 9 adopts an improved CMRC structure, which can greatly reduce the length of the filter circuit and thus reduce the circuit size while achieving high suppression of radio frequency signals. The first microstrip metal line 10 is connected to the low-pass filter 9 and plays the role of transmitting DC signals. The gold wire 12 is a connecting wire that connects the first microstrip metal line 10 and the second microstrip metal line 13, and also plays the role of transmitting DC signals. The second microstrip metal line 13 and the second dielectric substrate 14 together form a microstrip transmission line and are connected to the SMA connector to output the DC signal to the shielded cavity 15.

[0034] The ultra-wideband zero-bias detector in this invention employs a rectangular waveguide-suspended microstrip line structure. The radio frequency (RF) signal is input through a standard rectangular waveguide 1, transitions via a microstrip probe 4, and then enters the suspended microstrip line. After passing through the RF matching network on the suspended microstrip transmission line, it enters a low-barrier Schottky diode 8 for frequency conversion. The resulting signal is selected by a low-pass filter 9, resulting in a DC signal output circuit. After passing through the low-barrier Schottky diode 8, the RF signal is reflected back to the low-barrier Schottky diode 8 by the low-pass filter 9 to continue participating in frequency conversion, thus improving the efficiency of the frequency conversion of the low-barrier Schottky diode 8. Furthermore, since the detector circuit is very small in the submillimeter-wave band, a relatively large microstrip transmission line is required to connect to an SMA connector to output the DC signal to the shielded cavity 15. In this embodiment, the second microstrip metal line 13 is disposed on a second dielectric substrate 14 constructed from Rogers 5880 transistors.

[0035] In detector circuits, the construction of the diode RF signal grounding loop is crucial. Due to the presence of the shielding cavity, the width of the dielectric substrate is limited, and most dielectric materials used in the millimeter-wave band and above cannot be shaped, which restricts the implementation of the grounding structure. There are two main grounding methods in the prior art: RF waveguide transition grounding as shown in Figure 3(a), and single-sided grounding on the side of the signal transmission direction as shown in Figure 3(b).

[0036] This invention comprehensively considers the design of the matching network and the diode RF grounding structure. By introducing symmetrical grounding structures on both sides of the signal transmission direction, as shown in Figure 3(c), a fusion design of the diode grounding loop and the matching network is achieved on a narrow dielectric substrate. Compared with the prior art, this invention also utilizes impedance transformation on the grounding line to increase the dimension of the matching network design, effectively widening the operating bandwidth of the detection circuit. In addition, by setting the metal wires near the edge of the first dielectric substrate 11 in the first grounding impedance transformation line 6 and the second impedance transformation line 7 to a larger size and connecting them to the shielding cavity 15 using gold wire / gold strip jumpers, the impact of foreign objects introduced during assembly on circuit performance is minimized, thereby reducing assembly errors and improving the performance of the broadband detection circuit.

[0037] Figure 4 The simulation results of the dual-sided symmetrical grounding structure used in this embodiment are compared with those of existing detectors using RF waveguide grounding and single-sided grounding structures. It can be seen that the dual-sided symmetrical grounding structure proposed in this invention can effectively broaden the operating bandwidth of the detector. Taking the rectangular waveguide WR-6.5 as an example in this embodiment, its frequency coverage range is 110 GHz - 170 GHz. Therefore, it can be seen that the operating bandwidth of the detection circuit exceeds the coverage of the main mode frequency band of a standard rectangular waveguide.

Claims

1. An ultra-wideband zero-bias power detector, comprising: include: Input port, shielding cavity (15), first dielectric substrate (11), second dielectric substrate (14) placed in shielding cavity (15), microstrip metal circuit and low barrier Schottky diode (8) disposed on the two dielectric substrates. The microstrip metal circuit includes a microstrip probe (4), a suspended microstrip transmission line, a low-pass filter (9), a first microstrip metal line (10) disposed on a first dielectric substrate (11), and a second microstrip metal line (13) disposed on a second dielectric substrate (14). The suspended microstrip transmission line includes an impedance transformation line (5), a first ground impedance transformation line (6), and a second ground impedance transformation line (7). The first ground impedance transformation line (6) and the second ground impedance transformation line (7) are connected to the shielding cavity (15) through gold strips / gold wires to form a grounding loop, and are symmetrically distributed on both sides of the impedance transformation line (5). The impedance transformation line (5), the first ground impedance transformation line (6), and the second ground impedance transformation line (7) together constitute the radio frequency matching network of the detector circuit. The radio frequency matching network achieves the fusion design of the matching network and the grounding loop through the first ground impedance transformation line (6) and the second ground impedance transformation line (7), increases the adjustable dimension of the matching network, achieves the best impedance matching between the microstrip probe (4) and the low barrier Schottky diode (8), and expands the effective working bandwidth of the detector. The impedance transformation line (5) is connected to the microstrip probe (4); The first microstrip metal line (10) is connected to the second microstrip metal line (13) via a gold wire (12); The second microstrip metal wire (13) is connected to the SMA connector; The radio frequency signal is input through the input port, passes through the microstrip probe (4) and then enters the suspended microstrip transmission line and then enters the low barrier Schottky diode (8) for frequency conversion. After being filtered by the low-pass filter (9), a DC signal is generated. Finally, through the gold wire (12) and the second microstrip metal line (13), only the DC signal is output to the shielded cavity (15). The input port includes a standard rectangular waveguide (1) and a tapered waveguide (2). The radio frequency signal is input through the standard rectangular waveguide (1), passes through the tapered waveguide (2), and then transitions into the suspended microstrip transmission line via the microstrip probe (4). The obliquely tapered waveguide (2) is composed of rectangular waveguides with inconsistent widths at both ends, and has an obliquely tapered shape in the middle, gradually narrowing from the signal input port.

2. The ultra-wideband zero-bias power detector according to claim 1, characterized in that, The impedance transformation line (5) consists of five microstrip lines with different widths and lengths, forming an impedance transformation.

3. The ultra-wideband zero-bias power detector according to claim 1, characterized in that, The first grounding impedance transformation line (6) and the second grounding impedance transformation line (7) have the same shape. The first grounding impedance transformation line (6) is composed of two microstrip metals with different widths and lengths. The width and length of the microstrip metals near the edge of the first dielectric substrate (11) need to be greater than 50 μm.

4. The ultra-wideband zero-bias power detector according to claim 1, characterized in that, The low-barrier Schottky diode (8) is composed of a low-barrier Schottky junction formed by contacting semiconductor material InGaAs with metal Ti and a diode package.

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