Adjustable one-eighth-mode substrate integrated waveguide resonant cavity negative resistance type voltage-controlled oscillator

Abstract

The invention discloses an adjustable one-eighth-mode substrate integrated waveguide resonant cavity negative resistance type voltage-controlled oscillator which comprises an adjustable one-eighth-mode substrate integrated waveguide resonant cavity, a phase shift microstrip line, a negative resistance unit and an output microstrip line. The resonant cavity is obtained by dividing a substrate integrated waveguide circular cavity into eight equal parts, and a shielding through hole array is arranged on an open side so as to reduce electromagnetic leakage. And a variable capacitance diode and a biasing circuit are integrated in the resonant cavity, so that accurate tuning of the frequency is realized. The negative resistance unit is connected with the resonant cavity through the phase shift microstrip line and outputs an oscillation signal through the output microstrip line. Compared with a traditional substrate integrated waveguide circular cavity oscillator, the overall size is remarkably reduced, and the miniaturization performance is further improved. Due to the negative resistance type structure, a long feedback microstrip line does not need to be relied on, and meanwhile the excellent phase noise performance is kept. By introducing the adjustable one-eighth-mode substrate integrated waveguide resonant cavity, the oscillator realizes the precise tuning capability in a wide frequency range.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave millimeter wave substrate integrated waveguide active devices, and in particular relates to an adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator. Background Art

[0002] With the rapid development of modern communication technology, the demand for high-performance oscillators in fields such as mobile communications, satellite communications, and radar systems is growing. As the core component of signal source and frequency synthesis, the performance of the oscillator directly affects the overall stability and reliability of the system. In the field of high frequency and ultra-high frequency, the oscillator not only needs to have a high quality factor (Q value) to ensure frequency stability, but also needs to occupy as small a circuit area as possible in the trend of compact size, so as to adapt to the miniaturization requirements of modern electronic equipment.

[0003] As a new transmission line technology that combines traditional waveguide structure with planar circuit technology, substrate integrated waveguide has become an important technical means in high-frequency and millimeter-wave circuit design due to its advantages such as low loss, high Q value, easy integration and low manufacturing cost. However, the traditional substrate integrated waveguide structure is still relatively large in size, which limits its wide application in miniaturized devices. By performing special symmetrical division of the substrate integrated waveguide cavity, a one-eighth mode substrate integrated waveguide can be realized, which significantly reduces the size while maintaining a high Q value. Compared with the traditional substrate integrated waveguide, the one-eighth mode substrate integrated waveguide can maintain excellent electrical performance while maintaining about 1 / 8 of the physical volume, which is particularly suitable for oscillator design with extremely high requirements on size and performance.

[0004] However, current oscillator designs often face the problem of not being able to balance area and Q value. A high Q value often means a larger resonant cavity size, while a reduction in size may lead to a significant reduction in Q value, affecting the frequency stability of the oscillator. In addition, traditional feedback oscillators also have certain limitations in tuning range, making it difficult to meet the needs of broadband communication systems. In contrast, reflective oscillators, with their unique feedback mechanism, have a potentially wider tuning range, providing a possible solution for broadband applications. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide an adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator with miniaturization advantages.

[0006] Technical solution: To achieve this purpose, the present invention adopts the following technical solution:

[0007] The adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator of the present invention is characterized by comprising an adjustable one-eighth mode substrate integrated waveguide resonant cavity, a phase-shifting microstrip line, a negative resistance unit and an output microstrip line; wherein the output port of the adjustable one-eighth mode substrate integrated waveguide resonant cavity is connected to the phase-shifting microstrip line, the other end of the phase-shifting microstrip line is connected to the input end of the negative resistance unit; the output end of the negative resistance unit is connected to the output microstrip line, and the negative resistance oscillator outputs a signal through the output microstrip line.

[0008] Furthermore, the adjustable eighth-mode substrate integrated waveguide resonant cavity comprises a shielded through-hole array, an output port, a varactor diode, a bias circuit and an eighth-mode substrate integrated waveguide resonant cavity. The eighth-mode substrate integrated waveguide resonant cavity is composed of a dielectric substrate and two upper and lower metal sheets, and a metallized through-hole array distributed along the circumferential direction.

[0009] Furthermore, the shape of the one-eighth mode substrate integrated waveguide resonant cavity is obtained by dividing a circular substrate integrated waveguide resonant cavity into eight equal parts along an axis passing through the center of the circle.

[0010] Furthermore, the shielding through hole array is distributed on the open edge of the one-eighth mode substrate integrated waveguide resonant cavity.

[0011] Furthermore, the positive electrode of the varactor is connected to the top edge of the one-eighth mode substrate integrated waveguide resonant cavity to achieve coupling between the two, and the negative electrode of the varactor is connected to the bias circuit; through reverse bias, the capacitance of the varactor changes, thereby achieving the purpose of tuning.

[0012] Furthermore, the phase-shifting microstrip line and the output microstrip line are both 50 ohm feeding resistors.

[0013] Beneficial effects: The present invention discloses an adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage-controlled oscillator, which has a smaller size than a traditional substrate integrated waveguide circular cavity oscillator. At the same time, thanks to the use of a negative resistance oscillator structure, no longer feedback microstrip line structure is required, and the overall size of the oscillator is further reduced. In addition, by introducing the adjustable one-eighth mode substrate integrated waveguide resonant cavity into the negative resistance oscillator design, the size of the oscillator is effectively reduced, and its lower loss enables the oscillator to achieve precise tuning over a wide frequency range without significantly deteriorating its phase noise performance. In a traditional resonant cavity, the resonant frequency is directly related to the size of the cavity, and a larger size is usually required to meet the needs of low-frequency resonance. The one-eighth mode resonant cavity can effectively utilize the symmetry of the electromagnetic field by applying appropriate electric field or magnetic field boundary conditions at the boundary of the resonant cavity, and reduce the physical size of the entire resonant cavity to one-eighth of the original, so that the resonant unit of the oscillator only occupies one-eighth of the volume of a standard resonant cavity, while still achieving the same resonant frequency as the full mode resonant cavity and maintaining a higher Q value. This reduced size greatly reduces the physical space requirements. Therefore, the present invention can take into account the miniaturization, wide tuning range and low phase noise performance of the oscillator, and meet the needs of modern communication systems for high-performance oscillators. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of a negative resistance voltage controlled oscillator in a specific implementation manner of the present invention;

[0015] Figure 2 It is a structural diagram of a circular substrate integrated waveguide resonant cavity in a specific embodiment of the present invention;

[0016] Figure 3 This is a test diagram of the output power of the negative resistance oscillator in a specific implementation manner of the present invention;

[0017] Figure 4 This is a phase noise test diagram of a negative resistance oscillator in a specific implementation manner of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further introduced below in conjunction with specific implementation modes and drawings.

[0019] like Figure 1As shown, this specific embodiment discloses an adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator, comprising an adjustable one-eighth mode substrate integrated waveguide resonant cavity 1, a phase-shifting microstrip line 2, a negative resistance unit 3 and an output microstrip line 4; wherein the output port 8 of the adjustable one-eighth mode substrate integrated waveguide resonant cavity 1 is connected to the phase-shifting microstrip line 2, and the other end of the phase-shifting microstrip line 2 is connected to the input end of the negative resistance unit 3; the output end of the negative resistance unit 3 is connected to the output microstrip line 4, and the negative resistance oscillator outputs a signal through the output microstrip line 4; the phase-shifting microstrip line 2 and the output microstrip line 4 are both 50 ohm feeding resistors.

[0020] The adjustable eighth-mode substrate integrated waveguide resonant cavity 1 comprises a shielded through-hole array 5, an output port 8, a varactor diode 9, a bias circuit 10 and an eighth-mode substrate integrated waveguide resonant cavity 6. The eighth-mode substrate integrated waveguide resonant cavity 6 is composed of a dielectric substrate and two upper and lower metal sheets, and a metallized through-hole array 7 distributed along the circumferential direction.

[0021] The shape of the eighth mode substrate integrated waveguide resonant cavity 6 is as follows: Figure 2 The circular substrate integrated waveguide resonant cavity 11 shown is obtained by dividing it into eight equal parts along an axis passing through the center of the circle.

[0022] The shielding through hole array 5 is distributed on the open edge of the one-eighth mode substrate integrated waveguide resonant cavity 6, and is used to reduce electromagnetic leakage caused by the open cavity structure.

[0023] The positive electrode of the varactor diode 9 is connected to the top edge of the one-eighth mode substrate integrated waveguide resonant cavity 6 to achieve coupling between the two, and the negative electrode of the varactor diode 9 is connected to the bias circuit; through reverse bias, the capacitance of the varactor diode 9 changes, thereby achieving the purpose of tuning.

[0024] The negative resistance unit 3 generates a negative resistance signal by giving positive feedback to the transistor, thereby compensating for the energy loss generated by the adjustable one-eighth mode substrate integrated waveguide resonant cavity 1 to achieve continuous signal output of the oscillation circuit.

[0025] In this embodiment, the one-eighth mode substrate integrated waveguide resonant cavity 6 includes a dielectric substrate and two layers of metal sheets, and the upper and lower surfaces of the dielectric substrate are coated with metal sheets. The relative dielectric constant of the dielectric substrate is 2.2, and the thickness of the dielectric substrate is 0.508 mm. The circuit size of the oscillator is 20 mm*42 mm.

[0026] Figure 3 and Figure 4They are respectively the output power test graph and the phase noise test graph of the negative resistance oscillator in this specific implementation manner. The tuning range of the voltage-controlled oscillator in this specific implementation manner is 10.12GHz-11.02GHz, the phase noise at the center frequency offset by 1MHz within the tuning range varies around -105dBc / Hz, and the output power varies around 5dBm.

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. Adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator, characterized by: The invention comprises an adjustable one-eighth mode substrate integrated waveguide resonant cavity (1), a phase-shifting microstrip line (2), a negative resistance unit (3) and an output microstrip line (4); wherein the output port (8) of the adjustable one-eighth mode substrate integrated waveguide resonant cavity (1) is connected to the phase-shifting microstrip line (2), the other end of the phase-shifting microstrip line (2) is connected to the input end of the negative resistance unit (3); the output end of the negative resistance unit (3) is connected to the output microstrip line (4), and the negative resistance voltage-controlled oscillator outputs a signal via the output microstrip line (4).

2. The adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator according to claim 1, characterized in that: The adjustable eighth-mode substrate integrated waveguide resonant cavity (1) comprises an output port (8), a varactor diode (9), a bias circuit (10) and an eighth-mode substrate integrated waveguide resonant cavity (6); the eighth-mode substrate integrated waveguide resonant cavity (6) comprises a dielectric substrate and upper and lower metal sheets, and a metallized through-hole array (7) distributed along the circumferential direction; the positive electrode of the varactor diode (9) is connected to the top edge of the eighth-mode substrate integrated waveguide resonant cavity (6) to achieve coupling between the two, and the negative electrode of the varactor diode (9) is connected to the bias circuit (10).

3. The adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator according to claim 2, characterized in that: The shape of the one-eighth mode substrate integrated waveguide resonant cavity (6) is obtained by dividing a circular substrate integrated waveguide resonant cavity (11) into eight equal parts along an axis passing through the center of the circle.

4. The adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator according to claim 1, characterized in that: The phase-shifting microstrip line (2) and the output microstrip line (4) are both 50-ohm feeding resistors.

5. The adjustable one-eighth mode substrate integrated waveguide resonant cavity negative resistance voltage controlled oscillator according to claim 2, characterized in that: The adjustable eighth-mode substrate integrated waveguide resonant cavity (1) further comprises a shielding through hole array (5), wherein the shielding through hole array (5) is distributed on the open edge of the eighth-mode substrate integrated waveguide resonant cavity (6).

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