A resonant filter chip loaded with high-order suppression slots

Abstract

The present invention discloses a resonant filter chip loaded with high-order suppression slots, which is composed of a plurality of resonant units and input / output feed lines. The input and output feed lines feed microwave energy into the filter. Between the input and the output, there are more than two coupling channels formed by the resonant units, where at least one channel includes slot coupling and at least one channel includes edge coupling. A long strip-shaped slot is formed on the conductor of the resonant unit. The present invention enables the planar cross-coupled resonant filter to suppress its own high-order parasitic passbands and is applicable to miniaturized and highly integrated radar systems.

Description

Technical Field

[0001] The present invention relates to integrated circuits, and more particularly to a planar cross-coupled resonant filter chip capable of suppressing high-order parasitic passbands. Background Art

[0002] Currently, the common ways to implement filters are microelectromechanical systems (MEMS) filters and low-temperature co-fired ceramic (LTCC) filters. The MEMS filter adopts a microstrip line or a metal via cavity structure. Since the material commonly used in MEMS is high-resistivity silicon, the dielectric constant of this material is about 10. The LTCC filter uses a ceramic material as the dielectric, and the dielectric constant is about 9.7. When implementing a filter at 20 GHz with these two materials, the volume of the filter chip is still relatively large, and the height of the filter chip is relatively high compared to the GaAs (gallium arsenide semiconductor) process chip commonly used in microwave systems. Due to the height difference of the chips, it is not conducive to assembling and integrating with the same bonding process in microwave systems.

[0003] Moreover, neither the MEMS process nor the LTCC process can be integrated with the GaAs process. The GaAs process is used to implement functions such as amplification and mixing in microwave links, which is not conducive to improving the integration degree of the system. When using lumped elements in the GaAs process to implement a filter, above 20 GHz, the parasitic parameters of the lumped elements are too large to obtain a better filter passband form.

[0004] The cross-coupled filter has the advantage of simple implementation, but this implementation method will bring parasitic passbands of the filter. Summary of the Invention

[0005] The present invention proposes a planar cross-coupled resonant filter chip, enabling this planar cross-coupled resonant filter to suppress its own high-order parasitic passbands and being applicable to miniaturized and highly integrated radar systems.

[0006] A resonant filter chip with high-order suppression slots, composed of several resonant units and input / output feed lines, where the input / output feed lines feed microwave energy into the filter; there are more than two coupling channels formed by resonant units between the input and the output, with at least one channel including slot coupling and at least one channel including edge coupling; a long strip-shaped slot is opened on the conductor of the resonant unit.

[0007] Further, the width of the high-order suppression slot is less than 1 / 32 of the wavelength corresponding to the suppression frequency point, and the length is 1 / 8 of the wavelength corresponding to the suppression frequency point.

[0008] Further, each resonant unit with a high-order suppression slot is geometrically identical.

[0009] The present invention has the following beneficial effects:

[0010] After adopting this design method, a band-pass filter based on GaAs process with a high Q value above 20 GHz can be realized, and the second-order parasitic passband of the filter is suppressed by more than 20 dB. This filter has the advantages of small volume, matching with the GaAs bare chip bonding process, being conducive to realizing the integration of the amplifier and the filter, good specific consistency, and high integration. At the same time, without increasing the circuit area, the effective suppression of the second-order and higher-order parasitic passbands is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings included are used to provide a further understanding of the embodiments of the present invention, which form a part of the specification, are used to illustrate the embodiments of the present invention, and are used to explain the principles of the present invention together with the text description. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0012] Figure 1 : Schematic diagram of the four resonant units of the present invention;

[0013] Figure 2 : Layout of the resonant unit of the present invention being C-shaped. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The present invention will be further described in detail below with reference to the accompanying drawings.

[0015] The resonant units of the present invention can be several. As shown in the attached Figure 1 In this embodiment, it is composed of 4 resonant units with high-order suppression slots loaded and input / output feed lines. The high-order suppression slot is a long strip slot opened on the conductor of the resonant unit. The input and output feed lines are used to feed microwave energy into the filter. After the microwave energy enters the filter, it resonates in the first resonant unit with a high-order suppression slot loaded, and at the same time enters the second resonant unit with a high-order suppression slot loaded and the third resonant unit with a high-order suppression slot loaded through the coupling method.

[0016] Each resonant unit loaded with a high-order suppression slot is geometrically consistent, so its resonant frequency and Q value are also consistent. The resonant unit one 1 loaded with a high-order suppression slot and the resonant unit three 3 loaded with a high-order suppression slot, the resonant unit 3 loaded with a high-order suppression slot and the resonant unit 4 loaded with a high-order suppression slot, the resonant unit 2 loaded with a high-order suppression slot and the resonant unit 4 loaded with a high-order suppression slot are all coupled by edge coupling. The resonant unit one 1 loaded with a high-order suppression slot and the resonant unit two 2 loaded with a high-order suppression slot are coupled by a slot. The difference between these two coupling methods realizes the zeros in the stopband. From the perspective of the coupling route, there are two coupling routes from input to output, that is, from unit one to unit three, to unit four, and then to unit two; the other is directly from unit one to unit two input. There are two transmission routes from input to output, and the coupling methods show a cross-shaped trend, so this filter form is a cross-coupling method. Since the signal can be coupled from the input to the output through two different paths, there must be certain frequency points where the microwave signal passes through the two paths and arrives at the output end with exactly opposite phases, so the signals on the two paths cancel each other out, which is the formation of transmission zeros at certain frequency points. By adjusting the coupling path, that is, adjusting the distance between the edge coupling lines or the spacing of the coupling slots, the electrical length of the coupling path can be adjusted, and then the frequency point where the transmission zero is located can be adjusted.

[0017] Since ordinary resonant units themselves resonate at multiple frequency points, and each resonant frequency point is basically an integer multiple of the first resonant frequency point, filters using ordinary resonant units will have parasitic passbands of the second order or higher. In the present invention, by loading high-order suppression slots on the pattern of ordinary resonant units, the positions of the second-order or higher resonant frequency points of the resonant units themselves are changed, thereby suppressing the parasitic passbands of the second order and higher of the filters composed of the resonant units.

[0018] The size of the high-order suppression slot is: the width is less than 1 / 32 of the wavelength corresponding to the suppression frequency point, and the length is close to 1 / 8 of the wavelength corresponding to the suppression frequency point. When the width of the high-order suppression slot is too large, it will affect the lowest resonant frequency point of the resonant unit, and then affect the expected operating frequency band of the filter. When the width of the high-order suppression slot is too small, the GaAs process cannot be realized. Therefore, the width should be less than 1 / 32 of the wavelength corresponding to the suppression frequency point within the process realizable range. The length is close to 1 / 8 of the wavelength corresponding to the suppression frequency point. Due to the existence of this slot, the resonant unit no longer satisfies the resonant condition at the suppression frequency point. Therefore, the second-order and higher resonant frequencies of the resonant unit loaded with the high-order suppression slot are changed by this slot, and the filter composed of such resonant units realizes the suppression of the parasitic passbands of the second order and higher.

[0019] The resonant unit can be in the shape of "C", "B", "E" or "M". Figure 2The layout with a C-shaped resonant unit is shown.

[0020] The above specific embodiments are only limited to explaining and illustrating the technical solutions of the present invention, but do not constitute a limitation on the protection scope of the claims. Those skilled in the art should clearly understand that any new technical solutions obtained by making any simple deformation or substitution on the basis of the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A resonant filter chip loaded with high-order suppression slots, characterized in that, It is composed of several resonant units and input / output feed lines, and the input / output feed lines feed microwave energy into the filter; there are more than two coupling channels formed by the resonant units between the input and the output, and at least one channel includes slot coupling and at least one channel includes edge coupling; a long strip-shaped slot is opened on the conductor of the resonant unit; The width of the high-order suppression slot is less than 1 / 32 of the wavelength corresponding to the suppression frequency point, and the length is 1 / 8 of the wavelength corresponding to the suppression frequency point; The resonant unit is in the shape of "C", "B", "E" or "M".

2. The resonant filter chip with high-order suppression slots according to claim 1, characterized in that Each resonant unit loaded with a high-order suppression slot is geometrically consistent.

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