Filter circuit and electronic device

Abstract

The invention discloses a filter circuit and an electronic device. The filter circuit comprises a first resonator, a second resonator and a third resonator, the first end of the first resonator is connected with the signal input end, and the second end of the first resonator is connected with the signal output end; the first end of the second resonator is connected with the first end of the first resonator, and the second end of the second resonator is connected with the grounding end; the first end of the third resonator is connected with the second end of the first resonator, and the second end of the third resonator is connected with the grounding end. According to the invention, the three resonators are connected in a pi-shaped manner to form the filter circuit, and the order number of the resonators is increased, so that the target frequency can be more accurately selected, interference signals of other frequencies can be effectively suppressed, and the out-of-band rejection capability of the filter circuit is improved. The filter circuit provided by the invention is connected to the rear stage of the frequency multiplier circuit, so that the noise of the frequency multiplier circuit can be effectively reduced, and the purity and stability of an output signal are ensured.

Description

Technical Field

[0001] The present invention relates to the field of circuit technologies, and in particular, to a filtering circuit and an electronic device. Background Art

[0002] With the rapid development of the electronics industry, the requirements of electronic systems for internal frequency sources are increasing day by day, especially in terms of frequency stability, phase noise, and spurs.

[0003] Frequency multiplication technology is a method for generating high-frequency signals, which can effectively convert low-frequency signals into high-frequency microwave signals to meet the requirements of specific applications. However, frequency multiplication technology has the disadvantage of high noise. Summary of the Invention

[0004] The present invention provides a filtering circuit to solve the problem of high noise existing in frequency multiplication technology.

[0005] According to one aspect of the present invention, a filtering circuit is provided. The filtering circuit includes a first resonator, a second resonator, and a third resonator;

[0006] The first end of the first resonator is connected to a signal input end, and the second end of the first resonator is connected to a signal output end;

[0007] The first end of the second resonator is connected to the first end of the first resonator, and the second end of the second resonator is connected to a ground end;

[0008] The first end of the third resonator is connected to the second end of the first resonator, and the second end of the third resonator is connected to the ground end.

[0009] Optionally, the filtering circuit further includes: a first adjustment module and a second adjustment module;

[0010] The first adjustment module is connected in parallel with the second resonator, and the first adjustment module is used to adjust the bandwidth of the second resonator;

[0011] The second adjustment module is connected in parallel with the third resonator, and the second adjustment module is used to adjust the bandwidth of the third resonator.

[0012] Optionally, the filtering circuit further includes: a first matching module and a second matching module;

[0013] The first end of the first matching module is connected to the second end of the second resonator, and the second end of the first matching module is connected to the ground end. The first matching module is used to adjust the out-of-band rejection frequency and the center frequency of the second resonator;

[0014] The first end of the second matching module is connected to the second end of the third resonator, and the second end of the second matching module is connected to the ground terminal. The second matching module is used to adjust the out-of-band rejection frequency and the center frequency of the third resonator.

[0015] Optionally, the first adjustment module includes: a first capacitor;

[0016] The first capacitor is connected in parallel with the second resonator.

[0017] Optionally, the second adjustment module includes: a second capacitor;

[0018] The second capacitor is connected in parallel with the third resonator.

[0019] Optionally, the first matching module includes a first inductor and a third capacitor;

[0020] The first inductor is connected between the second end of the second resonator and the ground terminal;

[0021] The third capacitor is connected in parallel with the first inductor.

[0022] Optionally, the second matching module includes a second inductor and a fourth capacitor;

[0023] The second inductor is connected between the second end of the third resonator and the ground terminal;

[0024] The fourth capacitor is connected in parallel with the second inductor.

[0025] Optionally, the first resonator, the second resonator, and the third resonator all include surface acoustic wave resonators.

[0026] According to another aspect of the present invention, there is provided an electronic device, which includes the filter circuit according to any embodiment of the present invention.

[0027] The technical solution of the embodiment of the present invention uses three resonators connected in a π shape to form a filter circuit. Since the order of the resonator increases, the target frequency can be selected more precisely, and the interference signals of other frequencies can be effectively suppressed, thereby improving the out-of-band rejection ability of the filter circuit. Connecting the filter circuit proposed by the present invention to the subsequent stage of the frequency doubling circuit can effectively reduce the noise of the frequency doubling circuit and ensure the purity and stability of the output signal.

[0028] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0030] Figure 1 It is a schematic structural diagram of a filtering circuit provided by an embodiment of the present invention;

[0031] Figure 2 It is a schematic structural diagram of another filtering circuit provided by an embodiment of the present invention;

[0032] Figure 3 It is a schematic structural diagram of another filtering circuit provided by an embodiment of the present invention. Detailed implementation manners

[0033] In order to enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above accompanying drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0035] Figure 1 It is a schematic structural diagram of a filtering circuit provided by an embodiment of the present invention. This embodiment is applicable to filtering a frequency doubling circuit, and the filtering circuit can be configured in an electronic device. As Figure 1As shown, the filter circuit includes: a first resonator 110, a second resonator 120, and a third resonator 130; a first end of the first resonator 110 is connected to a signal input terminal 140, and a second end of the first resonator 110 is connected to a signal output terminal 150; a first end of the second resonator 120 is connected to the first end of the first resonator 110, and a second end of the second resonator 120 is connected to a ground terminal 160; a first end of the third resonator 130 is connected to the second end of the first resonator 110, and a second end of the third resonator 130 is connected to the ground terminal 160.

[0036] Specifically, a resonator refers to a circuit element or mechanical device that can generate resonance at a specific frequency. Resonators are commonly used in filtering, frequency selection, and signal processing. Exemplarily, resonators include LC resonators, mechanical resonators, optical resonators, etc. In the embodiments of the present invention, a resonator is used as a filtering device to filter the signal input from the signal input terminal 140. The first resonator 110 refers to a resonator in the filter circuit, whose first end is connected to the signal input terminal 140 and the second end is connected to the signal output terminal 150, and can receive the input signal from the signal input terminal 140 and filter the input signal through the resonance effect. Among them, the first resonator 110 presents a low impedance at the target frequency, allowing the signal to pass through efficiently, and presents a high impedance at non-target frequencies, blocking the transmission of interference signals.

[0037] The second resonator 120 refers to another resonator in the filter circuit, connected between the first end of the first resonator 110 and the ground terminal 160, and can further enhance the selectivity of the signal and suppress unwanted frequency components. Among them, the second resonator 120 presents a high impedance at the target frequency, preventing the signal from being short-circuited to the ground terminal 160, and presents a low impedance at non-target frequencies, short-circuiting the interference signal to the ground and suppressing the noise input from the signal input terminal 140.

[0038] The third resonator 130 refers to another resonator in the filter circuit, connected between the second end of the first resonator 110 and the ground terminal 160, and can receive the signal output from the first resonator 110 and further process it to ensure the quality of the signal output by the filter circuit. Among them, the third resonator 130 presents a high impedance at the target frequency, preventing the signal from being short-circuited to the ground terminal 160, and presents a low impedance at non-target frequencies, short-circuiting the interference signal to the ground and suppressing the noise input from the signal input terminal 140.

[0039] In an embodiment of the present invention, the first resonator 110, the second resonator 120, and the third resonator 130 form a π-type connection and can cooperate with each other to form a complete filter circuit. Among them, the first resonator 110 has a low impedance within the passband and a high impedance outside the passband, which can ensure lossless transmission of signals within the target frequency. The second resonator 120 and the third resonator 130 have a high impedance within the passband and filter the signals at the signal input terminal 140 and the signal output terminal 150 respectively, effectively suppressing the noise at the signal input terminal 140 and the residual interference at the signal output terminal 150, and improving the overall signal-to-noise ratio.

[0040] The technical solution of the embodiment of the present invention uses three resonators connected in a π-type to form a filter circuit. Due to the increase in the order of the resonators, the target frequency can be selected more precisely, effectively suppressing the interference signals of other frequencies, thereby improving the out-of-band rejection ability of the filter circuit. Connecting the filter circuit proposed by the present invention to the subsequent stage of the frequency doubling circuit can effectively reduce the noise of the frequency doubling circuit and ensure the purity and stability of the output signal.

[0041] Figure 2 FIG. is a schematic structural diagram of another filter circuit provided by an embodiment of the present invention. On the basis of the above embodiments, as Figure 2 shown, optionally, the filter circuit further includes: a first adjustment module 121 and a second adjustment module 131; the first adjustment module 121 is connected in parallel with the second resonator 120, and the first adjustment module 121 is used to adjust the bandwidth of the second resonator 120; the second adjustment module 131 is connected in parallel with the third resonator 130, and the second adjustment module 131 is used to adjust the bandwidth of the third resonator 130.

[0042] Specifically, the first adjustment module 121 refers to a component that adjusts the bandwidth of the second resonator 120 by changing its internal parameters. The second adjustment module 131 refers to a component that adjusts the bandwidth of the third resonator 130 by changing its internal parameters. By reasonably setting the parameters of the first adjustment module 121 and the second adjustment module 131, higher signal selectivity can be achieved, ensuring that the required signals are effectively transmitted when passing through the filter, while suppressing unnecessary interference signals.

[0043] In an embodiment of the present invention, the bandwidths of the second resonator 120 and the third resonator 130 can be adjusted through the first adjustment module 121 and the second adjustment module 131, further enhancing the flexibility and adaptability of the filter circuit.

[0044] On the basis of the above embodiments, optionally, continue to refer to Figure 2, the filter circuit further includes: a first matching module 122 and a second matching module 132; a first end of the first matching module 122 is connected to a second end of the second resonator 120, a second end of the first matching module 122 is connected to a ground terminal 160, and the first matching module 122 is configured to adjust an out-of-band rejection frequency and a center frequency of the second resonator 120; a first end of the second matching module 132 is connected to a second end of the third resonator 130, a second end of the second matching module 132 is connected to the ground terminal 160, and the second matching module 132 is configured to adjust an out-of-band rejection frequency and a center frequency of the third resonator 130.

[0045] Specifically, the out-of-band rejection frequency refers to the ability of the filter to suppress frequency components other than the target signal. A higher out-of-band rejection frequency means that the filter can more effectively suppress unnecessary frequency components. The center frequency refers to the frequency at which the filter has the maximum gain in its frequency response curve. At the center frequency, the signal will pass through to the greatest extent. In the embodiments of the present invention, a resonator is used as the filter, that is, the out-of-band rejection frequency refers to the ability of the resonator to suppress frequency components other than the target signal. The center frequency refers to the frequency at which the resonator has the maximum gain in its frequency response curve.

[0046] The first matching module 122 refers to a module for optimizing the impedance matching between the output of the second resonator 120 and the subsequent circuit. By changing the parameters of the second resonator 120, the attenuation degree of the signal output by the second resonator 120 in the non-target frequency range can be effectively controlled. The second matching module 132 refers to a module for optimizing the impedance matching between the output of the third resonator 130 and the subsequent circuit. By changing the parameters of the third resonator 130, the attenuation degree of the signal output by the third resonator 130 in the non-target frequency range can be effectively controlled.

[0047] In the embodiments of the present invention, the second resonator 120 and the third resonator 130 are grounded through the first matching module 122 and the second matching module 132 respectively, which can effectively reduce the reflection and loss of the signal during transmission and improve the signal integrity. At the same time, by adjusting the parameters of the second resonator 120 and the third resonator 130, the out-of-band rejection frequency and the center frequency of the second resonator 120 and the third resonator 130 can be adjusted to ensure that the attenuation effect of the resonator at non-target frequencies reaches the best, thereby effectively suppressing interference signals.

[0048] The technical solution of the embodiments of the present invention adjusts the bandwidth and center frequency of the second resonator through the first adjustment module and the first matching module, and adjusts the bandwidth and center frequency of the second resonator through the second adjustment module and the second matching module, enabling the user to flexibly adjust the circuit parameters according to different application requirements, effectively enhancing the flexibility and signal selectivity of the filter circuit, and making it adapt to diverse signal processing scenarios.

[0049] Figure 3 This is a schematic diagram of another filter circuit provided by an embodiment of the present invention. On the basis of the above embodiments, as Figure 3 shown, optionally, the first adjustment module 121 includes: a first capacitor 123; the first capacitor 123 is connected in parallel with the second resonator 120.

[0050] Specifically, in the signal processing process, the capacitor can effectively improve the response characteristics of the filter, enhance the signal selectivity and noise suppression ability. In the embodiment of the present invention, the first capacitor 123 changes the bandwidth of the second resonator 120 by affecting the quality factor of the second resonator 120. Exemplarily, when the first capacitor 123 increases, the quality factor of the second resonator 120 decreases, thereby increasing the bandwidth of the second resonator 120. In addition, the first capacitor 123 can also affect the resonance frequency of the second resonator 120 to achieve fine-tuning of the center frequency of the second resonator 120.

[0051] The technical solution of the embodiment of the present invention adjusts the bandwidth and center frequency of the second resonator by connecting the first capacitor in parallel to the second resonator, thereby improving the flexibility and selectivity of the filter circuit.

[0052] On the basis of the above embodiments, continue to refer to Figure 3 , optionally, the second adjustment module 131 includes: a second capacitor 133; the second capacitor 133 is connected in parallel with the third resonator 130.

[0053] In the embodiment of the present invention, the second capacitor 133 changes the bandwidth of the third resonator 130 by affecting the quality factor of the third resonator 130. Exemplarily, when the second capacitor 133 increases, the quality factor of the third resonator 130 decreases, thereby increasing the bandwidth of the third resonator 130. In addition, the second capacitor 133 can also affect the resonance frequency of the third resonator 130 to achieve fine-tuning of the center frequency of the third resonator 130.

[0054] The technical solution of the embodiment of the present invention adjusts the bandwidth and center frequency of the third resonator by connecting the second capacitor in parallel to the third resonator, thereby improving the flexibility and selectivity of the filter circuit.

[0055] On the basis of the above embodiments, continue to refer to Figure 3 , optionally, the first matching module 122 includes a first inductor 124 and a third capacitor 125; the first inductor 124 is connected between the second end of the second resonator 120 and the ground terminal 160; the third capacitor 125 is connected in parallel with the first inductor 124.

[0056] Specifically, an inductor is a component that stores magnetic energy. When current flows through the inductor, a magnetic field is generated around it. A capacitor is a component that stores electrical energy. It has a lower impedance to high-frequency signals, can pass high-frequency signals and suppress low-frequency signals. In addition, the capacitor will also cause the phase of the signal to advance, resulting in a phase difference between the signal passing through the capacitor and the input signal.

[0057] In an embodiment of the present invention, the first inductor 124 and the third capacitor 125 are connected in parallel to form a resonant circuit. This resonant circuit exhibits a low impedance near its resonant frequency, allowing the target signal to pass through effectively; while in the out-of-band frequency range, the impedances of the inductor and the capacitor are relatively high, thereby suppressing the transmission of out-of-band signals. Therefore, by adjusting the parameters of the first inductor 124 and the third capacitor 125, the operating frequency of the second resonator 120 can be controlled to achieve selective amplification or attenuation of the target frequency signal. That is, the parallel connection of the first inductor 124 and the third capacitor 125 can significantly improve the out-of-band signal suppression ability of the second resonator 120, ensuring that only the target signal can be effectively transmitted, while the non-target signals are suppressed.

[0058] Based on the above embodiments, continue to refer to Figure 3 , optionally, the second matching module 132 includes a second inductor 134 and a fourth capacitor 135; the second inductor 134 is connected between the second end of the third resonator 130 and the ground terminal 160; the fourth capacitor 135 is connected in parallel with the second inductor 134.

[0059] In an embodiment of the present invention, the second inductor 134 and the fourth capacitor 135 are connected in parallel to form a resonant circuit. This resonant circuit exhibits a low impedance near its resonant frequency, allowing the target signal to pass through effectively; while in the out-of-band frequency range, the impedances of the inductor and the capacitor are relatively high, thereby suppressing the transmission of out-of-band signals. Therefore, by adjusting the parameters of the second inductor 134 and the fourth capacitor 135, the operating frequency of the third resonator 130 can be controlled to achieve selective amplification or attenuation of the target frequency signal. That is, the parallel connection of the second inductor 134 and the fourth capacitor 135 can significantly improve the out-of-band signal suppression ability of the third resonator 130, ensuring that only the target signal can be effectively transmitted, while the non-target signals are suppressed.

[0060] Based on the above embodiments, continue to refer to Figure 3 , optionally, the first resonator 110, the second resonator 120, and the third resonator 130 all include surface acoustic wave resonators.

[0061] Specifically, a Surface Acoustic Wave Resonator (SAW resonator) is a resonator that utilizes the propagation of surface acoustic waves in a medium. Its working principle is to generate acoustic waves on the surface of the material, and these acoustic waves propagate on the surface of the material and interact with the structure of the resonator, thereby achieving frequency selectivity. SAW resonators have the advantages of high operating frequency, small size, low power consumption, and strong stability, and are widely used in fields such as wireless communication, radar systems, sensors, and audio processing.

[0062] In the embodiments of the present invention, since the SAW resonator can operate in a high-frequency range between dozens of megahertz and several gigahertz, and also has good frequency selectivity, it can accurately select and amplify signals of specific frequencies while suppressing out-of-band signals. Therefore, the first resonator 110, the second resonator 120, and the third resonator 130 all include SAW resonators to improve the performance of the filtering circuit.

[0063] The technical solution provided by the embodiments of the present invention enables the filtering circuit to process signals with higher frequencies and higher bandwidths by using SAW resonators. This not only optimizes the performance of the filtering circuit, improves its reliability and adaptability, but also effectively meets the requirements of modern communication technologies for high performance, high integration, and low power consumption.

[0064] The embodiments of the present invention also provide an electronic device, which includes the filtering circuit described in any of the above embodiments and has the corresponding functional modules and beneficial effects of the above filtering circuit.

[0065] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and no limitations are imposed herein.

[0066] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A filter circuit, characterized in that: The filter circuit includes a first resonator, a second resonator and a third resonator; The first end of the first resonator is connected to the signal input end, and the second end of the first resonator is connected to the signal output end; The first end of the second resonator is connected to the first end of the first resonator, and the second end of the second resonator is connected to the ground end; The first end of the third resonator is connected to the second end of the first resonator, and the second end of the third resonator is connected to the ground end.

2. The filter circuit according to claim 1, characterized in that: The filter circuit further includes: a first regulating module and a second regulating module; The first adjustment module is connected in parallel with the second resonator, and the first adjustment module is used to adjust the bandwidth of the second resonator; The second regulating module is connected in parallel with the third resonator, and the second regulating module is used to adjust the bandwidth of the third resonator.

3. The filter circuit according to claim 1, characterized in that: The filter circuit further includes: a first matching module and a second matching module; The first end of the first matching module is connected to the second end of the second resonator, the second end of the first matching module is connected to the ground end, and the first matching module is used to adjust the out-of-band suppression frequency and the center frequency of the second resonator; The first end of the second matching module is connected to the second end of the third resonator, the second end of the second matching module is connected to the ground end, and the second matching module is used to adjust the out-of-band suppression frequency and the center frequency of the third resonator.

4. The filter circuit according to claim 2, characterized in that: The first regulating module includes: a first capacitor; The first capacitor is connected in parallel with the second resonator.

5. The filter circuit according to claim 2, characterized in that: The second regulating module includes: a second capacitor; The second capacitor is connected in parallel with the third resonator.

6. The filter circuit according to claim 3, characterized in that: The first matching module includes a first inductor and a third capacitor; The first inductor is connected between the second end of the second resonator and a ground terminal; The third capacitor is connected in parallel with the first inductor.

7. The filter circuit according to claim 3, characterized in that: The second matching module includes a second inductor and a fourth capacitor; The second inductor is connected between the second end of the third resonator and the ground end; The fourth capacitor is connected in parallel with the second inductor.

8. The filter circuit according to claim 1, characterized in that: The first resonator, the second resonator, and the third resonator each include a surface acoustic wave resonator.

9. An electronic device, characterized in that: include: A filter circuit as claimed in any one of claims 1 to 8.

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