Filter circuit and electronic device

Abstract

The utility model 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 utility model, the three resonators are connected in the Pi shape to form the filter circuit, and the order number of the resonators is increased, so that the target frequency can be more accurately selected, and interference signals of other frequencies can be effectively suppressed, thereby improving the out-of-band rejection capability of the filter circuit. The filter circuit provided by the utility model 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 utility model relates to circuit technical field especially relates to a filter circuit and electronic device. BACKGROUND

[0002] With the rapid development of electronic industry, the requirement of electronic system to internal frequency source is increasing day by day, especially in frequency stability, phase noise and stray.

[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 needs of specific applications. However, frequency multiplication technology has the disadvantage of high noise. SUMMARY

[0004] The utility model provides a filter circuit to solve the problem of high noise of frequency multiplication technology.

[0005] According to an aspect of the utility model, a filter circuit is provided, the filter circuit comprises a first resonator, a second resonator and a third resonator;

[0006] 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;

[0007] 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 ground end;

[0008] 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 ground end.

[0009] Optionally, the filter circuit further comprises a first adjusting module and a second adjusting module;

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

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

[0012] Optionally, the filter circuit further comprises a first matching module and a second matching module;

[0013] The first end of the first matching module is connected with the second end of the second resonator, the second end of the first matching module is connected with the ground end, and 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 with the second end of the third resonator, and the second end of the second matching module is connected with a ground end, and the second matching module is used for adjusting the out-of-band rejection frequency and the center frequency of the third resonator.

[0015] Optionally, the first adjusting module comprises a first capacitor.

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

[0017] Optionally, the second adjusting module comprises a second capacitor.

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

[0019] Optionally, the first matching module comprises a first inductor and a third capacitor.

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

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

[0022] Optionally, the second matching module comprises a second inductor and a fourth capacitor.

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

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

[0025] Optionally, the first resonator, the second resonator and the third resonator each comprise a surface acoustic wave resonator.

[0026] According to another aspect of the present application, an electronic device is provided, which comprises the filter circuit according to any one of the embodiments of the present application.

[0027] The technical scheme of the present application comprises three resonators connected in a pi type to form a filter circuit, and the order of the resonator is increased, so that the target frequency can be selected more accurately, the interference signals of other frequencies are effectively suppressed, and the out-of-band rejection capability of the filter circuit is improved.

[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 application, nor is it used to limit the scope of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to make the technical scheme in the embodiments of the present application clearer, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

[0030] Figure 1 A structure diagram of a filter circuit provided by the embodiment of the present application is shown in the figure.

[0031] Figure 2 A structure diagram of another filter circuit provided by the embodiment of the present application is shown in the figure.

[0032] Figure 3 A structure diagram of another filter circuit provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0033] In order to make the technical scheme in the embodiments of the present application clearer, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings.

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

[0035] Figure 1 A structure diagram of a filter circuit provided by the embodiment of the present application is shown in the figure, and the embodiment can be applicable to filtering of a frequency multiplication circuit, and the filter circuit can be configured in an electronic device. Figure 1As shown, the filter circuit includes: a first resonator 110, a second resonator 120 and a third resonator 130; the first end of the first resonator 110 is connected with the signal input end 140, and the second end of the first resonator 110 is connected with the signal output end 150; the first end of the second resonator 120 is connected with the first end of the first resonator 110, and the second end of the second resonator 120 is connected with the ground end 160; the first end of the third resonator 130 is connected with the second end of the first resonator 110, and the second end of the third resonator 130 is connected with the ground end 160.

[0036] Specifically, the resonator refers to a circuit element or a mechanical device capable of producing resonance at a specific frequency, and the resonator is often used in filtering, frequency selection and signal processing. For example, the resonator includes an LC resonator, a mechanical resonator, an optical resonator, etc. In the embodiment of the utility model, the resonator is used as a filter device to filter the signal input by the signal input end 140. The first resonator 110 refers to a resonator in the filter circuit, and the first end is connected to the signal input end 140, and the second end is connected to the signal output end 150, which can receive the input signal of the signal input end 140 and filter the input signal through the resonance effect. Among them, the first resonator 110 presents low impedance at the target frequency, allowing the signal to pass efficiently, and presents high impedance at the non-target frequency, blocking the transmission of interference signals.

[0037] The second resonator 120 refers to another resonator in the filter circuit, which is connected between the first end of the first resonator 110 and the ground end 160, which can further enhance the selectivity of the signal and suppress the frequency components that are not needed. Among them, the second resonator 120 presents high impedance at the target frequency, preventing the signal from being shorted to the ground end 160, and presents low impedance at the non-target frequency, shorting the interference signal to the ground, and suppressing the noise input by the signal input end 140.

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

[0039] In the embodiment of the utility model, the first resonator 110, the second resonator 120 and the third resonator 130 form a π type connection, can mutually cooperate, form a complete filter circuit, wherein, the first resonator 110 is low impedance in passband, high impedance out of passband, can ensure the signal in target frequency lossless transmission, the second resonator 120 and the third resonator 130 are high impedance in passband, filter the signal of signal input end 140 and signal output end 150 respectively, effectively suppress the noise of signal input end 140 and the residual interference of signal output end 150, improve the overall signal-to-noise ratio.

[0040] The technical scheme of the embodiment of the utility model, use three resonators π type connection to constitute filter circuit, due to the order of resonator increases, can more accurately select target frequency, effectively suppress the interference signal of other frequency, thereby improve the out-of-band rejection capability of filter circuit, connect the filter circuit proposed in the utility model in the rear stage of frequency multiplication circuit, can effectively reduce the noise of frequency multiplication circuit, ensure the purity and stability of output signal.

[0041] Figure 2 Another filter circuit structure schematic view provided in the embodiment of the utility model is shown in the above various embodiments, as Figure 2 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 desired signal is effectively transmitted when passing through the filter, while suppressing unnecessary interference signals.

[0043] In the embodiment of the utility model, the bandwidth of the second resonator 120 and the third resonator 130 can be adjusted by 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 various embodiments, optionally, continue to refer to Figure 2The filter circuit further comprises a first matching module 122 and a second matching module 132; a first end of the first matching module 122 is connected with a second end of the second resonator 120, a second end of the first matching module 122 is connected with the ground end 160, and the first matching module 122 is used for adjusting the out-of-band rejection frequency and the center frequency of the second resonator 120; a first end of the second matching module 132 is connected with a second end of the third resonator 130, a second end of the second matching module 132 is connected with the ground end 160, and the second matching module 132 is used for adjusting the out-of-band rejection frequency and the center frequency of the third resonator 130.

[0045] Specifically, the out-of-band rejection frequency refers to the suppression ability of the filter to the frequency components outside the target signal, and 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, and at the center frequency, the signal will be passed through to the greatest extent. In the embodiment of the utility model, the resonator is used as the filter, that is, the out-of-band rejection frequency refers to the suppression ability of the resonator to the frequency components outside 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, and 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, and 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 embodiment of the utility model, 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 in the transmission process and improve the integrity of the signal. 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, ensuring that the attenuation effect of the resonator at the non-target frequency reaches the best, thereby effectively suppressing the interference signal.

[0048] The technical scheme of the embodiment of the utility model adjusts the bandwidth and center frequency of the second resonator through the first adjusting module and the first matching module, adjusts the bandwidth and center frequency of the second resonator through the second adjusting module and the second matching module, so that the user can flexibly adjust the circuit parameters according to different application requirements, which can effectively enhance the flexibility and signal selectivity of the filter circuit, and make it adapt to diversified signal processing scenes.

[0049] Figure 3 Another structure schematic diagram of the filter circuit is provided in the embodiment of the utility model. On the basis of the above-mentioned embodiments, as shown in Figure 3 Optionally, the first adjusting module 121 comprises a first capacitor 123; and 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 characteristic of the filter, and enhance the signal selectivity and noise suppression capability. In the embodiment of the utility model, 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 resonant frequency of the second resonator 120, thereby realizing fine adjustment of the center frequency of the second resonator 120.

[0051] The technical scheme of the embodiment of the utility model adjusts the bandwidth and the center frequency of the third resonator by connecting the second capacitor in parallel to the third resonator, thereby improving the flexibility and the selectivity of the filter circuit.

[0052] On the basis of the above-mentioned embodiments, continuing to refer to Figure 3 Optionally, the second adjusting module 131 comprises a second capacitor 133; and the second capacitor 133 is connected in parallel with the third resonator 130.

[0053] In the embodiment of the utility model, 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 resonant frequency of the third resonator 130, thereby realizing fine adjustment of the center frequency of the third resonator 130.

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

[0055] On the basis of the above-mentioned embodiments, continuing to refer to Figure 3 Optionally, the first matching module 122 comprises 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 end 160; and the third capacitor 125 is connected in parallel with the first inductor 124.

[0056] Specifically, the inductor is a component that stores magnetic energy, and when current flows through the inductor, a magnetic field is generated around it. The capacitor is a component that stores electrical energy, and its impedance to high-frequency signals is low, allowing high-frequency signals to pass through and suppressing low-frequency signals. In addition, the capacitor also causes 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 the embodiments of the present application, the first inductor 124 and the third capacitor 125 are connected in parallel to form a resonant circuit, which exhibits low impedance near its resonant frequency, allowing the target signal to pass through effectively. In the out-of-band frequency range, the impedance of the inductor and the capacitor is 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, and selective amplification or attenuation of the target frequency signal can be achieved. That is, the parallel connection of the first inductor 124 and the third capacitor 125 can significantly improve the suppression capability of the second resonator 120 to out-of-band signals, ensuring that only the target signal can be effectively transmitted, while non-target signals are suppressed.

[0058] Based on the above embodiments, further referring 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 end 160; and the fourth capacitor 135 is connected in parallel with the second inductor 134.

[0059] In the embodiments of the present application, the second inductor 134 and the fourth capacitor 135 are connected in parallel to form a resonant circuit, which exhibits low impedance near its resonant frequency, allowing the target signal to pass through effectively. In the out-of-band frequency range, the impedance of the inductor and the capacitor is 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, and selective amplification or attenuation of the target frequency signal can be achieved. That is, the parallel connection of the second inductor 134 and the fourth capacitor 135 can significantly improve the suppression capability of the third resonator 130 to out-of-band signals, ensuring that only the target signal can be effectively transmitted, while non-target signals are suppressed.

[0060] Based on the above embodiments, further referring to Figure 3 Optionally, the first resonator 110, the second resonator 120, and the third resonator 130 all include a surface acoustic wave resonator.

[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 a material, which 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 wireless communication, radar systems, sensors, audio processing, and other fields.

[0062] In the embodiments of the present application, the SAW resonator can work in a high frequency range of tens of megahertz to thousands of megahertz, and also has good frequency selectivity, which 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 contain SAW resonators to improve the performance of the filter circuit.

[0063] The technical scheme provided by the embodiments of the present application uses SAW resonators to enable the filter circuit to process signals of higher frequency and higher bandwidth, not only optimizing the performance of the filter circuit, improving its reliability and adaptability, but also effectively meeting the requirements of modern communication technology for high performance, high integration and low power consumption.

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

[0065] It should be understood that various forms of the flow shown above can be used to reorder, add or delete steps. For example, the steps described in the present application can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical scheme of the present application can be achieved, which is not limited herein.

[0066] The above specific embodiments do not constitute a limitation on the scope of protection of the present application. 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 application shall be included in the scope of protection of the present application.

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 terminal, and the second end of the first resonator is connected to the signal output terminal; 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 terminal; 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 terminal.

2. The filter circuit according to claim 1, characterized in that, The filtering circuit further includes: a first adjustment module and a second adjustment 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 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.

3. The filter circuit according to claim 1, characterized in that, The filtering 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, 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. 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.

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

6. The filtering 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 the 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 terminal of the third resonator and the ground terminal; 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 all include surface acoustic wave resonators.

9. An electronic device, characterized in that, include: The filter circuit as described in any one of claims 1-8.

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