Filter circuit, radio frequency circuit and electronic equipment

Abstract

The embodiment of the utility model provides a filter circuit, a radio frequency circuit and electronic equipment, the circuit comprises a controller, a voltage output module, a first inductor and a first variable capacitance diode, and the first inductor and the first variable capacitance diode are connected in series; the controller is used for changing the voltage between the two ends of the first variable capacitance diode by changing the voltage signal output by the voltage output module; when the voltage between the two ends of the first variable capacitance diode is changed, the frequency band of the signal allowed by the filter circuit to pass is changed. According to the embodiment of the invention, the cost of the filter circuit can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a filter circuit, a radio frequency circuit and an electronic device. Background Art

[0002] At present, the downlink receiving circuit receives signals of different frequency bands through the antenna port, and filters them to the corresponding filters through the internal circuit to achieve accurate frequency selection. After accurate frequency selection, the signal is processed by the transceiver. However, all frequency bands require independent filters, which is costly. Utility Model Content

[0003] The embodiments of the present application provide a filter circuit, a radio frequency circuit and an electronic device, which can reduce the cost of the filter circuit.

[0004] A first aspect of an embodiment of the present application provides a filter circuit, including a controller, a voltage output module, a first inductor and a first varactor diode, wherein the first inductor is connected in series with the first varactor diode;

[0005] The controller is used to change the voltage between the two ends of the first varactor diode by changing the voltage signal output by the voltage output module;

[0006] When the voltage between the two ends of the first varactor changes, the frequency band of the signal allowed to pass by the filtering circuit changes.

[0007] Optionally, the filtering circuit further includes a first capacitor, and the first inductor, the first capacitor and the first varactor diode are connected in series.

[0008] Optionally, the filtering circuit further includes a second inductor and a second varactor diode, the second inductor being connected in series with the second varactor diode; the first combination circuit is connected in parallel with the second combination circuit, the first combination circuit includes a circuit in which the first inductor is connected in series with the first varactor diode, and the second combination circuit includes a circuit in which the second inductor is connected in series with the second varactor diode;

[0009] The controller is further used to change the voltage between the two ends of the second varactor diode by changing the voltage signal output by the voltage output module;

[0010] When the voltage between the two ends of the second varactor diode changes, the frequency band of the signal allowed to pass by the filter circuit changes.

[0011] Optionally, the filtering circuit further includes a second capacitor, and the second inductor, the second capacitor and the second varactor diode are connected in series.

[0012] Optionally, the filtering circuit also includes a first voltage output module and a second voltage output module, the voltage signal output by the first voltage output module is used to change the voltage between the two ends of the first varactor diode, and the voltage signal output by the second voltage output module is used to change the voltage between the two ends of the second varactor diode.

[0013] Optionally, the filtering circuit also includes a first resistor and a second resistor, the first end of the first resistor is connected to the first end of the first varactor diode, the second end of the first varactor diode is connected to the second end of the second varactor diode, the first end of the second varactor diode is connected to the first end of the second resistor, and the second end of the first resistor is connected to the second end of the second resistor and the output end of the voltage output module.

[0014] Optionally, the filtering circuit also includes a third capacitor and a fourth capacitor, the first end of the third capacitor is connected to the first end of the fourth capacitor and the output end of the voltage output module, and the second end of the third capacitor and the second end of the fourth capacitor are grounded.

[0015] Optionally, the filtering circuit also includes a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor and a ninth capacitor; the first end of the fifth capacitor is connected to the input end of the transceiver, the second end of the fifth capacitor is connected to the first end of the sixth capacitor, the first end of the eighth capacitor and the first end of the first inductor, the second end of the sixth capacitor is connected to the first end of the seventh capacitor, the first end of the ninth capacitor and the first end of the second inductor, the second end of the seventh capacitor is connected to the first end of the switching circuit, the second end of the switching circuit is connected to the antenna, and the second end of the eighth capacitor and the second end of the ninth capacitor are grounded.

[0016] Optionally, the controller is used to control the voltage output module to output a first voltage signal to control the resonant frequency of the filter circuit to be a first resonant frequency, so that the filter circuit allows signals in a first frequency band to pass through;

[0017] The controller is further used to control the voltage output module to output a second voltage signal to control the resonant frequency of the filter circuit to be a second resonant frequency, so that the filter circuit allows signals in a second frequency band to pass through.

[0018] A second aspect of an embodiment of the present application provides a radio frequency circuit, comprising a filtering circuit, a controller, a transceiver, a switching circuit and an antenna as described in any one of the first aspects of the embodiments of the present application, wherein the transceiver forms a receiving path or a transmitting path through the filtering circuit, the switching circuit and the antenna, and the controller is used to process a signal received by the receiving path or to control a signal transmitted by the transmitting path.

[0019] A third aspect of the embodiments of the present application provides an electronic device, comprising the radio frequency circuit described in any one of the second aspects of the embodiments of the present application.

[0020] The filter circuit of the embodiment of the present application includes a controller, a voltage output module, a first inductor and a first varactor diode, wherein the first inductor is connected in series with the first varactor diode; the controller changes the voltage between the two ends of the first varactor diode by changing the voltage signal output by the voltage output module; when the voltage between the two ends of the first varactor diode changes, the frequency band of the signal allowed to pass by the filter circuit changes. In the embodiment of the present application, the frequency band of the signal allowed to pass by the filter circuit can be changed by only changing the voltage between the two ends of the first varactor diode, so that the filter circuit can be compatible with the filtering function of signals of at least two different frequency bands, and there is no need to use different independent filters for signals of different frequency bands, thereby reducing the cost of the filter circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 is a structural schematic diagram of a filter circuit provided in an embodiment of the present application;

[0023] Figure 2 is a structural schematic diagram of another filter circuit provided in an embodiment of the present application;

[0024] Figure 3 is a structural schematic diagram of another filter circuit provided in an embodiment of the present application;

[0025] Figure 4 is a structural schematic diagram of another filter circuit provided in an embodiment of the present application;

[0026] Figure 5 is a structural schematic diagram of another filter circuit provided in an embodiment of the present application;

[0027] Figure 6 is a structural schematic diagram of another filter circuit provided in an embodiment of the present application;

[0028] Figure 7 It is a structural schematic diagram of a radio frequency circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0030] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, products or devices.

[0031] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0032] See also Figure 1 , Figure 1 Schematic diagram of a filter circuit provided by an embodiment of the present application. Figure 1 As shown, the filter circuit may include a controller, a voltage output module, a first inductor L1 and a first varactor diode D1, wherein the first inductor L1 and the first varactor diode D1 are connected in series;

[0033] The controller is used to change the voltage VD1 between the two ends of the first varactor diode D1 by changing the voltage signal output by the voltage output module;

[0034] When the voltage VD1 between the two ends of the first varactor diode D1 changes, the frequency band of the signal allowed to pass by the filtering circuit changes.

[0035] In the embodiment of the present application, the varactor diode may include a PN junction ( Figure 1 (not shown in the figure), the varactor diode can change the PN junction capacitance by changing the reverse bias voltage on its PN junction, thereby changing the capacitance of the varactor diode. The capacitance of the varactor diode is negatively correlated with the reverse bias voltage on the PN junction of the capacitor diode. That is, the higher the reverse bias voltage, the less the capacitance. Generally speaking, the relationship between reverse bias voltage and capacitance is nonlinear.

[0036] Since the models of varactor diodes are different, the capacitance value ranges of varactor diodes are also different, which will lead to different frequency band tuning ranges. In the embodiment of the present application, a varactor diode with a large capacitance value range can be selected to be compatible with filtering in a wider range of frequency bands. Optionally, a suitable varactor diode model can also be selected according to different frequency bands.

[0037] The controller can control the voltage output module to output a voltage signal. For example, the controller can output a digital signal to the voltage output module, and the voltage output module outputs an analog voltage signal according to the digital signal to control the voltage VD1 between the two ends of the first varactor diode D1, thereby controlling the resonant frequency of the filter circuit.

[0038] The controller may be a central processing unit (CPU).

[0039] The voltage output module is used to output an analog voltage signal to change the voltage VD1 between the two ends of the first varactor diode D1. Exemplarily, the voltage output module can be a digital-to-analog conversion module, which can be a module that converts a digital signal into an analog signal, such as a digital to analog converter (DAC).

[0040] like Figure 1 As shown, the first inductor L1 is connected in series with the first varactor diode D1.

[0041] Optionally, the voltage VD1 between the two ends of the first varactor diode D1 may also be controlled by an adjustable power supply.

[0042] Changing the voltage VD1 between the two ends of the first varactor diode D1 can change the capacitance of the first varactor diode D1, thereby changing the resonant frequency of the filter circuit, and further changing the frequency band of the signal allowed to pass by the filter circuit. The resonant frequency of the filter circuit can be calculated according to the following formula:

[0043] f=1 / (2*π*√L1*C1);

[0044] Wherein, f is the resonant frequency, L1 is the inductance value of the first inductor L1, and C1 is the capacitance value of the first variable capacitance diode D1.

[0045] The filter circuit may be a low-pass filter or a high-pass filter. When the filter circuit is a low-pass filter, signals in a frequency band lower than f may be allowed to pass through the filter circuit. When the filter circuit is a high-pass filter, signals in a frequency band higher than f may be allowed to pass through the filter circuit.

[0046] In the embodiment of the present application, the frequency band of the signal allowed to pass by the filter circuit can be changed by only changing the voltage between the two ends of the first varactor diode, so that the filter circuit can be compatible with the filtering function of at least two signals of different frequency bands. There is no need to use different independent filters for signals of different frequency bands, thereby reducing the cost of the filter circuit.

[0047] See also Figure 2 , Figure 2 is a schematic diagram of the structure of another filter circuit provided in an embodiment of the present application. Figure 2 As shown, in Figure 1 On the basis of Figure 2 The filter circuit further includes a first capacitor C1, and the first inductor L1, the first capacitor C1 and the first variable capacitance diode D1 are connected in series.

[0048] Changing the voltage VD1 between the two ends of the first varactor diode D1 can change the capacitance of the first varactor diode D1, thereby changing the resonant frequency of the filter circuit, and further changing the frequency band of the signal allowed to pass by the filter circuit. The resonant frequency of the filter circuit can be calculated according to the following formula:

[0049] f=1 / (2*π*√L1*C 1’ );

[0050] Where, f is the resonant frequency, L1 is the inductance of the first inductor L1, C 1’ is the capacitance value of the first varactor diode D1 and the first capacitor C1 connected in series.

[0051] The filter circuit may be a low-pass filter or a high-pass filter. When the filter circuit is a low-pass filter, signals in a frequency band lower than f may be allowed to pass through the filter circuit. When the filter circuit is a high-pass filter, signals in a frequency band higher than f may be allowed to pass through the filter circuit.

[0052] The embodiment of the present application adds the first capacitor C1 to allow signals in a higher frequency band to pass through the filter circuit, thereby increasing the filtering range of the filter.

[0053] See also Figure 3 , Figure 3 is a schematic diagram of the structure of another filter circuit provided in an embodiment of the present application. Figure 3 As shown, in Figure 2 On the basis of Figure 2 The filter circuit further includes a second inductor L2 and a second varactor diode D2, wherein the second inductor L2 and the second varactor diode D2 are connected in series.

[0054] When the voltage between the two ends of the second varactor diode D2 changes, the frequency band of the signal allowed to pass by the filter circuit changes.

[0055] The voltage VD2 between the two ends of the second varactor diode D2 can also be controlled by an adjustable power supply.

[0056] In the embodiment of the present application, the frequency band of the signal allowed to pass by the filter circuit can be changed by only changing the voltage between the two ends of the second varactor diode, so that the filter circuit can be compatible with the filtering function of at least two signals of different frequency bands. There is no need to use different independent filters for signals of different frequency bands, thereby reducing the cost of the filter circuit.

[0057] Optional, such as Figure 3 As shown, the filtering circuit further includes a second capacitor, and the second inductor L2, the second capacitor C2 and the second varactor diode D2 are connected in series.

[0058] The filtering circuit may be a bandpass filter.

[0059] The filter circuit includes a first filter module and a second filter module. The first inductor L1, the first capacitor C1 and the first varactor D1 can constitute the first filter module, and the second inductor L2, the second capacitor C2 and the second varactor D2 can constitute the second filter module.

[0060] Changing the voltage VD1 between the two ends of the first varactor diode D1 can change the capacitance of the first varactor diode D1, thereby changing the resonant frequency of the first filter module, and further changing the frequency band of the signal allowed to pass by the first filter module. The resonant frequency of the first filter module can be calculated according to the following formula:

[0061] f1=1 / (2*π*√L1*C 1’ );

[0062] Wherein, f1 is the resonant frequency of the first filter module, L1 is the inductance value of the first inductor L1, C 1’ is the capacitance value of the first varactor diode D1 and the first capacitor C1 connected in series.

[0063] Changing the voltage VD2 between the two ends of the second varactor diode D2 can change the capacitance of the second varactor diode D2, thereby changing the resonant frequency of the second filter module, and further changing the frequency band of the signal allowed to pass by the second filter module. The resonant frequency of the second filter module can be calculated according to the following formula:

[0064] f2=1 / (2*π*√L2*C 2’ );

[0065] Wherein, f2 is the resonant frequency of the second filter module, L2 is the inductance value of the second inductor L2, C 2’ is the capacitance value of the second varactor diode D2 and the second capacitor C2 connected in series.

[0066] Among them, one of the first filter module and the second filter module is a low-pass filter and the other is a high-pass filter, and the two form a band-pass filter. When the resonant frequency f1 of the first filter module is less than the resonant frequency f2 of the second filter module, the first filter module is a high-pass filter, and the second filter module is a low-pass filter. The frequency band of the signal allowed to pass by the filter circuit is (f1, f2). When the resonant frequency f1 of the first filter module is greater than the resonant frequency f2 of the second filter module, the first filter module is a low-pass filter, and the second filter module is a high-pass filter. The frequency band of the signal allowed to pass by the filter circuit is (f2, f1).

[0067] Exemplarily, if the resonant frequency f1 of the first filter module is less than the resonant frequency f2 of the second filter module, and the signal frequency band that needs to pass through the filter circuit is 800Mhz~850Mhz, the voltage across the first varactor diode D1 can be adjusted so that the resonant frequency f1 of the first filter module is equal to 800Mhz, and the voltage across the second varactor diode D2 can be adjusted so that the resonant frequency f2 of the second filter module is equal to 850Mhz.

[0068] Optionally, the filtering circuit further includes a third filtering module, the third filtering module includes a third inductor and a third varactor diode, and the third inductor and the third varactor diode are connected in series.

[0069] The first filter module and the second filter module can realize first-order filtering, and the third filter module can realize second-order filtering, thereby avoiding interference from second harmonics.

[0070] Optionally, the filtering circuit further includes a fourth filtering module, the fourth filtering module includes a fourth inductor and a fourth varactor diode, and the fourth inductor and the fourth varactor diode are connected in series.

[0071] The third filtering module and the fourth filtering module can realize second-order filtering and avoid interference from second harmonics.

[0072] It should be noted that the third filter module and the fourth filter module are similar to the first filter module and the second filter module. The specific structures of the third filter module and the fourth filter module are not shown in the figure. Figure 3The connection method of the first filtering module (the first inductor L1, the first capacitor C1 and the first varactor diode D1 constitute the first filtering module) and the second filtering module (the second inductor L2, the second capacitor C2 and the second varactor diode D2 constitute the second filtering module) will not be repeated here.

[0073] Optionally, when the voltage output module is a digital-to-analog conversion module, the voltage signal output by the digital-to-analog conversion module is used to change the voltage between two ends of the first varactor diode and the voltage between two ends of the second varactor diode.

[0074] The digital-to-analog conversion module can receive a digital signal and output an analog voltage signal, wherein the analog voltage signal is used to change the voltage between the two ends of the first varactor diode and the voltage between the two ends of the second varactor diode.

[0075] In one embodiment, the output end of the digital-to-analog conversion module may be directly connected to the cathode of the first varactor diode and the cathode of the second varactor diode.

[0076] In another embodiment, the output end of the digital-to-analog conversion module can be connected to the cathode of the first varactor diode through a resistor, and connected to the cathode of the second varactor diode through another resistor, wherein the resistor can play the role of current limiting and filtering.

[0077] The embodiment of the present application uses a digital-to-analog conversion module to adjust the voltage between the two ends of the first varactor diode and the voltage between the two ends of the second varactor diode, which can reduce the number of digital-to-analog conversion modules required to adjust the voltage between the two ends of the varactor diode, thereby reducing costs.

[0078] Optionally, the filtering circuit also includes a first digital-to-analog conversion module and a second digital-to-analog conversion module, the voltage signal output by the first digital-to-analog conversion module is used to change the voltage between the two ends of the first varactor diode, and the voltage signal output by the second digital-to-analog conversion module is used to change the voltage between the two ends of the second varactor diode.

[0079] The embodiment of the present application adopts two digital-to-analog conversion modules, which can respectively adjust the voltage between the two ends of the first varactor diode and the voltage between the two ends of the second varactor diode, independently and flexibly adjust the voltages at the two ends of the two varactor diodes, and thus flexibly adjust the resonant frequencies of the two filter modules.

[0080] See also Figure 4 , Figure 4 is a schematic diagram of the structure of another filter circuit provided in an embodiment of the present application. Figure 4 As shown, in Figure 3 On the basis of Figure 4The filtering circuit also includes a first resistor R1 and a second resistor R2, wherein the first end of the first resistor R1 is connected to the first end of the first varactor diode D1, the second end of the first varactor diode D1 is connected to the second end of the second varactor diode D2, the first end of the second varactor diode D2 is connected to the first end of the second resistor R2, and the second end of the first resistor R1 is connected to the second end of the second resistor R2 and the output end of the digital-to-analog conversion module. Figure 4 In the example, the voltage output module is a digital-to-analog conversion module, which is connected to the first end of the first variable capacitance diode D1 through the first resistor R1 and connected to the first end of the second variable capacitance diode D2 through the second resistor R2.

[0081] Figure 4 In the embodiment, the first end of the first varactor diode D1 is the cathode of the first varactor diode D1, and the second end of the first varactor diode D1 is the anode of the first varactor diode D1. The first end of the second varactor diode D2 is the cathode of the second varactor diode D2, and the second end of the second varactor diode D2 is the anode of the second varactor diode D2.

[0082] Figure 4 The second end of the first varactor D1 and the second end of the second varactor D2 are connected to an equipotential point, that is, the second end of the first varactor D1 is connected to the second end of the second varactor D2. An equipotential point is a point with the same voltage. Exemplarily, the equipotential point may be a ground point.

[0083] The first resistor R1 and the second resistor R2 can play the role of current limiting and filtering.

[0084] See also Figure 5 , Figure 5 is a schematic diagram of the structure of another filter circuit provided in an embodiment of the present application. Figure 5 As shown, in Figure 4 On the basis of Figure 5 The filtering circuit also includes a third capacitor C3 and a fourth capacitor C4, wherein a first end of the third capacitor C3 is connected to a first end of the fourth capacitor C4 and an output end of the digital-to-analog conversion module, and a second end of the third capacitor C3 and a second end of the fourth capacitor C4 are grounded.

[0085] Among them, the third capacitor C3 and the fourth capacitor C4 can play the role of voltage stabilization and filtering, and can stabilize the voltage at both ends of the first varactor diode D1 and the voltage at both ends of the second varactor diode D2, avoid the voltage at both ends of the first varactor diode D1 and the voltage at both ends of the second varactor diode D2 from drastic fluctuations, ensure the stability of the frequency band of the bandpass filtering of the filtering circuit, thereby improving the filtering effect of the filtering circuit.

[0086] See also Figure 6 , Figure 6 is a schematic diagram of the structure of another filter circuit provided in an embodiment of the present application. Figure 6 As shown, in Figure 5 On the basis of Figure 6 The filtering circuit also includes a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8 and a ninth capacitor C9; the first end of the fifth capacitor C5 is connected to the input end of the transceiver, the second end of the fifth capacitor C5 is connected to the first end of the sixth capacitor C6, the first end of the eighth capacitor C8 and the first end of the first inductor L1, the second end of the sixth capacitor C6 is connected to the first end of the seventh capacitor C7, the first end of the ninth capacitor C9 and the first end of the second inductor L2, the second end of the seventh capacitor C7 is connected to the first end of the switching circuit, the second end of the switching circuit is connected to the antenna, and the second end of the eighth capacitor C8 and the second end of the ninth capacitor C9 are grounded.

[0087] Among them, the fifth capacitor C5, the sixth capacitor C6, the seventh capacitor C7, the eighth capacitor C8 and the ninth capacitor C9 can form a matching circuit for impedance matching.

[0088] See also Figure 7 , Figure 7 Schematic diagram of a radio frequency circuit provided in an embodiment of the present application. Figure 7 As shown, the radio frequency circuit includes Figure 6 The filter circuit also includes a controller, a transceiver, a switch circuit and an antenna. The transceiver forms a receiving path or a transmitting path through the filter circuit, the switch circuit and the antenna. The controller is used to process the signal received by the receiving path or to control the signal transmitted by the transmitting path.

[0089] When the transceiver forms a receiving path through the filter circuit, the switch circuit and the antenna, and the controller detects that a signal of a set frequency band needs to be received, the controller is used to control the digital-to-analog conversion module to output a voltage signal to control the resonant frequency of the filter circuit so that the filter circuit allows the signal of the set frequency band to pass through. The signal received by the antenna is filtered by the filter circuit after passing through the switch circuit, and the signal of the set frequency band is allowed to pass through. The transceiver processes the signal passing through the filter circuit (for example, performs demodulation processing). The signal received by the antenna may be a discontinuous reception (DRX) signal.

[0090] The controller can control the digital-to-analog conversion module to output a voltage signal. For example, the controller can output a digital signal to the digital-to-analog conversion module, and the digital-to-analog conversion module outputs an analog voltage signal according to the digital signal to control the resonant frequency of the filter circuit.

[0091] The controller may be a central processing unit (CPU).

[0092] The transceiver can receive wireless signals and can also send wireless signals. Exemplarily, the transceiver can be a wireless transmitter / receiver (WTR).

[0093] When the transceiver forms a transmission path through the filter circuit, the switch circuit and the antenna, and the controller detects that a signal of a set frequency band needs to be transmitted, the controller is used to control the digital-to-analog conversion module to output a voltage signal to control the resonant frequency of the filter circuit so that the filter circuit allows the signal of the set frequency band to pass. After the transceiver processes the transmitted signal (for example, performs modulation processing), it is filtered by the filter circuit, allowing the signal of the set frequency band to pass, and then converted into electromagnetic waves through the antenna and sent out.

[0094] Exemplarily, when the filter circuit is used to allow signals in a first frequency band (for example, a B5 frequency band) to pass through, the controller is used to control the digital-to-analog conversion module to output a first voltage signal to control the resonant frequency of the filter circuit to be a first resonant frequency, and the filter circuit allows signals in the first frequency band to pass through;

[0095] When the filter circuit is used to allow signals in a second frequency band (for example, the B8 frequency band) to pass through, the controller is used to control the digital-to-analog conversion module to output a second voltage signal to control the resonant frequency of the filter circuit to be a second resonant frequency, and the filter circuit allows signals in the second frequency band to pass through.

[0096] The controller can control the digital-to-analog conversion module to output different voltage signals, thereby controlling the filter circuit to be at different resonant frequencies, thereby having different filtering effects, thereby reducing the cost of the filter circuit.

[0097] An embodiment of the present application also provides an electronic device, which may include the above-mentioned radio frequency circuit.

[0098] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0099] In the several embodiments provided in this application, it should be understood that the disclosed filter circuit and charging pile can be implemented in other ways. For example, the filter circuit embodiments described above are only schematic, and the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

Claims

1. A filter circuit, characterized in that: It includes a controller, a voltage output module, a first inductor and a first varactor diode, wherein the first inductor is connected in series with the first varactor diode; The controller is used to change the voltage between the two ends of the first varactor diode by changing the voltage signal output by the voltage output module; When the voltage between the two ends of the first varactor changes, the frequency band of the signal allowed to pass by the filtering circuit changes.

2. The filter circuit according to claim 1, characterized in that: The filter circuit further includes a first capacitor, and the first inductor, the first capacitor and the first varactor diode are connected in series.

3. The filter circuit according to claim 2, characterized in that: The filter circuit further includes a second inductor and a second varactor diode, the second inductor being connected in series with the second varactor diode; a first combination circuit is connected in parallel with a second combination circuit, the first combination circuit includes a circuit in which the first inductor is connected in series with the first varactor diode, and the second combination circuit includes a circuit in which the second inductor is connected in series with the second varactor diode; The controller is further used to change the voltage between the two ends of the second varactor diode by changing the voltage signal output by the voltage output module; When the voltage between the two ends of the second varactor diode changes, the frequency band of the signal allowed to pass by the filter circuit changes.

4. The filter circuit according to claim 3, characterized in that: The filter circuit further includes a second capacitor, and the second inductor, the second capacitor and the second varactor diode are connected in series.

5. The filter circuit according to claim 4, characterized in that: The filtering circuit also includes a first resistor and a second resistor, wherein the first end of the first resistor is connected to the first end of the first varactor diode, the second end of the first varactor diode is connected to the second end of the second varactor diode, the first end of the second varactor diode is connected to the first end of the second resistor, and the second end of the first resistor is connected to the second end of the second resistor and the output end of the voltage output module.

6. The filter circuit according to claim 5, characterized in that: The filter circuit also includes a third capacitor and a fourth capacitor, the first end of the third capacitor is connected to the first end of the fourth capacitor and the output end of the voltage output module, and the second end of the third capacitor and the second end of the fourth capacitor are grounded.

7. The filter circuit according to claim 6, characterized in that: The filtering circuit also includes a fifth capacitor, a sixth capacitor, a seventh capacitor, an eighth capacitor and a ninth capacitor; the first end of the fifth capacitor is connected to the input end of the transceiver, the second end of the fifth capacitor is connected to the first end of the sixth capacitor, the first end of the eighth capacitor and the first end of the first inductor, the second end of the sixth capacitor is connected to the first end of the seventh capacitor, the first end of the ninth capacitor and the first end of the second inductor, the second end of the seventh capacitor is connected to the first end of the switching circuit, the second end of the switching circuit is connected to the antenna, and the second end of the eighth capacitor and the second end of the ninth capacitor are grounded.

8. The filter circuit according to any one of claims 1 to 7, characterized in that: The controller is used to control the voltage output module to output a first voltage signal to control the resonant frequency of the filter circuit to be a first resonant frequency, so that the filter circuit allows signals in a first frequency band to pass through; The controller is further used to control the voltage output module to output a second voltage signal to control the resonant frequency of the filter circuit to be a second resonant frequency, so that the filter circuit allows signals in a second frequency band to pass through.

9. A radio frequency circuit, characterized in that: It comprises the filtering circuit, controller, transceiver, switching circuit and antenna as described in any one of claims 1 to 8, wherein the transceiver forms a receiving path or a transmitting path through the filtering circuit, the switching circuit and the antenna, and the controller is used to process the signal received by the receiving path or to control the signal transmitted by the transmitting path.

10. An electronic device, characterized in that: Comprising the radio frequency circuit as claimed in claim 9.

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