Filter driving circuit, YIG filtering device, and tuning method

Abstract

The present application discloses a filter driving circuit, a YIG filtering device, and a tuning method, the filter driving circuit comprising an adjustable filter circuit and a voltage / current conversion circuit. The adjustable filter circuit is used for filtering a preset driving control signal according to a preset filter parameter, and outputting to the voltage / current conversion circuit a driving first control signal acquired from filtering, the filter parameter being related to a tuning rate of a YIG filter. The voltage / current conversion circuit is used for outputting a control voltage signal on the basis of the driving first control signal, so as to adjust a driving current signal of the YIG filter by means of the control voltage signal. Because a tuning parameter of the driving control signal is set on the basis of the tuning rate during operation of the YIG filter to specifically filter out control voltage noise of the driving control signal, the YIG filter can achieve optimal additional phase noise while having a fast tuning rate.

Description

Filter drive circuit, YIG filter device and tuning method Technical Field

[0001] This application relates to the field of electronic measuring instruments and meters, specifically to a filter drive circuit, a YIG filter device, and a tuning method. Background Technology

[0002] YIG filters are tunable filters that adjust the tuning rate by tuning the current flowing through the filter coil. Due to their very high Q value and selectivity, as well as their very wide tuning range, they are widely used in various microwave and millimeter-wave receivers. The tuning sensitivity of YIG filters is typically tens of MHz / mA, which is extremely high. Therefore, they are also very sensitive to noise in the control signal, requiring the noise of the control current to be controlled to the μA or even nA level. Thus, the design of the filter drive circuit for YIG filters must pay particular attention to reducing the filter's additional phase noise while meeting the high tuning rate requirements.

[0003] In existing technologies, the filter drive circuit of a YIG filter typically includes a DAC circuit and a voltage / current conversion circuit, with the DAC circuit outputting a drive control signal U. YIG A voltage / current conversion circuit is provided, which is connected to a YIG filter. Please refer to Figure 1 for a schematic diagram of the YIG filter circuit connection. The current / voltage conversion circuit 20 of the filter drive circuit is connected to the filter equivalent circuit 10, which is the equivalent circuit of the resonant coil of the YIG filter. The voltage / current conversion circuit includes a conversion amplifier U0, a first resistor R1 (sampling resistor), and a first switch Q0. The first terminal of the first switch Q0 is connected to the filter equivalent circuit 10, the control terminal of the first switch Q0 is connected to the output terminal of the conversion amplifier U0, and the second terminal of the first switch Q0 is connected to the negative input terminal of the conversion amplifier U0. The positive input terminal of the conversion amplifier U0 is connected to the DAC circuit to drive the control signal U. YIG The input is the first resistor R1. One end of R1 is grounded, and the other end is connected to the negative input terminal of the conversion amplifier U0. In the voltage / current conversion circuit, the conversion amplifier U0 compares the control signal with the voltage across the sampling resistor, and then outputs a voltage to control the on-resistance of the first switching transistor Q0 (MOS transistor). Finally, the voltage across the sampling resistor equals the control signal voltage, at which point: V = I YIG *Rsample;

[0004] Where V is the control voltage, I YIG Rsample represents the current flowing through the sampling resistor, i.e., the current flowing through the YIG filter coil. Rsample is the resistance value of the sampling resistor.

[0005] The control voltage signal V output by a DAC is typically a precision control voltage to accurately control a YIG filter. While the DAC output control voltage signal V can achieve a fast rate of change and fine adjustment steps, it struggles to achieve very low noise, leading to increased additional phase noise in the YIG filter and consequently deteriorating the phase noise of the output signal. For example, to achieve fast tuning of the YIG filter, a high-speed DAC is required. However, high-speed DACs usually have higher output voltage noise, failing to meet the low-noise requirements of the YIG filter, especially low-frequency noise (≤100kHz), which will directly modulate the input signal through the YIG filter, worsening the phase noise of the input signal. Summary of the Invention

[0006] The technical problem this application aims to solve is how to effectively reduce the additional phase noise of YIG filters through reasonable circuit design and tuning methods, so as to meet the requirements of low phase noise and high tuning rate application scenarios.

[0007] According to a first aspect, one embodiment provides a filter driving circuit for providing a drive current signal to a YIG filter, the filter driving circuit including an adjustable filter circuit and a voltage / current conversion circuit;

[0008] The adjustable filter circuit is connected to the voltage / current conversion circuit. The adjustable filter circuit is used to filter a preset drive control signal according to a preset filter parameter, and output the filtered first drive control signal to the voltage / current conversion circuit. The preset filter parameter is related to the tuning rate of the YIG filter.

[0009] The voltage / current conversion circuit is connected to the YIG filter and is used to output a control voltage signal according to the first drive control signal, and to adjust the drive current signal of the YIG filter through the control voltage signal.

[0010] In one embodiment, the adjustable filter circuit includes a charge / discharge module, a filter module connected to the charge / discharge module, and a switch module connected to the charge / discharge module and the filter module.

[0011] The filtering module includes at least two filter capacitors with different capacitance values;

[0012] The switching module is used to electrically connect the charging / discharging module to the filter capacitor in the filtering module via a switching device;

[0013] The charging and discharging module is used to charge and discharge the filter capacitor of the filtering module.

[0014] The filtering module is also used to filter the drive control signal through the filter capacitor after charging and discharging.

[0015] In one embodiment, the charging and discharging module includes a first amplifier U11 and a second amplifier U12;

[0016] The positive input terminals of the first amplifier U11 and the second amplifier U12 are electrically connected and used as inputs for the drive control signal;

[0017] The negative input terminal and output terminal of the first amplifier U11 are electrically connected, and are also connected to the switching module;

[0018] The negative input terminal and output terminal of the second amplifier U12 are electrically connected, and it is also connected to the filter module.

[0019] In one embodiment, the filtering module includes a filtering element and at least two filtering capacitors, and each filtering capacitor is connected to a capacitor switch.

[0020] The filter element includes a first component connection terminal and a second component connection terminal. The first component connection terminal of the filter element is electrically connected to the output terminal of the second amplifier U12, and the second component connection terminal of the filter element is used to output the driving first control signal.

[0021] Each of the filter capacitors is connected in series with one of the capacitor switches, one end of the series connection is connected to the second element connection terminal of the filter element, and the other end of the series connection is grounded.

[0022] The filtering element is either a filter resistor R30 or a filter inductor L1.

[0023] In one embodiment, the switching device of the switching module includes a first switch S21 and a capacitor connection switch;

[0024] The two ends of the first switch S21 are respectively connected to the first element connection end and the second element connection end of the filter element;

[0025] One end of the capacitor connection switch is electrically connected to the output terminal of the first amplifier U11, and the other end is connected to the second element connection terminal of the filter element.

[0026] In one embodiment, the switching device of the switching module includes a first switch S21 and a capacitor connection switch having the same number as the filter capacitors;

[0027] The two ends of the first switch S21 are respectively connected to the first element connection end and the second element connection end of the filter element;

[0028] One end of the capacitor connection switch is electrically connected to the output terminal of the first amplifier U11, and the other end is electrically connected to the non-grounded terminal of one of the filter capacitors; wherein, each capacitor connection switch is connected to a different filter capacitor.

[0029] In one embodiment, the voltage / current conversion circuit includes a conversion amplifier U0, a first resistor R1, and a first switching transistor Q0;

[0030] The first terminal of the first switch Q0 is connected to the control output terminal of the YIG filter, the control terminal of the first switch Q0 is connected to the output terminal of the conversion amplifier U0, and the second terminal of the first switch Q0 is electrically connected to the negative input terminal of the conversion amplifier U0.

[0031] The positive input terminal of the conversion amplifier U0 is connected to the adjustable filter circuit and is used as the input of the driving first control signal;

[0032] One end of the first resistor R1 is grounded, and the other end is connected to the negative input terminal of the conversion amplifier U0;

[0033] The voltage / current conversion circuit also includes a second resistor R2, which is connected between the negative input terminal of the conversion amplifier U0 and the second terminal of the first switching transistor Q0.

[0034] In one embodiment, the voltage / current conversion circuit further includes a third resistor R3 and a first capacitor C21; the third resistor R3 and the first capacitor C21 are connected in parallel, and the parallel connection is between the output terminal of the conversion amplifier U0 and the control electrode of the first switching transistor Q0.

[0035] And / or, the voltage / current conversion circuit further includes a fourth resistor R4 and a second capacitor C22; the fourth resistor R4 and the second capacitor C22 are connected in series and then connected between the control output terminal and the operating power input terminal of the YIG filter.

[0036] According to a second aspect, one embodiment provides a YIG filtering device, including a YIG filter and a filter driving circuit as described in the first aspect.

[0037] According to a third aspect, one embodiment provides a YIG filter tuning method applied to the YIG filter device as described in the second aspect, the YIG filter tuning method comprising:

[0038] Obtain the tuning rate required for the YIG filter to operate;

[0039] The tuning parameters are obtained based on the tuning rate.

[0040] The filter capacitor corresponding to the tuning parameters is charged and discharged according to the tuning parameters.

[0041] The drive control signal is filtered by a filter circuit including the filter capacitor for charging and discharging, and the filtered first drive control signal is given to a voltage / current conversion circuit so that the voltage / current conversion circuit can adjust the drive current signal of the YIG filter according to the first drive control signal.

[0042] In one embodiment, charging and discharging the filter capacitor corresponding to the tuning parameters according to the tuning parameters includes:

[0043] In the filter module of the adjustable filter circuit, a filter capacitor that matches the tuning parameters is selected as the filter capacitor to be charged and discharged.

[0044] The electrical connection between the charge / discharge module of the adjustable filter circuit and the filter capacitor to be charged / discharged is established through the switching device in the switching module of the adjustable filter circuit.

[0045] The charge / discharge module charges and discharges the filter capacitor to be charged or discharged, so as to charge or discharge the voltage of the filter capacitor to a preset value;

[0046] The switching device in the switching module connects the charged and discharged filter capacitor to the filter circuit to filter the drive control signal.

[0047] According to the YIG filter device of the above embodiment, the voltage of the drive control signal is set according to the center frequency of the YIG filter when it is working, and the tuning parameters of the drive control signal are set according to the required YIG filter tuning rate, so as to specifically filter out the control voltage noise of the drive control signal, so that the YIG filter can achieve the best additional phase noise. Attached Figure Description

[0048] Figure 1 shows a schematic diagram of the circuit connection of the YIG filter;

[0049] Figure 2 is a schematic diagram of the circuit connection of the filter driving circuit in one embodiment;

[0050] Figure 3 is a schematic diagram of the circuit connection of the adjustable filter circuit in another embodiment;

[0051] Figure 4 is a schematic diagram of the circuit connection of the filter drive circuit in another embodiment;

[0052] Figure 5 is a flowchart illustrating a YIG filter tuning method in one embodiment;

[0053] Figure 6 is a schematic diagram of the process of tuning a YIG filter in one embodiment. Detailed Implementation

[0054] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0055] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0056] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0057] In this embodiment, an adjustable filter circuit is provided between the DAC circuit and the voltage / current conversion circuit. The adjustable filter circuit outputs a drive control signal to filter out control voltage noise according to the center frequency of the YIG filter and the required tuning rate, so that the YIG filter can achieve the best additional phase noise.

[0058] Example 1:

[0059] Please refer to Figure 2, which is a schematic diagram of the circuit connection of the filter drive circuit in one embodiment. The filter drive circuit is used to provide a drive current signal to the YIG filter and includes an adjustable filter circuit 30 and a voltage / current conversion circuit 20. The adjustable filter circuit 30 is connected to the voltage / current conversion circuit 20, and the adjustable filter circuit 30 is used to apply a preset drive control signal U according to a preset filter parameter. YIG Filter the signal, and then obtain the first drive control signal U after filtering. Y0The output is given to voltage / current conversion circuit 20, and the preset filtering parameters are related to the tuning rate required by the YIG filter. Voltage / current conversion circuit 20 is connected to equivalent circuit 10 (YIG filter) and is used to drive the first control signal U. Y0 Adjust the drive current signal of the YIG filter.

[0060] In one embodiment, the adjustable filter circuit 30 includes a charging / discharging module 31, a filter module 33 connected to the charging / discharging module 31, and a switching module 32 connecting the charging / discharging module 31 and the filter module 33. The filter module 33 includes at least two filter capacitors with different capacitance values. The switching module 32 is used to electrically connect the charging / discharging module 31 and the filter capacitors in the filter module 33 via a switching device. The charging / discharging module 31 is used to charge and discharge the filter capacitors in the filter module 33. The filter module 33 is also used to control the drive signal U through the charged / discharged filter capacitors. YIG Filtering is performed to obtain the first control signal U. Y0 .

[0061] As shown in Figure 2, in one embodiment, the charging / discharging module 31 includes a first amplifier U11 and a second amplifier U12. The positive input terminals of the first amplifier U11 and the second amplifier U12 are electrically connected and used to drive the control signal U. YIG The negative input and output terminals of the first amplifier U11 are electrically connected and connected to the switching module 32. The negative input and output terminals of the second amplifier U12 are electrically connected and connected to the filtering module 33. In one embodiment, the filtering module 33 includes a filtering element and at least two filtering capacitors, and each filtering capacitor (filtering capacitor C30, filtering capacitor C31, filtering capacitor C32, and filtering capacitor C34) is connected to a capacitor switch (capacitor switch S30, capacitor switch S31, capacitor switch S32, and capacitor switch S33). The filtering element includes a first element connection terminal and a second element connection terminal. The first element connection terminal of the filtering element is electrically connected to the output terminal of the second amplifier U12, and the second element connection terminal of the filtering element is used to output a driving first control signal U. Y0 Each filter capacitor is connected in series with a capacitor switch. One end of the series connection is connected to the second element connection terminal of the filter element, and the other end is grounded.

[0062] In one embodiment, as shown in Figure 2, the filtering element is a filter resistor R30. Please refer to Figure 3, which is a circuit connection diagram of an adjustable filter circuit in another embodiment. In one embodiment, the filtering element is a filter inductor L1.

[0063] In one embodiment, the switching device of the switching module 32 includes a first switch S21 and a capacitor-connected switch S22. One end of the capacitor-connected switch S22 is electrically connected to the output terminal of the first amplifier U11, and the other end is connected to the second element connection terminal of the filter element in the filter module 33. The two ends of the first switch S21 are respectively connected to the first element connection terminal and the second element connection terminal of the filter element in the filter module 33.

[0064] Please refer to Figure 4, which is a schematic diagram of the circuit connection of the filter drive circuit in another embodiment. In one embodiment, the switching devices of the switching module 32 include a first switch S21 and capacitor connection switches (capacitor connection switches S22, S23, S24, and S25) in the same number as the filter capacitors (filter capacitors C30, C31, C32, and C34). The two ends of the first switch S21 are respectively connected to the first element connection terminal and the second element connection terminal of the filter element. One end of the capacitor connection switch is electrically connected to the output terminal of the first amplifier U11, and the other end is electrically connected to the non-grounded terminal of a filter capacitor. Each capacitor connection switch is connected to a different filter capacitor. As shown in Figure 4, one end of the capacitor connection switch S22 is electrically connected to the output terminal of the first amplifier U11, and the other end is electrically connected to the non-grounded terminal of the filter capacitor C30 (i.e., the series connection terminal of the filter capacitor C30 and the capacitor switch S30). One end of capacitor connection switch S23 is electrically connected to the output terminal of the first amplifier U11, and the other end is electrically connected to the non-grounded terminal of filter capacitor C31 (i.e., the series connection terminal of filter capacitor C31 and capacitor switch S31). One end of capacitor connection switch S24 is electrically connected to the output terminal of the first amplifier U11, and the other end is electrically connected to the non-grounded terminal of filter capacitor C32 (i.e., the series connection terminal of filter capacitor C32 and capacitor switch S32). One end of capacitor connection switch S25 is electrically connected to the output terminal of the first amplifier U11, and the other end is electrically connected to the non-grounded terminal of filter capacitor C33 (i.e., the series connection terminal of filter capacitor C33 and capacitor switch S33).

[0065] As shown in Figure 2, in one embodiment, the voltage / current conversion circuit 20 includes a conversion amplifier U0, a first resistor R1, and a first switch Q0. The first terminal of the first switch Q0 is connected to the control output terminal of the equivalent circuit 10 (YIG filter), the control terminal of the first switch Q0 is connected to the output terminal of the conversion amplifier U0, and the second terminal of the first switch Q0 is electrically connected to the negative input terminal of the conversion amplifier U0. The positive input terminal of the conversion amplifier U0 is connected to the adjustable filter circuit 30 and is used to drive the first control signal U. Y0The input is provided. One end of the first resistor R1 is grounded, and the other end is connected to the negative input terminal of the conversion amplifier U0. The voltage / current conversion circuit 20 also includes a second resistor R2, which is connected between the negative input terminal of the conversion amplifier U0 and the second terminal of the first switching transistor Q0. In one embodiment, the voltage / current conversion circuit 20 further includes a third resistor R3 and a first capacitor C21, which are connected in parallel and then connected between the output terminal of the conversion amplifier U0 and the control terminal of the first switching transistor Q0. In another embodiment, the voltage / current conversion circuit 20 further includes a fourth resistor R4 and a second capacitor C22. The fourth resistor R4 and the second capacitor C22 are connected in series and then connected between the control output terminal and the operating power input terminal of the equivalent circuit 10 (YIG filter).

[0066] One embodiment of this application also discloses a YIG filtering device, including a YIG filter and a filter driving circuit as described above.

[0067] Please refer to Figure 5, which is a flowchart illustrating a YIG filter tuning method in one embodiment. In another embodiment of this application, a YIG filter tuning method is also disclosed, applied to the YIG filter device described above. This YIG filter tuning method includes:

[0068] Step 101: Obtain the tuning rate.

[0069] Obtain the tuning rate required for the YIG filter to operate.

[0070] Step 102: Obtain the tuning parameters.

[0071] The tuning parameters are obtained based on the tuning rate.

[0072] Step 103: Charge and discharge the filter capacitor.

[0073] The filter capacitors corresponding to the tuning parameters are charged and discharged according to the tuning parameters, specifically including:

[0074] First, a filter capacitor with suitable tuning parameters is selected as the filter capacitor to be charged and discharged in the filter module of the adjustable filter circuit. Then, through the switching device in the switching module of the adjustable filter circuit, an electrical connection is established between the charging and discharging module of the adjustable filter circuit and the filter capacitor to be charged and discharged. Next, the charging and discharging module charges and discharges the filter capacitor to be charged and discharged to charge and discharge the voltage of the filter capacitor to a preset value. Finally, through the switching device in the switching module, the charged and discharged filter capacitor is connected to the filter circuit to filter the drive control signal.

[0075] Different capacitance values ​​of the filter capacitors correspond to different tuning parameters. When the preset voltage increases, and the original voltage value of the filter capacitor to be connected is lower than the preset voltage, the filter capacitor needs to be charged. When the preset voltage decreases, and the original voltage value of the filter capacitor to be connected is higher than the preset voltage, the filter capacitor needs to be discharged.

[0076] Step 104: Connect the charging filter capacitor to the filter circuit.

[0077] The drive control signal is filtered by a filter circuit that includes a charging filter capacitor, and the filtered first drive control signal is given to a voltage / current conversion circuit so that the voltage / current conversion circuit can adjust the drive current signal of the YIG filter according to the first drive control signal.

[0078] To facilitate understanding of the application of the YIG filter tuning method disclosed in this application, specific embodiments are described below, including:

[0079] Please refer to Figure 6, which is a schematic diagram of the tuning process of a YIG filter in one embodiment. The tuning process of the YIG filter using the filter driving circuit shown in Figure 2 includes:

[0080] Step 201: Obtain the YIG filter tuning command.

[0081] Once the user sends a tuning command for the YIG filter, the tuning process for the YIG filter begins.

[0082] Step 202: Select the filter capacitor.

[0083] Based on the tuning parameters, select a suitable filter capacitor from filter capacitors C30, C31, C32, and C33 as the filter capacitor to be charged and discharged.

[0084] Step 203: Close the filter switch of the selected filter capacitor.

[0085] After identifying the filter capacitor to be charged and discharged, close the filter switch connected to that filter capacitor. For example, if filter capacitor C30 is selected as the filter capacitor to be charged and discharged, close capacitor switch S30 to connect filter capacitor C30 to the circuit.

[0086] Step 204: Close the capacitor connection switch.

[0087] When capacitor connection switch S22 is closed (first switch S21 is open), the filter capacitor C30 is connected to the output terminal of the first amplifier U11 through the closed capacitor connection switch S22 and capacitor switch S30.

[0088] Step 205, set the drive control signal U YIGVoltage.

[0089] A drive control signal U with a preset voltage value is output through the DAC. YIG This is to charge and discharge the filter capacitor C30.

[0090] Step 206: Charge and discharge the filter capacitor to a preset value.

[0091] The filter capacitor C30 is charged and discharged for a preset fixed time to ensure that the voltage on the filter capacitor C30 reaches a preset threshold range. In one embodiment, the threshold range is ±1% of the preset value.

[0092] Step 207: Close the first switch and disconnect the capacitor connection switch.

[0093] When the voltage on the filter capacitor C30 reaches the preset threshold range, the first switch S21 is closed and the capacitor connection switch S22 is disconnected.

[0094] Step 208: Charge and discharge the filter capacitor to the preset value.

[0095] The second amplifier U12 continues to charge and discharge the filter capacitor C30, and charges and discharges the voltage of the filter capacitor C30 to a preset value.

[0096] Step 209: Disconnect the first switch.

[0097] Disconnect the first switch S21, thereby enabling the drive control signal U. YIG The first control signal U is output through the filtering module. Y0 Provide voltage / current conversion circuit 20.

[0098] Step 210: Determine if the tuning is complete.

[0099] Determine whether the tuning has ended based on the tuning results of the YIG filter; if not, repeat the steps.

[0100] ˉ

[0101] 204210.

[0102] As shown in Figure 2, the voltage / current conversion circuit 20 takes the feedback voltage from the sampling resistor R1 and compares it with the first control signal U that drives the input voltage / current conversion circuit 20. Y0 The voltage values ​​are compared, and then the output voltage of the conversion amplifier U0 controls the on-resistance of the first switching transistor Q0 (MOS transistor), ultimately achieving a balance between the feedback voltage on the sampling resistor R1 and the input voltage of the voltage / current conversion circuit 20. The first control signal U is driven by this process. Y0 As the control voltage V, I YIGLet Rsample be the current flowing through the sampling resistor R1, and Rsample be the resistance of the sampling resistor R1. Then, the input voltage value V and the current I flowing through the sampling resistor R1 are... YIG The relationship is V = I YIG *Rsample. The adjustable filter circuit 30 includes a charge / discharge module 31, a switching module 32, and a filter module 33. The charge / discharge module 31 includes a first amplifier U11 and a second amplifier U12, wherein the first amplifier U11 is a high-current operational amplifier and the second amplifier U12 is a low-noise operational amplifier. The first switch S21 of the switching module 32 is connected to a capacitor switch for switching between different charge / discharge paths. The capacitance values ​​of the filter capacitors C30, C31, C32, and C33 in the filter module 33 increase sequentially.

[0103] When the center frequency of the YIG filter remains constant, its tuning current also remains constant. Therefore, there is no need to worry about the tuning speed of the YIG filter. It is only necessary to adjust the cutoff frequency of the adjustable filter circuit to the lowest level. By disconnecting the first switch S21 and the capacitor connection switch, and selecting a suitable filter capacitor, the cutoff frequency can be reduced to 10Hz or even below 1Hz, thus filtering out the noise of the control voltage to the greatest extent. At this time, the YIG filter can achieve the best additional phase noise.

[0104] When the center frequency of the YIG filter needs to be tuned to another frequency, if the state of the adjustable filter network remains unchanged, only the first control signal U is adjusted. Y0 Because the cutoff frequency of the adjustable filter network is very low, the selected filter capacitor needs a very long charging and discharging time to reach the preset voltage. If the selected capacitor value is very large, this time can be more than 1 second.

[0105] The following uses the filter drive circuit shown in Figure 4 to illustrate how to shorten the charging and discharging time using the adjustable filter network of an adjustable filter circuit, specifically including:

[0106] In response to the user's tuning command for the YIG filter, perform the following operations:

[0107] Disconnect capacitor switches S30, S31, S32, and S33; close switch S21; close one of capacitor connection switches S22, S23, S24, and S25. The output of the first amplifier U11 is then directly connected to the selected filter capacitors (filter capacitors C30, C31, C32, and C33). Then, adjust the drive control signal U. YIG When the voltage value reaches the preset value, the first amplifier U11 will charge and discharge the filter capacitor, while the second amplifier U12 will charge and discharge according to the drive control signal U. YIGThe voltage value output corresponds to the first control signal U. Y0 The YIG filter center frequency is tuned to a preset frequency point; when it is charged and discharged to a preset voltage range, the capacitor connection switch is disconnected, and then the charged and discharged filter capacitor is connected to the filter network through capacitor switches (capacitor switch S30, capacitor switch S31, capacitor switch S32 and capacitor switch S33). At this time, the second amplifier U12 continues to charge and discharge the filter capacitor until the voltage on the filter capacitor reaches the preset voltage. Then, switch S21 is disconnected, so that the drive control signal U YIG The first control signal U is output after filtering by the filtering module. Y0 Provide voltage / current conversion circuit 20. Since the frequency tuning time of a typical YIG filter is several milliseconds to hundreds of milliseconds, this operation simultaneously charges and discharges the filter capacitor and tunes the YIG filter frequency, thus shortening the total tuning time.

[0108] In one embodiment, the first amplifier U11 and the second amplifier U12 are a high-current operational amplifier and a low-noise operational amplifier, respectively. Since the first amplifier U11 is a high-current operational amplifier and is directly connected to the filter capacitor to be charged and discharged, the charging and discharging process time of the filter capacitor can be greatly shortened.

[0109] The output voltages of the first amplifier U11 and the second amplifier U12 may have slight differences. If the filter capacitor is directly connected to the adjustable filter circuit after the first amplifier U11 has finished charging and discharging, there will be a voltage difference between the voltage on the charged filter capacitor and the output voltage of the first amplifier U11. The filter capacitor needs to be recharged and discharged until the voltage on the capacitor is equal to the output voltage of the first amplifier U11. At this time, due to the current limiting effect of the filter resistor R30, the charging and discharging time may be long. Therefore, when the voltage on the filter capacitor reaches within ±1% of the preset voltage, the switch between the output terminal of the second amplifier U12 and the filter capacitor (one of capacitor connection switches S22, S23, S24, and S25) is disconnected, while the first switch S21 and the switch between the output terminal of the first amplifier U11 and the corresponding filter capacitor (one of capacitor switches S30, S31, S32, and S33) are closed. The second amplifier U12 then charges the filter capacitor. When the voltage of the filter capacitor reaches the preset voltage, the first switch S21 is disconnected, and the filter resistor R30 is connected to the filter network. At this time, the filtering takes effect, which can improve the additional phase noise of the YIG filter.

[0110] If you need to continuously tune the center frequency of the YIG filter, repeat the above operation, but different preset voltages need to be set for different center frequencies.

[0111] If the center frequency tuning rate of the YIG filter is very fast (e.g., in high-speed frequency hopping communication), charging the filter capacitor using the first amplifier U11 cannot meet the tuning speed requirements. In this case, the capacitor in the filter module needs to be replaced with a smaller capacitance value (by switching the switching states of capacitor connection switches S22, S23, S24, S25, S30, S31, S32, and S33) to ensure a faster tuning rate. This increases the cutoff frequency of the tunable filter network, and the improvement effect of the YIG filter on the additional phase noise decreases as the cutoff frequency of the tunable filter network increases. In Figure 2, only four different capacitance values ​​of the filter capacitors are shown, corresponding to four tuning rates. If more tuning rate settings are needed, more filter switches and capacitors can be added.

[0112] In voltage-to-current conversion circuits, increasing the value of the sampling resistor R1 can reduce current noise while keeping the noise voltage constant. However, this comes at the cost of increased power consumption on the sampling resistor. Doubling the resistance of the sampling resistor reduces current noise by 50% and additional phase noise by 6dB, but also doubles the power consumption. YIG filter driving requires a large current, with a maximum current of 0.5-2A. Excessive power consumption on the sampling resistor can drastically increase costs, making it difficult to find resistors with sufficient rated power (sampling resistors require ultra-low temperature drift and high rated power, which are already scarce and expensive; further increasing the rated power would drastically increase costs). The technical solution in this application, however, can optimize the additional phase noise of the YIG filter with only a small increase in cost.

[0113] The filter driving circuit disclosed in this application includes an adjustable filter circuit and a voltage / current conversion circuit. The adjustable filter circuit filters a preset drive control signal according to preset filter parameters and outputs the filtered first drive control signal to the voltage / current conversion circuit. The filter parameters are related to the tuning rate of the YIG filter. The voltage / current conversion circuit outputs a control voltage signal based on the first drive control signal to adjust the drive current signal of the YIG filter. By setting the tuning parameters of the drive control signal according to the tuning rate of the YIG filter during operation, control voltage noise in the drive control signal is specifically filtered out, allowing the YIG filter to achieve optimal additional phase noise.

[0114] Those skilled in the art will understand that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, which may include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to achieve the above functions. For example, the program can be stored in the memory of a device, and when the program in the memory is executed by the processor, all or part of the above functions can be achieved. In addition, when all or part of the functions in the above embodiments are implemented by computer programs, the program can also be stored in a server, another computer, disk, optical disk, flash drive, or external hard drive, etc., and can be downloaded or copied to the memory of a local device, or the system of the local device can be updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be achieved.

[0115] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A filter driving circuit for providing a driving current signal to a YIG filter, characterized in that, Includes adjustable filter circuits and voltage / current conversion circuits; The adjustable filter circuit is connected to the voltage / current conversion circuit. The adjustable filter circuit is used to filter a preset drive control signal according to a preset filter parameter, and output the filtered first drive control signal to the voltage / current conversion circuit. The preset filter parameter is related to the tuning rate of the YIG filter. The voltage / current conversion circuit is connected to the YIG filter and is used to output a control voltage signal according to the first drive control signal, and to adjust the drive current signal of the YIG filter through the control voltage signal. The adjustable filter circuit includes a charge / discharge module, a filter module connected to the charge / discharge module, and a switch module connected to the charge / discharge module and the filter module. The filtering module includes at least two filter capacitors with different capacitance values; The switching module is used to electrically connect the charging / discharging module to the filter capacitor in the filtering module via a switching device; The charging and discharging module is used to charge and discharge the filter capacitor of the filtering module. The filtering module is also used to filter the drive control signal through the filter capacitor after charging and discharging; The charging and discharging module includes a first amplifier U11 and a second amplifier U12; The positive input terminals of the first amplifier U11 and the second amplifier U12 are electrically connected and used as inputs for the drive control signal; The negative input terminal and output terminal of the first amplifier U11 are electrically connected and connected to the switching module; the negative input terminal and output terminal of the second amplifier U12 are electrically connected and connected to the filtering module.

2. The filter drive circuit as described in claim 1, characterized in that, The filtering module includes a filtering element and at least two filtering capacitors, and each filtering capacitor is connected to a capacitor switch. The filter element includes a first component connection terminal and a second component connection terminal. The first component connection terminal of the filter element is electrically connected to the output terminal of the second amplifier U12, and the second component connection terminal of the filter element is used to output the driving first control signal. Each of the filter capacitors is connected in series with one of the capacitor switches, one end of the series connection is connected to the second element connection terminal of the filter element, and the other end of the series connection is grounded. The filtering element is either a filter resistor R30 or a filter inductor L1.

3. The filter drive circuit as described in claim 2, characterized in that, The switching devices of the switching module include a first switch S21 and a capacitor connection switch; The two ends of the first switch S21 are respectively connected to the first element connection end and the second element connection end of the filter element; One end of the capacitor connection switch is electrically connected to the output terminal of the first amplifier U11, and the other end is connected to the second element connection terminal of the filter element.

4. The filter drive circuit as described in claim 2, characterized in that, The switching devices of the switching module include a first switch S21 and a capacitor connection switch with the same number of filter capacitors. The two ends of the first switch S21 are respectively connected to the first element connection end and the second element connection end of the filter element; One end of the capacitor connection switch is electrically connected to the output terminal of the first amplifier U11, and the other end is electrically connected to the non-grounded terminal of one of the filter capacitors; wherein, each capacitor connection switch is connected to a different filter capacitor.

5. The filter drive circuit as described in claim 1, characterized in that, The voltage / current conversion circuit includes a conversion amplifier U0, a first resistor R1, and a first switching transistor Q0; The first terminal of the first switch Q0 is connected to the control output terminal of the YIG filter, the control terminal of the first switch Q0 is connected to the output terminal of the conversion amplifier U0, and the second terminal of the first switch Q0 is electrically connected to the negative input terminal of the conversion amplifier U0. The positive input terminal of the conversion amplifier U0 is connected to the adjustable filter circuit and is used as the input of the driving first control signal; One end of the first resistor R1 is grounded, and the other end is connected to the negative input terminal of the conversion amplifier U0; the voltage / current conversion circuit also includes a second resistor R2, which is connected between the negative input terminal of the conversion amplifier U0 and the second terminal of the first switching transistor Q0; And / or, the voltage / current conversion circuit further includes a third resistor R3 and a first capacitor C21; the third resistor R3 and the first capacitor C21 are connected in parallel, and the parallel connection is connected between the output terminal of the conversion amplifier U0 and the control electrode of the first switching transistor Q0; And / or, the voltage / current conversion circuit further includes a fourth resistor R4 and a second capacitor C22; the fourth resistor R4 and the second capacitor C22 are connected in series and then connected between the control output terminal and the operating power input terminal of the YIG filter.

6. A YIG filter device, characterized in that, It includes a YIG filter and a filter drive circuit as described in any one of claims 1 to 5.

7. A YIG filter tuning method, characterized in that, Applied to the YIG filter device as described in claim 6, the YIG filter tuning method includes: Obtain the tuning rate required for the YIG filter to operate; The tuning parameters are obtained based on the tuning rate. The filter capacitor corresponding to the tuning parameters is charged and discharged according to the tuning parameters. The drive control signal is filtered by a filter circuit including the filter capacitor for charging and discharging, and the filtered first drive control signal is given to a voltage / current conversion circuit so that the voltage / current conversion circuit can adjust the drive current signal of the YIG filter according to the first drive control signal.

8. The YIG filter tuning method as described in claim 7, characterized in that, The charging and discharging of the filter capacitor corresponding to the tuning parameters according to the tuning parameters includes: In the filter module of the adjustable filter circuit, a filter capacitor that matches the tuning parameters is selected as the filter capacitor to be charged and discharged. The electrical connection between the charge / discharge module of the adjustable filter circuit and the filter capacitor to be charged / discharged is established through the switching device in the switching module of the adjustable filter circuit. The charge / discharge module charges and discharges the filter capacitor to be charged or discharged, so as to charge or discharge the voltage of the filter capacitor to a preset value; The switching device in the switching module connects the charged and discharged filter capacitor to the filter circuit to filter the drive control signal.

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