Filter driving circuit, YIG filter device and tuning method

Abstract

The present application discloses a filter driving circuit, a YIG filtering device and a tuning method, wherein the filter driving circuit includes an adjustable filtering circuit and a voltage / current conversion circuit. The adjustable filtering circuit is used to filter a preset driving control signal according to a preset filtering parameter, and output the first driving control signal obtained after filtering to the voltage / current conversion circuit, wherein the filtering parameter is related to the tuning rate of the YIG filter. The voltage / current conversion circuit is used to output a control voltage signal according to the first driving control signal, so as to adjust the driving current signal of the YIG filter through the control voltage signal. Since the tuning parameter of the driving control signal is set according to the tuning rate when the YIG filter is working, the control voltage noise of the driving control signal is filtered out in a targeted manner, so that the YIG filter can achieve the best additional phase noise while having a faster tuning rate.

Description

Technical Field

[0001] The present application relates to the technical field of electronic measuring instruments and meters, and in particular to a filter drive circuit, a YIG filter device and a tuning method. Background Art

[0002] YIG filters are tunable filters that adjust the filter's tuning rate by tuning the current flowing through the filter coil. Due to their very high Q and selectivity, as well as their 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, making them very sensitive to control signal noise. Controlling the control current noise must be kept to the uA or even nA level. Therefore, the design of the YIG filter's filter driver circuit requires particular attention to reducing the filter's additive phase noise while meeting the requirements for a high tuning rate.

[0003] In the prior art, the filter driving circuit of the YIG filter generally includes a DAC circuit and a voltage / current conversion circuit. The DAC circuit outputs a driving control signal U YIG To the voltage / current conversion circuit, the voltage / current conversion circuit is connected to the YIG filter. Please refer to Figure 1 , is a circuit connection diagram of a YIG filter. The current / voltage conversion circuit 20 of the filter drive circuit is connected to the filter equivalent circuit 10. The filter equivalent circuit 10 is the resonant coil equivalent circuit of the YIG filter. The voltage / current conversion circuit includes a conversion amplifier U0, a first resistor R1 (sampling resistor), and a first switch tube Q0. The first electrode of the first switch tube Q0 is connected to the filter equivalent circuit 10, the control electrode of the first switch tube Q0 is connected to the output of the conversion amplifier U0, and the second electrode of the first switch tube 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 for driving the control signal U YIG One end of the first resistor R1 is grounded, and the other end is connected to the negative input of the conversion amplifier U0. The conversion amplifier U0 in the voltage / current conversion circuit compares the control signal with the voltage on the sampling resistor, and then outputs the voltage to control the on-resistance of the first switch Q0 (MOS transistor). Finally, the voltage on the sampling resistor is equal to the control signal voltage. At this time, we have:

[0004] V=I YIG *Rsample;

[0005] Where V is the control voltage, I YIG is the current flowing through the sampling resistor, that is, the current flowing through the YIG filter coil, and Rsample is the resistance value of the sampling resistor.

[0006] The control voltage signal V output by the DAC is typically a precision control voltage to achieve precise control of the YIG filter. Although the DAC output control voltage signal V can achieve a relatively fast rate of change and finer adjustment steps, it struggles to achieve very low noise, which degrades the YIG filter's additive phase noise and, consequently, the output signal's phase noise. For example, to achieve fast YIG filter tuning, the DAC circuit requires a high-speed DAC. However, high-speed DACs typically have high output voltage noise, which cannot meet the YIG filter's low-noise requirements. Low-frequency noise (≤100kHz) in particular will be directly modulated by the YIG filter onto the input signal, degrading the input signal's phase noise. Summary of the Invention

[0007] The technical problem to be solved by this application is how to effectively reduce the additional phase noise of the YIG filter through reasonable circuit design and tuning methods to meet the requirements of low phase noise and high tuning rate application scenarios.

[0008] According to the first aspect, an embodiment provides a filter driving circuit for providing a driving current signal to a YIG filter, the filter driving circuit comprising an adjustable filter circuit and a voltage / current conversion circuit;

[0009] The adjustable filter circuit is connected to the voltage / current conversion circuit, and is used to filter a preset drive control signal according to a preset filter parameter, and output the first drive control signal obtained after filtering to the voltage / current conversion circuit; the preset filter parameter is related to the tuning rate of the YIG filter;

[0010] The voltage / current conversion circuit is connected to the YIG filter, and is used to output a control voltage signal according to the first driving control signal, and adjust the driving current signal of the YIG filter through the control voltage signal.

[0011] In one embodiment, the adjustable filter circuit includes a charge and discharge module, a filter module connected to the charge and discharge module, and a switch module connecting the charge and discharge module and the filter module;

[0012] The filtering module includes at least two filter capacitors with different capacitance values;

[0013] The switch module is used to electrically connect the charge and discharge module with the filter capacitor in the filter module through a switch device;

[0014] The charging and discharging module is used to charge and discharge the filter capacitor of the filter module;

[0015] The filtering module is further configured to filter the driving control signal through the charged and discharged filtering capacitor.

[0016] In one embodiment, the charge and discharge module includes a first amplifier U11 and a second amplifier U12;

[0017] The positive input terminals of the first amplifier U11 and the second amplifier U12 are electrically connected and used for inputting the driving control signal;

[0018] The negative input terminal and the output terminal of the first amplifier U11 are electrically connected and connected to the switch module;

[0019] The negative input terminal and the output terminal of the second amplifier U12 are electrically connected and connected to the filtering module.

[0020] 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;

[0021] The filter element includes a first element connection end and a second element connection end, the first element connection end of the filter element is electrically connected to the output end of the second amplifier U12, and the second element connection end of the filter element is used to output the first driving control signal;

[0022] 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 end of the filter element, and the other end of the series connection is grounded;

[0023] The filter element is a filter resistor R30 or a filter inductor L1.

[0024] In one embodiment, the switch device of the switch module includes a first switch S21 and a capacitor connection switch;

[0025] 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;

[0026] One end of the capacitor connection switch is electrically connected to the output end of the first amplifier U11 , and the other end is connected to the second element connection end of the filter element.

[0027] In one embodiment, the switch device of the switch module includes a first switch S21 and capacitor connection switches having the same number as the filter capacitors;

[0028] 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;

[0029] One end of the capacitor connection switch is electrically connected to the output end of the first amplifier U11, and the other end is electrically connected to the non-grounded end of one of the filter capacitors; wherein each of the capacitor connection switches is correspondingly connected to a different filter capacitor.

[0030] In one embodiment, the voltage / current conversion circuit includes a conversion amplifier U0, a first resistor R1 and a first switch tube Q0;

[0031] The first electrode of the first switch tube Q0 is connected to the control output terminal of the YIG filter, the control electrode of the first switch tube Q0 is connected to the output terminal of the conversion amplifier U0, and the second electrode of the first switch tube Q0 is electrically connected to the negative input terminal of the conversion amplifier U0;

[0032] The positive input terminal of the conversion amplifier U0 is connected to the adjustable filter circuit for inputting the first driving control signal;

[0033] 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;

[0034] The voltage / current conversion circuit further includes a second resistor R2 , which is connected between the negative input terminal of the conversion amplifier U0 and the second electrode of the first switch tube Q0 .

[0035] 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 connected between the output terminal of the conversion amplifier U0 and the control electrode of the first switch Q0;

[0036] 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 after being connected in series, are connected between the control output end and the working power input end of the YIG filter.

[0037] According to a second aspect, an embodiment provides a YIG filtering device, comprising a YIG filter and the filter driving circuit as described in the first aspect.

[0038] According to a third aspect, an embodiment provides a YIG filter tuning method, which is applied to the YIG filter device according to the second aspect. The YIG filter tuning method includes:

[0039] Get the tuning rate required when the YIG filter works;

[0040] Obtaining a tuning parameter according to the tuning rate;

[0041] charging and discharging a filter capacitor corresponding to the tuning parameter according to the tuning parameter;

[0042] The drive control signal is filtered by a filter circuit including the charged and discharged filter capacitor, and the first drive control signal obtained after filtering is given to a voltage / current conversion circuit, so that the voltage / current conversion circuit adjusts the drive current signal of the YIG filter according to the first drive control signal.

[0043] In one embodiment, charging and discharging a filter capacitor corresponding to the tuning parameter according to the tuning parameter includes:

[0044] Selecting a filter capacitor adapted to the tuning parameters in a filter module of the adjustable filter circuit as the filter capacitor to be charged and discharged;

[0045] Establishing an electrical connection between the charge and discharge module of the adjustable filter circuit and the filter capacitor to be charged and discharged through a switch device in the switch module of the adjustable filter circuit;

[0046] The charge and discharge module charges and discharges the filter capacitor to be charged and discharged, so as to charge and discharge the voltage of the filter capacitor to a preset value;

[0047] The charged and discharged filter capacitor is connected to the filter circuit through the switch device in the switch module to filter the drive control signal.

[0048] 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 operating, and the tuning parameters of the drive control signal are set according to the required YIG filter tuning rate to specifically filter out the control voltage noise of the drive control signal, so that the YIG filter can achieve optimal additional phase noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a circuit connection diagram of the YIG filter;

[0050] Figure 2 A circuit connection diagram of a filter drive circuit in one embodiment;

[0051] Figure 3 A circuit connection diagram of an adjustable filter circuit in another embodiment;

[0052] Figure 4 A circuit connection diagram of a filter driving circuit in another embodiment;

[0053] Figure 5 1 is a flow chart of a YIG filter tuning method according to an embodiment;

[0054] Figure 6FIG. 4 is a schematic diagram of a process for tuning a YIG filter in an embodiment. DETAILED DESCRIPTION

[0055] The present invention will be further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. Similar elements in different embodiments are numbered with associated similar elements. In the following embodiments, many detailed descriptions are provided to enable the present application to be better understood. However, those skilled in the art will readily appreciate that some of the features may be omitted in different circumstances, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification. This is to avoid the core portion of the present application being overwhelmed by excessive descriptions, and for those skilled in the art, it is not necessary to describe these related operations in detail. They will fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0056] In addition, the features, operations, or characteristics described in the specification may be combined in any appropriate manner to form various embodiments. Furthermore, the steps or actions in the method description may be reordered or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various sequences in the specification and drawings are provided solely for the purpose of clearly describing a particular embodiment and are not intended to be mandatory, unless otherwise specified.

[0057] Component numbers used herein, such as "first" and "second," are used solely to distinguish the components being described and do not convey any sequential or technical meaning. References to "connection" and "coupling" herein, unless otherwise specified, include both direct and indirect connections (couplings).

[0058] In an embodiment of the present application, 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 for filtering out the control voltage noise according to the center frequency of the YIG filter and the required tuning rate, so that the YIG filter can achieve optimal additional phase noise.

[0059] Example 1:

[0060] Please refer to Figure 2 , is a circuit connection diagram of a filter driving circuit in an embodiment. The filter driving circuit is used to provide a driving 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 adjust a preset driving control signal U according to a preset filtering parameter. YIG Filtering is performed, and the first driving control signal U obtained after filtering isY0 Output to the voltage / current conversion circuit 20, the preset filtering parameters are related to the tuning rate required by the YIG filter. The voltage / current conversion circuit 20 is connected to the equivalent circuit 10 (YIG filter) and is used to drive the first control signal U Y0 Adjust the driving current signal of the YIG filter.

[0061] In one embodiment, the adjustable filter circuit 30 includes a charge and discharge module 31, a filter module 33 connected to the charge and discharge module 31, and a switch module 32 connected to the charge and discharge module 31 and the filter module 33. The filter module 33 includes at least two filter capacitors with different capacitances. The switch module 32 is used to electrically connect the charge and discharge module 31 with the filter capacitors in the filter module 33 through a switch device. The charge and discharge module 31 is used to charge and discharge the filter capacitor of the filter module 33. The filter module 33 is also used to adjust the drive control signal U through the charged and discharged filter capacitor. YIG Filter to obtain the first driving control signal U Y0 .

[0062] like Figure 2 As shown, in one embodiment, the charge and discharge 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 Input. The negative input terminal and the output terminal of the first amplifier U11 are electrically connected, and are connected to the switch module 32. The negative input terminal and the output terminal of the second amplifier U12 are electrically connected, and are connected to the filter module 33. In one embodiment, the filter module 33 includes a filter element and at least two filter capacitors, and each filter capacitor (filter capacitor C30, filter capacitor C31, filter capacitor C32 and filter capacitor C34) is respectively connected to a capacitor switch (capacitor switch S30, capacitor switch S31, capacitor switch S32 and capacitor switch S33). The filter element includes a first element connection terminal and a second element connection terminal. The first element connection terminal of the filter element is electrically connected to the output terminal of the second amplifier U12, and the second element connection terminal of the filter element is used to output the first drive 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 end of the filter element, and the other end of the series connection is grounded.

[0063] In one embodiment, if Figure 2 As shown, the filter element is the filter resistor R30. Figure 3 , is a circuit connection diagram of an adjustable filter circuit in another embodiment. In one embodiment, the filter element is a filter inductor L1.

[0064] In one embodiment, the switch components of the switch module 32 include a first switch S21 and a capacitor connection switch S22. One end of the capacitor connection switch S22 is electrically connected to the output end of the first amplifier U11, and the other end is connected to the second element connection end 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 end and the second element connection end of the filter element in the filter module 33.

[0065] Please refer to Figure 4 , is a circuit connection diagram of the filter drive circuit in another embodiment. In one embodiment, the switch device of the switch module 32 includes a first switch S21 and capacitor connection switches (capacitor connection switch S22, capacitor connection switch S23, capacitor connection switch S24 and capacitor connection switch S25) with the same number as the filter capacitors (filter capacitor C30, filter capacitor C31, filter capacitor C32 and filter capacitor C34). 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 end of the first amplifier U11, and the other end is electrically connected to the non-grounded end of a filter capacitor, wherein each capacitor connection switch is respectively connected to a different filter capacitor. As Figure 4 As shown, one end of capacitor connection switch S22 is electrically connected to the output of the first amplifier U11, and the other end is electrically connected to the non-grounded end of filter capacitor C30 (i.e., the series connection end of filter capacitor C30 and capacitor switch S30). One end of capacitor connection switch S23 is electrically connected to the output of the first amplifier U11, and the other end is electrically connected to the non-grounded end of filter capacitor C31 (i.e., the series connection end of filter capacitor C31 and capacitor switch S31). One end of capacitor connection switch S24 is electrically connected to the output of the first amplifier U11, and the other end is electrically connected to the non-grounded end of filter capacitor C32 (i.e., the series connection end of filter capacitor C32 and capacitor switch S32). One end of capacitor connection switch S25 is electrically connected to the output of the first amplifier U11, and the other end is electrically connected to the non-grounded end of filter capacitor C33 (i.e., the series connection end of filter capacitor C33 and capacitor switch S33).

[0066] like Figure 2 As shown, 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 electrode of the first switch Q0 is connected to the control output terminal of the equivalent circuit 10 (YIG filter), the control electrode of the first switch Q0 is connected to the output terminal of the conversion amplifier U0, and the second electrode 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, which is used to drive the first control signal U Y0Input. 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 electrode of the first switch tube Q0. In one embodiment, the voltage / current conversion circuit 20 also includes a third resistor R3 and a first capacitor C21. The third resistor R3 and the first capacitor C21 are connected in parallel and connected in parallel between the output terminal of the conversion amplifier U0 and the control electrode of the first switch tube Q0. In one embodiment, the voltage / current conversion circuit 20 also includes a fourth resistor R4 and a second capacitor C22. The fourth resistor R4 and the second capacitor C22 are connected in series and connected in series between the control output terminal of the equivalent circuit 10 (YIG filter) and the working power input terminal.

[0067] In one embodiment of the present application, a YIG filter device is further disclosed, including a YIG filter and the filter driving circuit as described above.

[0068] Please refer to Figure 5 , which is a flow chart of a YIG filter tuning method in one embodiment, further discloses a YIG filter tuning method in one embodiment of the present application, which is applied to the YIG filter device described above. The YIG filter tuning method includes:

[0069] Step 101: Obtain a tuning rate.

[0070] Gets the tuning rate required for YIG filter operation.

[0071] Step 102: Obtain tuning parameters.

[0072] Get the tuning parameters based on the tuning rate.

[0073] Step 103: charge and discharge the filter capacitor.

[0074] The filter capacitor corresponding to the tuning parameter is charged and discharged according to the tuning parameter, specifically including:

[0075] First, a filter capacitor with adapted tuning parameters is selected in the filter module of the adjustable filter circuit as the filter capacitor to be charged and discharged; then, an electrical connection is established between the charge and discharge module of the adjustable filter circuit and the filter capacitor to be charged and discharged through the switch device in the switch module of the adjustable filter circuit; then, the charge and discharge 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, the charged and discharged filter capacitor is connected to the filter circuit through the switch device in the switch module to filter the drive control signal.

[0076] Filter capacitors of different capacitance values correspond to different tuning parameters. When the preset voltage increases and the original voltage 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 of the filter capacitor to be connected is higher than the preset voltage, the filter capacitor needs to be discharged.

[0077] Step 104: Connect the charging filter capacitor to the filter circuit.

[0078] The driving control signal is filtered by a filtering circuit including a charged filter capacitor, and the first driving control signal obtained after filtering is given to a voltage / current conversion circuit, so that the voltage / current conversion circuit adjusts the driving current signal of the YIG filter according to the first driving control signal.

[0079] To facilitate understanding of the application of the YIG filter tuning method disclosed in this application, the following is a description through specific embodiments, specifically including:

[0080] Please refer to Figure 6 , is a schematic diagram of a process for tuning a YIG filter in an embodiment, Figure 2 The filter drive circuit shown in the figure realizes the tuning process of the YIG filter, including:

[0081] Step 201: Obtain a YIG filter tuning instruction.

[0082] After receiving the YIG filter tuning instruction from the user, the YIG filter tuning process is started.

[0083] Step 202: Select a filter capacitor.

[0084] According to the tuning parameters, an adapted filter capacitor is selected from the filter capacitor C30 , the filter capacitor C31 , the filter capacitor C32 , and the filter capacitor C33 as the filter capacitor to be charged and discharged.

[0085] Step 203: Close the filter switch of the selected filter capacitor.

[0086] After determining the filter capacitor to be charged and discharged, the filter switch connected to the filter capacitor is closed. For example, if the filter capacitor C30 is used as the filter capacitor to be charged and discharged, the capacitor switch S30 is closed to connect the filter capacitor C30 to the circuit.

[0087] Step 204: Close the capacitor connection switch.

[0088] When the capacitor connecting switch S22 is closed (the first switch S21 is open), the filter capacitor C30 is connected to the output terminal of the first amplifier U11 through the closed capacitor connecting switch S22 and the capacitor switch S30.

[0089] Step 205: Set the drive control signal U YIG Voltage.

[0090] The DAC outputs a drive control signal U with a preset voltage value YIG , to charge and discharge the filter capacitor C30.

[0091] Step 206 , charging and discharging the filter capacitor to a preset approximate value.

[0092] The filter capacitor C30 is charged and discharged for a predetermined fixed time to ensure that the voltage on the filter capacitor C30 reaches a threshold range of a predetermined value. In one embodiment, the threshold range is ±1% of the predetermined value.

[0093] Step 207: close the first switch and open the capacitor connection switch.

[0094] When the voltage on the filter capacitor C30 reaches a preset threshold value, the first switch S21 is closed and the capacitor connection switch S22 is opened.

[0095] Step 208: charge and discharge the filter capacitor to a preset value.

[0096] The filter capacitor C30 continues to be charged and discharged through the second amplifier U12, and the voltage of the filter capacitor C30 is charged and discharged to a preset value.

[0097] Step 209: Turn off the first switch.

[0098] The first switch S21 is turned off so that the driving control signal U YIG The first control signal U is driven by the filter module output Y0 to the voltage / current conversion circuit 20.

[0099] Step 210: Determine whether the tuning is completed.

[0100] Whether the tuning is completed is determined based on the tuning result of the YIG filter. If not completed, steps 204 to 210 are repeated.

[0101] like Figure 2 As shown, the voltage / current conversion circuit 20 takes the feedback voltage from the sampling resistor R1 and compares it with the first driving control signal U of the input voltage / current conversion circuit 20. Y0 The output voltage of the conversion amplifier U0 is used to control the on-resistance of the first switch tube Q0 (MOS tube), and finally the feedback voltage on the sampling resistor R1 is equal to the input voltage of the voltage / current conversion circuit 20, wherein the first control signal U is driven Y0 As the control voltage V, I YIGThe current flowing through the sampling resistor R1, Rsample is the resistance of the sampling resistor R1, then the input voltage value V and the current flowing through the sampling resistor R1 I YIG The relationship is V=I YIG *Rsample. The adjustable filter circuit 30 includes a charge-discharge module 31, a switch module 32, and a filter module 33. The charge-discharge module 31 includes a first amplifier U11 and a second amplifier U12. 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 and the capacitor connection switch of the switch module 32 are used to switch between different charge and discharge paths. The capacitance values of the filter capacitors C30, C31, C32, and C33 in the filter module 33 increase in sequence.

[0102] When the center frequency of the YIG filter remains unchanged, its tuning current also remains unchanged. 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, disconnect the first switch S21 and the capacitor connection switch, and select a suitable filter capacitor at the same time. The cutoff frequency can be reduced to 10Hz or even below 1Hz, thereby filtering out the noise of the control voltage to the greatest extent. At this time, the YIG filter can achieve the best additive phase noise.

[0103] When the center frequency of the YIG filter needs to be tuned to other frequencies, if the state of the adjustable filter network is kept unchanged, only the first control signal U is adjusted. Y0 If the voltage value is too low, because the cutoff frequency of the adjustable filter network is very low, the filter capacitor selected for charging needs a very long charging and discharging time to reach the preset voltage. If the capacitance selected for charging is very large, this time can be more than 1s.

[0104] Below Figure 4 The filter drive circuit shown in the figure shows how to use the adjustable filter network of the adjustable filter circuit to shorten the charge and discharge time, including:

[0105] In response to the user's instruction to tune the YIG filter, the following operations are performed:

[0106] Disconnect the capacitor switches S30, S31, S32, and S33, close the switch S21, close the capacitor connection switch S22, the capacitor connection switch S23, the capacitor connection switch S24, and one of the capacitor connection switches S25, and directly connect the output end of the first amplifier U11 to the selected filter capacitor (filter capacitor C30, filter capacitor C31, filter capacitor C32, and filter capacitor C33). Then adjust the drive control signal U YIG The voltage value of the filter capacitor is increased to the preset value. At this time, the first amplifier U11 will charge and discharge the filter capacitor. At the same time, the second amplifier U12 will charge and discharge the filter capacitor according to the driving control signal UYIG The voltage value outputs the corresponding driving first control signal U Y0 , tune the center frequency of the YIG filter to a preset frequency point; when the charge and discharge voltage reaches a preset range, disconnect the capacitor connection switch, and then connect the charged and discharged filter capacitor to the filter network through the capacitor switch (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, disconnect the switch S21, so that the drive control signal U YIG After filtering by the filtering module, the first driving control signal U is output. Y0 To the voltage / current conversion circuit 20. Because the frequency tuning time of the YIG filter is usually several ms to hundreds of ms, this operation performs the charging and discharging of the filter capacitor and the frequency tuning of the YIG filter at the same time, shortening the total tuning time.

[0107] In one embodiment, the first amplifier U11 and the second amplifier U12 are respectively a high-current operational amplifier and a low-noise operational amplifier. 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 time of the filter capacitor can be greatly shortened.

[0108] The voltages output by the first amplifier U11 and the second amplifier U12 may differ slightly. If the filter capacitor is directly connected to the adjustable filter circuit after charging and discharging by the first amplifier U11, there will be a voltage difference between the voltage on the charged filter capacitor and the voltage output by the first amplifier U11. The filter capacitor needs to be recharged and discharged until the voltage on the capacitor equals 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 longer. Therefore, when the voltage on the filter capacitor reaches within the range of ±1% of the preset voltage, the switch between the output end of the second amplifier U12 and the filter capacitor (one of the capacitor connection switch S22, capacitor connection switch S23, capacitor connection switch S24 and capacitor connection switch S25) is disconnected, and the first switch S21 and the switch between the output end of the first amplifier U11 and the corresponding filter capacitor (one of the capacitor switch S30, capacitor switch S31, capacitor switch S32 and capacitor switch S33) are closed, and the second amplifier U12 is used to charge 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.

[0109] If you need to continuously tune the center frequency of the YIG filter, repeat the above steps, except that different preset voltages need to be set for different center frequencies.

[0110] If the center frequency tuning rate of the YIG filter is very fast (such as high-speed frequency hopping communication), using the first amplifier U11 to charge the filter capacitor cannot meet the tuning speed requirement. At this time, the capacitor of the filter module needs to be replaced with a filter capacitor with a smaller capacitance (through the switching states of the capacitor connection switch S22, capacitor connection switch S23, capacitor connection switch S24, capacitor connection switch S25, capacitor switch S30, capacitor switch S31, capacitor switch S32 and capacitor switch S33) to ensure a faster tuning rate. At this time, the cutoff frequency of the adjustable filter network becomes higher, and the improvement effect of the additional phase noise of the YIG filter will decrease as the cutoff frequency of the adjustable filter network increases. Figure 2 In the figure, only four filter capacitors with different capacitance values are marked, which also correspond to four tuning speeds. If more tuning speed divisions are required, just add more filter switches and filter capacitors.

[0111] In a voltage / current conversion circuit, increasing the resistance of sampling resistor R1 can also reduce current noise while keeping the noise voltage constant, but this comes at the cost of increased power consumption in the sampling resistor. For every doubling of the sampling resistor's resistance, current noise decreases by 50% and additive phase noise decreases by 6dB, but the power consumption of the sampling resistor also doubles. YIG filters require a large current, with a maximum current of 0.5 to 2A. Excessive power consumption in the sampling resistor can lead to a sharp increase in cost, and it may even be difficult to select a resistor with a sufficient power rating. (Sampling resistors require ultra-low temperature drift and high power ratings, which are already rare and expensive on the market. Increasing the power rating would significantly increase the cost.) The technical solutions in the embodiments of the present application can also optimize the additive phase noise of YIG filters while adding only a small amount of cost.

[0112] The filter drive circuit disclosed in the embodiment of the present application includes an adjustable filter circuit and a 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 first drive control signal obtained after filtering to the voltage / current conversion circuit, wherein the filter parameter is related to the tuning rate of the YIG filter. The voltage / current conversion circuit is used to output a control voltage signal according to the first drive control signal, so as to adjust the drive current signal of the YIG filter through the control voltage signal. Since the tuning parameter of the drive control signal is set according to the tuning rate when the YIG filter is working, the control voltage noise of the drive control signal is filtered out in a targeted manner, so that the YIG filter can achieve the best additional phase noise.

[0113] Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments can be implemented by hardware or by computer program. When all or part of the functions in the above embodiments are implemented by computer program, the program can be stored in a computer-readable storage medium, and the storage medium can include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to implement the above functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the above functions can be implemented. In addition, when all or part of the functions in the above embodiments are implemented by computer program, the program can also be stored in a storage medium such as a server, another computer, disk, optical disk, flash disk or mobile hard disk, and saved in the memory of the local device by downloading or copying, or the system of the local device is updated. When the program in the memory is executed by the processor, all or part of the functions in the above embodiments can be implemented.

[0114] The above examples are used to illustrate the present invention, which are only used to help understand the present invention and are not intended to limit the present invention. Those skilled in the art can make several simple deductions, modifications or substitutions based on the concept of the present invention.

Claims

1. A filter driving circuit for providing a driving current signal to a YIG filter, characterized in that: Including adjustable filter circuit and voltage / current conversion circuit; The adjustable filter circuit is connected to the voltage / current conversion circuit, and is used to filter a preset drive control signal according to a preset filter parameter, and output the first drive control signal obtained after filtering 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 driving control signal, and adjust the driving current signal of the YIG filter through the control voltage signal; The adjustable filter circuit includes a charge and discharge module, a filter module connected to the charge and discharge module, and a switch module connecting the charge and discharge module and the filter module; The filtering module includes at least two filter capacitors with different capacitance values; The switch module is used to electrically connect the charge and discharge module with the filter capacitor in the filter module through a switch device; The charging and discharging module is used to charge and discharge the filter capacitor of the filter module; The filtering module is further configured to filter the driving control signal through the charged and discharged filter capacitor; 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 for inputting the driving control signal; The negative input terminal and the output terminal of the first amplifier U11 are electrically connected and connected to the switch module; The negative input terminal and the output terminal of the second amplifier U12 are electrically connected and connected to the filtering module.

2. The filter driving circuit according to claim 1, wherein: The filtering module includes a filtering element and at least two filtering capacitors, and each filtering capacitor is connected to a capacitor switch respectively; The filter element includes a first element connection end and a second element connection end, the first element connection end of the filter element is electrically connected to the output end of the second amplifier U12, and the second element connection end of the filter element is used to output the first driving 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 end of the filter element, and the other end of the series connection is grounded; The filter element is a filter resistor R30 or a filter inductor L1.

3. The filter driving circuit according to claim 2, wherein: The switch device of the switch module includes a first switch S21 and a capacitor connection switch; 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 end of the first amplifier U11 , and the other end is connected to the second element connection end of the filter element.

4. The filter driving circuit according to claim 2, wherein: The switch device of the switch module includes a first switch S21 and capacitor connection switches having the same number as the filter capacitors; 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 end of the first amplifier U11, and the other end is electrically connected to the non-grounded end of one of the filter capacitors; wherein each of the capacitor connection switches is correspondingly connected to a different filter capacitor.

5. The filter driving circuit according to claim 1, wherein: The voltage / current conversion circuit includes a conversion amplifier U0, a first resistor R1 and a first switch tube Q0; The first electrode of the first switch tube Q0 is connected to the control output terminal of the YIG filter, the control electrode of the first switch tube Q0 is connected to the output terminal of the conversion amplifier U0, and the second electrode of the first switch tube 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 for inputting the first driving 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 further includes a second resistor R2, which is connected between the negative input terminal of the conversion amplifier U0 and the second electrode of the first switch tube 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 connected between the output end of the conversion amplifier U0 and the control electrode of the first switch tube 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 after being connected in series, are connected between the control output end and the working power input end of the YIG filter.

6. A YIG filter device, characterized in that: The invention comprises a YIG filter and a filter driving circuit as claimed in any one of claims 1 to 5.

7. A YIG filter tuning method, characterized in that: Applied to the YIG filter device according to claim 6, the YIG filter tuning method comprises: Get the tuning rate required when the YIG filter works; Obtaining a tuning parameter according to the tuning rate; charging and discharging a filter capacitor corresponding to the tuning parameter according to the tuning parameter; The drive control signal is filtered by a filter circuit including the charged and discharged filter capacitor, and the first drive control signal obtained after filtering is given to a voltage / current conversion circuit, so that the voltage / current conversion circuit adjusts the drive current signal of the YIG filter according to the first drive control signal.

8. The YIG filter tuning method according to claim 7, wherein: The charging and discharging of the filter capacitor corresponding to the tuning parameter according to the tuning parameter includes: Selecting a filter capacitor adapted to the tuning parameters in a filter module of the adjustable filter circuit as the filter capacitor to be charged and discharged; Establishing an electrical connection between the charge and discharge module of the adjustable filter circuit and the filter capacitor to be charged and discharged through a switch device in the switch module of the adjustable filter circuit; The charge and discharge module charges and discharges the filter capacitor to be charged and discharged, so as to charge and discharge the voltage of the filter capacitor to a preset value; The charged and discharged filter capacitor is connected to the filter circuit through the switch device in the switch module to filter the drive control signal.

Images