Filtering driving circuit, YIG filtering device and tuning method

Abstract

The invention discloses a filter driving circuit, a YIG filter device and a tuning method. The filter driving circuit comprises 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 filtering parameter and outputting a first driving control signal obtained after filtering to the voltage / current conversion circuit, and the filtering parameter is related to the tuning rate of the YIG filter. The voltage / current conversion circuit is used for outputting a control voltage signal according to the driving first control signal so as to adjust a driving current signal of the YIG filter through the control voltage signal. The tuning parameter of the driving control signal is set according to the tuning rate when the YIG filter works, and the control voltage noise of the driving control signal is filtered in a targeted manner, so that the YIG filter can achieve the optimal additional phase noise, and meanwhile, the YIG filter has a relatively high 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 filter is a tunable filter. The tuning rate of the filter is adjusted by tuning the current flowing through the filter coil. It is widely used in various microwave and millimeter wave receivers because it not only has a very high Q value and selectivity, but also has a very wide tuning range. The tuning sensitivity of the YIG filter is usually tens of MHz / mA, which is very sensitive, so it is also very sensitive to the noise of the control signal. The noise of the control current needs to be controlled at the uA or even nA level. Therefore, the design of the filter drive circuit of the YIG filter needs to pay special attention to reducing the additional phase noise of the filter while meeting the requirements of 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 For 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 the YIG filter, the current / voltage conversion circuit 20 of the filter driving circuit is connected to the filter equivalent circuit 10, and 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 pole of the first switch tube Q0 is connected to the filter equivalent circuit 10, the control pole of the first switch tube Q0 is connected to the output end of the conversion amplifier U0, and the second pole of the first switch tube Q0 is connected to the negative input end of the conversion amplifier U0. The positive input end of the conversion amplifier U0 is connected to the DAC circuit, which is used to drive the control signal U YIG Input. One end of the first resistor R1 is grounded, and the other end is connected to the negative input end 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 the output voltage controls the on-resistance of the first switch tube Q0 (MOS tube). Finally, the voltage on the sampling resistor is equal to the control signal voltage. At this time, we have: V=I YIG *Rsample; 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.

[0004] The control voltage signal V output by the DAC is usually a precision control voltage to achieve the purpose of accurately controlling the YIG filter. Although the control voltage signal V output by the DAC can achieve a faster rate of change and a finer adjustment step, it is difficult to achieve very low noise, which causes the additional phase noise of the YIG filter to deteriorate, thereby deteriorating the phase noise of the output signal. For example, if you want to meet the fast tuning of the YIG filter, the DAC circuit needs to use a high-speed DAC, but the high-speed DAC usually has a high output voltage noise and cannot meet the low-noise requirements of the YIG filter, especially low-frequency (frequency value ≤ 100kHz) noise, which will be directly modulated to the input signal through the YIG filter, deteriorating the phase noise of the input signal. Summary of the invention

[0005] The technical problem to be solved by the present 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.

[0006] 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; The adjustable filter circuit is connected to the voltage / current conversion circuit, and 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; 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.

[0007] 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 connected to the charge and discharge module and the filter module; The filtering module includes at least two filtering 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 used to filter the driving control signal through the charged and discharged filtering capacitor.

[0008] In one embodiment, 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 are 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.

[0009] 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 respectively; The filter element comprises 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.

[0010] In one embodiment, 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.

[0011] In one embodiment, the switch device of the switch module includes a first switch S21 and capacitor connecting 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 a non-grounded end of the filter capacitor; wherein each of the capacitor connection switches is respectively connected to a different filter capacitor.

[0012] In one embodiment, 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 end of the YIG filter, the control electrode of the first switch tube Q0 is connected to the output end of the conversion amplifier U0, and the second electrode of the first switch tube Q0 is electrically connected to the negative input end 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, and the second resistor R2 is connected between the negative input terminal of the conversion amplifier U0 and the second electrode of the first switch tube Q0.

[0013] 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 after being connected in parallel, are 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 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 after being connected in series, are connected between the control output end and the working power input end of the YIG filter.

[0014] According to the second aspect, an embodiment provides a YIG filter device, comprising a YIG filter and a filter driving circuit as described in the first aspect.

[0015] According to the third aspect, an embodiment provides a YIG filter tuning method, which is applied to the YIG filter device as described in the second aspect, and the YIG filter tuning method includes: Get the tuning rate required when the YIG filter works; Acquiring tuning parameters 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.

[0016] In one embodiment, charging and discharging a 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.

[0017] According to the YIG filter device of the above embodiment, the voltage of the driving control signal is set according to the center frequency of the YIG filter when it is working, and the tuning parameters of the driving control signal are set according to the required YIG filter tuning rate to specifically filter out the control voltage noise of the driving control signal, so that the YIG filter can achieve the best additional phase noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the circuit connection diagram of the YIG filter; Figure 2 A circuit connection diagram of a filter driving circuit in an embodiment; Figure 3 A circuit connection diagram of an adjustable filter circuit in another embodiment; Figure 4 A circuit connection diagram of a filter driving circuit in another embodiment; Figure 5 A schematic diagram of a flow chart of a YIG filter tuning method in an embodiment; Figure 6 A schematic diagram of a process for tuning a YIG filter in an embodiment. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, 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 part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0020] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0021] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0022] In an embodiment of the present application, an adjustable filter circuit is arranged between the DAC circuit and the voltage / current conversion circuit. The adjustable filter circuit outputs a driving 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 the optimal additional phase noise.

[0023] Embodiment 1: 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, including 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 drive control signal U according to a preset filter parameter. YIG Filtering is performed, and the first driving control signal U obtained after filtering is Y0 The output is sent to the voltage / current conversion circuit 20, and 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 drive current signal of the YIG filter.

[0024] 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 capacitor 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. Among them, 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 .

[0025] 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.

[0026] 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.

[0027] In one embodiment, the switch device of the switch module 32 includes 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. Both ends of the first switch S21 are connected to the first element connection end and the second element connection end of the filter element in the filter module 33, respectively.

[0028] Please refer to Figure 4, is a circuit connection diagram of the filter driving 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 the capacitor connection switch S22 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 the filter capacitor C30 (that is, the series connection end of the filter capacitor C30 and the capacitor switch S30). One end of the capacitor connection switch S23 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 the filter capacitor C31 (that is, the series connection end of the filter capacitor C31 and the capacitor switch S31). One end of the capacitor connection switch S24 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 the filter capacitor C32 (that is, the series connection end of the filter capacitor C32 and the capacitor switch S32). One end of the capacitor connection switch S25 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 the filter capacitor C33 (that is, the series connection end of the filter capacitor C33 and the capacitor switch S33).

[0029] 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 tube Q0. The first electrode of the first switch tube Q0 is connected to the control output end of the equivalent circuit 10 (YIG filter), the control electrode of the first switch tube Q0 is connected to the output end of the conversion amplifier U0, and the second electrode of the first switch tube Q0 is electrically connected to the negative input end of the conversion amplifier U0. The positive input end 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, and the second resistor R2 is connected between the negative input terminal of the conversion amplifier U0 and the second pole 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, and the third resistor R3 and the first capacitor C21 are connected in parallel, and after being connected in parallel, they are connected between the output terminal of the conversion amplifier U0 and the control pole 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 after being connected in series, they are connected between the control output terminal and the working power input terminal of the equivalent circuit 10 (YIG filter).

[0030] In one embodiment of the present application, a YIG filtering device is also disclosed, including a YIG filter and the filtering driving circuit as described above.

[0031] Please refer to Figure 5 , is a flow chart of a YIG filter tuning method in an embodiment. In an embodiment of the present application, a YIG filter tuning method is also disclosed, which is applied to the YIG filter device as described above. The YIG filter tuning method includes: Step 101, obtaining a tuning rate.

[0032] Get the tuning rate required for YIG filter operation.

[0033] Step 102: Obtain tuning parameters.

[0034] Get the tuning parameters based on the tuning rate.

[0035] Step 103, charging and discharging the filter capacitor.

[0036] The filter capacitor corresponding to the tuning parameter is charged and discharged according to the tuning parameter, specifically including: First, a filter capacitor with an adaptive tuning parameter is selected in a filter module of an adjustable filter circuit as a filter capacitor to be charged and discharged; then, an electrical connection between the charge and discharge module of the adjustable filter circuit and the filter capacitor to be charged and discharged is established through a switch device in a switch module of the adjustable filter circuit; then, 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; finally, the charged and discharged filter capacitor is connected to the filter circuit through a switch device in the switch module, so as to filter the drive control signal.

[0037] Among them, filter capacitors with different capacitances 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.

[0038] Step 104, connecting the charging filter capacitor to the filter circuit.

[0039] The driving control signal is filtered by a filtering circuit including a charged filtering 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.

[0040] In order to facilitate understanding of the application of the YIG filter tuning method disclosed in the present application, the following is described through specific embodiments, specifically including: Please refer to Figure 6 , is a schematic diagram of a process of tuning a YIG filter in an embodiment, Figure 2 The filter driving circuit shown implements the tuning process of the YIG filter including: Step 201, obtaining a YIG filter tuning instruction.

[0041] After obtaining the YIG filter tuning instruction issued by the user, the tuning process for the YIG filter begins.

[0042] Step 202, selecting a filter capacitor.

[0043] 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.

[0044] Step 203, closing the filter switch of the selected filter capacitor.

[0045] 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.

[0046] Step 204, closing the capacitor connection switch.

[0047] 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.

[0048] Step 205, setting the drive control signal U YIG Voltage.

[0049] The DAC outputs a drive control signal U with a preset voltage value YIG , to charge and discharge the filter capacitor C30.

[0050] Step 206, charging and discharging the filter capacitor to a preset approximate value.

[0051] 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 threshold interval range of a preset value. In one embodiment, the threshold interval range is ±1% of the preset value.

[0052] Step 207, close the first switch and open the capacitor connection switch.

[0053] 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.

[0054] Step 208, charging and discharging the filter capacitor to a preset value.

[0055] The filter capacitor C30 is continuously charged and discharged through the second amplifier U12, and the voltage of the filter capacitor C30 is charged and discharged to a preset value.

[0056] Step 209, turn off the first switch.

[0057] 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.

[0058] Step 210, determining whether the tuning is completed.

[0059] Determine whether the tuning is completed based on the tuning result of the YIG filter. If not completed, repeat steps 204 to 210.

[0060] 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 voltage value of the first control signal U is compared, and then the on-resistance of the first switch tube Q0 (MOS tube) is controlled by the output voltage of the conversion amplifier U0, 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 driving first control signal U Y0 As the control voltage V, I YIG The 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 YIGThe relationship is V=I YIG *Rsample. The adjustable filter circuit 30 includes a charge and discharge module 31, a switch module 32 and a filter module 33. The charge and 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 switch module 32 and the capacitor connection switch are used to switch 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.

[0061] When the center frequency of the YIG filter remains unchanged, its tuning current also remains unchanged, so there is no need to worry about the tuning speed of the YIG filter. You only need 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 to make the cutoff frequency reach 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 additional phase noise.

[0062] 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 high, 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 may be more than 1s.

[0063] Below Figure 4 The filter drive circuit shown in the figure introduces how to use the adjustable filter network of the adjustable filter circuit to shorten the charging and discharging time, including: In response to the user's instruction to tune the YIG filter, the following operations are performed: The capacitor switches S30, S31, S32, and S33 are disconnected, the switch S21 is closed, and one of the capacitor connection switches S22, S23, S24, and S25 is closed. The output end of the first amplifier U11 is directly electrically connected to the selected filter capacitor (filter capacitor C30, filter capacitor C31, filter capacitor C32, and filter capacitor C33), and then the drive control signal U is adjusted. YIG The voltage value of the filter capacitor is increased to a 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 U YIG 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 is within a preset voltage 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, and 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 outputted Y0 to the voltage / current conversion circuit 20. Since the frequency tuning time of a YIG filter is usually several ms to several hundred ms, this operation simultaneously performs the charging and discharging of the filter capacitor and the frequency tuning of the YIG filter, thus shortening the total tuning time.

[0064] 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.

[0065] The voltages output by the first amplifier U11 and the second amplifier U12 may be slightly different. If the filter capacitor is directly connected to the adjustable filter circuit after the first amplifier U11 is used for charging and discharging, 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 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 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 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.

[0066] If the center frequency of the YIG filter needs to be continuously tuned, the above operation is repeated, except that different preset voltages need to be set for different center frequencies.

[0067] 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 speed levels. If more tuning speed levels are required, more filter switches and filter capacitors can be added.

[0068] In the voltage / current conversion circuit, increasing the resistance of the sampling resistor R1 can also reduce the current noise while keeping the noise voltage unchanged, but the cost is that the power consumption of the sampling resistor will increase. For every doubling of the resistance of the sampling resistor, the current noise will decrease by 50%, and the additional phase noise will decrease by 6dB, but the power consumption of the sampling resistor will also double. The YIG filter requires a large current to drive, and the maximum current can reach 0.5~2A. If the power consumption of the sampling resistor is too large, the cost will increase sharply, and even a resistor with sufficient rated power cannot be selected (the sampling resistor requires ultra-low temperature drift and large rated power. Such resistors are rare on the market and are expensive. Increasing the rated power will increase the cost sharply). The technical solution in the embodiment of the present application can also optimize the additional phase noise of the YIG filter while only increasing the cost.

[0069] 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.

[0070] Those skilled in the art will appreciate that all or part of the functions of the various methods in the above-mentioned embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above-mentioned embodiments are implemented by computer programs, 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-mentioned 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-mentioned functions can be implemented. In addition, when all or part of the functions in the above-mentioned embodiments are implemented by computer programs, 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 can be downloaded or copied and saved in the memory of the local device, or the system of the local device is updated, and when the program in the memory is executed by the processor, all or part of the functions in the above-mentioned embodiments can be implemented.

[0071] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

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 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; 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.

2. The filter driving circuit according to claim 1, characterized in that: The adjustable filter circuit includes a charge and discharge module, a filter module connected to the charge and discharge module, and a switch module connected to the charge and discharge module and the filter module; The filtering module includes at least two filtering 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 used to filter the driving control signal through the charged and discharged filtering capacitor.

3. The filter driving circuit according to claim 2, characterized in that: 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 are 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.

4. The filter driving circuit according to claim 3, 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 respectively; The filter element comprises 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.

5. The filter driving circuit according to claim 4, characterized in that: 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.

6. The filter driving circuit according to claim 4, characterized in that: The switch device of the switch module includes a first switch S21 and capacitor connecting 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 a non-grounded end of the filter capacitor; wherein each of the capacitor connection switches is respectively connected to a different filter capacitor.

7. The filter driving circuit according to claim 1, characterized in that: 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 end of the YIG filter, the control electrode of the first switch tube Q0 is connected to the output end of the conversion amplifier U0, and the second electrode of the first switch tube Q0 is electrically connected to the negative input end 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, and the second resistor R2 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 after being connected in parallel, are 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 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 after being connected in series, are connected between the control output end and the working power input end of the YIG filter.

8. 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 7.

9. A YIG filter tuning method, characterized in that: Applied to the YIG filter device as claimed in claim 8, the YIG filter tuning method comprises: Get the tuning rate required when the YIG filter works; Acquiring tuning parameters 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.

10. The YIG filter tuning method according to claim 9, characterized in that: 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.

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