CN115800945A - A Matched Filter Circuit for Solid State Low Frequency Transmitter - Google Patents

Abstract

The invention discloses a matching filter circuit for a solid-state low-frequency transmitter, comprising: a first intermediate tank circuit, a Butterworth filter and a second intermediate tank circuit electrically connected in sequence; the Butterworth filter is used for impedance matching and suppressing High-order harmonic components; the first and second intermediate tank circuits each include a capacitor frame group and an adjustable inductance coil group connected in series; both the capacitor frame group and the adjustable inductance coil group are set by switching the switch to realize grounding as required Connect the corresponding capacitance or inductance to the main loop of matching filter. In particular, the present invention adds the first intermediate tank circuit, which can adjust the impedance characteristics of the access circuit of the sending host to make the access impedance approximately reach a pure resistive state, and reduce the power device of the solid-state sending machine. The voltage and current transient impact; through the closing and opening of the switch, the working frequency segment tuning of the solid-state low-frequency transmitter can be realized; therefore, it has the characteristics of good access impedance matching and segment tuning .

Description

A Matched Filter Circuit for Solid State Low Frequency Transmitter

technical field

The invention relates to the technical field of communication electronic devices, and more specifically, to a matched filter circuit for a solid-state low-frequency transmitter.

Background technique

Low-frequency communication refers to a communication method that uses radio waves for long-distance signal transmission. The matching filter circuit of the low-frequency transmitter is designed according to the characteristics of the tube transmitter, which uses more switches, which increases the complexity of the control system.

The solid-state transmitter power amplifier circuit is composed of high power density power electronic devices, which are different from electron tubes or hydrogen-filled thyratrons. These devices are more sensitive to the circuit characteristics of the load connected to the circuit. When the power device is turned on or off, it will generate a higher voltage spike or a larger transient pulsating current, and it will also increase the high-order harmonic content in the power amplifier circuit. Therefore, the circuit characteristics after sending the host have a greater impact on the power amplifier circuit, which may shorten the life of the power amplifier or damage the device. If the aforementioned matching filter circuit suitable for the electronic tube transmitter is directly used, and the output of the solid-state transmitter is directly connected to the filter, the above-mentioned problems will exist.

In addition, before the low-frequency transmitter works, it needs to be tuned according to different operating frequencies, and when the frequency changes, it must be tuned by switching. The sub-band 3rd-order π-type filter needs at least 12 switching switches The switching operation of the switch is controlled, and the sub-band 7th-order Butterworth filter needs to control the switching operation of more switches. Although the tuning control system will automatically perform the switching action according to the tuning operation table during tuning, but The switching time required for a series of switching operations is still relatively long.

Contents of the invention

Aiming at at least one defect or improvement requirement of the prior art mentioned in the background technology section above, the present invention provides a matched filter circuit for a solid-state low-frequency transmitter, wherein the structure of its key components and the design of its circuit connection method Correspondingly, it can greatly reduce the complexity of the control system while achieving the desired matched filtering effect, and at the same time has the characteristics of compact structure, easy manipulation, and meeting the working requirements of high-power solid-state low-frequency transmitters.

To achieve the above object, the present invention provides a matched filter circuit for a solid-state low-frequency transmitter, comprising: a first intermediate tank circuit, a Butterworth filter, and a second intermediate tank circuit electrically connected in sequence;

The Butterworth filter is used for impedance matching and suppression of higher harmonic components;

Each of the first and second intermediate tank circuits includes a capacitor frame group and an adjustable inductance coil group connected in series;

The capacitor rack group is composed of a main capacitor rack with a relatively large overall capacitance value and several additional capacitor racks with a relatively small overall capacitance value, and the main capacitor rack is always connected in series with the main circuit of the matched filter, and the The additional capacitor racks are respectively connected in parallel with the main capacitor racks to the matched filter main loop through corresponding switchover switches; the first intermediate tank is connected to the external sending host through the access point of its capacitor rack group;

The adjustable inductance coil group is composed of several adjustable inductance coils connected in series with each other in the main loop of the matched filter, and the adjustable inductance coils of the first intermediate tank circuit are connected to each other via a switch and The access points of the Butterworth filter are connected, and the connection between the adjustable inductance coils of the second intermediate tank circuit is connected to the access point of the external post-stage coupling circuit via a switch.

Further, the capacitor frame group of the first intermediate tank circuit is composed of a main capacitor frame with a relatively large overall capacitance value and an additional capacitor frame with a relatively small overall capacitance value; the first intermediate tank circuit can be The adjustable inductance coil group is composed of two adjustable inductance coils connected in series with each other in the main circuit of the matched filter.

Further, the capacitor frame group of the second intermediate tank circuit is composed of a main capacitor frame with a relatively large overall capacitance value and an additional capacitor frame with a relatively small overall capacitance value; the second intermediate tank circuit can be The inductance-adjusting coil group is composed of three adjustable inductance coils connected in series with each other in the main loop of the matched filter.

Further, each of the main capacitor frame and the additional capacitor frame includes a plurality of capacitor groups arranged in series on the bus bar, and each of the capacitor groups is composed of a plurality of capacitors connected in parallel.

Further, each of the adjustable inductance coils has the same adjustable inductance range, and the linkage of multiple adjustable inductance coils is controlled by a servo motor.

Further, the Butterworth filter is composed of several fixed inductance coils and several capacitor frames, several of the fixed inductance coils are connected in series in the main loop of the matched filter, and each of the capacitor frames are connected in parallel with each other A plurality of capacitors arranged on the busbar are jointly composed; one end of the overall structure of each capacitor frame is respectively connected to the connection between several fixed inductance coils, and the other end of the overall structure of each capacitor frame is grounded.

Further, the Butterworth filter is composed of four fixed inductance coils and three capacitor frames, wherein the inductance values of the first and fourth fixed inductance coils at both ends are the same, and the second fixed inductance coil in the middle , the inductance value of the third fixed inductance coil is the same; for the above three capacitor frames, the overall capacitance values of the first capacitor frame at both ends and the third capacitor frame are the same, and the overall capacitance value of the second capacitor frame in the middle is the same as The other two capacitor racks have different overall capacitance values.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

(1) The present invention designs the specific structure and circuit connection mode of its matching filter circuit key components in conjunction with the working characteristics of the high-power solid-state low-frequency transmitter, especially increases the first intermediate tank circuit, which can correspondingly send letters The impedance characteristics of the host access circuit are adjusted so that the access impedance of the transmitting host can approximately reach a purely resistive state, reducing the voltage and current transient impacts on the power devices of the solid-state transmitter during operation. In addition, it also plays a certain filtering role.

(2) The present invention designs the internal structure of the first and second intermediate tank circuits, especially the setting method of the changeover switch. Only by closing and disconnecting the first and second intermediate tank circuit changeover switches can the The solid-state low-frequency transmitter performs segmented tuning of the working frequency band, and the adjustable inductance coils of the first and second intermediate tank circuits can also play the role of adjusting the inductance values of the first and last two fixed inductance coils of the Butterworth filter, thereby This enables the Butterworth filter to perform better as a matched filter.

(3) The present invention designs the internal structure of the Butterworth filter, which can save the use of a large number of switches, so that on the one hand, the complexity of the tuning control system can be effectively reduced, and on the other hand, the frequency point switching can be shortened. time.

(4) The overall structure of the matched filter circuit designed in the present invention is compact, easy to control, and has the characteristics of good access impedance matching and segmental tuning. Practical tests show that it can greatly reduce the output current of the transmitter. wave content, has flexible impedance matching characteristics, and can effectively reduce the complexity of the tuning control system, so it is especially suitable for matching filtering applications of solid-state low-frequency transmitters.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is the schematic block diagram of the overall structure of the matched filter circuit of the solid-state low-frequency transmitter provided by the embodiment of the present invention;

FIG. 2 is a specific circuit structure diagram of a matched filter circuit for a solid-state low-frequency transmitter provided by an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

The terms "first", "second" or "third" in the specification, claims or above drawings of the present application are used to distinguish different objects, rather than to describe a specific order. Furthermore, the terms "include" and "have", as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally also include Other steps or elements inherent to the process, method, product or apparatus may be included.

In one embodiment, a schematic diagram of the overall structure of the matched filter circuit of the solid-state low-frequency transmitter designed according to the present invention is shown in Figure 1. The matched filter circuit includes the first intermediate tank circuit, the Butterworth filter device and the second intermediate tank circuit, wherein the two ends of the Butterworth filter are respectively connected in series with the first intermediate tank circuit and the second intermediate tank circuit, and its grounding end is connected to the earth; one end of the first intermediate tank circuit (shown as the left end in the figure) is connected to the output end of the sending host, and the other end (shown as the right end in the figure) is connected to the input end of the Butterworth filter; one end of the second intermediate tank circuit (shown as the left end in the figure) ) is connected to the output of the Butterworth filter, while the other end (shown as the right end in the figure) is connected to the input of the post-stage coupling circuit.

As shown in Figure 2, the first and second intermediate tank circuits each include a capacitor frame group and an adjustable inductance coil group connected in series, wherein the capacitor frame group consists of a main capacitor frame with a relatively large overall capacitance value and an overall capacitance More than one additional capacitor frame with relatively small value is composed together, and the main capacitor frame is always connected in series to the matching filter main circuit, and the additional capacitor frames are respectively connected in parallel with the main capacitor frame through the corresponding switch to the matching filter main circuit, by This can be done through the operation of closing the switch, so that the additional capacitor frame is connected to the main circuit of the matched filter; The connection between the adjustable inductance coils of the tank circuit is connected to the access point of the Butterworth filter via a switch, and the connection between the adjustable inductance coils of the second intermediate tank circuit is connected via a switch It is connected to the access point of the post-stage coupling circuit, so that part of the adjustable inductance coil can be short-circuited from the main circuit of the matched filter by closing the switch.

Referring to FIG. 2 , a schematic diagram of a circuit configuration of a matched filter circuit according to a preferred embodiment of the present invention is exemplarily shown. As shown in Figure 2, the matched filter circuit includes a first intermediate tank circuit, a Butterworth filter, and a second intermediate tank circuit connected in sequence, wherein for the first intermediate tank circuit, its capacitor frame group It is composed of a main capacitor rack C11 with a relatively large overall capacitance value and an additional capacitor rack C12 with a relatively small overall capacitance value, and the main capacitor rack C11 is always connected in series to the main circuit of the matching filter, while the additional capacitor rack C12 is connected via The corresponding switch K11 and the main capacitor frame C11 are connected in parallel to the main circuit of the matched filter; its adjustable inductance coil group is composed of two adjustable inductance coils L11 and L12 connected in series with each other in the main circuit of the matched filter, and the two The intermediate connection of the adjustable inductance coil is connected to the access point of the Butterworth filter through a switch K12.

For the second intermediate tank circuit, its capacitor frame group is composed of a main capacitor frame C31 with a relatively large overall capacitance value and an additional capacitor frame C32 with a relatively small overall capacitance value, and the main capacitor frame C31 It is always connected in series to the main circuit of matching filter, and the additional capacitor frame C32 is connected in parallel with the main capacitor frame C31 to the main circuit of matching filter via corresponding switch K31; its adjustable inductance coil group is connected in series with each other in the main circuit of matching filter Three adjustable inductance coils L31 , L32 and L33 are jointly formed, and the connections between the three adjustable inductance coils are respectively connected to the access points of the subsequent stage coupling circuit via switches K32 and K33 .

For the Butterworth filter, it is composed of four fixed inductance coils L21, L22, L23 and L24 and three capacitor frames C21, C22 and C23, wherein the first fixed inductance coil L21 at both ends and the fourth fixed inductance coil The inductance value of the inductance coil L24 is the same, and the inductance value of the second fixed inductance coil L22 and the third fixed inductance coil L23 in the middle is the same; The overall capacitance value of rack C23 is the same, while the overall capacitance value of the centrally disposed second capacitor rack C22 is different from the overall capacitance value of either C21 or C23.

According to a preferred embodiment of the present invention, for the main capacitor frame and the additional capacitor frame of the above-mentioned first and second intermediate tank circuits, they each include a plurality of capacitor groups arranged in series with each other on the busbar, and each capacitor group is composed of It is composed of multiple capacitors connected in parallel; in addition, the capacitor frame as a whole is fixed to the ground by insulating brackets, and at the same time, it prevents its internal capacitance from discharging to the ground. In addition, for the multiple adjustable inductance coils of the adjustable inductance coil groups of the first and second intermediate tank circuits, their respective adjustable ranges of inductance values are the same, and it is preferable to control the linkage of multiple inductance coils through a servo motor. In this way, the inductance value adjustment of the inductance coil is realized.

According to another preferred embodiment of the present invention, the Butterworth filter is composed of multiple fixed inductors and multiple capacitor frames, wherein the multiple fixed inductors are connected in series with each other in the main circuit of the matched filter, and each of the capacitor frames is respectively It is composed of a plurality of capacitors arranged in parallel with each other on the busbar, and one end of the overall structure of each capacitor frame is respectively connected to the connection between the plurality of fixed inductances, and the other end of the overall structure of each capacitor frame is respectively grounded. In addition, as a further preference, the Butterworth filter is composed of four fixed inductors and three capacitor frames, wherein the first fixed inductor at both ends has the same inductance value as the fourth fixed inductor, and the second fixed inductor in the middle The inductance values of the fixed inductance and the third fixed inductance are the same; for the above three capacitor frames, the overall capacitance values of the first capacitor frame and the third capacitor frame are the same, while the overall capacitance values of the second capacitor frame are different.

The conceptual principles and related technical effects of the present invention will be further explained in detail below.

By adding an intermediate tank circuit and designing the capacitor rack groups of the first and second intermediate tank circuits to be adjustable in sections as described above, and the main capacitor rack with a relatively large overall capacitance value is always connected in series in the main circuit of the matched filter In the above, the additional capacitor racks with relatively small overall capacitance values are respectively connected in parallel with the main capacitor racks via the corresponding switches to the main matching filter circuit. break away. At the same time, the inductance coil groups of the first and second intermediate tank circuits are designed to be continuously adjustable as described above, and the connections between these adjustable inductance coils are respectively connected to the Butterfly via corresponding switches. In this way, by closing the switch, some of the adjustable inductance coils can be short-circuited from the main circuit of the matched filter.

According to the above design, the capacitor frame group and the adjustable inductance coil group can form a series resonant circuit, and the frequency segmentation can be realized by changing the number of capacitor frames connected to the matching filter main circuit, and by changing the inductance of the adjustable inductance coil group value to achieve series resonance, the corresponding first intermediate tank can make the access impedance of the sending host approximately purely resistive, thereby reducing the influence of the access loop on the power amplifier circuit of the sending host, and the second intermediate tank can make the Bart The access impedance of the circuit after the Worth filter is approximately purely resistive, thereby reducing the influence of the primary self-inductance of the coupling circuit on the resonant previous stage loop; especially, the first and second intermediate tank circuits themselves can Play a certain role in suppressing harmonics, and their adjustable inductance coils can also adjust the inductance value of the two fixed inductance coils at the beginning and end of the Butterworth filter, so that the Butterworth filter can play a better role Matched filtering effect.

The Butterworth filter is composed of a plurality of fixed inductance coils and a plurality of capacitor frames, and the multiple fixed inductance coils are connected in series with each other in the main circuit of the matched filter, and the capacitor frames are respectively arranged in parallel with each other on the busbar. A plurality of capacitors are jointly formed, and one end of the overall structure of each capacitor frame is respectively connected to the connection between the plurality of fixed inductance coils, and the other end of the overall structure of each capacitor frame is grounded.

According to the above design, the Butterworth filter composed of a fixed capacitor frame and a fixed inductance coil can suppress the high-order harmonic component of the output current of the sending host, and can realize the impedance matching between the sending host and the subsequent circuit. At the same time, the use of a large number of switching switches can be omitted, the complexity of the tuning control system can be effectively reduced, and the frequency point switching time can also be shortened.

In practical applications, for example, for the embodiment shown in Figure 2, the number of capacitor frames selected within a frequency range is fixed, and the continuous adjustment of the inductance value is realized by controlling the rotation of the adjustable inductance coil by the servo motor , so that the tuning operation of the first intermediate tank circuit at any frequency point within the frequency band can be realized. For example, the angular frequency of the center frequency point of the first frequency band of the first intermediate tank circuit is ω. In order to ensure that the actual Q value conforms to the engineering experience value, the Q value at the center frequency point is selected as 6, and the characteristic impedance is 10Ω. According to the formula C=1 /ωRQ can calculate the capacitance value required for the first frequency band, and at the same time, the range of inductance required for the first frequency band can be calculated by the formula L=1/ω ² C. The same method can be used to calculate the required capacitance value and required inductance range of the second frequency band. The capacitance value of the main capacitor frame is the capacitance value required by the second frequency band, and the capacitance value of the additional capacitor frame is the difference between the respective required capacitance values of the first and second frequency bands. In order to facilitate the linkage tuning operation of the adjustable inductance coil with the servo motor, the two adjustable inductance coils of the adjustable inductance coil group are designed to be the same, and the use of the adjustable inductance coil group in conjunction with the switch can provide a range of inductance values The lower limit is not greater than the minimum value of the inductance required by the two frequency bands, and the upper limit is not less than the maximum value of the inductance required by the two frequency bands respectively.

The second intermediate tank circuit is also designed according to the aforementioned two frequency bands. The difference is that since the coupling circuit is connected behind the second intermediate tank circuit, the range of inductance adjustment needs to be larger, so three adjustable inductance coil groups are selected. An adjustable inductance coil, and the Q value at the center frequency point is selected to be 7 during calculation, and the calculation method of its electrical parameters is consistent with that of the first intermediate tank circuit.

In addition, it can be seen from the structure of a typical Butterworth filter that the inductance values of the fixed inductance coils L21 and L24 of the Butterworth filter can be the same, the inductance values of the fixed inductance coils L22 and L23 can be the same, and the inductance values of the fixed capacitor frames C21 and C23 can be the same. Capacitor values are the same. The above-mentioned capacitance and inductance values can be calculated according to the cut-off frequency and characteristic impedance value required by the design. In particular, in order to maintain design consistency, the structures of the three required fixed capacitor frames can be kept exactly the same, and only the fixed capacitor frame C21 needs to be equipped with some capacitors more than the other two capacitor frames.

What is described above is only an exemplary embodiment of the present disclosure, and should not limit the scope of the present disclosure. That is, all equivalent changes and modifications made according to the teachings of the present disclosure still fall within the scope of the present disclosure. Other embodiments of the disclosure will be readily apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. The present invention intends to cover any modification, use or adaptation of the present disclosure. These modifications, uses or adaptations follow the general principles of the present disclosure and include common knowledge or conventional technical means in the technical field not recorded in the present disclosure. . The specification and examples are to be considered exemplary only, with the scope and spirit of the present disclosure defined by the claims.

The technical features of the above embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, they should be It is considered to be within the range described in this specification.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (7)

1. A solid state low frequency transmitter matched filter circuit, comprising: the first intermediate tank circuit, the Butterworth filter and the second intermediate tank circuit are electrically connected in sequence;

the Butterworth filter is used for impedance matching and restraining higher harmonic components;

the first middle tank circuit and the second middle tank circuit respectively comprise a capacitor frame group and an adjustable inductance coil group which are connected in series;

the capacitor rack group is composed of a main capacitor rack with a relatively large overall capacitance value and a plurality of additional capacitor racks with relatively small overall capacitance values, the main capacitor rack is always connected into the main matched filter loop in series, and the additional capacitor racks are respectively connected into the main matched filter loop in parallel with the main capacitor rack through corresponding change-over switches; the first middle tank circuit is connected with an external transmitting host through an access point of a capacitor rack group;

the adjustable inductance coil group is composed of a plurality of adjustable inductance coils which are connected in series with each other in the main matched filter loop, the connection position of the adjustable inductance coils of the first middle tank circuit is connected with the access point of the Butterworth filter through a change-over switch, and the connection position of the adjustable inductance coils of the second middle tank circuit is connected with the access point of an external rear coupling circuit through a change-over switch.

2. The matched filter circuit as claimed in claim 1, wherein the capacitor holder set of the first intermediate tank circuit is composed of a main capacitor holder having a relatively large overall capacitance value and an additional capacitor holder having a relatively small overall capacitance value; the adjustable inductance coil group of the first middle tank circuit is formed by two adjustable inductance coils which are mutually connected in series in the matched filtering main loop.

3. The matched filter circuit as recited in claim 1, wherein the capacitor bank of the second middle tank circuit is comprised of a main capacitor bank having a relatively large overall capacitance value and an additional capacitor bank having a relatively small overall capacitance value; and the adjustable inductance coil group of the second middle tank circuit is formed by three adjustable inductance coils which are mutually connected in series in the matched filtering main circuit.

4. The matched filter circuit as claimed in any one of claims 1 to 3, wherein the main capacitor holder and the additional capacitor holder each comprise a plurality of capacitor groups arranged in series with each other on a busbar, each of the capacitor groups being composed of a plurality of capacitors connected in parallel with each other.

5. A matched filter circuit as claimed in any one of claims 1 to 3 wherein the adjustable range of inductance values of each of said adjustable inductors is the same and the linkage of the plurality of adjustable inductors is controlled by a servo motor.

6. The matched filter circuit as claimed in claim 1, wherein said butterworth filter is composed of a plurality of fixed inductors connected in series in said matched filter main loop and a plurality of capacitor holders each composed of a plurality of capacitors disposed in parallel with each other on a bus bar; one end of the integral structure of each capacitor rack is respectively connected to the connection position of the fixed inductance coils, and the other end of the integral structure of each capacitor rack is respectively grounded.

7. The matched filter circuit as claimed in claim 6, wherein said Butterworth filter is composed of four said fixed inductors and three said capacitor holders, wherein the inductance values of the first and fourth fixed inductors at both ends are the same, and the inductance values of the second and third fixed inductors in the middle are the same; for the three capacitor holders, the total capacitance values of the first capacitor holder and the third capacitor holder at two ends are the same, and the total capacitance value of the second capacitor holder in the middle is different from the total capacitance values of the other two capacitor holders.

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