Design method for miniaturization of fine stepping direct combination source

Abstract

The invention belongs to the technical field of direct frequency synthesis, and relates to a design method for miniaturization of a fine-stepping direct synthesis source, which comprises the following steps of: obtaining a frequency interval and a frequency range according to a design target; analyzing the stray according to the frequency division of the high-frequency standard and the low-frequency standard; the high-frequency standard is filtered out through a switch filter, and the low-frequency standard is obtained by carrying out variable frequency division, frequency mixing, amplification and switch filtering on part of frequency points; performing frequency mixing and switch filtering on the high-frequency standard and the low-frequency standard to obtain a design target; the integrated level is high, and miniaturization and light weight are achieved. A cavity filter and an LC filter are all replaced by strip line interdigital filters to be embedded in a PCB, the strip line interdigital filters and other microwave radio frequency devices are subjected to integrated design, and the advantage that the high-frequency strip line interdigital filters are small in size is utilized, so that miniaturization design and light weight are achieved; by adopting a variable frequency division thought, the circuit complexity is simplified, and the filtering difficulty is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of direct frequency synthesis, and in particular relates to a design method for miniaturizing a fine-step direct frequency synthesis source. Background Art

[0002] Frequency source is the basic signal source of all electronic systems (radar, communication, measurement and control, navigation, etc.), so it is regarded as the "heart" of many electronic systems. The realization of electronic system functions directly depends on the performance of frequency source. With the development of modern electronic technology, electronic systems such as radar, wireless communication, electronic countermeasures, etc. have put forward higher and higher requirements for frequency source. Ultra-wideband, low phase noise, low spurious, fast frequency agility and miniaturization of frequency source have become a hot research topic and the main development trend. Especially for electronic equipment on airborne platforms, the miniaturization requirements of its core components are getting higher and higher. Direct analog frequency synthesizer is a frequency synthesis technology based on a reference crystal oscillator, which is combined by frequency multiplication, frequency division, mixing and switch filtering. The generated signal has the advantages of high frequency stability, fast frequency conversion speed and low close-load phase noise. However, since this method uses more frequency division, frequency multiplication and mixing structures, and these frequency change structures are usually not simple, the designed fine-step direct frequency synthesizer has the disadvantages of large size, more spurious and difficult to suppress, high manufacturing cost and power consumption.

[0003] Therefore, how to achieve the miniaturization of fine-step direct frequency synthesizer is a problem that needs to be solved. Summary of the invention

[0004] The purpose of the present application is to provide a design method for miniaturizing a fine-step direct frequency synthesizer to solve the shortcomings of existing fine-step direct frequency synthesizers, such as large size, more spurious signals that are difficult to suppress, and high manufacturing costs and power consumption.

[0005] The technical solution of the present application is: a design method for miniaturizing a fine-step direct-combination source, comprising:

[0006] First determine the design goal, and then obtain the frequency interval and frequency range based on the design goal;

[0007] Determine the frequency division of the high-frequency frequency mark and the low-frequency frequency mark according to the frequency interval and the frequency range, analyze the spurious according to the frequency division of the high-frequency frequency mark and the low-frequency frequency mark, and determine whether the spurious can be filtered out by the filter. If not, re-divide the frequency; if yes, proceed to the next step; the frequency division is uniform, and the frequency interval of the high-frequency frequency mark is less than or equal to the bandwidth of the low-frequency frequency mark;

[0008] A comb spectrum generator is used to generate several frequency points with the same frequency interval as the high-frequency frequency standard, and the high-frequency frequency standard is filtered out through a switch filter. The low-frequency frequency standard is obtained by variable frequency division, mixing, amplification, and switch filtering of some frequency points;

[0009] The high-frequency and low-frequency standards are mixed and switched to obtain the design target.

[0010] Preferably, after generating a number of frequency points with the same frequency interval as the high-frequency frequency mark, the frequency points are divided into three paths through a power divider, namely a high-frequency path, an intermediate-frequency path and a low-frequency path; a mixer is arranged between the intermediate-frequency path and the low-frequency path, and the low-frequency frequency mark is obtained through the mixer; the high-frequency path obtains the high-frequency frequency mark.

[0011] Preferably, the stepping of a plurality of frequency points having the same frequency interval as the high frequency standard is 600 MHz.

[0012] Preferably, the switch filter is a stripline interdigital filter.

[0013] Preferably, when performing mixing filtering, the stripline interdigital filter is embedded in the PCB board, and the stripline interdigital filter signal is transmitted to the microstrip line layer through the stripline to microstrip line transition structure, which is integrated with the amplifier, mixer and RF switch.

[0014] Preferably, the frequency interval of the low-frequency marker is the same as the frequency interval of the design target.

[0015] The design method of the fine-step direct-combination source miniaturization of the present application has the following advantages:

[0016] 1) High integration, miniaturization and lightweight. The cavity filter and LC filter are completely replaced by stripline interdigital filters embedded in the PCB board, and integrated with other microwave RF devices. The small size advantage of high-frequency stripline interdigital filters is used to achieve miniaturization and lightweight.

[0017] 2) Low-cost design. By adopting the idea of ​​variable frequency division, the circuit complexity is simplified and the filtering difficulty is reduced. Since the filter is embedded in the PCB board, the cost of the filter after batch production can be basically ignored, thus achieving low-cost design.

[0018] 3) Low assembly difficulty and high reliability. The filter is directly processed in the PCB, which has strong batch consistency and reliability, eliminating the assembly of LC filters and cavity filters, and avoiding the risk of performance degradation due to unreliable fixing of the filter in a vibration environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0020] Figure 1 This is a schematic diagram of the overall process of this application;

[0021] Figure 2 This is the design principle diagram of the fine-step direct-coupled source for this application;

[0022] Figure 3 This is a block diagram of the implementation principle of the detailed step-by-step direct-integrated source of this application. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] A design method for miniaturization of fine-step direct-combination sources, such as Figure 1 and Figure 2 As shown, the following steps are included:

[0025] Step S100, first determine the design goal, and obtain the frequency interval and frequency range according to the design goal; for example, obtain signals of 1.1-1.4 GHz, 900-1510 MHz, and 6.6-11.4 GHz respectively, and generate a group of n points with a frequency interval of Δf (L band) and a group of m points with a frequency interval of Δf×n (X band).

[0026] Step S200, determining the frequency division of the high-frequency mark and the low-frequency mark according to the frequency interval and the frequency range, analyzing the spurious according to the frequency division of the high-frequency mark and the low-frequency mark, and determining whether the spurious can be filtered out by the filter, if not, re-dividing the frequency; if yes, proceeding to the next step; the frequency division is uniform, and the frequency interval of the high-frequency mark is less than or equal to the bandwidth of the low-frequency mark;

[0027] After generating several frequency points with the same frequency interval as the high-frequency frequency standard, the frequency points are divided into three paths through a power divider, namely, a high-frequency path, an intermediate-frequency path, and a low-frequency path; a mixer is set between the intermediate-frequency path and the low-frequency path, and a low-frequency frequency standard is obtained through the mixer; a high-frequency path obtains a high-frequency frequency standard. Among them, the stepping of several frequency points with the same frequency interval as the high-frequency frequency standard is 600MHz.

[0028] Step S300, a comb spectrum generator is used to generate a number of frequency points with the same frequency interval as the high-frequency frequency mark, the high-frequency frequency mark is filtered out by a switch filter, and the low-frequency frequency mark is obtained by variable frequency division, mixing, amplification, and switch filtering of some frequency points;

[0029] Preferably, the switch filter is a stripline interdigital filter.

[0030] When performing mixing filtering, the stripline interdigital filter is embedded in the PCB board, and the stripline interdigital filter signal is transmitted to the microstrip layer through the stripline to microstrip transition structure, which is integrated with the amplifier, mixer and RF switch.

[0031] The stripline interdigital filter has obvious advantages in high isolation design, which can ensure that the extracted signal has low spurious characteristics. At the same time, the small size advantage of the high-frequency stripline interdigital filter is used to achieve low-cost and miniaturized design.

[0032] Step S400, mixing and switching filtering the high frequency mark and the low frequency mark to obtain the design target. Preferably, the frequency interval of the low frequency mark is the same as the frequency interval of the design target.

[0033] As a specific implementation method, the following is described with a specific example:

[0034] like Figure 3 As shown, the 100M signal is first multiplied by 6, and then a 600MHz signal is obtained after amplification and filtering. After the 600MHz signal passes through the comb spectrum generator, a comb spectrum signal with a spacing of 600MHz is obtained. After the comb spectrum signal is amplified, the power is divided into 3 paths. One path passes through the switch filter group 3, amplification, 6-frequency division, filtering and amplification to obtain a signal frequency range of 1.1~1.4GHz, with a step of 100MHz, which is used as the local oscillator input signal of mixer 1. One path passes through the switch filter group 2, amplification, variable frequency division and filtering to obtain a signal frequency range of 120~210MHz, with a step of 10MHz, which is used as the intermediate frequency input signal of mixer 1. The signal obtained by mixing is amplified and the switch filter group 4 to obtain a signal frequency range of 900~1510MHz, with a step of 10MHz. This signal is used as the intermediate frequency input signal of mixer 2.

[0035] The last comb spectrum signal passes through the switch filter group 3 and is amplified to obtain a signal frequency range of 9.6 to 11.4 GHz with a step of 600 MHz. This signal is used as the local oscillator input signal of mixer 2. The output signal of mixer 2 passes through the switch filter group 5 and is amplified to obtain a signal frequency range of 6.6 to 11.4 GHz with a step of 10 MHz.

[0036] The frequency division of the switch filter group mentioned above is shown in Table 1. The filters in the switch filter group are all implemented in the form of stripline interdigital filters and are integrated with microwave devices.

[0037] Table 1 Frequency planning of switch filter bank

[0038]

[0039] Through the above design, the advantages of this application are as follows:

[0040] 1) High integration, miniaturization and lightweight. The cavity filter and LC filter are completely replaced by stripline interdigital filters embedded in the PCB board, and integrated with other microwave RF devices. The small size advantage of high-frequency stripline interdigital filters is used to achieve miniaturization and lightweight.

[0041] 2) Low-cost design. By adopting the idea of ​​variable frequency division, the circuit complexity is simplified and the filtering difficulty is reduced. Since the filter is embedded in the PCB board, the cost of the filter after batch production can be basically ignored, thus achieving low-cost design.

[0042] 3) Low assembly difficulty and high reliability. The filter is directly processed in the PCB, which has strong batch consistency and reliability, eliminating the assembly of LC filters and cavity filters, and avoiding the risk of performance degradation due to unreliable fixing of the filter in a vibration environment.

[0043] Finally, it should be noted that: the drawings of the embodiments disclosed in the present invention only involve structures related to the embodiments disclosed in the present invention, and other structures can refer to common designs. In the absence of conflicts, the same embodiment and different embodiments of the present invention can be combined with each other;

[0044] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A design method for miniaturizing a fine-step direct-coupled source, characterized in that: include: First determine the design goal, and then obtain the frequency interval and frequency range based on the design goal; Determine the frequency division of the high-frequency frequency mark and the low-frequency frequency mark according to the frequency interval and the frequency range, analyze the spurious according to the frequency division of the high-frequency frequency mark and the low-frequency frequency mark, and determine whether the spurious can be filtered out by the filter. If not, re-divide the frequency; if yes, proceed to the next step; the frequency division is uniform, and the frequency interval of the high-frequency frequency mark is less than or equal to the bandwidth of the low-frequency frequency mark; A comb spectrum generator is used to generate several frequency points with the same frequency interval as the high-frequency frequency standard, and the high-frequency frequency standard is filtered out through a switch filter. The low-frequency frequency standard is obtained by variable frequency division, mixing, amplification, and switch filtering of some frequency points; The high-frequency and low-frequency standards are mixed and switched to obtain the design target.

2. The low-cost miniaturized design method of the fine-step direct-coupled source according to claim 1, characterized in that: After generating several frequency points with the same frequency interval as the high-frequency frequency mark, the frequency points are divided into three paths through a power divider, namely a high-frequency path, an intermediate-frequency path and a low-frequency path; a mixer is set between the intermediate-frequency path and the low-frequency path, and the low-frequency frequency mark is obtained through the mixer; the high-frequency path obtains the high-frequency frequency mark.

3. The low-cost miniaturized design method of the fine-step direct-coupled source according to claim 1, characterized in that: The step size of several frequency points with the same frequency interval as the high-frequency standard is 600MHz.

4. The low-cost miniaturized design method of the fine-step direct-coupled source according to claim 1, characterized in that: The switch filter adopts a stripline interdigital filter.

5. The low-cost miniaturized design method of the fine-step direct-coupled source according to claim 4, characterized in that: When performing mixing filtering, the stripline interdigital filter is embedded in the PCB board, and the stripline interdigital filter signal is transmitted to the microstrip layer through the stripline to microstrip transition structure, which is integrated with the amplifier, mixer and RF switch.

6. The low-cost miniaturized design method of a fine-step direct-coupled source as claimed in claim 1, characterized in that: The frequency interval of the low frequency marker is the same as the frequency interval of the design target.

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