CN111953302A

CN111953302A - Design scheme of EHF frequency band up-converter

Info

Publication number: CN111953302A
Application number: CN201910395881.4A
Authority: CN
Inventors: 吕涛
Original assignee: Sichuan Tianhesheng Electronic Technology Co ltd
Current assignee: Mianyang Tianhe Microwave Technology Co.,Ltd.
Priority date: 2019-05-14
Filing date: 2019-05-14
Publication date: 2020-11-17

Abstract

The invention discloses a design scheme of an EHF frequency band up-converter. The device is realized by 6 modules including an intermediate frequency processing module, a reference processing module, a C-waveband local oscillation frequency source module, a C-waveband up-conversion module, a K-waveband local oscillation frequency source module and a Q-waveband up-conversion module. The realization function is that the intermediate frequency input range is 950-1700 MHz, the radio frequency output range is 42500-45500 MHz, the input power range is-50 dBm-0 dBm, and the output power is not less than 0 dBm.

Description

Design scheme of EHF frequency band up-converter

Technical Field

The invention relates to the field of microwave engineering.

Background

With the rapid development of communication, millimeter waves have gradually become hot spots. Many civilian and military devices have moved gradually to millimeter wave. The millimeter wave is one of the main frequency bands developed in the international communication in recent years, and is characterized by narrow wave beam, strong secrecy and anti-interference capability, large capacity, easy image and digital compatibility, small system volume, low weight, low-voltage power supply and quasi-all-weather working capability. These features are precisely what is needed for precision guided weapons and various aircraft. In view of these advantages, with the advent of the information age, the microwave band is becoming more crowded, and with the demand for the development of precision guided weapon systems, the development of millimeter wave technology is very rapid.

Through long-term continuous efforts, the satellite communication ground station of our army at present covers frequency bands such as UHF, C, Ku, Ka and the like, and realizes the localization of part of equipment. The EHF satellite communication is used as a newly developed military satellite communication frequency spectrum resource in China, and has the advantages of large communication capacity, strong anti-jamming capability and anti-interception capability, high viability and the like. The development of foreign EHF frequency band satellite communication starts earlier. The first military relay star (Milstar) was launched in 1994 in the united states. The Milstar system is used to command strategic and tactical forces and relay intelligence from spyware satellites and other sources to provide a global, high-viability, interference-free, secure, extremely high frequency satellite communication system in all levels of conflict, including full combat. The Milstar in the united states has now evolved to the third generation. In addition to the united states, the united kingdom and the north organization also own satellites with EHF transponders.

Since the EHF band is mainly applied to military satellite communications, there are few reports on detailed disclosure of its earth station radio frequency equipment. It can be confirmed that the working principle, the composition scheme and the key indexes of the radio frequency equipment are not substantially different from those of the radio frequency equipment of the earth station in other frequency bands.

Disclosure of Invention

The invention provides a design scheme of an EHF frequency band up-converter, which comprises the following specific steps:

1. the up-converter consists of 6 modules including an intermediate frequency processing module, a reference processing module, a C-band local oscillation frequency source module, a C-band up-converter, a K-band local oscillation frequency source module and a Q-band up-converter;

2. the intermediate frequency processing module finishes the dynamic amplification of 0.95 GHz-1.7 GHz signals and sends the signals to the frequency mixing unit;

3. the reference processing module completes the processing of the external reference signal and the built-in reference signal;

4. the C-band local oscillation frequency source module completes the generation of a 5GHz local oscillation source;

5. the C-band up-converter completes the functions of first up-conversion, filtering, amplification and the like of the intermediate frequency signal, and outputs 5.95-6.7 GHz by adopting addition;

6. the K-waveband local oscillation frequency source module completes the generation of 36.55-38.8 GHz local oscillation sources;

7. and the Q-band up-converter completes the functions of secondary up-conversion, filtering and the like of the K-band local oscillator and the intermediate frequency signal.

Drawings

FIG. 1 is a schematic diagram of an EHF frequency band up-converter design;

FIG. 2 is a schematic diagram of an implementation of an intermediate frequency processing module;

FIG. 3 is a schematic diagram of a detailed implementation of an intermediate frequency processing module;

FIG. 4 is a schematic diagram of a reference signal processing module implementation;

FIG. 5 is a schematic diagram of an implementation of a local oscillator frequency source module;

FIG. 6 is a schematic diagram of an expected completion indicator for a local oscillator frequency source module;

FIG. 7 is a schematic diagram of a C-band up-converter design;

FIG. 8 is a detailed design diagram of a C-band up-converter;

FIG. 9 is a schematic diagram of a design scheme of an X-band local oscillation source module;

FIG. 10 is a schematic diagram of a design scheme for frequency doubling of an X-band signal to a K-band signal;

FIG. 11 is a schematic diagram of a Q-band upconverter design;

FIG. 12 is a schematic diagram of a detailed design scheme of a Q-band up-converter.

Detailed Description

1. Design scheme of intermediate frequency processing module

As shown in fig. 2, the module realizes dynamic amplification of 0.95GHz to 1.7GHz signals, and sends the amplified signals to the mixer unit, which is realized in detail as shown in fig. 3.

As shown in fig. 2, a high pass filter is used for filtering to filter unnecessary low frequency interference, and a low pass filter is used for filtering high frequency spurs; the numerical control attenuation is to control the power and make the link work in a linear region as much as possible; the amplifier is used for amplifying a signal to a certain power and considering both the power distribution and the linearity of each frequency component after frequency mixing.

As shown in fig. 2, the step precision of each stage of the numerical control attenuator is 0.5dB, which effectively ensures the dynamic range and noise coefficient of the link; the OIP3 of the amplifier is larger than 35dBm, which can effectively guarantee the non-linearity requirement of the link.

To achieve the above requirements, the circuit of fig. 2 is shown in detail in fig. 3.

In fig. 3, it is emphasized that the rf choke of the amplifier is implemented with standard power supply devices, and the design is implemented with the power supply product TCCH-80+ of mini corporation.

2. Reference processing module design

The module completes the processing of the external reference signal and the built-in reference signal, as shown in fig. 4.

In fig. 4, the switching of the internal and external 10MHz reference signals is accomplished by an alternative switch, and both the control signal of the switch and the control signal of the internal crystal oscillator power supply are accomplished by an energy detection circuit of the external reference signal; after the selection of the reference signal is completed, the distribution circuit performs power division on the reference signal and supplies the reference signal to the central control unit and the local oscillator phase-locked loop respectively.

Because the reference index is directly related to the noise index of the whole machine, the power supply of the reference signal unit needs to strengthen filtering, and meanwhile, the isolation of other signals is paid attention to.

Index estimation:

a100 MHz VCXO was used, having the index

1) Tuning range: about + -10 ppm;

2) tuning voltage: 5V, and (5);

3) the impedance of the tuning end is more than 100 k;

4) phase noise: -115dBc/Hz (100Hz), -140dBc/Hz (1kHz), -150dBc/Hz (10kHz), -155dBc/Hz (100 kHz).

When the loop bandwidth is less than 100Hz, the upper phase noise limit for the generated 50GHz signal is: -61dBc/Hz (100Hz), -86dBc/Hz (1kHz), -96dBc/Hz (10kHz), -101dBc/Hz (100 kHz).

3. Design scheme of C-band local oscillator frequency source module

As shown in fig. 5, the module performs 5GHz local oscillator generation, which is performed by the integrated phase locked loop ADF 4355. The output of the phase-locked loop is passed through an amplifier and a low-pass filter to ensure power and harmonic levels. The predicted completion criteria are shown in FIG. 6.

4. Design scheme of C-band up-converter

As shown in fig. 7, the module performs the first up-conversion, filtering, amplification, and other functions of the intermediate frequency signal. Because the relative bandwidth becomes smaller after frequency conversion, the flatness of the in-band power is not a main contradiction, and the stability of the power in the full temperature range, the out-of-band spurious suppression, the nonlinear characteristic and the like are the main points of concern. In terms of engineering implementation, the power stabilization is completed by the intermediate frequency processing unit AGC shown in FIG. 2 in cooperation with the temperature detection data of the whole machine; the out-of-band spurious suppression is realized by a filter; the non-linear characteristic is guaranteed by the non-linear index of the amplifier.

In fig. 7, the high performance index is important, and the indexes such as out-of-band rejection, in-band flatness, port standing-wave ratio, etc. need to be paid attention to, and the implementation by using a cavity filter is considered.

Considering components:

1) a mixer: integrating the intermediate frequency and the flatness, and selecting SIM-83 +;

2) band-pass filter: in order to improve the local oscillation suppression degree, a high-order number metal cavity type filter is adopted, the filter is an important factor influencing flatness, and special attention is needed in design. The use of a limiter can be considered if necessary.

3) The amplifier and the low-pass filter are selected from common ones.

The clutter suppression index should preferably be greater than 65dBc or more, so the if input power and the filter out-of-band suppression characteristics are closely related. In addition, a reflection suppression circuit is needed at three ports of the mixer, so that standing waves are reduced.

Band-pass filter: the passband is 5.95 GHz-6.70 GHz, and the out-of-band rejection: 5GHz and below 65 dBc; frequencies of 6.90GHz and above are greater than 15 dBc. If the first filtering cannot complete the task, the filtering can be considered to be performed again after amplification, but the brought pressure is the flatness in the band.

The detailed implementation is shown in fig. 8.

5. K-band local vibration source module design scheme

According to the planning, the module is completed by adopting two parts, namely the X-band 9.1-9.7 GHz local vibration source generation respectively, as shown in figure 9; the frequency doubling generates 18.2 to 19.4GHz, as shown in FIG. 10.

And finally, the frequency of a signal input to a local oscillation port of the Q-band mixer is 36.55-39.8 GHz, and the phase noise index is limited by reference. If the selected VCXO is used as a reference and the loop bandwidth of the phase-locked loop is about 100Hz, the index of the 50GHz frequency point meets the following requirements: -63dBc/Hz (100Hz), -88dBc/Hz (1kHz), -98dBc/Hz (10kHz), -103dBc/Hz (100 kHz).

6. Q-band up-converter

The module is obviously different from the previous module, and in the implementation process, the C-band signal can be transited in the modes of common welding, gold wire bonding and the like; the active parts of local oscillation signals of K wave band, frequency mixing and amplification after frequency mixing, etc. must be realized by adopting micro-assembly process. The module is divided into two parts, namely a local oscillator signal generating part and an up-conversion link part, which are connected through a waveguide. The basic scheme is shown in fig. 11.

Considering the device type selection, the detailed design part is shown in fig. 12.

Claims

1. The utility model provides a design of EHF frequency channel up-converter which characterized in that comprises 6 modules altogether through intermediate frequency processing module, reference processing module, C wave band local oscillator frequency source module, C wave band up-conversion module, K wave band local oscillator frequency source module, Q wave band up-conversion module.

2. The up-conversion module of claim 1, wherein the radio frequency input range is 950-1700 MHz, the radio frequency output range is 42500-45500 MHz, the input power range is-50 dBm-0 dBm, the output power is not less than 0dBm, and internal and external references can be selected.