CN203675099U - Radio frequency front end of high-performance monitoring receiver - Google Patents

Abstract

The utility model relates to a radio frequency front end of a high-performance monitoring receiver, which is characterized in that an amplitude limiting and amplifying unit is an input end of the radio frequency front end and sequentially connected to a sub-octave filter bank unit and a first hybrid frequency unit; an output end 1 and an output end 2 of the first frequency mixing unit are connected to a low-frequency band second intermediate frequency processing unit and a high-frequency band second intermediate frequency processing unit respectively; an output end of the low-frequency band second intermediate frequency processing unit and an output end of the high-frequency band second intermediate frequency processing unit are connected with a signal input end of a third frequency mixing unit; 20MHz-3000MHz radio frequency signals get into the radio frequency front end of the receiver, amplitude limiting and amplification are carried out on the 20MHz-300MHz radio frequency signals at first, the 20MHz-300MHz radio frequency signals are transmitted to the sub-octave filter bank unit, 20-3000MHz signals within the bandwidth are divided into six sections, then high local oscillation frequency mixing and low local oscillation frequency mixing are carried out, the third frequency mixing unit output 10.7MHz signals, the 10.7MHz signals get into an automatic gain control unit and receive amplitude limiting control, and 10.7MHz intermediate frequency signals with the amplitude being maintained at about 0dbm are outputted. The radio frequency front end of the high-performance monitoring receiver is applicable to base band processing, and has the sufficient receiving bandwidth, image rejection, high complete machine gain and a low noise factor.

Description

A kind of high-performance monitoring receiver radio-frequency front-end

Technical field

The utility model relates to the equipment of radio communication, satellite communication field, particularly a kind of based on high-performance monitoring receiver radio-frequency front-end.A kind of design that image frequency is had to the radio-frequency front-end of the high-performance spectrum monitoring receiver of good inhibition, high sensitivity, low-noise factor more specifically.

Background technology

Along with the fast development without line computation and mobile device, the available bandwidth of radio-frequency spectrum is proposed to more and more higher requirement.Spectrum monitoring makes the supplier of communication and the supervision aspect can supervisory control system running, solves interference problem and carries out allocation rule.In the design of spectrum monitoring receiver, radio-frequency front-end index is harsher, generally needs the reception bandwidth of several GHz, and mirror image suppresses, and improves complete machine gain, and the problems such as noise-reduction coefficient are following.So the design studies of radio-frequency front-end plays a decisive role to the overall performance of receiver.

Summary of the invention

The purpose of this utility model, exactly for overcoming the deficiencies in the prior art, provides a kind of high-performance monitoring receiver radio-frequency front-end design, makes every effort to meet by this programme the harsh requirement of the property indices of monitoring receiver.Assurance has enough reception bandwidth, and mirror image suppresses, and improves complete machine gain, noise-reduction coefficient.

Make every effort to realize following characteristics: 1, adopt the method for frequency-division section Frequency mixing processing, full bandwidth is done to spectrum division, for different radiofrequency signals, do different Frequency mixing processing, reduced the frequency sweep bandwidth of a local oscillator, and effectively improve mirror image and suppress, reduce signal spuious.2. pair noise factor, complete machine gain, receiving sensitivity is calculated in detail, and index is outstanding.

The utility model is to realize by such technical scheme: a kind of high-performance monitoring receiver radio-frequency front-end, it is characterized in that, high-performance monitoring receiver radio-frequency (RF) front-end circuit is made up of limited range enlargement unit, sub-octave filter group unit, the first mixing unit, the first local oscillator unit, low-frequency range the second IF processing unit, high band the second IF processing unit, the second local oscillator unit, the 3rd mixing unit, the 3rd local oscillator unit and automatic gain control unit;

Limited range enlargement unit is the input of radio-frequency front-end, after connect successively sub-octave filter group unit, the first mixing unit; Connected the local oscillation signal input of the first mixing unit by the output of the first local oscillator unit, for it provides the first local oscillation signal;

Output 1 end of the first mixing unit is connected respectively the input of low-frequency range the second IF processing unit, the input of high band the second IF processing unit with output 2 ends;

The output of low-frequency range the second IF processing unit connects the 3rd mixing cell signal input;

The output of high band the second IF processing unit connects the 3rd mixing cell signal input;

The output of the second local oscillator unit connects high band the second IF processing unit local oscillation signal input provides the second local oscillation signal for it;

The output of the 3rd local oscillator unit connects the 3rd mixing unit local oscillation signal input; For it provides the 3rd local oscillation signal;

The 3rd mixing unit output is connected with automatic gain control unit input.

The beneficial effects of the utility model are: meet the harsh requirement of the property indices of monitoring receiver by this programme.Assurance has enough reception bandwidth, and mirror image suppresses, and improves complete machine gain, noise-reduction coefficient.

Accompanying drawing explanation:

Fig. 1, be the high-performance radio-frequency front end theory diagram the utility model proposes.

Fig. 2, be that the complete machine gain the utility model proposes distributes block diagram with noise factor.

Embodiment

Understand the utility model for clearer, describe in conjunction with the accompanying drawings and embodiments the utility model in detail:

As Figure 1-Figure 2, after the first frequency conversion, be exactly that intermediate-freuqncy signal is processed and intermediate-freuqncy signal detection.If use so high intermediate frequency, narrowband intermediate frequency filter is difficult to realize, and therefore intermediate-freuqncy signal must change to lower IF-FRE (for example 10.7MHz).While converting directly to 10.7MHz from the first high intermediate frequency, image frequency only departs from the signal 2 × 10.7MHz=21.4MHz being transformed.Due to limited isolation between the RF of frequency mixer and IF port, RF signal may lead directly to the first intermediate frequency, forms intermediate frequency feedthrough.Therefore, just very important to the inhibition of this image frequency.If the image frequency of corresponding the second frequency conversion of the frequency of input signal, this impact will appear on the second intermediate frequency.Therefore, require harsher to the inhibition of this image frequency response.Suppress requirement in order easily to realize mirror image, conventionally input signal is first transformed to the intermediate frequency of a centre from the first intermediate frequency, for example 321.4MHz.Then being just easier to realize mirror image by a suitable band pass filter suppresses.Again the second medium-frequency transformation is become to the 3rd intermediate frequency of 10.7MHz with same processing mode, thereby make intermediate-freuqncy signal reach easy-to-handle frequency range.

First radio-frequency input signals delivers to interdigital filter group after stepping decay, is strobed into frequency mixer by radio-frequency (RF) switch.Interdigital filter group is made up of 6 way switch band pass filters, for suppressing image frequency, and first via gating 2500～3000MHz signal; Second road gating 2100～2500MHz signal; Third Road selects 1800～2100MHz signal; Si road gating 1600～1800MHz signal; Wu road gating 1100MHz～1600MHz signal; Wu road gating 20MHz～1100MHz signal.

1100MHz adopts 601.4MHz Low IF principle with super band, takes respectively again high local oscillator and two kinds of modes of low local oscillator, that is: in this frequency range

In the time of≤1800MHz, local frequency f _lO=f _rF-601.4MHz, is 2398.6 MHz to the maximum, and minimum is 1198.6 MHz.

In the time of≤1800MHz, local frequency f _lO=f _rF+ 601.4MHz, is 2401.4 MHz to the maximum, and minimum is 1701.4MHz.

In the time of 20MHz～1100MHz, local frequency f _lO=f _rF+ 1221.4MHz, is 2321.4MHz to the maximum, and minimum is 1241.4MHz.

Owing to taking multiple mixing mode to switch, the first local oscillator only need cover 1198.6MHz-2401.4MHz frequency range.For realizing above requirement.The first local oscillator can adopt PLL monocycle fractional frequency division frequency synthesis technique, and reference frequency output is 1198.6MHz-2401.4MHz.601.4MHz and 1221.4MHz the first intermediate-freuqncy signal are after bandpass filtering, amplification, selected and the second local oscillator 620MHz signal mixing by radio-frequency (RF) switch, produce 601.4MHz the second intermediate-freuqncy signal, then with 590.7MHz the 3rd local oscillator mixing, produce 10.7MHz the 3rd intermediate-freuqncy signal, after intermediate-frequency filter, processed by baseband portion.

Following table is local oscillator harmonic wave table corresponding to input signal

Frequency input signal	20MHz～1100MHz	1100MHz～1600MHz	1600MHz～1800MHz
				Local frequency	1220MHz～2300MHz	1700MHz～2200MHz	2200MHz～2400MHz
Harmonic frequency	2440MHz～4600MHz	3400MHz～4400MHz	4400MHz～4800MHz
				Have or not in-band harmonic	Nothing	Nothing	Nothing
Frequency input signal	1800MHz～2100MHz	2100MHz～2500MHz	2500MHz～3000MHz
				Local frequency	1200MHz～1500MHz	1500MHz～1900MHz	1900MHz～2400MHz
Harmonic frequency	2400MHz～3000MHz	3000MHz～3800MHz	3800MHz～4800MHz
				Have or not in-band harmonic	Nothing	Nothing	Nothing

Take multiple mixing mode to switch, the first local oscillator only need cover 1198.6MHz-2401.4MHz frequency range, and has realized higher mirror image and suppressed, and has gone back simultaneously and has avoided radio frequency input and local oscillation signal to produce intermodulation, reference table 1.

The sensitivity of spectrum monitoring receiver is normally defined and shows average noise level (DANL), and this index has determined that spectrum monitoring receiver can measure the limit capacity of small-signal.According to the communication theory of receiver, for 290K(17 degree Celsius) ambient temperature, show average noise level by: LDAN=-174dBm(1Hz)+(10log(BN, IF/Hz)) dB+NFSA-2.5dB formula determine.Wherein BN, IF is the noise bandwidth of IF filter, NFSA is the noise factor (dB) of spectrum analyzer,-2.5dB is because sampling wave detector is owed to increase the weight of and the noise on average causing of logarithm level value to noise, thermal noise power when-174dBm (1Hz) is 290K for corresponding ambient temperature in 1Hz bandwidth, be exactly so-called noise floor, in other words conj.or perhaps to the absolute minimal noise level under fixed temperature.

According to design object requirement, minimum intermediate-frequency bandwidth is that 200Hz, optimum sensitivity are-107dBm.We regard noise bandwidth as by approximate three dB bandwidth, obtain NFSA < 46.5dB.Calculate by maximum sensitivity, step attenuator zero arranges, and stays 3dB surplus to distribute total noise of centrifuge coefficient and gain.Result of calculation is: NFSA=33dB.

Above result of calculation meets machine sensitivity index request.Can find out from index apportion model, in all kinds of radio-frequency devices and amplifier, the noise factor of putting during conversion loss, the second frequency converter conversion loss and the 10.7MHz low noise of programmable step attenuator Insertion Loss, radio frequency and intermediate-frequency filter and frequency mixer are preposition is that we must consider, catch these critical piece optimal design, complete indicator of distribution, guarantee to meet machine sensitivity.

According to the above description, can realize scheme of the present utility model in conjunction with art technology.

Claims (1)

1. a high-performance monitoring receiver radio-frequency front-end, it is characterized in that, high-performance monitoring receiver radio-frequency (RF) front-end circuit is made up of limited range enlargement unit, sub-octave filter group unit, the first mixing unit, the first local oscillator unit, low-frequency range the second IF processing unit, high band the second IF processing unit, the second local oscillator unit, the 3rd mixing unit, the 3rd local oscillator unit and automatic gain control unit;

Limited range enlargement unit is the input of radio-frequency front-end, after connect successively sub-octave filter group unit, the first mixing unit; Connected the local oscillation signal input of the first mixing unit by the output of the first local oscillator unit, for it provides the first local oscillation signal;

Output 1 end of the first mixing unit is connected respectively the input of low-frequency range the second IF processing unit, the input of high band the second IF processing unit with output 2 ends;

The output of low-frequency range the second IF processing unit connects the 3rd mixing cell signal input;

The output of high band the second IF processing unit connects the 3rd mixing cell signal input;

The output of the second local oscillator unit connects high band the second IF processing unit local oscillation signal input provides the second local oscillation signal for it;

The output of the 3rd local oscillator unit connects the 3rd mixing unit local oscillation signal input; For it provides the 3rd local oscillation signal;

The 3rd mixing unit output is connected with automatic gain control unit input.

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