CN105549038A - Radio frequency front-end circuit of L1-L2 dual-band satellite navigation receiver - Google Patents

Abstract

Disclosed in the invention is a radio frequency front-end circuit of an L1-L2 dual-band satellite navigation receiver. The radio frequency front-end circuit is composed of a radio frequency low-noise amplifier, a first-stage mixer, a second-stage mixer, a low-pass filter, a configurable complex band-pass filter, a variable-gain intermediate-frequency amplifier, an analog-digital converter, a frequency synthesizer and an eight-frequency divider. The circuit is capable of receiving dual-band satellite signals like GPS L1 and L2 signals, Beidou B1 and B2 signals, Glonass L1 and L2 signals; and demands of high-precision dual-band satellite positioning and navigation can be satisfied. Meanwhile, the circuit is characterized in that the circuit structure of the traditional dual-band receiver is simplified and simultaneous receiving of dual-band signals can be realized only by using one frequency synthesizer; single-antenna inputting is supported and image rejection by using an off-chip radio frequency unit and an intermediate-frequency filter is not needed, so that the power consumption and cost of the receiver radio frequency front-end circuit can be effectively reduced. Therefore, the provided circuit has the great industrial value in use.

Description

L1 and L2 two-band satellite navigation receiver radio-frequency (RF) front-end circuit

Technical field

The invention belongs to wireless communications chips design field, in particular to satellite navigation receiver radio-frequency (RF) front-end circuit.

Background technology

GPS (Global Position System) (GNSS) can be supplied to user's position, speed, temporal information accurately, and have round-the-clock, global, the feature such as real-time, high precision, therefore development in recent years is very rapid.At present, GPS (Global Position System) mainly comprises the GPS (GPS) of the U.S., Muscovite glonass system (Glonass), the Galileo system (Galileo) of European Union and the dipper system (BDS) of China.The satellite of each system all can launch the satellite-signal of multiple carrier frequency simultaneously earthward, such as: for commercial satellite signal, gps satellite sends L1 (1575.42MHz), L2 (1227.6MHz) two frequency band signals simultaneously, and the gps satellite of a new generation also add the satellite-signal of L5 (1176.45MHz) frequency range; Glonass satellite sends L1 (1602MHz), L2 (1246MHz) two frequency band signals simultaneously; There is E1 (1575.42MHz), E5 (1176.45MHz and 1207.14MHz) two frequency band signals in Galileo satellite simultaneously; Big-dipper satellite sends the signal of B1 (1561.098MHz), B2 (1207.14MHz) two frequency range simultaneously.If ground satellite receiver can receive the satellite-signal of two even multiple frequency ranges simultaneously, just can estimate ionosphere delay time error, improve positioning precision, hi-Fix application is very helpful.At present, most commercial satellite navigation neceiver can only receive the satellite-signal of single frequency band for the consideration of cost and power consumption, and positioning precision is not also generally very high.And the cost of existing dual band receiver is still comparatively high, domestic consumer cannot bear.Along with the development of infotech, the demand of high-precision applications can get more and more, in the urgent need to reducing cost and the power consumption of two-band satellite navigation receiver, so that be integrated in individual terminal devices.And radio-frequency (RF) front-end circuit is the key modules in satellite navigation receiver, it has very large impact to the performance of whole receiver, power consumption and cost.

Radio-frequency (RF) front-end circuit in traditional double band receiver generally by two independently radio frequency reception path form, as shown in Figure 1, every bar path all contains complete receiver components, generally comprises radio frequency low-noise amplifier LNA10/11, frequency mixer 20/21, wave filter 50/51, intermediate frequency amplifier 60/61, analog to digital converter ADC70/71 and frequency synthesizer 80/81 etc.Obviously, the circuit overhead of this dual band receiver is the twice of single frequency receiving, and needs double antenna to input, cost and power consumption higher.In addition, two frequency synthesizers are operated in different rf frequency places, easily produce interference mutually.In order to reduce cost and the power consumption of radio-frequency (RF) front-end circuit, improve stability, current existing document proposes some and improves one's methods.Such as, Chinese invention patent CN200710107693.4 proposes " adopting unipath radio-frequency front-end to realize GNSS multimode to walk abreast the method and device that receive ", adopt the method periodically switching receiving mode, realize the function of mono-channel radio-frequency front end receiver multi-mode signal.But, this method has some problems in practical engineering application, lack feasibility, such as: when receiving the satellite-signal of different frequency, the local oscillation signal switching different frequency is needed, if adopt multiple frequency synthesizer to realize, then can increase cost and power consumption, if adopt single frequency synthesizer to realize, during switching frequency, phaselocked loop needs longer stabilization time, generally can reach a few microsecond to tens microseconds.In addition, also need normally to work longer stabilization time in the process that radio frequency analog circuit switches in pattern.Therefore be difficult to the design philosophy realizing this invention in actual applications, do not see the example of application.Chinese invention patent application CN201010620937.0 proposes " a kind of single-chip dual-frequency global satellite navigation receiver ", satellite navigation signals is divided into the frequency separation of two image signals each other, two receiving cables receive the signal in different frequency interval respectively, two receiving cables share two frequency synthesizers, receive while achieving double frequency satellite navigation signals.When receiving two-band signal, the circuit structure of this invention is compared with the structure shown in Fig. 1, only two radio band frequency synthesizers are changed into a shared radio band frequency synthesizer (1.10GHz ~ 1.61GHz) and a Mid Frequency frequency synthesizer (150MHz ~ 220MHz), each receiver path changes the receiver of superhet into, need to use the outer passive intermediate-frequency filter of sheet, not there is cost advantage.In addition, when practical application, two receiver radio frequency input ends all must increase the suppression that radio-frequency filter carries out image frequency, otherwise cannot reach good receiving sensitivity performance.Chinese invention patent CN201010206235.8 proposes " a kind of radio frequency front-end device for dual-system and dual-frequency navigation receiver ", this invention realize circuit that two-band receives and the circuit structure that proposes of Chinese invention patent application CN201010620937.0 similar, also use superhet double conversion technology, difference is that two-band signal has shared radio frequency low-noise amplifier and first order frequency mixer, second level local oscillation signal is produced by first order local oscillation signal frequency division, saves the frequency synthesizer producing intermediate frequency local oscillator signal.Same, this circuit also needs to increase at rf inputs the suppression that radio-frequency filter carries out image frequency in the application, otherwise cannot suppress the interference of image frequency place noise, causes the decline of receiving sensitivity.But because this circuit having shared a road rf inputs when receiving two-band signal, causing certain difficulty to choosing suitable radio-frequency filter so again, therefore also not there is very strong practicality.

In sum, the existing receiver radio frequency front-end circuit that simultaneously can receive two-band satellite navigation signals maybe cannot realize lower cost and power consumption, or do not possess feasibility when practical application, low cost cannot be met, application demand that low-power consumption, two-band satellite-signal receive simultaneously.

Summary of the invention

Fundamental purpose of the present invention receives on the basis of L1 and L2 two-band satellite navigation signals at the same time, realize the function without the need to using outer radio frequency, intermediate-frequency filter and the support single antenna input of sheet, solution available circuit complex structure, the problem that cost is high, power consumption is large.

For achieving the above object, the present invention proposes a kind of two-band satellite navigation receiver radio-frequency (RF) front-end circuit, its circuit structure as shown in Figure 2, is made up of following module:

(1) radio frequency low-noise amplifier (LNA) 10, it is input as received RF signal, exports radiofrequency signal A, connect first order frequency mixer 20 after amplifying;

(2) first order frequency mixer 20, its input radio frequency signal A, mixing is carried out respectively with I road first local oscillation signal LO1_I and Q road first local oscillation signal LO1_Q, signal A is down-converted to the first IF-FRE by rf frequency, that is: A and LO1_I mixing exports I road first intermediate-freuqncy signal B1, A and LO1_Q mixing exports Q road first intermediate-freuqncy signal B2, B1 and B2 connects second level frequency mixer 30; Wherein, described I road, Q road are signal path, usually, and to be phase place be on the I road signal path of 0 degree, to be phase place be on the Q road signal path of 90 degree;

(3) second level frequency mixer 30, it is input as I, Q two-way first intermediate-freuqncy signal B1, B2, mixing is carried out respectively with I road second local oscillation signal LO2_I and Q road second local oscillation signal LO2_Q, first IF signal frequency is down-converted to the second IF-FRE, that is: B1 and LO2_I mixing exports first via II road second intermediate-freuqncy signal C1, B1 and LO2_Q mixing exports IQ road second intermediate-freuqncy signal C2, B2 and LO2_I mixing exports QI road second intermediate-freuqncy signal C3, B2 and LO2_Q mixing exports QQ road second intermediate-freuqncy signal C4, second intermediate-freuqncy signal C1, C2, C3, C4 connects low-pass filter 40,

(4) low-pass filter 40, it is input as II, IQ, QI, QQ tetra-tunnel second intermediate-freuqncy signal C1, C2, C3, C4, signal syntheses and low-pass filtering are carried out to it, that is: C1-C4 as I road the 3rd intermediate-freuqncy signal D1 of passage one after low-pass filtering, C2+C3 as Q road the 3rd intermediate-freuqncy signal D2 of passage one after low-pass filtering, C3-C2 as Q road the 3rd intermediate-freuqncy signal D3 of passage two after low-pass filtering, C1+C4 as I road the 3rd intermediate-freuqncy signal D4 of passage two after low-pass filtering, through above-mentioned process, passage one filters out the signal of L1 frequency range, suppress L2 frequency band signals, passage two filters out the signal of L2 frequency range, suppress the signal of L1 frequency range, achieve the separation of different frequency range signal, low-pass filter serves inhibiting effect to high frequency noise and undesired signal simultaneously, output signal D1, D2 connects the configurable multiple bandpass filter 50 in road one, D3, D4 connects the configurable multiple bandpass filter 51 in road two,

(5) the configurable multiple bandpass filter 50 of passage one, it is input as I road the 3rd intermediate-freuqncy signal D1 of passage one and Q road the 3rd intermediate-freuqncy signal D2 of passage one, plural bandpass filtering is carried out to it, filtering image frequency, 4th intermediate-freuqncy signal E1 of output channel one, connects variable-gain intermediate frequency amplifier 60;

(6) the configurable multiple bandpass filter 51 of passage two, it is input as Q road the 3rd intermediate-freuqncy signal D3 of passage two and I road the 3rd intermediate-freuqncy signal D4 of passage two, plural bandpass filtering is carried out to it, filtering image frequency, 4th intermediate-freuqncy signal E2 of output channel two, connects variable-gain intermediate frequency amplifier 61;

(7) the variable-gain intermediate frequency amplifier 60 of passage one, it is input as the 4th intermediate-freuqncy signal E1 of passage one, amplifies it, and the 5th intermediate-freuqncy signal F1 of output channel one connects the analog to digital converter (ADC) 70 in road one;

(8) the variable-gain intermediate frequency amplifier 61 of passage two, it is input as the 4th intermediate-freuqncy signal E2 of passage two, amplifies it, and the 5th intermediate-freuqncy signal F2 of output channel two connects the ADC71 in road two;

(9) ADC70, it is input as the 5th intermediate-freuqncy signal F1 of passage one, is converted into passage one digital signal and exports;

(10) ADC71, it is input as the 5th intermediate-freuqncy signal F2 of passage two, is converted into passage two digital signal and exports;

(11) frequency synthesizer 80, produces I, Q two-way first local oscillation signal LO1_I and LO1_Q, outputs to the first frequency mixer 20;

(12) 8 frequency dividers 90, it is input as the first local oscillation signal LO1_I or LO2_Q that frequency synthesizer 80 produces, 8 frequency divisions are carried out to it, produces I, Q two-way second local oscillation signal LO2_I and LO2_Q of 1/8 times of first local oscillator signal frequency, output to the second frequency mixer 30.

Wherein, radio frequency low-noise amplifier 10 can receive L1, L2 two-band satellite navigation signals simultaneously, such as GPSL1 and L2 signal, Big Dipper B1 and B2 signal, GlonassL1 and L2 signal etc.I, Q orthogonal mixer that first order frequency mixer 20 is made up of two sub-frequency mixer 201,202, for being down-converted to the first IF-FRE by radiofrequency signal.Second level frequency mixer 30 is made up of four sub-frequency mixer 301,302,303,304, sub-frequency mixer 301 and 302 forms road I, Q orthogonal mixer, sub-frequency mixer 303 and 304 forms another road I, Q orthogonal mixer, for the first IF-FRE signal is down-converted to the second IF-FRE.Low-pass filter 40 is made up of four subfilters 401,402,403,404, all can realize the synthesis of two-way input signal and the function of low-pass filtering, reaches the object being separated different frequency range signal and suppressing high frequency noise.Radio frequency low-noise amplifier 10, first order frequency mixer 20, second level frequency mixer 30 and the low-pass filter 40 with signal syntheses function can adopt different circuit typess to realize.Such as, above-mentioned several module all can adopt voltage mode (voltage input, voltage export) work, also radio frequency low-noise amplifier 10 can be designed to transconductance mode (voltage input, electric current export), now, first order frequency mixer 20 and second level frequency mixer 30 are current-mode (electric current input, electric current export), and low-pass filter 40 is across resistance pattern (electric current input, voltage export).Configurable multiple bandpass filter 50,51 realizes plural band-pass filtering function, and for filtering image frequency and the outer interference of band, its filter parameter can be configured, such as passband central frequency, pass band width etc.Variable-gain intermediate frequency amplifier 60,61 can amplify the 4th IF-FRE signal, its gain amplifier can be controlled by automatic gain control loop respectively, its amplitude exporting intermediate-freuqncy signal is made to reach the scope of ADC70,71 normally required by work, scope required by described normal work determined by ADC self-characteristic, the precision of such as ADC, or the maximum input range of ADC etc.The function of variable-gain intermediate frequency amplifier also can be merged in the configurable multiple bandpass filter 50,51 of prime and realize, multiple bandpass filter 50,51 is designed to the pattern of gain-variable, so just can dispense variable-gain intermediate frequency amplifier module, reduce circuit scale.I, Q two-way first local oscillation signal LO1_I and LO1_Q needed for first order frequency mixer 20 is produced by frequency synthesizer 80.I, Q two-way second local oscillation signal LO2_I and LO2_Q needed for second frequency mixer 30 is produced the first local oscillation signal LO1_I (or LO1_Q) frequency division by 8 frequency dividers, and its frequency is 1/8 times of the first local oscillator signal frequency.

The specific works principle of this circuit is as follows:

As shown in Figure 2, first the two-band satellite navigation signals that antenna receives enters radio frequency low-noise amplifier 10, and Received signal strength is exaggerated thus reduces the noise contribution of post-module generation.Following low noise amplifier output signal A needs to be further processed by being down-converted to IF-FRE.

As shown in Figure 3, first local oscillation signal LO1_I, LO1_Q can use cos (ω to the principle of work of down coversion part respectively ₁t) with sin (ω ₁t) represent, second local oscillation signal LO2_I, LO2_Q can use cos (ω respectively ₂t) with sin (ω ₂t) represent, wherein ω ₁and ω ₂be respectively the angular frequency of the first and second local oscillation signals.First local oscillator signal frequency roughly can be set to the centre of L1 band satellite signal(-) carrier frequency and L2 band satellite signal(-) carrier frequency, second local oscillation signal frequency is 1/8 of the first local oscillator signal frequency, and concrete set of frequency can set of frequency scheme in reference table 1.Signal C1, C2, C3, C4 that signal A exports after twice down coversion then can be expressed as:

$C1=A\cos \left({\mathrm{\ω}}_{1}t\right)\cos \left({\mathrm{\ω}}_{2}t\right)=\frac{A}{2}\cos \left[({\mathrm{\ω}}_1+{\mathrm{\ω}}_2)t\right]+\frac{A}{2}\cos \left[({\mathrm{\ω}}_1-{\mathrm{\ω}}_2)t\right]---\left(1a\right)$

$C2=A\cos \left({\mathrm{\ω}}_{1}t\right)\sin \left({\mathrm{\ω}}_{2}t\right)=\frac{A}{2}\sin \left[({\mathrm{\ω}}_1+{\mathrm{\ω}}_2)t\right]-\frac{A}{2}\sin \left[({\mathrm{\ω}}_1-{\mathrm{\ω}}_2)t\right]---\left(1b\right)$

$C3=A\sin \left({\mathrm{\ω}}_{1}t\right)\cos \left({\mathrm{\ω}}_{2}t\right)=\frac{A}{2}\sin \left[({\mathrm{\ω}}_1+{\mathrm{\ω}}_2)t\right]+\frac{A}{2}\sin \left[({\mathrm{\ω}}_1-{\mathrm{\ω}}_2)t\right]---\left(1c\right)$

$C4=A\sin \left({\mathrm{\ω}}_{1}t\right)\sin \left({\mathrm{\ω}}_{2}t\right)=-\frac{A}{2}\cos \left[({\mathrm{\ω}}_1+{\mathrm{\ω}}_2)t\right]+\frac{A}{2}\cos \left[({\mathrm{\ω}}_1-{\mathrm{\ω}}_2)t\right]---\left(1d\right)$

C1, C2, C3, C4 carry out the synthesis of signal again by the low-pass filter 40 with signal syntheses function:

C1-C4＝Acos[(ω ₁+ω ₂)t](2a)

C2+C3＝Asin[(ω ₁+ω ₂)t](2b)

C1+C4＝Acos[(ω ₁-ω ₂)t](2c)

C3-C2＝Asin[(ω ₁-ω ₂)t](2d)

Because ω ₂=ω ₁/ 8, so have:

$C1-C4=A\cos \left(\frac{9}{8}{\mathrm{\ω}}_{1}t\right)---\left(3a\right)$

$C2+C3=A\sin \left(\frac{9}{8}{\mathrm{\ω}}_{1}t\right)---\left(3b\right)$

$C1+C4=A\cos \left(\frac{7}{8}{\mathrm{\ω}}_{1}t\right)---\left(3c\right)$

$C3-C2=A\sin \left(\frac{7}{8}{\mathrm{\ω}}_{1}t\right)---\left(3d\right)$

Can see, after twice down coversion and signal syntheses, C1-C4 and C2+C3 signal is equivalent to the first local oscillator signal frequency ω of input signal A and 9/8 times ₁quadrature downconvert, exports as passage one signal.C1+C4 and C3-C2 signal is equivalent to the first local oscillator signal frequency ω of input signal A and 7/8 times ₁quadrature downconvert, exports as passage binary signal.Because input signal A had both contained the higher L1 frequency band signals of frequency, contain again the L2 frequency band signals that frequency is lower, if choose the first suitable local oscillator signal frequency, so L1 frequency band signals can be down converted to lower IF-FRE at passage one, L2 frequency band signals can be down converted to lower IF-FRE at passage two, receives while so just achieving L1 and L2 navigation signal.Table 1 lists several typical frequency planning scheme.

The double conversion of above-mentioned radio-frequency front-end and the synthesis of signal, receive while not only can realizing two-band signal, but also achieve the function of mirror image suppression simultaneously.The low intermediate frequency receiver of double conversion in theory, there are 3 image frequencies in useful signal, and can see from formula (3a) ~ (3b), after adopting this receiver circuit structure, useful signal is equivalent to only carry out a down coversion, therefore the radio-frequency (RF) front-end circuit shown in Fig. 2 can be equivalent to the circuit structure shown in Fig. 4, and such receiver only need suppress for an image frequency.In fact, the image frequency that receiver first time frequency conversion produces has been cancelled, and the image frequency only having second time frequency conversion to produce needs to process in the multiple bandpass filter of rear class.

Table 1 receiver radio frequency front-end circuit set of frequency scheme is illustrated

	GPS L1+L2	BDS B1+B2	Glonass L1+L2
				L1 band satellite signal frequency	1575.42MHz	1561.098MHz	1602MHz
L2 band satellite signal frequency	1227.6MHz	1207.14MHz	1246MHz
				First local oscillator signal frequency	1396.85MHz	1384.12MHz	1416.25MHz
Second local oscillation signal frequency	174.61MHz	173.02MHz	177.03MHz
				IF-FRE (passage one) after L1 signal double conversion	3.96MHz	3.96MHz	8.44MHz
IF-FRE (passage two) after L2 signal double conversion	5.36MHz	-3.97MHz	6.78MHz

Low-pass filter 401,402,403,404 can carry out filtering to the intermediate-freuqncy signal after down coversion, and filter away high frequency noise and undesired signal alleviate the linearity of late-class circuit.Configurable multiple bandpass filter 50,51 realizes the suppression of image frequency, and further filter away high frequency noise and undesired signal.Its passband central frequency, pass band width according to the difference of Received signal strength, can be configured and regulate.Variable-gain intermediate frequency amplifier 60,61 and analog to digital converter 70,71 respectively settling signal amplify and analog-to-digital function, deliver to digital baseband processor and carry out further signal transacting.So just achieve the function of whole radio-frequency (RF) front-end circuit.

In sum, the beneficial effect that radio-frequency (RF) front-end circuit disclosed by the invention has is: this circuit reduction circuit structure of traditional double band receiver radio-frequency front-end, receive while only needing single frequency synthesizer can realize two-band satellite-signal, and support that single antenna inputs, the suppression to image frequency can be realized without the need to using passive intermediate-frequency filter outside the outer radio-frequency filter of sheet or sheet, effectively can reduce power consumption and the cost of receiver radio frequency front-end circuit, there is higher industrial utilization.

It should be noted that, radio-frequency (RF) front-end circuit disclosed by the invention does not have special restriction to the physical circuit implementation of each submodule, as long as the function realizing aforementioned modules can realize the present invention.Therefore, to the change, optimization etc. of each submodule physical circuit implementation, do not change essence of the present invention, should be encompassed in content of the present invention.

Accompanying drawing explanation

Fig. 1 is traditional double frequency range radio-frequency (RF) front-end circuit structural drawing.

Fig. 2 is two-band radio-frequency (RF) front-end circuit structural drawing of the present invention.

Fig. 3 is the schematic diagram of radio-frequency (RF) front-end circuit signal down coversion part of the present invention.

Fig. 4 is the equivalent circuit theory figure of radio-frequency (RF) front-end circuit of the present invention.

Embodiment

A kind of preferred embodiment of the present invention is as follows:

As shown in Figure 2, dual band receiver radio-frequency (RF) front-end circuit forms by with lower part:

(1) radio frequency low-noise amplifier 10, it is input as received RF signal, exports radiofrequency signal A, connect first order frequency mixer 20 after amplifying;

(2) first order frequency mixer 20, its input radio frequency signal A, mixing is carried out respectively with passage one I road first local oscillation signal LO1_I and two passage Q road first local oscillation signal LO1_Q, signal A is down-converted to the first IF-FRE by rf frequency, that is: A and LO1_I mixing exports I road first intermediate-freuqncy signal B1, A and LO1_Q mixing exports Q road first intermediate-freuqncy signal B2, B1 and B2 connects second level frequency mixer 30;

(3) second level frequency mixer 30, it is input as I, Q two-way first intermediate-freuqncy signal B1, B2, mixing is carried out respectively with I road second local oscillation signal LO2_I and Q road second local oscillation signal LO2_Q, first IF signal frequency is down-converted to the second IF-FRE, that is: B1 and LO2_I mixing exports II road second intermediate-freuqncy signal C1, B1 and LO2_Q mixing exports IQ road second intermediate-freuqncy signal C2, B2 and LO2_I mixing exports QI road second intermediate-freuqncy signal C3, B2 and LO2_Q mixing exports QQ road second intermediate-freuqncy signal C4, second intermediate-freuqncy signal C1, C2, C3, C4 connects low-pass filter 40,

(4) low-pass filter 40, it is input as II, IQ, QI, QQ tetra-tunnel second intermediate-freuqncy signal C1, C2, C3, C4, signal syntheses and low-pass filtering are carried out to it, that is: C1-C4 as I road the 3rd intermediate-freuqncy signal D1 of passage one after low-pass filtering, C2+C3 as Q road the 3rd intermediate-freuqncy signal D2 of passage one after low-pass filtering, C3-C2 as Q road the 3rd intermediate-freuqncy signal D3 of passage two after low-pass filtering, C1+C4 as I road the 3rd intermediate-freuqncy signal D4 of passage two after low-pass filtering, through above-mentioned process, passage one filters out the signal of L1 frequency range, suppress L2 frequency band signals, passage two filters out the signal of L2 frequency range, suppress the signal of L1 frequency range, achieve the separation of different frequency range signal, low-pass filter serves inhibiting effect to high frequency noise and undesired signal simultaneously, output signal D1, D2 connects the configurable multiple bandpass filter 50 in road one, D3, D4 connects the configurable multiple bandpass filter 51 in road two,

(5) the configurable multiple bandpass filter 50 of passage one, it is input as I road the 3rd intermediate-freuqncy signal D1 of passage one and Q road the 3rd intermediate-freuqncy signal D2 of passage one, plural bandpass filtering is carried out to it, filtering image frequency, 4th intermediate-freuqncy signal E1 of output channel one, connects variable-gain intermediate frequency amplifier 60;

(6) the configurable multiple bandpass filter 51 of passage two, it is input as Q road the 3rd intermediate-freuqncy signal D3 of passage two and I road the 3rd intermediate-freuqncy signal D4 of passage two, plural bandpass filtering is carried out to it, filtering image frequency, 4th intermediate-freuqncy signal E2 of output channel two, connects variable-gain intermediate frequency amplifier 61;

(7) the variable-gain intermediate frequency amplifier 60 of passage one, it is input as the 4th intermediate-freuqncy signal E1 of passage one, amplifies it, and the 5th intermediate-freuqncy signal F1 of output channel one connects the ADC70 in road one;

(8) the variable-gain intermediate frequency amplifier 61 of passage two, it is input as the 4th intermediate-freuqncy signal E2 of passage two, amplifies it, and the 5th intermediate-freuqncy signal F2 of output channel two connects the ADC71 in road two;

(9) ADC70, it is input as the 5th intermediate-freuqncy signal F1 of passage one, is converted into passage one digital signal and exports;

(10) ADC71, it is input as the 5th intermediate-freuqncy signal F2 of passage two, is converted into passage two digital signal and exports;

(11) frequency synthesizer 80, produces I, Q two-way first local oscillation signal LO1_I and LO1_Q, outputs to the first frequency mixer 20;

(12) 8 frequency dividers 90, it is input as the first local oscillation signal LO1_I that frequency synthesizer 80 produces, and carries out 8 frequency divisions to it, produces I, Q two-way second local oscillation signal LO2_I and LO2_Q of 1/8 times of first local oscillator signal frequency, outputs to the second frequency mixer 30.

Wherein, radio frequency low-noise amplifier (LNA) 10 can receive L1, L2 two-band satellite navigation signals simultaneously, adopts transconductance mode.I, Q orthogonal mixer that first order frequency mixer 20 is made up of two sub-frequency mixer 201,202, for radiofrequency signal is down-converted to the first IF-FRE, adopts current-mode.Second level frequency mixer 30 is made up of four sub-frequency mixer 301,302,303,304, sub-frequency mixer 301 and 302 forms road I, Q orthogonal mixer, sub-frequency mixer 303 and 304 forms another road I, Q orthogonal mixer, for the first IF-FRE signal is down-converted to the second IF-FRE, adopt current-mode.The low-pass filter 40 with signal syntheses function is made up of four subfilters 401,402,403,404, all can realize the synthesis to two-way input signal and low-pass filtering function, adopt across resistance pattern.Configurable multiple bandpass filter 50,51 realizes plural band-pass filtering function, and for filtering image frequency and the outer interference of band, its filter parameter can be configured, such as passband central frequency, pass band width etc.Variable-gain intermediate frequency amplifier 60,61 can amplify IF-FRE signal, and its gain amplifier can be controlled by automatic gain control loop respectively, makes its amplitude exporting intermediate-freuqncy signal reach the scope of analog to digital converter 70,71 normally required by work.I, Q two-way first local oscillation signal LO1_I and LO1_Q needed for first order frequency mixer 20 is produced by frequency synthesizer 80.I, Q two-way second local oscillation signal LO2_I and LO2_Q needed for second frequency mixer 30 is produced the first local oscillation signal LO1_I frequency division by 8 frequency dividers, and output frequency is 1/8 times of the first local oscillator signal frequency.According to the difference receiving satellite system, can adjust the frequency of the first local oscillation signal, concrete set of frequency can refer to table 1 and realizes.

Claims (10)

1. a L1 and L2 two-band satellite navigation receiver radio-frequency (RF) front-end circuit, is characterized in that, this circuit comprises:

Radio frequency low-noise amplifier LNA, it is input as received RF signal, exports radiofrequency signal A, connect first order frequency mixer after amplifying;

First order frequency mixer, it is input as radiofrequency signal A, mixing is carried out respectively with I, Q two-way first local oscillation signal LO1_I, LO1_Q, signal A is down-converted to the first IF-FRE by rf frequency, wherein A and LO1_I mixing exports I road first intermediate-freuqncy signal B1, A and LO2_Q mixing exports Q road first intermediate-freuqncy signal B2, B1 and B2 connects second level frequency mixer;

Second level frequency mixer, it is input as I, Q two-way first intermediate-freuqncy signal B1, B2, mixing is carried out respectively with I, Q two-way second local oscillation signal LO2_I, LO2_Q, input signal is down-converted to the second IF-FRE by the first IF-FRE, wherein B1 and LO2_I mixing exports II road second intermediate-freuqncy signal C1, B1 and LO2_Q mixing exports IQ road second intermediate-freuqncy signal C2, B2 and LO2_I mixing exports QI road second intermediate-freuqncy signal C3, B2 and LO2_Q mixing exports QQ road second intermediate-freuqncy signal C4, exports the second intermediate-freuqncy signal C1, C2, C3, C4 connect low-pass filter;

Low-pass filter, it is input as II, IQ, QI, QQ tetra-tunnel second intermediate-freuqncy signal C1, C2, C3, C4, signal syntheses and low-pass filtering are carried out to it, wherein C1-C4 and after low-pass filtering I road the 3rd intermediate-freuqncy signal D1 of output channel one, C2+C3 and after low-pass filtering Q road the 3rd intermediate-freuqncy signal D2 of output channel one, C3-C2 and after low-pass filtering Q road the 3rd intermediate-freuqncy signal D3 of output channel two, C1+C4 and after low-pass filtering I road the 3rd intermediate-freuqncy signal D4 of output channel two, D1, D2 connects the configurable multiple bandpass filter in road one, D3, D4 connects the configurable multiple bandpass filter in road two,

The configurable multiple bandpass filter of passage one, it is input as I, Q two-way the 3rd intermediate-freuqncy signal D1, the D2 of passage one, carries out plural bandpass filtering to it, and the 4th intermediate-freuqncy signal E1 of output channel one, connects variable-gain intermediate frequency amplifier;

The configurable multiple bandpass filter of passage two, it is input as I, Q two-way the 3rd intermediate-freuqncy signal D3, the D4 of tool passage two, carries out plural bandpass filtering to it, and the 4th intermediate-freuqncy signal E2 of output channel two, connects variable-gain intermediate frequency amplifier;

The variable-gain intermediate frequency amplifier of passage one, it is input as the 4th intermediate-freuqncy signal E1 of passage one, amplifies it, and the 5th intermediate-freuqncy signal F1 of output channel one connects the analog to digital converter ADC in road one;

The variable-gain intermediate frequency amplifier of passage two, it is input as the 4th intermediate-freuqncy signal E2 of passage two, amplifies it, and the 5th intermediate-freuqncy signal F2 of output channel two connects the ADC in road two;

The ADC of passage one, it is input as the 5th intermediate-freuqncy signal F1 of passage one, is converted into digital signal and exports;

The ADC of passage two, it is input as the 5th intermediate-freuqncy signal F2 of passage two, is converted into digital signal and exports;

Frequency synthesizer, produces I, Q two-way first local oscillation signal LO1_I and LO1_Q, outputs to the first frequency mixer;

8 frequency dividers, it is input as the first local oscillation signal LO1_I or LO2_Q that frequency synthesizer produces, and carries out 8 frequency divisions to it, produces the second local oscillation signal LO2_I and LO2_Q of I, Q two-way 1/8 times of first local oscillator signal frequency, outputs to the second frequency mixer.

2. circuit according to claim 1, is characterized in that, described radio frequency low-noise amplifier receives L1, L2 two-band satellite navigation signals: GPSL1 and L2 frequency band signals, Big Dipper B1 and B2 frequency band signals, GlonassL1 and L2 frequency band signals.

3. circuit according to claim 1, is characterized in that, described first order frequency mixer is made up of two sub-frequency mixer, for radiofrequency signal is down-converted to the first IF-FRE.

4. circuit according to claim 1, is characterized in that, described second level frequency mixer is made up of four sub-frequency mixer, and combination of two becomes a road orthogonal mixer, for the first IF-FRE is down-converted to the second IF-FRE.

5. circuit according to claim 1, is characterized in that, described low-pass filter is made up of four subfilters, for synthesizing and low-pass filtering two-way input signal.

6. circuit according to claim 1, it is characterized in that, the configurable multiple bandpass filter of described passage one and the configurable multiple bandpass filter of passage two are used for plural bandpass filtering, and its filter parameter can be configured, and described filter parameter comprises passband central frequency, pass band width.

7., according to the arbitrary described circuit of claim 1 to 5, it is characterized in that, described radio frequency low-noise amplifier, first order frequency mixer, second level frequency mixer and low-pass filter all adopt voltage mode.

8. according to the arbitrary described circuit of claim 1 to 5, it is characterized in that, described radio frequency low-noise amplifier adopts transconductance mode, and described first order frequency mixer and second level frequency mixer adopt current-mode, and described low-pass filter adopts across resistance pattern.

9. circuit according to claim 1, it is characterized in that, described circuit can omit the variable-gain intermediate frequency amplifier of passage one and the variable-gain intermediate frequency amplifier of passage two, and the function that its variable gain is amplified can be realized by the configurable multiple bandpass filter of the configurable multiple bandpass filter of prime passage one and passage two.

10. circuit according to claim 1, is characterized in that, described second local oscillation signal frequency is 1/8 of the first local oscillator signal frequency.