CN209088931U - Device based on I/Q modulator interpolation phaselocked loop complex RF signal - Google Patents

Abstract

The utility model belongs to ultra-short wave radio field of communication technology, disclose a kind of device based on I/Q modulator interpolation phaselocked loop complex RF signal, comprising: reference oscillator, phase locked-loop unit, loop filter, voltage controlled oscillator, I/Q modulator, IQ output filter；Wherein, the phase locked-loop unit includes parametric frequency divider, program divider and phase discriminator；The I/Q modulator includes phase shifter, synthesizer and two frequency mixers；It improves baseband signal and moves the Frequency spectrum quality after radiofrequency signal.

Description

Device based on I/Q modulator interpolation phaselocked loop complex RF signal

Technical field

The utility model belongs to ultra-short wave radio field of communication technology, more particularly to a kind of based on mortise lock in I/Q modulator Phase cyclization at radiofrequency signal device.

Background technique

The principle of ultrashort wave transmitter be the voice signal to be transmitted or data-signal be first modulated to frequency it is lower in Baseband signal is formed on frequency, baseband signal is then moved into radiofrequency signal again, and baseband signal moves the tradition of radiofrequency signal Method generally has mixing method and IQ modulator approach.

Mixing method is by baseband signal by being mixed with local oscillation signal by one or many, needed for being selected by filter The radiofrequency signal wanted, Fig. 1 are the functional block diagrams of two-stage mixing method, and the major defect for being mixed method is that baseband signal and local oscillation signal are logical A large amount of new frequency content is generated after crossing non-linear mixer, unwanted frequency components is curbed and obtain useful frequency content pair Filter specifications are very high, and when radiofrequency signal bandwidth is wider, the frequency characteristic of frequency mixer will cause mixing output amplitude fluctuation, Filter may need subrane to design simultaneously, increase design difficulty and equipment complexity.

IQ modulator approach is current ultrashort wave radio set using most methods, and Fig. 2 is that baseband signal moves radiofrequency signal IQ modulator approach functional block diagram, baseband signal generates the road I and the road Q digital orthogonal baseband signal by phase shifter, is added to I/Q modulator Mixer input, local oscillation signal is added to I/Q modulator input terminal, passes through phase shifter inside I/Q modulator and generates the road I and the road Q Orthogonal local oscillation signal, the signal are also added to I/Q modulator mixer input, and two frequency mixer outputs are added to inside IQ modulation Synthesizer input terminal, synthesizer output are radiofrequency signal.The shortcomings that IQ modulator approach, is due to phase shifter, frequency mixer and synthesizer It is not ideal, it is thus possible to the leakage that will lead to unwanted sideband and local oscillation signal, especially when frequency range is wider in full frequency band Be difficult preferably to draw up the leakage of unwanted sideband and local oscillation signal.This directly affects the Frequency spectrum quality of radiofrequency signal.

Utility model content

It is penetrated in view of the above-mentioned problems, the purpose of this utility model is to provide one kind based on the synthesis of I/Q modulator interpolation phaselocked loop The device of frequency signal realizes that the frequency of baseband signal to radiofrequency signal is removed by using the method for I/Q modulator interpolation phaselocked loop It moves, this method had both maintained the simple feature of I/Q modulator route, while having filtered out IQ using the effect of phaselocked loop tracking filter The leakage of modulator unwanted sideband and carrier wave improves baseband signal and moves the Frequency spectrum quality after radiofrequency signal.

In order to achieve the above objectives, the utility model adopts the following technical solution is achieved.

Technical solution one:

A kind of device based on I/Q modulator interpolation phaselocked loop complex RF signal, described device include: reference oscillator, Phase locked-loop unit, loop filter, voltage controlled oscillator, I/Q modulator, IQ output filter；

Wherein, the phase locked-loop unit includes parametric frequency divider, program divider and phase discriminator；

The I/Q modulator includes phase shifter, synthesizer and two frequency mixers.

The characteristics of technical solutions of the utility model one and further improvement are as follows:

(1) signal output end of the reference oscillator is connect with the signal input part of the parametric frequency divider, the ginseng The signal output end for examining frequency divider is connect with the first signal input part of the phase discriminator, the signal output end of the phase discriminator with The signal input part of the loop filter connects, the letter of the signal output end of the loop filter and the voltage controlled oscillator The RF signal output of the connection of number input terminal, the voltage controlled oscillator exports radiofrequency signal；

The feedback signal output of the voltage controlled oscillator is connect with the signal input part of the phase shifter, the phase shifter The first phase shift signal output end connect with the phase shift signal input terminal of the first frequency mixer, the second phase shift signal of the phase shifter Output end is connect with the phase shift signal input terminal of the second frequency mixer, and another signal input part of first frequency mixer connects the road I Another signal input part of baseband signal, second frequency mixer connects Q roadbed band signal；The signal of first frequency mixer is defeated The connection of first signal input part of outlet and synthesizer, the signal output end of second frequency mixer and the second signal of synthesizer Input terminal connection, the signal output end of synthesizer are connect with the signal input part of IQ output filter, the IQ output filter Signal output end connect with the signal input part of described program frequency divider, the signal output end of described program frequency divider with it is described The second signal input terminal of phase discriminator connects.

Technical solution two:

A method of based on I/Q modulator interpolation phaselocked loop complex RF signal, described method includes following steps:

Reference oscillator output frequency is f_RSignal, frequency be fR signal divided by reference to frequency divider after export frequency Rate is f_rSignal, frequency f_rThe signal input part for being signally attached to phase discriminator；

Voltage controlled oscillator output frequency is f_VCOSignal, all the way as radiofrequency signal export, another way be connected to IQ modulation The local oscillator input terminal of device exports two paths of signals by phase shifter, all the way 0 degree of phase shift, and 90 degree of another way phase shift；

Another signal of 0 degree of phase shift of the signal input part for being signally attached to the first frequency mixer, first frequency mixer is defeated Entering to hold rate of connections is f_IBaseband signal the road I input, 90 degree of phase shift be signally attached to the second frequency mixer signal input End, another signal input part rate of connections of second frequency mixer are f_IBaseband signal the road Q input；

The signal output end of the first mixer signal output end and second frequency mixer is connected respectively to synthesizer Two signal input parts, the output frequency of synthesizer is f_OUTSignal, the frequency be f_OUTSignal pass through IQ output filter The signal input part of program divider is connected to after the filtering of wave device；

Described program frequency divider output frequency is f_VSignal, the frequency be f_VSignal be input to the second of phase discriminator Signal input part；

The first signal input part input frequency of the phase discriminator is f_rSignal, second signal input terminal input frequency be f_VSignal, the phase discriminator is by f_rAnd f_VIt is compared, phase error is converted into DC voltage and is output to loop filter It is filtered, obtains control voltage signal, the control terminal that the control voltage signal is input to voltage controlled oscillator controls voltage-controlled vibration Swing the frequency of oscillation of device.

The characteristics of technical solutions of the utility model two and further improvement are as follows:

(1) reference oscillator output frequency is f_RSignal, the frequency dividing ratio of parametric frequency divider is R, then parametric frequency divider point The frequency f of output signal after frequency_r=f_R÷R；

The output signal of I/Q modulator is that the frequency of synthesizer output is f_OUTSignal, and f_OUT=f_VCO-f_I|；

If the frequency dividing ratio of program divider is N.FFFF, then program divider output frequency is f_VSignal, and f_V=f_OUT ÷ N.FFFF=(f_VCO-f_I)÷N.FFFF；

After the signal frequency exported in phase discriminator to parametric frequency divider and program divider locks, f_V=f_r, obtain (f_VCO-f_I) ÷ N.FFFF=f_R÷ R, thus f_VCO=(f_R÷R)×N.FFFF+f_I。

The utility model combines the advantages of phaselocked loop and I/Q modulator, and the tracking filter effect of phaselocked loop is utilized, Full frequency band has filtered out the unwanted sideband and local-oscillator leakage of I/Q modulator output well, improves the Frequency spectrum quality of radiofrequency signal. Due to being mixed using I/Q modulator, so the advantages that route for just taking full advantage of I/Q modulator is simple, simultaneously because adopting With the method for hybrid, baseband signal maintains original modulating characteristic, and frequency deviation does not change.

Detailed description of the invention

In order to illustrate the embodiment of the utility model or the technical proposal in the existing technology more clearly, below will be to embodiment Or attached drawing needed to be used in the description of the prior art is briefly described, it should be apparent that, the accompanying drawings in the following description is only It is some embodiments of the utility model, for those of ordinary skill in the art, in the premise not made the creative labor Under, it is also possible to obtain other drawings based on these drawings.

Fig. 1 is the mixing method functional block diagram that baseband signal moves radiofrequency signal；

Fig. 2 is the I/Q modulator method functional block diagram that baseband signal moves radiofrequency signal；

Fig. 3 is the functional block diagram of technical solutions of the utility model I/Q modulator interpolation phaselocked loop；

Fig. 4 is cycle of phase-locked loop filter schematic；

Fig. 5 is the utility model applicating example functional block diagram；

Fig. 6 is applicating example frequency switching time simulation result diagram；

Fig. 7 is applicating example loop filter simulation result diagram.

Specific embodiment

The following will be combined with the drawings in the embodiments of the present invention, carries out the technical scheme in the embodiment of the utility model Clearly and completely describe, it is clear that the described embodiments are only a part of the embodiments of the utility model, rather than whole Embodiment.Based on the embodiments of the present invention, those of ordinary skill in the art are without making creative work Every other embodiment obtained, fall within the protection scope of the utility model.

The utility model embodiment provides a kind of device based on I/Q modulator interpolation phaselocked loop complex RF signal, by joining Examine six part structures such as oscillator, phase-locked loop circuit, loop filter, voltage controlled oscillator, I/Q modulator, IQ output filter At Fig. 3 is the I/Q modulator interpolation phaselocked loop solution principle block diagram, wherein includes parametric frequency divider (÷ inside phase-locked loop circuit R), program divider (÷ N.FFFF) and phase discriminator etc..Program divider includes multidigit fractional frequency division, is guaranteed in any phase demodulation frequency Frequency interval required for being realized under the premise of rate.Include the 3 part function such as phase shifter, frequency mixer and synthesizer inside I/Q modulator Energy.Phase shifter exports two paths of signals after the local oscillation signal of input is passed through phase shift, all the way 0 ° of phase shift, and 90 ° of another way phase shift.Synthesis Device output frequency is the difference of local frequency and baseband intermediate frequency frequency.

The main connection relationship of technical solutions of the utility model is shown in that Fig. 3, reference oscillator can use high stability and height The compensation crystal oscillator or constant-temperature crystal oscillator of Frequency spectrum quality, the frequency f of output_RIt is signally attached to the reference of phaselocked loop Input REF_INFoot, the signal export f after dividing inside phaselocked loop by reference to frequency divider (÷ R)_rSignal, f_rIt is signally attached to Phase discriminator input terminal, voltage controlled oscillator export f_VCOIt is exported all the way as radiofrequency signal, another way is connected to the local oscillator of I/Q modulator Input terminal L_O, which exports two paths of signals by the phase shifter inside I/Q modulator, all the way 0 ° of phase shift, and 90 ° of another way phase shift, The two signals are added separately to two mixer inputs, baseband signal f_IThe orthogonal letter of two-way is had been designed as in outside when input Number, 90 ° of phase phase difference, the two signals are connected respectively to the road I and the road the Q input terminal of I/Q modulator, and are separately connected two and mix Frequency device input terminal, two frequency mixer outputs are connected respectively to the synthesizer input terminal inside I/Q modulator, synthesizer output frequency For f_OUTSignal, which is connected to the RF of phaselocked loop after filtering by IQ output filter_INInput terminal, inside phaselocked loop Output frequency is f after being divided by program divider (÷ N.FFFF)_VSignal, this is signally attached to the phase demodulation inside phaselocked loop Device input terminal and f_rIt carries out than phase, and phase error is converted to and is exported from phaselocked loop CP foot after DC voltage, the DC voltage Output control voltage VT after being filtered by loop filter, the voltage are connected to the control terminal control voltage controlled oscillation of voltage controlled oscillator Device frequency.

When radio frequency band is wider, and a voltage controlled oscillator does not cover, two or more voltage controlled oscillators can be used It is covered each by, bandwidth varying voltage controlled oscillator can also be used.

Specifically, according to the connection relationship of Fig. 3, reference oscillator frequencies f_R, parametric frequency divider frequency dividing ratio is R, then reflects Phase frequency f_rFor f_R÷ R, I/Q modulator output frequency f_OUTFor local frequency f_VCOWith baseband intermediate frequency frequency f_IDifference, it may be assumed that

f_OUT=f_VCO-f_I

Program divider frequency dividing ratio is N.FFFF, then program divider output frequency f_VAre as follows:

f_V=f_OUT÷ N.FFFF=(f_VCO-f_I)÷N.FFFF

F after locking_V=f_r

(f_VCO-f_I) ÷ N.FFFF=f_R÷R

f_VCO=(fR ÷ R) × N.FFFF+f_I

From f_VCOIt is N.FFFF ÷ R that expression formula, which can be seen that the multiple that reference frequency passes through frequency multiplication of phase locked loop, and base band is believed Number f_IThere is no frequency multiplication, i.e., by the way that after the hybrid, baseband signal maintains original modulating characteristic, and frequency deviation does not change.

Further, the structure of cycle of phase-locked loop filter is as shown in figure 4, PLL loop bandwidth design principle is first will Loop bandwidth is designed as baseband signal frequency deviation, and on this basis, if frequency switching time is met the requirements, loop bandwidth is equal to Baseband signal frequency deviation increases loop bandwidth if frequency switching time is unsatisfactory for requiring, until frequency switching time satisfaction is wanted It asks.Frequency switching time can use ADIsimPLL software emulation.Simulation process is mainly by F_VCO、f_R、f_r、K_VCO, k substitute into ADIsimPLL software emulation frequency switching time is gradually increased loop bandwidth until frequency switching time is met the requirements.It imitates at this time Genuine loop filter component parameter C1, C2, C3, R1, R2 value is then actual design value.

Due in ADIsimPLL software without mixing ring model, according to monocycle fractional frequency division model emulation to ring when emulation The influence of path filter component parameter C1, C2, C3, R1, R2 are little.

Technical solutions of the utility model should determine associated technical parameters according to specific technical requirement when in use.

Applicating example:

Reference frequency: 19.2MHz；

Baseband intermediate frequency: 14.5MHz；

Frequency deviation: 11kHz；

Rf frequency: 225-512MHz；

Frequency interval: 25kHz；

Frequency switching time: 100 μ S.

According to the above technical requirements, main components (including phase-locked loop circuit, voltage controlled oscillator, I/Q modulator, ginseng are determined Examine oscillator frequency etc.) and the emulation such as phase demodulation frequency, loop bandwidth k needed for major parameter.

Voltage controlled oscillator uses bandwidth varying voltage controlled oscillator, and 225-512MHz, the voltage-controlled spirit of voltage controlled oscillator is completely covered Sensitivity is designed as K_VCO=30MHz/V.

As long as frequency range needed for I/Q modulator meets selects AD8345.

Reference oscillator frequencies are selected as 19.2MHz.

Since frequency switching time is shorter, 9.6MHz phase demodulation frequency is selected.

Due to the frequency interval of 25kHz to be met, therefore the phase-locked loop circuit with fractional frequency division function is selected, selected ADF4157。

Applicating example functional block diagram is shown in Fig. 5.Reference oscillator uses 19.2MHz compensation crystal oscillator, the frequency of output Rate f_R(19.2MHz) is signally attached to the reference input REF of phase-locked loop circuit ADF4157_INFoot, the signal lead to inside phaselocked loop It crosses parametric frequency divider frequency dividing (R=2) and exports f afterwards_r(9.6MHz) signal, f_rIt is signally attached to phase discriminator input terminal, voltage controlled oscillator Export f_VCO(225-512MHz) is exported as radiofrequency signal all the way, and another way is connected to the local oscillator input of I/Q modulator AD8345 Hold L₀, which exports two paths of signals by the phase shifter inside I/Q modulator, all the way 0 ° of phase shift, and 90 ° of another way phase shift, this two A signal is added separately to two mixer inputs, baseband signal f_ITwo-way is had been designed as in outside when (14.5MHz) is inputted Orthogonal signalling, 90 ° of phase phase difference, the two signals are connected respectively to the road I and the road the Q input terminal of I/Q modulator, and are separately connected Two mixer inputs, two frequency mixer outputs are connected respectively to the synthesizer input terminal inside I/Q modulator, and synthesizer is defeated Frequency is f out_OUTThe signal of (210.5-497.5MHz), the signal are connected to phaselocked loop after filtering by IQ output filter RF_INInput terminal, output frequency is f after being divided inside phaselocked loop by program divider (÷ N.FFFF)_VSignal, the signal Phase discriminator input terminal and the f being connected to inside phaselocked loop_rIt carries out than phase, and phase error is converted to after DC voltage from locking phase The output of ring CP foot, output control voltage V after which is filtered by loop filter_T, which is connected to voltage controlled oscillation The control terminal of device controls pressuring controlling oscillator frequency.

The voltage controlled oscillator uses bandwidth varying voltage controlled oscillator, 4 sections of covering 225-512MHz frequency ranges is shared, by K1 and K2 Carry out wave band control.Voltage controlled oscillator Discrete control relationship is shown in Table 1.

1 voltage controlled oscillator Discrete control relationship of table

Loop bandwidth is gradually increased, simulation calculation frequency switching time, until frequency from 11kHz (being greater than frequency deviation 11kHz) Conversion time meets 100 μ S.Determine loop filter component parameter C1, C2, C3, R1, R2.

Simulation process is mainly by F_VCO、f_R、f_r、K_VCO, k substitute into ADIsimPLL software emulation frequency switching time, gradually Increase loop bandwidth until frequency switching time meets 100 μ S.Loop filter component parameter C1, C2 for emulating at this time, C3, R1, R2 value are then actual design value.

Due in ADIsimPLL software without mixing ring model, according to monocycle fractional frequency division model emulation not shadow when emulation Ring the accuracy of loop filter component parameter C1, C2, C3, R1, R2.

Following parameters substitute into ADIsimPLL in this citing, and other settings are emulated according to default value in ADIsimPLL:

F_VCO=285.025~355 (frequency range medians)

f_R=19.2MHz

f_r=9.6MHz

K_VCO=30MHz/V

K increases since 11KHz.

Through emulating, when loop bandwidth k reaches 70KHz, frequency switching time has reached 100 μ S and has seen Fig. 6, principle at this time Figure is shown in 7.The value of loop filter component parameter C1, C2, C3, R1, R2 is thereby determined that.

According to mixing frequencies relationship f in design application_VCO=(f_R÷R)×N.FFFF+f_IWith AD4157 register frequency dividing ratio Algorithm calculates N.FFFF, and is converted to control word format, and required radio frequency frequency can be obtained by the merging of AD4157 serial ports Rate.

It is calculated by taking 430.025MHz as an example:

R=2

f_VCO-f_I=f_r×(N+FRAC/2²⁵)

430.025-14.5=9.6 × (N+FRAC/2²⁵)

N=44

In this example, 0.FFFF=FRAC/2²⁵

FRAC=FMSB × 2¹³+FLSB

FMSB=int ((((f_VCO-f_I)/f_r)-N)×2¹²)=1162

FLSB=int ((((((f_VCO-f_I)/f_r)-N)×2¹²)-FMSB)×2¹³)

=5461

The utility model combines the advantages of phaselocked loop and I/Q modulator, and the tracking filter effect of phaselocked loop is utilized, Full frequency band has filtered out the unwanted sideband and local-oscillator leakage of I/Q modulator output well, improves the Frequency spectrum quality of radiofrequency signal. Due to being mixed using I/Q modulator, so the advantages that route for just taking full advantage of I/Q modulator is simple, simultaneously because adopting With the method for hybrid, baseband signal maintains original modulating characteristic, and frequency deviation does not change.

Those of ordinary skill in the art will appreciate that: realize that all or part of the steps of above method embodiment can pass through The relevant hardware of program instruction is completed, and program above-mentioned can be stored in a computer readable storage medium, the program When being executed, step including the steps of the foregoing method embodiments is executed；And storage medium above-mentioned includes: ROM, RAM, magnetic disk or light The various media that can store program code such as disk.

Above description is only a specific implementation of the present invention, but the protection scope of the utility model is not limited to In this, anyone skilled in the art within the technical scope disclosed by the utility model, can readily occur in variation Or replacement, it should be covered within the scope of the utility model.Therefore, the protection scope of the utility model should be with the power Subject to the protection scope that benefit requires.

Claims (2)

1. a kind of device based on I/Q modulator interpolation phaselocked loop complex RF signal, which is characterized in that

Described device includes: reference oscillator, phase locked-loop unit, loop filter, voltage controlled oscillator, I/Q modulator, IQ output Filter；

Wherein, the phase locked-loop unit includes parametric frequency divider, program divider and phase discriminator；

The I/Q modulator includes phase shifter, synthesizer and two frequency mixers.

2. a kind of device based on I/Q modulator interpolation phaselocked loop complex RF signal according to claim 1, feature It is,

The signal output end of the reference oscillator is connect with the signal input part of the parametric frequency divider, the parametric frequency divider Signal output end connect with the first signal input part of the phase discriminator, the signal output end of the phase discriminator and the loop The signal input part of filter connects, the signal input part of the signal output end of the loop filter and the voltage controlled oscillator The RF signal output of connection, the voltage controlled oscillator exports radiofrequency signal；

The feedback signal output of the voltage controlled oscillator is connect with the signal input part of the phase shifter, and the of the phase shifter One phase shift signal output end is connect with the phase shift signal input terminal of the first frequency mixer, the second phase shift signal output of the phase shifter End is connect with the phase shift signal input terminal of the second frequency mixer, and another signal input part of first frequency mixer connects I roadbed band Another signal input part of signal, second frequency mixer connects Q roadbed band signal；The signal output end of first frequency mixer It is connect with the first signal input part of synthesizer, the signal output end of second frequency mixer and the second signal of synthesizer input End connection, the signal output end of synthesizer are connect with the signal input part of IQ output filter, the letter of the IQ output filter Number output end is connect with the signal input part of described program frequency divider, the signal output end of described program frequency divider and the phase demodulation The second signal input terminal of device connects.