CN106549640A - A kind of predistortion drive circuit - Google Patents
A kind of predistortion drive circuit Download PDFInfo
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- CN106549640A CN106549640A CN201610971171.8A CN201610971171A CN106549640A CN 106549640 A CN106549640 A CN 106549640A CN 201610971171 A CN201610971171 A CN 201610971171A CN 106549640 A CN106549640 A CN 106549640A
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- predistortion
- amplification
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/32—Modifications of amplifiers to reduce non-linear distortion
- H03F1/3241—Modifications of amplifiers to reduce non-linear distortion using predistortion circuits
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
- H03F3/211—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only using a combination of several amplifiers
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
Abstract
The embodiment of the invention discloses a kind of predistortion drive circuit, the predistortion drive circuit includes：Input signal processing circuit, for being processed to be divided into main path signal, linear branch signal and non-linear branch signal and export to input signal；Power amplification circuit, for Linear Amplifer being carried out to main path signal and exporting main road amplify signal, Linear Amplifer is carried out to linear branch signal and output linearity branch road amplifies signal, and non-linear amplification and output nonlinear branch road amplification signal is carried out to non-linear branch signal；Termination power, for eliminating the keynote signal in linear branch amplification signal and non-linear branch amplification signal to generate error signal, and error signal and main road amplification signal is overlapped, to generate pre-distorted signals and export；Final stage amplifying circuit, for amplifying to eliminate error signal by pre-distorted signals non-linear, and exports undistorted linear signal.In the embodiment of the present invention, predistortion drive circuit can effectively eliminate error signal.
Description
Technical field
The present embodiments relate to the communication technology, more particularly to a kind of predistortion drive circuit.
Background technology
The development trend of Modern wireless communication technology is that the letter of Large Copacity and two-forty is realized in limited frequency band range
Number transmission.The primary signal produced based on information source typically can not be directly transmitted in most of channels, it is therefore desirable to original letter
Number it is modulated so which is transformed to be suitable for the signal in band transmissions, modulation realizes the frequency spectrum of information source and the frequency of channel
Band matching.According to signal transmission characteristicses, signal modulation mode is divided into linear modulation and non-linear modulation.
Based on the characteristic of linear modulation, Modern Communication System is intended to using linear modulation mode, and power amplifier is existing
For the important devices in communication system, with the fast development of linearity modulation technique, the linearity to power amplifier
It is higher.When the linearity of power amplifier is high, possible efficiency is low, in order to solve between the efficiency of power amplifier and the linearity
Contradiction, linearization technique are widely applied.
A kind of existing linearization technique is analog predistortion linear technology.Analog predistortion linear technology would generally
Certain insertion loss is brought to communication system, increases the complexity and cost of communication system, meanwhile, analog predistortion is linear
Change technology is generally concentrated mainly on the improvement to third order intermodulation nonlinear component (IMD3), it is impossible to the nonlinear component to high-order
(IMD5, IMD7 ...) is suppressed.
The content of the invention
The embodiment of the present invention provides a kind of predistortion drive circuit, cannot be to high-order non-thread to solve existing linearization technique
The problem suppressed by property component.
Input signal processing circuit, for input signal is processed be divided into main path signal, linear branch signal and
Non-linear branch signal is simultaneously exported；
Power amplification circuit, amplifies signal for carrying out Linear Amplifer to the main path signal and exporting main road, to described
Linear branch signal carries out Linear Amplifer and output linearity branch road amplifies signal, and the non-linear branch signal is carried out non-
Linear Amplifer output nonlinear branch road amplification signal；
Termination power, for eliminating, the linear branch amplifies signal and the non-linear branch amplifies the keynote in signal
Signal is to generate error signal, and the error signal and main road amplification signal are overlapped, to generate predistortion letter
Number and export；
Final stage amplifying circuit, for the pre-distorted signals are carried out non-linear amplification to eliminate the error signal, and
Export undistorted linear signal.
Further, the input signal processing circuit includes：
First electric bridge, for being processed to be divided into the main path signal and distortion tributary signal simultaneously to the input signal
Output；
Second electric bridge, for being processed to be divided into the linear branch signal and described non-to the distortion tributary signal
Linear branch signal is simultaneously exported.
Further, the Magnitude Difference of the linear branch signal and the non-linear branch signal is more than or equal to
10dB。
Further, the power amplification circuit includes：
Variable gain power amplifier, amplifies letter for Linear Amplifer is carried out to the main path signal and the main road is exported
Number；
First power amplifier, puts for carrying out Linear Amplifer to the linear branch signal and exporting the linear branch
Big signal；
Second power amplifier, for non-linear amplification being carried out to the non-linear branch signal and exporting described non-linear
Branch road amplifies signal.
Further, the termination power includes：
First coupler, for adjusting, the linear branch amplifies signal and the non-linear branch amplifies the keynote of signal
Signal amplitude generates the error signal to eliminate keynote signal therein；
3rd electric bridge, amplifies signal for being superimposed the error signal and the main road, to generate pre-distorted signals defeated
Go out.
Further, the error signal at least includes third-order non-linear component, fifth-order nonlinearity component and seven rank non-thread
Property component.
Further, the final stage amplifying circuit includes：
3rd power amplifier, for the pre-distorted signals are carried out with non-linear amplification, and according to the 3rd power
The nonlinear component that amplifier itself is produced offsets the error signal in the pre-distorted signals, described undistorted linear to generate
Signal is simultaneously exported.
Further, the final stage amplifying circuit also includes：
Second coupler, for carrying out linearity test to the undistorted linear signal and exporting；
Automatic electric-level ALC control loops, the undistorted linear signal after detecting for acquisition simultaneously control the power amplification
Circuit carries out Gain tuning, so that the 3rd power amplifier linear signal of the output with gain.
Input signal is divided into master by input signal processing circuit by predistortion drive circuit provided in an embodiment of the present invention
Road signal, linear branch signal and non-linear branch signal, by power amplification circuit by main path signal and linear branch signal
Linear Amplifer is carried out respectively and non-linear branch signal is carried out into non-linear amplification, then linear branch is eliminated by termination power
Amplify the keynote signal in signal and non-linear branch amplification signal to generate error signal, and error signal and main road are amplified
Signal is overlapped, and to generate pre-distorted signals and export, pre-distorted signals is carried out non-linear amplification by final amplifier,
Eliminate error signal therein to export undistorted linear signal.It can thus be appreciated that predistortion drive circuit effectively can suppress to miss
Difference signal, such as lower order nonlinear component signal and high-order nonlinear component signal, realize linearisation, possess the good linearity
Improvement ability.
Description of the drawings
For the technical scheme being illustrated more clearly that in the embodiment of the present invention, below will be to making needed for embodiment description
Accompanying drawing does one and simply introduces, it should be apparent that, drawings in the following description are some embodiments of the present invention, for this
For the those of ordinary skill of field, on the premise of not paying creative work, can be with other according to these accompanying drawings acquisitions
Accompanying drawing.
Fig. 1 is the schematic diagram of the predistortion drive circuit that the embodiment of the present invention one is provided；
Fig. 2 is the schematic diagram of the predistortion drive circuit that the embodiment of the present invention two is provided；
Fig. 3 is the schematic diagram of the nonlinear distortion characteristicses of two-tone signal provided in an embodiment of the present invention；
Fig. 4 is the phase place schematic diagram of predistortion drive circuit provided in an embodiment of the present invention.
Specific embodiment
To make the object, technical solutions and advantages of the present invention clearer, hereinafter with reference to the embodiment of the present invention in it is attached
Figure, clearly and completely describes technical scheme by embodiment, it is clear that described embodiment is the present invention one
Section Example, rather than the embodiment of whole.Based on the embodiment in the present invention, those of ordinary skill in the art are not doing
The every other embodiment obtained under the premise of going out creative work, belongs to the scope of protection of the invention.
As shown in figure 1, the schematic diagram of the predistortion drive circuit provided for the embodiment of the present invention one.What the present embodiment was provided
Predistortion drive circuit includes：Input signal processing circuit 110, power amplification circuit 120, termination power 130 and final stage are amplified
Circuit 140.
In the present embodiment input signal processing circuit 110 for input signal is processed be divided into main path signal,
Linear branch signal and non-linear branch signal are simultaneously exported；Power amplification circuit 120 is for carrying out Linear Amplifer to main path signal
And main road amplification signal is exported, Linear Amplifer is carried out to linear branch signal and output linearity branch road amplifies signal, and to non-
Linear branch signal carries out non-linear amplification and output nonlinear branch road amplification signal；Termination power 130 is used to eliminate linear
Keynote signal in road amplification signal and non-linear branch amplification signal is to generate error signal, and error signal and main road are put
Big signal is overlapped, to generate pre-distorted signals and export；Final stage amplifying circuit 140 is for carrying out non-thread by pre-distorted signals
Property amplify eliminating error signal, and export undistorted linear signal.
In the present embodiment optional input signal be two-tone signal, two-tone signal have certain frequency interval and amplitude phase
Deng the linearisation of the mechanism of production and the present invention of error signal to power amplifier can be better illustrated using two-tone signal
Improvement.It will be understood by those skilled in the art that input signal includes but is not limited to two-tone signal, the present invention is to different moulds
The input signal of formula is respectively provided with the effect of linear improvement, does not carry out concrete restriction to input signal in the present invention.
The input of input signal processing circuit 110 receives two-tone signal, and output end is electrically connected with power amplification circuit 120
Connect.Input signal is divided into main path signal and tributary signal by input signal processing circuit 110, and tributary signal is divided into linear branch again
Signal and non-linear branch signal, in 180 ° of the phase of this main path signal and tributary signal, linear branch signal and non-thread
180 ° of the phase of property tributary signal, therefore non-linear branch signal is identical with the phase place of main path signal.
Power amplification circuit 120 carries out Linear Amplifer to main path signal and generates main road amplifying signal output to termination power
130 first input end, power amplification circuit 120 carry out Linear Amplifer to linear branch signal and generate linear branch amplifying letter
Number export to the second input of termination power 130, and power amplification circuit 120 non-linear branch signal is carried out it is non-linear
Amplify and generate non-linear branch and amplify coupled end of the signal output to termination power 130.
It should be noted that power amplification circuit 120 carries out non-linear amplification and generates non-thread to non-linear branch signal
Property branch road amplify signal, wherein, the non-linear branch includes nonlinear component (IMD3, IMD5, IMD7 ...) in amplifying signal.
180 ° of the phase of known linear tributary signal and non-linear branch signal, then linear branch amplify signal and non-linear branch
The phase place for amplifying signal also differs 180 °.
Termination power 130 makes linear branch amplify keynote signal amplitude and non-thread in signal by rationally arranging the degree of coupling
Property branch road amplify signal in keynote signal amplitude it is identical, then signal and non-linear branch are amplified based on linear branch and amplify signal
180 ° of phase, in linear branch amplification signal, keynote signal and non-linear branch amplify keynote signal cancellation in signal, only
Remaining non-linear branch amplifies the nonlinear component signal (IMD3, IMD5, IMD7 ...) in signal, and the nonlinear component is believed
It is known as error signal.The error signal of generation and main road are amplified signal and are overlapped by termination power 130 again, based on non-linear
Tributary signal is identical with the phase place of main path signal, can generate pre-distorted signals and export to final stage amplifying circuit 140 after superposition.
Final stage amplifying circuit 140 is eliminated to the error signal in pre-distorted signals, then remaining signal is linear point
Amount, i.e., undistorted linear signal, final stage amplifying circuit 140 export the undistorted linear signal.In this final stage amplifying circuit 140
Do not include any error signal in undistorted linear signal produced by after eliminating to the error signal in pre-distorted signals,
Known error signal can may enter to error signal for high-order and/or lower order nonlinear component signal, final stage amplifying circuit 140
Row is completely eliminated, it is clear that, the circuit can either effectively suppress lower order nonlinear component signal, additionally it is possible to effectively suppress high
Rank nonlinear component signal.
Input signal is divided into main road letter by input signal processing circuit by the predistortion drive circuit that the present embodiment is provided
Number, linear branch signal and non-linear branch signal, main path signal and linear branch signal are distinguished by power amplification circuit
Carry out Linear Amplifer and non-linear branch signal carried out non-linear amplification, then eliminate linear branch by termination power amplifying
Keynote signal in signal and non-linear branch amplification signal is to generate error signal, and error signal and main road are amplified signal
It is overlapped, to generate pre-distorted signals and export, by final amplifier by pre-distorted signals non-linear amplification, eliminates error
Signal, with output linearity signal.It can thus be appreciated that predistortion drive circuit can effectively suppress error signal, i.e. lower order nonlinear point
Amount signal and high-order nonlinear component signal, realize linearisation, possess good linearity improvement ability.
As shown in Fig. 2 the schematic diagram of the predistortion drive circuit provided for the embodiment of the present invention two.What the present embodiment was provided
Predistortion drive circuit includes：Input signal processing circuit 110, power amplification circuit 120, termination power 130 and final stage are amplified
Circuit 140.
Wherein, input signal processing circuit 110 includes：First electric bridge 111 and the second electric bridge 112.First electric bridge 111, uses
In being processed to be divided into main path signal and distortion tributary signal and export to input signal；Second electric bridge 112, for distortion
Tributary signal is processed to be divided into linear branch signal and non-linear branch signal and export.
Optional input signal is two-tone signal in the present embodiment, but does not limit the type of input signal in the present invention.
First electric bridge 111 is used to process input signal, i.e., input signal is processed to be divided into main path signal and distortion tributary signal.
In 180 ° of the phase of this main path signal and distortion tributary signal, the phase place of optional main path signal is 0 °, distortion tributary signal
Phase place be 180 °.
Second electric bridge 112 is used to process distortion tributary signal, i.e., distortion tributary signal is processed to be divided into linear
Road signal and non-linear branch signal.In 180 ° of the phase of this linear branch signal and non-linear branch signal, can route selection
Property tributary signal phase place be 180 °, the phase place of non-linear branch signal is 360 °, is postponed identical.It should be noted that linear
The Magnitude Difference of tributary signal and non-linear branch signal is more than or equal to 10dB.
Wherein, power amplification circuit 120 includes：Variable gain power amplifier 121, the first power amplifier 122 and
Two power amplifiers 123.Variable gain power amplifier 121, puts for carrying out Linear Amplifer to main path signal and exporting main road
Big signal；First power amplifier 122, for Linear Amplifer output linearity branch road amplification letter are carried out to linear branch signal
Number；Second power amplifier 123, for non-linear amplification and output nonlinear branch road amplification letter is carried out to non-linear branch signal
Number.
The input of variable gain power amplifier 121 receives the main path signal of the transmission of the first electric bridge 111, and to the main road
Signal carries out Linear Amplifer and amplifies signal to export main road.It is exaggerated in the amplitude of this main path signal, while variable gain power
Amplifier 121 also make main road amplify signal delay it is identical with the delay of distortion tributary signal, not limited delay in the present invention
Value.
The input of the first power amplifier 122 receives the linear branch signal of the transmission of the second electric bridge 112, and linear to this
Tributary signal carries out Linear Amplifer and output linearity branch road amplifies signal, and here 122 Linear Amplifers of the first power amplifier are linear
During tributary signal, based on Linear Amplifer, linear branch will not produce high-order nonlinear component signal in amplifying signal, i.e.,
High-order error signal.
The input of the second power amplifier 123 receives the non-linear branch signal of the transmission of the second electric bridge 112, and non-to this
Linear branch signal carries out non-linear amplification and output nonlinear branch road amplification signal.123 non-thread of the second power amplifier of here
Property amplify non-linear branch signal during, based on non-linear amplification, it is non-that non-linear branch generates high-order in amplifying signal
Linear component signal (IMD3, IMD5, IMD7 ...).
It should be noted that 180 ° of the phase based on linear branch signal and non-linear branch signal, linear branch
The phase place of signal is 180 °, and the phase place of non-linear branch signal is 360 °, postpones identical, and linear branch amplifies signal and non-linear
Branch road amplifies the phase place of signal and also differs 180 °, and it is 180 ° that linear branch amplifies the phase place of signal, and non-linear branch amplifies signal
Phase place be 360 °, postpone it is identical.
Compared with existing predistortion drive circuit, using two power amplifiers in parallel in the same direction in the embodiment of the present invention
(the first power amplifier and the second power amplifier) extracts error signal, with linearizing effect is improved, with prior art
Compare, also there is under high/low temperature good characteristic.Optional first power amplifier of here and the complete phase of the second power amplifier
With but be operated in different states, specific first power amplifier is operated in linear condition and the work of the second power amplifier
In nonlinear state, therefore, it is possible to extract error signal completely, it is clear that possess changing for high-order nonlinear component signal
Kind ability and with larger dynamic range.The main path signal of input is linearly put in this variable gain power amplifier
Greatly, gain is provided for whole circuit, while provide postponing with distortion tributary signal identical so that predistortion drive circuit has
Standby gain and broadband ability.
Wherein, termination power 130 includes：First coupler 131 and the 3rd electric bridge 132.First coupler 131, for adjusting
Whole linear branch amplifies signal and non-linear branch amplifies the keynote signal amplitude of signal to eliminate keynote signal therein, generates
Error signal；3rd electric bridge 132, amplifies signal for overlay error signal and main road, to generate pre-distorted signals and export.
Optional first coupler 131 of here is directional coupler, and the input of the first coupler 131 is used to receive linear
Road amplify signal, its coupled end be used for receive non-linear branch amplify signal, its function be by linear branch amplify signal and
Non-linear branch amplifies the keynote signal cancellation in signal.Here can pass through the degree of coupling for rationally arranging the first coupler 131, make
The amplitude that linear branch amplifies signal is identical with the keynote signal amplitude that non-linear branch amplifies signal, then linear after adjusting
The keynote signal amplitude that signal is amplified on road is identical with the keynote signal amplitude that non-linear branch amplifies signal.Put based on linear branch
Big signal and non-linear branch amplify 180 ° of the phase of signal, then linear branch amplify the keynote signal of signal with it is non-linear
Branch road amplify the keynote signal of signal amplitude is identical and opposite in phase, be thus capable of achieving the counteracting of keynote signal, then the first coupling
Signal after the process of clutch 131 only remains the error signal that non-linear branch is amplified in signal, also becomes distortion component signal
Or nonlinear component signal (IMD3, IMD5, IMD7 ...).The error signal is exported by the output end of the first coupler 131.
The first input end of the 3rd electric bridge 132 receives the main road of the output of variable gain power amplifier 121 and amplifies signal, phase
Position keeps constant；Its second input receives the error signal of the output of the first coupler 131, then the phase place change of error signal
180°.3rd electric bridge 132 is used for overlay error signal and main road amplifies signal, to generate pre-distorted signals and export.
Three phse conversions of the specific error signal through the first electric bridge 111, the second electric bridge 112 and the 3rd electric bridge 132
Afterwards, its phase place and the opposite in phase of main road amplification signal, postpone identical.The 3rd electric bridges 132 of pre-distorted signals Jing after superposition are defeated
Go out, wherein, the keynote signal of pre-distorted signals is that main road amplifies signal, and component signal is error signal, in this pre-distorted signals
Keynote signal and error signal 180 ° of phase.Optional error signal at least includes third-order non-linear component, five ranks
Nonlinear component and seven rank nonlinear components (IMD3, IMD5, IMD7 ...).It will be understood by those skilled in the art that in other realities
It is likely to only have third-order non-linear component signal in applying example, or also creates non-linear point of nine ranks in other embodiments
Amount signal, in the present invention error signal refer to all of nonlinear component signal of generation, here not concrete restriction.
From foregoing circuit, by rationally arranging the first electric bridge 111, the second electric bridge 112, the 3rd electric bridge 132 and first
The parameter of coupler 131, through variable gain power amplifier 121, the first power amplifier 122 and the second power amplifier
123 signal amplifies, and the keynote signal amplitude in pre-distorted signals has been significantly higher than the amplitude of input signal, therefore the pre- mistake
True drive circuit possesses certain gain.
Wherein, final stage amplifying circuit 140 includes：3rd power amplifier 141.3rd power amplifier 141 is for pre-
Distorted signal carries out non-linear amplification, and the nonlinear component produced according to the 3rd power amplifier 141 itself offsets predistortion
Error signal in signal, to generate undistorted linear signal and export.
Pre-distorted signals are entered by amplification of the pre-distorted signals through the 3rd power amplifier 141, the 3rd power amplifier 141
The non-linear amplification of row.Here can make 141, the 3rd power amplifier by the parameter for rationally arranging the 3rd power amplifier 141
The amplitude of the nonlinear component signal of body is equal with the amplitude of the error signal after amplification, and 141, the 3rd power amplifier
180 ° of the phase of the error signal after the nonlinear component signal of body and amplification, therefore in the pre-distorted signals after amplifying
Error signal is cancelled completely, and thus only remains the i.e. undistorted linear signal of pure two-tone signal after amplifying, and then
Realize the linearisation to the 3rd power amplifier 141.
It should be noted that after pre-distorted signals are linearly amplified, intermodulation component signal (error signal) therein and
The intermodulation component that three power amplifiers itself are produced can be offset, and only retain linear component signal, realize linearisation.
On the basis of above-mentioned technical proposal, in order to optimize the linearisation effect of predistortion linear signal, here is also optional
Final stage amplifying circuit 140 also includes：Second coupler 142 and automatic electric-level ALC control loops 143.Second coupler 142 is used for
Linearity test is carried out to undistorted linear signal and is exported；Automatic electric-level ALC control loops 143 be used for obtain detection after without mistake
True linear signal simultaneously controls power amplification circuit 120 and carries out Gain tuning, so that the output of the 3rd power amplifier 141 is with gain
Linear signal.
Optional second coupler 142 of here is directional coupler, and the function of second coupler 142 is detection linearisation
Undistorted linear signal afterwards.The output end electricity of the input and the 3rd power amplifier 141 of specific second coupler 142
To obtain undistorted linear signal, the coupled end of the second coupler 142 is electrically connected with the input of ALC control loops 143 for connection
And by undistorted linear signal transmission to ALC control loops 143, it is linear after the output end output detection of the second coupler 142
Change undistorted linear signal.If the linearisation that the second coupler 142 detects undistorted linear signal is undesirable, or this is linear
Changing has different with required linearisation, then undistorted linear signal transmission can be given ALC control loops by the second coupler 142
143 carry out linear optimization；If the second coupler 142 detects the linearisation excellent effect of undistorted linear signal without the need for excellent again
Change, then the output end of the second coupler 142 directly exports the undistorted linear signal after the completion of detection.
ALC control loops 143 obtain the undistorted linear signal after detection and control power amplification circuit 120 carries out gain
Adjustment, so that the output high linearity linear signal of final stage amplifying circuit 140.Specifically, the output end of ALC control loops 143 with
The control end of variable gain power amplifier 121 is electrically connected, then ALC control loops 143 get undistorted linear after detecting
Linearisation effect can be analyzed after signal, according to linearisation effect, control variable gain power amplifier 121 carries out gain tune
Whole, i.e. gain of the ALC control loops 143 to variable gain power amplifier 121 is adjusted, and further optimizes linearizing effect
Really.Here can adjust predistortion drive circuit different working condition by the gain of regulation variable gain power amplifier 121
Under performance.
ALC control loops 143 control the gain of variable gain power amplifier 121, realize predistortion drive circuit
Adaptive characteristic.
The predistortion drive circuit that the present embodiment is provided, using the first power amplification in parallel in the same direction in power amplification circuit
Device and the second power amplifier extract error signal, with linearizing effect is improved, compared with prior art, under high/low temperature
Also there is good characteristic；Additionally, main path signal is eliminated and mistake after variable gain power amplifier carries out Linear Amplifer
Delay between true tributary signal, circuit structure are better than traditional delay line so that predistortion drive circuit possesses broadband ability；
And, by the parameter for rationally arranging each electric bridge and each coupler, using the gain of variable gain power amplifier so that without mistake
True linear signal possesses gain.The predistortion drive circuit that the present embodiment is provided is improving linearizing while additionally providing driving
Gain so that predistortion drive circuit does not contain decay in possessing the broadband ability for having gain, and the predistortion drive circuit
The devices such as device, phase shifter, reduce insertion loss and reduce complexity in circuits.
Exemplary, on the basis of above-described embodiment, need rationally to arrange power amplifier in predistortion drive circuit
With the parameter of the device such as coupler, here describes each device parameters in predistortion drive circuit in detail by following derivation formula and sets
The mode put.
1st, the nonlinear characteristic of power amplifier
To simplify the analysis, it is assumed that the output voltage of power amplifier is only the function of a certain moment input voltage, the function
Can be expressed as：
v0(t)=f [vi(t)]
Wherein, viT () is input voltage instantaneous value, v0T () is output voltage instantaneous value.
If there is all-order derivative in above-mentioned function, then power series form can be spread out into：
v0(t)=k1vi(t)+k2vi 2(t)+k3vi 3(t)+…(1)
When power amplifier is operated in linear condition, k2, k3, k4...=0, vo(t)=k1vi(t)。
When power amplifier is operated in nonlinear state, the higher order term that can ignore below only takes first three items approximately, i.e.,：
v0(t)=k1vi(t)+k2vi 2(t)+k3vi 3(t)
When the input signal of predistortion drive circuit is respectively for two frequency components for two-tone signal, i.e. input signal
ω1And ω2Constant-amplitude signal when, it is assumed that：
vi(t)=Vi(cosω1t+cosω2t)
Above formula is substituted into into formula (1), and by power series expansion, obtains following derivation formula：
From above formula, under double-tone input condition, the output end of predistortion drive circuit does not only exist direct current, fundamental frequency omega1
And ω2, 2 ω of second harmonic1With 2 ω2, also there is second order intermodulation product ω1±ω2, 2 ω of third-order intermodulation product1±ω2And ω1±
2ω2Deng.Work as ω1And ω2When frequency interval is less, 2 ω1-ω2With 2 ω2-ω1Component can fall in frequency band, wave filter is difficult to
Filter, its reason is, it is that the component is mainly caused by the cube item in non-linear and easily fall in frequency band.
Generally, third-order intermodulation product represented with relative power, by the power of third-order intermodulation product with carry
The ratio of the input power of ripple is defined as IM3, and unit is dBc, and the non-linear distortion for characterizing two-tone signal as shown in Figure 3 is special
Property.
2nd, in predistortion drive circuit each parameter reasonable setting
In order to realize the predistortion function of predistortion drive circuit in the embodiment of the present invention, key point is accurate construction
It is input into the pre-distorted signals of the 3rd power amplifier so that the 3rd power amplifier is only retained after pre-distorted signals are amplified to be needed
Keynote signal to be retained, realizes Linear Amplifer.During construction is input to the pre-distorted signals of the 3rd power amplifier, close
Key point is the extraction of nonlinear component (error) signal and the synthesis of pre-distorted signals, is needed to amplitude, phase place and delay
It is accurately controlled and is calculated.Detailed process is as follows：
1. amplitude：
Input signal after the first electric bridge and the second electric bridge, the first power amplifier of linear branch signal input, non-thread
Property tributary signal be input into the second power amplifier, it is more than power difference 10dB of the two-way tributary signal.Arrange the first power to put
Big device is operated in linear condition, and the second power amplifier is operated in nonlinear state, and the first power amplifier and the second power are put
The linear gain of big device is G0, then the output of the first power amplifier and the second power amplifier is respectively：
vo2(t)=α2β1G01vi(t) (2-1)
vo3(t)=α2β2[G01vi(t)+G02vi 2(t)+G03vi 3(t)+...] (2-2)
The output signal of the first power amplifier and the second power amplifier after the first coupler, then believe by distortion branch road
Keynote signal (i.e. linear component signal) in number is eliminated, and the nonlinear component signal of the first coupler output is
For complete counteracting keynote signal, need to meet following formula：
δ1α2β1+δ2α2β2=0 (2-4)
Error signal d (t) can be expressed as d (t)=δ2α2β2[G02vi 2(t)+G03vi 3(t)+...] (2-5)
After the main path signal that error signal is exported with variable gain power amplifier is superimposed by the 3rd electric bridge, work is sent into
Make in the 3rd power amplifier of nonlinear state.The superposed signal is
Wherein, Vin(t) be input main path signal, d (t) be generate error signal, 180 ° of both phases.
In order to accurately be fitted the nonlinear characteristic of the 3rd power amplifier, the error signal after amplification should be with the 3rd power
Amplifier nonlinearity component signal is equal.
The nonlinear characteristic for assuming the 3rd power amplifier is
Vout (t)=G21vin(t)+G22vin 2(t)+G23vin 3(t)+... (2-7)
After pre-distorted signals are input into, its 3rd power amplifier is output as
G after realizing the counteracting of nonlinear component signal, in a hold mode (2-8)21[γ1α1G10vi(t)] item, then can
：
I.e., the 3rd power amplifier and the second power amplifier are operated in identical rollback shape to the essence of above-mentioned derivation
State.
With reference to (2-4) and (2-9), it may be determined that the size of the degree of coupling and coupled end of each coupler, and each electric bridge
Straight-through size.
The gain of whole predistortion drive circuit can be expressed as：
Gain=γ1α1G1 (2-10)
2nd, phase place
In whole predistortion drive circuit, in two output ends of each electric bridge, output signal does not have phase place change then all the way
0 ° is defined as, another road has 180 ° of phase difference.Then the phase place of predistortion drive circuit is as shown in Figure 4.When phase place is 0 °,
The arrow of two-tone signal is upwards；When phase place is 180 °, under the arrow of two-tone signal is pointed to.
By the port phase for designing each electric bridge, it is possible to achieve：
The input of (1) first coupler, 180 ° of the phase of two-way input signal, it is possible thereby to distortion branch road is believed
Keynote signal in number is completely counterbalanced by, and extracts the error signal of needs；
The output end of (2) the 3rd electric bridges, after two-way input signal superposition synthesis pre-distorted signals, main path signal is believed with error
Number 180 ° of phase.
3rd, postpone
In the present invention in three branch roads of predistortion drive circuit, employing three power amplifiers guarantees three branch roads
Signal delay it is identical, realize wideband operation.
Note, above are only presently preferred embodiments of the present invention and institute's application technology principle.It will be appreciated by those skilled in the art that
The invention is not restricted to specific embodiment described here, can carry out for a person skilled in the art various obvious changes,
Readjust and substitute without departing from protection scope of the present invention.Therefore, although the present invention is carried out by above example
It is described in further detail, but the present invention is not limited only to above example, without departing from the inventive concept, also
More other Equivalent embodiments can be included, and the scope of the present invention is determined by scope of the appended claims.
Claims (8)
1. a kind of predistortion drive circuit, it is characterised in that include：
Input signal processing circuit, for being processed to be divided into main path signal, linear branch signal and non-thread to input signal
Property tributary signal is simultaneously exported；
Power amplification circuit, amplifies signal for carrying out Linear Amplifer to the main path signal and exporting main road, to described linear
Tributary signal carries out Linear Amplifer and output linearity branch road amplifies signal, and the non-linear branch signal is carried out non-linear
Amplify and output nonlinear branch road amplifies signal；
Termination power, for eliminating, the linear branch amplifies signal and the non-linear branch amplifies the keynote signal in signal
To generate error signal, and the error signal and main road amplification signal are overlapped, to generate pre-distorted signals simultaneously
Output；
Final stage amplifying circuit, for the pre-distorted signals are carried out non-linear amplification to eliminate the error signal, and exports
Undistorted linear signal.
2. predistortion drive circuit according to claim 1, it is characterised in that the input signal processing circuit includes：
First electric bridge, for being processed to be divided into the main path signal and distortion tributary signal defeated to the input signal
Go out；
Second electric bridge, for being processed to be divided into the linear branch signal and described non-linear to the distortion tributary signal
Tributary signal is simultaneously exported.
3. predistortion drive circuit according to claim 2, it is characterised in that the linear branch signal and the non-thread
Property tributary signal Magnitude Difference be more than or equal to 10dB.
4. predistortion drive circuit according to claim 1, it is characterised in that the power amplification circuit includes：
Variable gain power amplifier, amplifies signal for Linear Amplifer is carried out to the main path signal and the main road is exported；
First power amplifier, amplifies letter for Linear Amplifer is carried out to the linear branch signal and the linear branch is exported
Number；
Second power amplifier, for non-linear amplification is carried out to the non-linear branch signal and the non-linear branch is exported
Amplify signal.
5. predistortion drive circuit according to claim 1, it is characterised in that the termination power includes：
First coupler, for adjusting, the linear branch amplifies signal and the non-linear branch amplifies the keynote signal of signal
Amplitude generates the error signal to eliminate keynote signal therein；
3rd electric bridge, amplifies signal for being superimposed the error signal and the main road, to generate pre-distorted signals and export.
6. predistortion drive circuit according to claim 5, it is characterised in that the error signal at least includes that three ranks are non-
Linear component, fifth-order nonlinearity component and seven rank nonlinear components.
7. predistortion drive circuit according to claim 1, it is characterised in that the final stage amplifying circuit includes：
3rd power amplifier, for the pre-distorted signals are carried out with non-linear amplification, and according to the 3rd power amplification
The nonlinear component that device itself is produced offsets the error signal in the pre-distorted signals, to generate the undistorted linear signal
And export.
8. predistortion drive circuit according to claim 7, it is characterised in that the final stage amplifying circuit also includes：
Second coupler, for carrying out linearity test to the undistorted linear signal and exporting；
Automatic electric-level ALC control loops, the undistorted linear signal after detecting for acquisition simultaneously control the power amplification circuit
Gain tuning is carried out, so that the 3rd power amplifier linear signal of the output with gain.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6385436B1 (en) * | 1998-11-05 | 2002-05-07 | Mitsubishi Denki Kabushiki Kaisha | Distortion compensation circuit |
| CN101286962A (en) * | 2008-05-30 | 2008-10-15 | 北京北方烽火科技有限公司 | Carrier balancing radio frequency predistortion power amplifier realizing apparatus and method |
| CN103314523A (en) * | 2011-09-30 | 2013-09-18 | 瑞典爱立信有限公司 | Systems and methods for digital predistortion in a dual band transmitter |
| CN103401512A (en) * | 2013-08-01 | 2013-11-20 | 绵阳灵通电讯设备有限公司 | Dual-loop structural simulation predistorter of BUC module |
| CN105897191A (en) * | 2016-05-24 | 2016-08-24 | 中国科学院电子学研究所 | Predistortion linearizer and application of the predistortion linearizer |
-
2016
- 2016-11-02 CN CN201610971171.8A patent/CN106549640A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6385436B1 (en) * | 1998-11-05 | 2002-05-07 | Mitsubishi Denki Kabushiki Kaisha | Distortion compensation circuit |
| CN101286962A (en) * | 2008-05-30 | 2008-10-15 | 北京北方烽火科技有限公司 | Carrier balancing radio frequency predistortion power amplifier realizing apparatus and method |
| CN103314523A (en) * | 2011-09-30 | 2013-09-18 | 瑞典爱立信有限公司 | Systems and methods for digital predistortion in a dual band transmitter |
| CN103401512A (en) * | 2013-08-01 | 2013-11-20 | 绵阳灵通电讯设备有限公司 | Dual-loop structural simulation predistorter of BUC module |
| CN105897191A (en) * | 2016-05-24 | 2016-08-24 | 中国科学院电子学研究所 | Predistortion linearizer and application of the predistortion linearizer |
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