CN103187932B - power amplifier and predistorter thereof - Google Patents

Abstract

The invention discloses a kind of power amplifier and predistorter thereof, described predistorter comprises the sub-predistorter of predetermined quantity; Described in each, sub-predistorter comprises basic function, one or more basic function that has time delay without time delay, the output of the described basic function without time delay with described in have the linear combination of the output of the basic function of time delay to form the output of sub-predistorter; The output sum of the sub-predistorter of described predetermined quantity forms the output of predistorter; Wherein, the basic function without time delay in every sub-predistorter with have the basic function of time delay orthogonal.

Description

Power amplifier and predistorter thereof

Technical field

Relate generally to nonlinear system, particularly nonlinear power amplifier, especially wireless communication system of the present inventionEmitter (such as base station and travelling carriage) in use nonlinear power amplifier. More particularly, the present invention relates to forThe power amplification device of the predistorter of nonlinear power amplifier and use predistorter, it mainly utilizes digital technology to existBase band realizes predistortion, to make up memoryless nonlinear characteristic and the memory characteristic of nonlinear power amplifier.

Background technology

As the Typical Representative of nonlinear system, power amplifier is the important component part of a lot of electronic equipments, and it canSo that the faint signal of telecommunication is amplified, to meet the needs of remote transmission. Wherein, the energy of amplification comes from dc source, i.e. meritRate amplifier can be converted into AC signal by DC energy, and the power level of AC signal is satisfied the demand. Power amplificationThe ratio that DC energy is converted to AC energy by device is known as the efficiency of power amplifier.

According to the physical characteristic of power amplifier, along with the power of input signal is ascending, reflection power amplifierThe characteristic curve of the power relation of input signal and output signal can be divided into linear zone, inelastic region and saturation region. Fig. 1 illustratesThe non-linear input/output signal characteristic of power amplifier. At input signal V_INThe region that amplitude is less, power amplifier PA'sOutput V_OUTAlmost input signal V_INLinearity amplify, but along with input signal V_INThe increase of amplitude, power amplifierNonlinear characteristic is obviously to the last saturated gradually. This non-linear behavior is in time domain, and output signal is not input signalDesirable amplification; This non-linear behavior is on frequency domain, and due to intermodulation effect, video stretching appears outward in the band of the signal being exaggerated, there is distortion (main lobe distortion) in (secondary lobe rising), as shown in Figure 2, has shown by nonlinear power amplifier and caused in bandVideo stretching. Video stretching can affect the normal operation of the miscellaneous equipment that works in adjacent channel.

Ideally, wish that power amplifier only plays linear effect of amplifying, i.e. just input letter of output signalNumber simple linear amplify, therefore allow power amplifier be operated in linear zone. But now power amplifier turns direct current signalThe efficiency that is changed to AC signal is very low, causes the waste of large energy, and need to increase extra heat dissipation equipment. Due to thingReason in reason, gos deep into inelastic region when the envelope fluctuation of input signal, and the efficiency of power amplifier will be far above only existingSituation when linear zone fluctuation. And along with the appearance of new-type modulation system, the dynamic range of signal envelope is increasing, therefore sends outRaw nonlinear distortion is inevitable.

Therefore, on the one hand in order to improve the efficiency of power amplifier, on the other hand due in a lot of Modern Communication SystemSignal has very large dynamic range (peak-to-average power ratio), so power amplifier often need to be in inelastic region work, therebyCause the distortion (on frequency domain, occurring distortion in band, the outer video stretching that occurs of band) of output signal. Lead at power amplifierTerritory, is only subject to this current output the distortion of the nonlinear power amplifier that current input affects to be called power amplifier conventionallyMemoryless nonlinear characteristic.

In numerous methods that overcome non-linearity of power amplifier characteristic, base band predistortion is a kind of side receiving much concernMethod. The input of the predistorter for power amplifier for offsetting the nonlinear characteristic shown in Fig. 1 is shown as shown in Figure 3,The schematic diagram of output signal characteristics. Base band predistortion technology passes through to use the contrary characteristic of predistorter PD simulated power amplifier,Make original input signal V_INPredistortion occurred before being input to power amplifier, thereby compensating power amplifier is non-linear,And obtain at the output of power amplifier the amplification output signal V that there is no distortion_OUT. There is the power of pre-distortion functionThe input/output signal characteristic of amplifier all shows extraordinary linear characteristic before until approach saturation region, as shown in Figure 4,The schematic diagram of the input/output signal characteristic of the power amplifier that is provided with predistorter is shown.

But the good predistorter of much working is all for tone signal or narrow band frequency signal. That is to say, largeAll for compensating the memoryless non-linear of the power amplifier mentioned above. But, along with the bandwidth of signal is more and more wider, meritRate amplifier shows again certain memory characteristic (frequency selectivity), and current output signal is not only believed with current inputNumber relevant, also relevant with input signal before, as shown in Figure 5, the nonlinear power amplifier with memory characteristic is shownThe schematic diagram of input/output signal characteristic. The memory characteristic of power amplifier shows as near carrier wave asymmetric in its outputFrequency spectrum, as shown in Figure 6, illustrates by the spectrum diagram of nonlinear power amplifier institute amplifying signal with memory characteristic.That is to say, the frequency spectrum that distortion causes is asymmetrical for centered carrier.

Therefore,, in order to simulate exactly the contrary characteristic of the power amplifier with above-mentioned memory characteristic, just must adopt moreAdd complicated structure and method the contrary characteristic of power amplifier is carried out to modeling and parameter Estimation, to realize predistortion. OrderBefore mainly comprise that for the memoryless nonlinear characteristic of while compensating power amplifier and the technology of memory characteristic memory is manyItem formula model and look-up-table method.

Memory multinomial model is the simplified model of Volterra model. Volterra model adopts Volterra progressionNonlinear system is carried out to Accurate Model, can support theoretically by the contrary Volterra series model of emulation power amplifierMemoryless nonlinear characteristic and the memory characteristic of power amplifier disappear. Although Volterra model is for offsetting power amplifierMemoryless nonlinear characteristic and memory characteristic are very effective, but its physics realization is almost impossible, use because needComplicated formula, and need the mathematical operation of flood tide. For this reason, the Volterra model of simplifying has been proposed, that is, and memory multinomialModel. As shown in Figure 7, illustrate according to prior art and use memory multinomial model to put the non-linear power with memory characteristicThe input signal of large device carries out the schematic diagram of pre-distortion, wherein remembers multinomial model and uses and current input and previously defeatedEnter relevant polynomial function and represent output. The nonlinear ability of offsetting power amplifier depends on used previous inputQuantity and polynomial exponent number. Non-linear polynomial non-linear (multistage) can describe the non-linear spy of power amplifierProperty, and multinomial is reused the memory characteristic that can describe power amplifier on different delay point. But, different delayCorrelation between multinomial on point can have a strong impact on the training of predistorter, finally have influence on to power amplifier without noteRecall the compensation ability of nonlinear characteristic and memory characteristic.

Look-up-table method is the pass according to the current output of power amplifier and its current input and between previously having inputtedSystem, makes question blank by the contrary characteristic of power amplifier, thereby utilizes from inquiry before input signal is carried out to power amplificationThe weight coefficient obtaining in table carries out predistortion to input signal, and nonlinear characteristic and the memory of offsetting thus power amplifier are specialProperty. As shown in Figure 8, illustrate according to prior art and use two-dimensional polling list to thering is the nonlinear power amplifier of memory characteristicInput signal carries out the schematic diagram of pre-distortion. By using question blank, effectively improve the processing speed of predistorter,And be conducive to the realization of software. But the data source of question blank, from the training result to predistorter, is therefore also subject to different delayThe impact of the correlation between the multinomial on point.

Also there is above similar technical problem for other nonlinear system that is similar to nonlinear power amplifier.

Summary of the invention

Provide hereinafter about brief overview of the present invention, to basic about some aspect of the present invention is providedUnderstand. Should be appreciated that this general introduction is not about exhaustive general introduction of the present invention. It is not that intention is determined pass of the present inventionKey or pith, nor is it intended to limit the scope of the present invention. Its object is only that the form of simplifying provides some concept,Using this as the preorder in greater detail of discussing after a while

The object of this invention is to provide a kind of predistorter for power amplifier, can improve predistorter to powerThe memoryless nonlinear characteristic of amplifier and the compensation ability of memory characteristic.

To achieve these goals, according to an aspect of the present invention, provide a kind of predistortion for power amplifierDevice, described predistorter comprises the sub-predistorter of predetermined quantity; Described in each, sub-predistorter comprises the base letter without time delayNumber, one or more has the basic function of time delay, the output of the described basic function without time delay with described in have the basic function of time delayThe linear combination of output forms the output of sub-predistorter; The output sum of the sub-predistorter of described predetermined quantity forms pre-mistakeThe output of true device; Wherein, the basic function without time delay in every sub-predistorter with have the basic function of time delay orthogonal.

According to a specific embodiment of the present invention, the basic function that has time delay in every sub-predistorter is that same son is pre-The linear combination of the time delay pattern of the basic function without time delay in distorter and the described basic function without time delay, described linear combinationCoefficient make the basic function without time delay in every sub-predistorter and have the basic function of time delay orthogonal.

According to a specific embodiment of the present invention, by minimization covariance matrixOff-diagonal element or barNumber of packages obtains the coefficient u of described linear combination, wherein,

$U=\left(\begin{array}{cccccccc}1& 0& 0& ...& u_{101}& 0& ...& 0\\ 0& 1& 0& ...& 0& u_{102}& ...& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& ...& u_{111}& 0& ...& 0\\ 0& 0& 0& ...& 0& u_{112}& ...& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& ...& 0& 0& ...& u_{\mathrm{PPK}}\end{array}\right),$

Basic function ψ_pkExpansion on time shaft, 0≤p≤P, 1≤k≤K, K is described predetermined quantity, P is eachThe quantity of the basic function that has time delay in individual sub-predistorter, in the time of p=0, ψ_pkThe basic function without time delay, in the time of p ≠ 0, ψ_pkThe time delay pattern without the basic function of time delay,It is the basic function that has time delayExpansion on time shaft, 1≤i≤P, 1≤ m≤K, U is the matrix that described linear combination coefficient u forms.

According to a further aspect in the invention, provide a kind of power amplification device, having comprised: predistorter, for to originalInput signal carries out predistortion, output predistorted input signal; Digital to analog converter, for the predistortion that predistorter is exportedInput signal is converted to analog signal; Upconverter, for up-converting to radio frequency from the analog signal of digital to analog converter outputSignal; Power amplifier, for carrying out the letter after power amplification power output are amplified to the radiofrequency signal of upconverter outputNumber as output signal; Wherein, the structure of described predistorter and the predistorter for power amplifier as aboveStructure is identical.

In accordance with a further aspect of the present invention, provide a kind of pre-distortion method for power amplifier, described method bagDraw together following steps: use the sub-predistortion module of predetermined quantity to process input signal, and by each sub-predistortion moduleOutput sum export to power amplifier; Wherein, described in each, sub-predistortion module comprises without time delay module, one or moreMultiple have a time delay module, and described processing comprises: describedly calculate without the basic function of time delay and act on input signal without time delay moduleResult is as the described output without time delay module; Described have time delay module to calculate to have the basic function of time delay to act on input signalResult is as the described output that has time delay module; And calculate the described output without time delay module in described sub-predistortion moduleThere is the linear combination of output of time delay module as the output of described sub-predistortion module with described one or more; Wherein,The basic function without time delay in every sub-predistortion module with have the basic function of time delay orthogonal.

According to a specific embodiment of the present invention, the basic function that has time delay in every sub-predistortion module is same sonThe linear combination of the time delay pattern of the basic function without time delay in predistortion module and the described basic function without time delay, described linearityThe coefficient of combination makes every basic function without time delay in sub-predistortion module and has the basic function of time delay orthogonal.

According to a specific embodiment of the present invention, by minimization covariance matrixOff-diagonal element or barNumber of packages obtains the coefficient u of described linear combination, wherein,

$U=\left(\begin{array}{cccccccc}1& 0& 0& ...& u_{101}& 0& ...& 0\\ 0& 1& 0& ...& 0& u_{102}& ...& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& ...& u_{111}& 0& ...& 0\\ 0& 0& 0& ...& 0& u_{112}& ...& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& ...& 0& 0& ...& u_{\mathrm{PPK}}\end{array}\right),$

Basic function ψ_pkExpansion on time shaft, 0≤p≤P, 1≤k≤K, K is described predetermined quantity, P is eachThe quantity that has time delay module in individual sub-predistortion module, in the time of p=0, ψ_pkThe basic function without time delay, in the time of p ≠ 0, ψ_pkBeWithout the time delay pattern of the basic function of time delay,It is the basic function that has time delayExpansion on time shaft, 1≤i≤P, 1≤ m≤K, U is the matrix that described linear combination coefficient u forms.

In accordance with a further aspect of the present invention, provide a kind of power-magnifying method, described method comprises original input letterNumber carry out predistortion, output predistorted input signal; Predistorted input signal is converted to analog signal; To in analog signal, becomeFrequently be radiofrequency signal; And radiofrequency signal is carried out to signal after power amplification power output are amplified as output signal; ItsIn, described predistortion step adopts pre-distortion method as above.

In addition, according to a further aspect in the invention, also provide a kind of storage medium. Described storage medium comprises that machine canThe program code of reading, when carry out described program code on messaging device time, described program code makes described information placeReason equipment is carried out according to said method of the present invention.

In addition, in accordance with a further aspect of the present invention, also provide a kind of program product. Described program product comprises that machine canThe instruction of carrying out, when carry out described instruction on messaging device time, described instruction is carried out described messaging deviceAccording to said method of the present invention.

According to the above-mentioned predistorter for power amplifier of the present invention, use the power amplification of this predistorter to establishStandby, pre-distortion method and power-magnifying method, avoided because the correlation between the multinomial on different delay point causesThe adverse effect to predistorter training, improve predistorter special to the memoryless nonlinear characteristic of power amplifier and memoryThe compensation performance of property.

In description part below, provide other aspects of the present invention, wherein, describe in detail for open fullyThe preferred embodiments of the present invention, and it is not applied to restriction.

Brief description of the drawings

Below with reference to the accompanying drawings illustrate embodiments of the invention, can understand more easily of the present invention above and itsIts objects, features and advantages. Parts in accompanying drawing are just in order to illustrate principle of the present invention. In the accompanying drawings, identical or similarTechnical characterictic or parts will adopt same or similar Reference numeral to represent. In accompanying drawing:

Fig. 1 is the schematic diagram that the nonlinear characteristic of the input/output signal of nonlinear power amplifier is shown;

Fig. 2 is the spectrum diagram illustrating by nonlinear power amplifier institute amplifying signal;

Fig. 3 is the input and output letter that the power amplifier pre-distortion device for offsetting the nonlinear characteristic shown in Fig. 1 is shownThe schematic diagram of number characteristic;

Fig. 4 is the schematic diagram that the input/output signal characteristic of the power amplifier that is provided with predistorter is shown;

Fig. 5 is the schematic diagram that the input/output signal characteristic of the nonlinear power amplifier with memory characteristic is shown;

Fig. 6 is the spectrum diagram of nonlinear power amplifier institute amplifying signal illustrating by having memory characteristic;

Fig. 7 illustrates according to prior art to use memory multinomial model to amplify the non-linear power with memory characteristicThe input signal of device carries out the schematic diagram of pre-distortion;

Fig. 8 illustrates according to using question blank to carry out the input signal of the nonlinear power amplifier with memory characteristicThe schematic diagram of pre-distortion;

Fig. 9 is the figure that the relation of power amplifier and predistorter is shown;

Figure 10 according to of the present invention for obtaining and adjust the schematic diagram of connecting structure between predistorter coefficient;

Figure 11 shows the schematic diagram of predistorter of the prior art;

Figure 12 shows the schematic diagram according to predistorter of the present invention;

Figure 13 is the block diagram illustrating according to the non-linear power multiplying arrangement that can realize predistortion of the present invention;And

Figure 14 is the block diagram that the example arrangement of personal computer is shown.

Detailed description of the invention

In connection with accompanying drawing, example embodiment of the present invention is described in detail hereinafter. Rise for clarity and concisenessSee, in description, do not describe all features of actual embodiment. But, should understand, in any this reality of exploitationIn the process of embodiment, must make much decisions specific to embodiment, to realize developer's objectives, exampleAs, meet and those restrictive conditions of system and traffic aided, and these restrictive conditions may along with embodiment notChange together and to some extent. In addition, although will also be appreciated that development is likely very complicated and time-consuming, to having benefited fromThose skilled in the art of present disclosure, this development is only routine task.

At this, also it should be noted is that, for fear of the details because of unnecessary fuzzy the present invention, in the accompanying drawingsOnly show with according to the closely-related apparatus structure of the solution of the present invention and/or treatment step, and omitted and the present inventionOther details that relation is little. In addition, also it is pointed out that in an accompanying drawing of the present invention or a kind of embodiment and describeElement and feature can combine with element and feature shown in one or more other accompanying drawing or embodiment.

Embodiments of the invention are described with reference to the accompanying drawings.

Fig. 9 is the figure that the relation of power amplifier and predistorter is shown.

The input of pre-distorter is x (t), and output is z (t), and the input of power amplifier is the output z of predistorter(t), output is y (t).

The response of predistorter is described by following formula (1).

$z\left(t\right)=\underset{p=0}{\overset{P}{\mathrm{\Σ}}}\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{w}_{\mathrm{pk}}{\mathrm{\ψ}}_k\left(x(t-p)\right)---\left(1\right)$

Wherein, x (t-p) is the time delay item of input x (t), ψ_kRepresent the polynomial basis function of structure predistorter, ψ_k(x(t) be) that the response to x (t) of basic function without time delay (is that x (t) is through the basic function ψ without time delay_kOutput after effect), ψ_k(x(t-P) be) response of basic function to x (t) that has a time delay, K is the number that forms the sub-predistorter of predistorter, and P is each heightThe quantity of the basic function that has time delay in predistorter, w_pkBe predistorter coefficient, in predistorter, have a time delay basic functionWith the weight coefficient without time delay basic function. As described above, the exponent number of basic function has embodied the benefit to memoryless nonlinear characteristicRepay, the time delay of basic function has embodied the compensation to memory characteristic.

Conventionally, expect by training and adjust predistorter coefficient w_pkMake

y(t)＝Gx(t)(2)

Wherein G is a constant, and expression signal is expected the multiple being exaggerated.

Between the present invention adopts, connecting structure is trained, to obtain and to adjust predistorter coefficient w_pk。

Figure 10 according to of the present invention for obtaining and adjust the schematic diagram of connecting structure between predistorter coefficient.

Under normal circumstances, the characteristic of nonlinear system can not change in time continually, therefore can collect oneAfter a little input and output data samples, carry out off-line data processing. After training, new argument (predistorter coefficient) is sent toThe predistorter of nonlinear system, to compensate the non-linear and memory characteristic of nonlinear system. In Figure 10, x (t)For the input of nonlinear system, the output that y (t) is nonlinear system, the expected gain coefficient that G is nonlinear system, and y (t)Weaken as y (t)/G is imported into training as input and prop up through attenuator. Therefore the output that, training is propped up is as following formula (3) instituteShow.

$\hat{z}\left(t\right)=\underset{p=0}{\overset{P}{\mathrm{\Σ}}}\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{w}_{\mathrm{pk}}{\mathrm{\ψ}}_k(y(t-p)/G)---\left(3\right)$

The expectation of the e (t) calculating by the following formula of adaptive algorithm minimization (4), can train acquisition predistorterCoefficient w_pk, then given predistorter, complete predistortion. Dotted line in figure shows, in adaptive algorithm process, to pass throughParameter is transmitted, and the parameter that predistorter and predistorter training are propped up is consistent.

$e\left(t\right)=\hat{z}\left(t\right)-z\left(t\right)---\left(4\right)$

For ease of describing, by ψ_k(y (t-p)/G) writes a Chinese character in simplified form and makes ψ_pk, its expansion writing vector on time shaft ${\stackrel{\→}{\mathrm{\ψ}}}_{\mathrm{pk}}({\stackrel{\→}{\mathrm{\ψ}}}_{\mathrm{pk}}={[{\mathrm{\ψ}}_k\left(x(t_1-p)\right),...,{\mathrm{\ψ}}_k\left(x(t_n-p)\right)]}^T,$ T1 ..., tn represents different time points), can obtain thus numberAccording to matrix:

$\mathrm{\Ψ}=[{\stackrel{\→}{\mathrm{\ψ}}}_{01},...,{\stackrel{\→}{\mathrm{\ψ}}}_{0K},{\stackrel{\→}{\mathrm{\ψ}}}_{11},...,{\stackrel{\→}{\mathrm{\ψ}}}_{1K},...,{\stackrel{\→}{\mathrm{\ψ}}}_{\mathrm{PK}}]---\left(5\right)$

The characteristic of matrix Ψ can have a strong impact on the performance for the adaptive algorithm of the above-mentioned e of minimization (t), and then has influence onThe acquisition of pre-distortion coefficients. Wherein, the correlation of each column vector of matrix Ψ and the covariance matrix that formed by matrix ΨΨ^HThe characteristic value diffusion (conditional number) of Ψ is the common index of the characteristic of Description Matrix Ψ.

About the correlation of each column vector of matrix Ψ, it is desirable to each vector orthogonal, wish covariance matrixΨ^HAll off-diagonal elements in Ψ go to zero.

About conditional number, it is defined as follows shown in formula (6).

$\mathrm{\ρ}=\frac{{\mathrm{\λ}}_{\max }}{{\mathrm{\λ}}_{\min }}---\left(6\right)$

, conditional number equals covariance matrix Ψ^HThe eigenvalue of maximum λ of Ψ_maxWith minimal eigenvalue λ_minRatio. DesirableBe that conditional number levels off to 1, this characterization value diffusion is very slight.

As mentioned above, in prior art, the correlation between the multinomial on different delay point can have a strong impact on predistorterTraining (being difficult to obtain suitable predistorter coefficient), finally have influence on the memoryless nonlinear characteristic of power amplifier andThe compensation ability of memory characteristic.

Particularly, due to relativity of time domain, Ψ^HThe off-diagonal element of Ψ and conditional number all can be along with time domain tap number is (everyThe quantity of the basic function that has time delay in a sub-predistorter) P increase and increase.

The impact causing for overcoming relativity of time domain, according to an embodiment of the invention data matrix corresponding to predistorterAs shown in following formula (7).

Wherein,

In formula (7),Basic function ψ_pkExpansion on time shaft, 0≤p≤P, 1≤k≤K, K is described predetermined numberAmount, P is the quantity of the basic function that has time delay in each sub-predistorter, in the time of p=0, ψ_pkThe basic function without time delay, whenP ≠ 0 o'clock, ψ_pkThe time delay pattern without the basic function of time delay,It is the basic function that has time delayExpansion on time shaft, 1≤i≤P，1≤m≤K。

Formula (8) shows the basic function of time delayFormation.

Orthogonalization coefficient matrix U is as shown in following formula (9).

$U=\left(\begin{array}{cccccccc}1& 0& 0& ...& u_{101}& 0& ...& 0\\ 0& 1& 0& ...& 0& u_{102}& ...& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& ...& u_{111}& 0& ...& 0\\ 0& 0& 0& ...& 0& u_{112}& ...& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& ...& 0& 0& ...& u_{\mathrm{PPK}}\end{array}\right)---\left(9\right)$

By design matrix U, can make new covariance matrixDiagonal angle and conditional number improve (non-Diagonal element goes to zero, and conditional number is lower), and then improve the performance of adaptive training algorithm and the effect of predistorter.

Wherein, new covariance matrix ${\widehat{\mathrm{\Ψ}}}^H\widehat{\mathrm{\Ψ}}=U^H{\mathrm{\Ψ}}^H\mathrm{\ΨU}---\left(10\right)$

That is to say the basic function without time delay in every sub-predistorter and sometimes all that has its source in of the problems referred to aboveThe basic function prolonging is not orthogonal. Can find out from above-mentioned formula (7)-(9), can solve prior art by following mannerIn problem: the basic function that has time delay in every sub-predistorter is configured to the base without time delay in same sub-predistorterThe linear combination of the time delay pattern of function and the described basic function without time delay, and the coefficient of described linear combination is designed to makeThe basic function without time delay in every sub-predistorter and all basic functions that has time delay are orthogonal.

The structure of predistorter is described with reference to Figure 11,12 hereinafter.

Figure 11 shows a kind of predistorter of the prior art, it comprise predetermined quantity sub-predistorter I, II,III, IV...... etc. Output (z1 (t), z2 (t), z3 (t) ...) sum of sub-predistorter forms the output z of predistorter(t). The structure of every sub-predistorter is identical, taking sub-predistorter I as example, it comprise a basic function branch road without time delay withAnd one or more has the basic function branch road of time delay. The output sum of each branch road forms the output of sub-predistorter.

Input signal x (t) enters the basic function branch road without time delay without time delay, and wherein, input signal x (t) is through baseAfter function ψ 01 effect, be multiplied by weight coefficient ω 01, as the output of the basic function branch road without time delay.

At the first basic function branch road that has a time delay, input signal x (t), after basic function ψ 11 effects, is multiplied by weight coefficientω 11, as the first output that has a basic function branch road of time delay. Note, delayer D is only that the object of expressing illustrates this hereinThe size of the time delay of branch road. In fact, as mentioned above, there is the basic function ψ 11 of time delay itself to represent the time delay with p=1. CauseThis, here and do not mean that input signal is both through delayer D time delay, also can doing the used time via the basic function ψ 11 that has time delay againAgain experience time delay. Basic function ψ shown in figure 11 represents this first overall transfer function that has a basic function branch road of time delay.

Each has time delay branch road on the basis of last branch road, to increase a timer.

At the second basic function branch road that has a time delay, input signal x (t), after basic function ψ 21 effects, is multiplied by weight coefficientω 21, as the second output that has a basic function branch road of time delay.

By that analogy, the output sum of each branch road forms the output of sub-predistorter.

The structure of sub-predistorter II is identical with the structure of sub-predistorter I, difference be sub-predistorter II have withThe basic function (ψ 02, ψ 12, ψ 22......) that sub-predistorter I is different and weight coefficient (ω 02, ω 12, ω 22......).

As mentioned above, in prior art, orthogonal without the basic function of time delay. But, belong to same sub-predistorterHave without the basic function of time delay and each between basic function of time delay owing to only having increased time delay, thus not orthogonal.

Correlation between multinomial on different delay point can have a strong impact on the training of predistorter, and it is right finally to have influence onThe memoryless nonlinear characteristic of power amplifier and the compensation ability of memory characteristic. Particularly, each branch road in predistorterBasic function not orthogonally will cause being difficult to calculate weight coefficient ω ij.

Therefore, as long as make, the basic function of each branch road in predistorter is orthogonal (especially belongs to same son pre-The basic function without time delay of distorter and allly have the basic function of time delay orthogonal), just can overcome and exist in prior artProblem. From above-mentioned formula (7)-(9), making one of orthogonal means of multinomial on different delay point is by eachThe basic function that has time delay in sub-predistorter be configured to the basic function without time delay in same sub-predistorter and described without timeThe linear combination of the time delay pattern of the basic function prolonging, and the coefficient of described linear combination is designed to make to belong to same son loses in advanceThe basic function without time delay of true device and all basic functions that has time delay are orthogonal. According to the present invention, a sub-predistorterOrthogonal between interior all basic functions (without the basic function of time delay, all basic functions that has time delay), and then predistorterInterior all basic functions are orthogonal.

To corresponding circuit structure be described referring to Figure 12 below.

Figure 12 shows the schematic diagram according to predistorter of the present invention. Pre-mistake according to an embodiment of the inventionTrue utensil has the structure identical with the predistorter shown in Figure 11, and its difference is, basic function ψ ij (i > 0) is replaced by new baseFunction That (0 < q < linear combination i), the coefficient of design linear combination makes for ψ 0j and ψ qjObtain every basic function without time delay in sub-predistorter and have the basic function of time delay orthogonal.

WithFor example,Design u101 and u111 makeWith ψ 01Orthogonal.

Similarly, for DesignU201,211, u221 make ψ 01,Orthogonal. By that analogy.

The coefficient u of above-mentioned linear combination has formed the orthogonalization coefficient matrix U in formula 9 as above.CalculatingMethod as shown in Equation 8.

Covariance matrixDiagonal angle and conditional number can reflect relevant between the multinomial on different delay pointProperty, off-diagonal element more goes to zero, and conditional number is lower, and orthogonality is better. Therefore, the coefficient u (orthogonalization of above-mentioned linear combinationElement in coefficient matrix U) can pass through minimization covariance matrixOff-diagonal element or conditional number solve and draw.

Except can, with above-mentioned circuit structure structure predistorter, adopting the look-up-table method of introducing aboveRealize the present invention. , can, in advance according to input signal, basic function and orthogonalization coefficient, calculate output signal, and will input letterNumber be stored in question blank with the mapping relations of output signal, wherein, input signal has specific span, and can be measuredTurn to limited value. In the time receiving real input signal, obtain output signal by the mode of searching question blank. Pass throughUse question blank, effectively improved the processing speed of predistorter, and be conducive to the realization of software.

Figure 13 shows the block diagram that can realize the power amplification device of predistortion according to embodiments of the invention.

As shown in figure 13, this power amplification device 1300 that can realize predistortion comprises: predistortion module 1301, forInput signal x (t) is carried out to predistortion, output pre-distorted signals; Digital to analog converter 1302, for by 1301 of predistortion moduleThe pre-distorted signals of output is converted to analog signal (for baseband signal); Upconverter 1303, for will be from digital to analog converterThe baseband signal of 1302 outputs up-converts to radiofrequency signal; And power amplifier 1304, for upconverter 1303 is exportedRadiofrequency signal carry out the output signal y (t) after power amplification power output are amplified. Now, power amplification device is exportedSignal y (t) eliminated memoryless nonlinear characteristic and the memory characteristic of power amplifier, there is good linearity spyProperty.

According to the power amplification device with predistorter module as above configuring, utilize digital technology to realize in base bandPredistortion, can make up memoryless nonlinear characteristic and the memory characteristic of nonlinear power amplifier.

Can find out by above description, according to embodiments of the invention, also can obtain and predistortion as abovePre-distortion method and power-magnifying method that device and power amplification device are corresponding are as follows:

For a pre-distortion method for power amplifier, comprise the steps: to use the sub-predistortion mould of predetermined quantityPiece is processed input signal, and the output sum of each sub-predistortion module is exported to power amplifier; Wherein, eachIndividual described sub-predistortion module comprises without time delay module, one or more has time delay module, and described processing comprises: described without timeProlong module and calculate the result that acts on input signal without the basic function of time delay as the described output without time delay module; Sometimes describedProlonging module calculates and has result that the basic function of time delay acts on input signal as the described output that has time delay module; And calculateThe described output without time delay module in described sub-predistortion module and described one or more have the output of time delay moduleLinear combination is as the output of described sub-predistortion module; Wherein, the basic function without time delay in every sub-predistortion module withThere is the basic function of time delay orthogonal.

As one of embodiment, the basic function that has time delay in every sub-predistortion module is same sub-predistortion moduleThe linear combination of the interior basic function without time delay and the time delay pattern of the described basic function without time delay, the coefficient of described linear combinationMake every basic function without time delay in sub-predistortion module and have the basic function of time delay orthogonal.

As one of embodiment, can pass through minimization covariance matrixOff-diagonal element or conditional number obtainObtain the coefficient u of described linear combination, wherein,

$U=\left(\begin{array}{cccccccc}1& 0& 0& ...& u_{101}& 0& ...& 0\\ 0& 1& 0& ...& 0& u_{102}& ...& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& ...& u_{111}& 0& ...& 0\\ 0& 0& 0& ...& 0& u_{112}& ...& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& ...& 0& 0& ...& u_{\mathrm{PPK}}\end{array}\right),$

Basic function ψ_pkExpansion on time shaft, 0≤p≤P, 1≤k≤K, K is described predetermined quantity, P is eachThe quantity that has time delay module in individual sub-predistortion module, in the time of p=0, ψ_pkThe basic function without time delay, in the time of p ≠ 0, ψ_pkBeWithout the time delay pattern of the basic function of time delay,It is the basic function that has time delayExpansion on time shaft, 1≤i≤P, 1≤ m≤K, U is the matrix that described linear combination coefficient u forms.

A kind of power-magnifying method, comprising: original input signal is carried out to predistortion, output predistorted input signal; WillPredistorted input signal is converted to analog signal; Analog signal is up-converted to radiofrequency signal; And radiofrequency signal is carried out to meritSignal after rate amplification power output are amplified is as output signal; Wherein, described predistortion step adopts as above pre-Distortion methods.

In addition, should also be noted that all modules in said apparatus, unit can pass through software, firmware, hardwareOr the mode of its combination is configured. Configure spendable concrete means or mode and be well known to those skilled in the art, at thisRepeat no more. In the situation that realizing by software and/or firmware, from storage medium or network to thering is specialized hardware structureComputer, example general purpose personal computer 1400 is as shown in figure 14 installed the program that forms this software, and this computer is being provided withWhen various program, can carry out various functions etc.

In Figure 14, CPU (CPU) 1401 according in read-only storage (ROM) 1402 storage program or fromStorage area 1408 is loaded into the program of random access memory (RAM) 1403 and carries out various processing. In RAM1403, also rootAccording to needs storage required data in the time that CPU1401 carries out various processing etc.

CPU1401, ROM1402 and RAM1403 are connected to each other via bus 1404. Input/output interface 1405 also connectsReceive bus 1404.

Following parts are connected to input/output interface 1405: importation 1406, comprises keyboard, mouse etc.; EfferentDivide 1407, comprise display, such as cathode-ray tube (CRT), liquid crystal display (LCD) etc., and loudspeaker etc.; Storage partDivide 1408, comprise hard disk etc.; With communications portion 1409, comprise that NIC is such as LAN card, modem etc. LogicalLetter part 1409 via network such as internet executive communication processing.

As required, driver 1410 is also connected to input/output interface 1405. Detachable media 1411 such as disk,CD, magneto-optic disk, semiconductor memory etc. are installed on driver 1410 as required, make the computer of therefrom readingProgram is installed in storage area 1408 as required.

In the situation that realizing above-mentioned series of processes by software, from network such as internet or storage medium are such as removableUnload medium 1411 program that forms software is installed.

It will be understood by those of skill in the art that this storage medium is not limited to wherein stores journey shown in Figure 14Order, with equipment distribute separately the detachable media 1411 so that program to be provided to user. The example bag of detachable media 1411Containing disk (comprising floppy disk (registration mark)), CD (comprising compact disc read-only memory (CD-ROM) and digital universal disc (DVD)),Magneto-optic disk (comprising mini-disk (MD) (registration mark)) and semiconductor memory. Or storage medium can be ROM1402, depositHard disk comprising in storage part 1408 etc., wherein computer program stored, and be distributed to user together with comprising their equipment.

The present invention also proposes a kind of program product that stores the instruction code that machine readable gets. Described instruction code is by machineWhen device reads and carries out, can carry out above-mentioned according to the method for the embodiment of the present invention.

Correspondingly, also wrap for the storage medium that carries the above-mentioned program product that stores the instruction code that machine readable getsDraw together in of the present invention disclosing. Described storage medium includes but not limited to floppy disk, CD, magneto-optic disk, storage card, memory stick etc.Deng.

In the above in the description of the specific embodiment of the invention, the feature of describing and/or illustrating for a kind of embodimentCan in one or more other embodiment, use in same or similar mode, with the feature in other embodimentCombined, or substitute the feature in other embodiment.

Should emphasize, term " comprises/comprises " existence that refers to feature, key element, step or assembly while use herein, but alsoDo not get rid of the existence of one or more further feature, key element, step or assembly or add.

In addition, the time sequencing that method of the present invention is described in being not limited to is to specifications carried out, also can be according to itHis time sequencing ground, carry out concurrently or independently. The execution sequence of the method for therefore, describing in this description is not to thisBright technical scope is construed as limiting.

Although described the present invention and advantage thereof in detail, be to be understood that and do not departing from by appended claimIn the situation of the spirit and scope of the present invention that limit, can carry out various changes, substitute and conversion. And, the application's artLanguage " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thereby makes to comprise a series of wantingProcess, method, article or the equipment of element not only comprise those key elements, but also comprise other key elements of clearly not listing,Or be also included as the intrinsic key element of this process, method, article or equipment. In the situation that there is no more restrictions,The key element being limited by statement " comprising ... ", and be not precluded within and comprise process, method, the article of described key element or establishIn standby, also there is other identical element.

Claims (4)

1. for a predistorter for power amplifier, described predistorter comprises the sub-predistorter of predetermined quantity; EachIndividual described sub-predistorter comprises without the basic function of time delay, one or more basic function that has time delay, the described base without time delayThe output of function with described in have the linear combination of the output of the basic function of time delay to form the output of sub-predistorter; Described predetermined numberThe output sum of the sub-predistorter of amount forms the output of predistorter; It is characterized in that, in every sub-predistorter without timeThe basic function prolonging with have the basic function of time delay orthogonal; Wherein, the basic function that has time delay in every sub-predistorter is sameThe linear combination of the time delay pattern of the basic function without time delay in one sub-predistorter and the described basic function without time delay, described lineThe coefficient of property combination makes every basic function without time delay in sub-predistorter and has the basic function of time delay orthogonal; ItsIn, by minimization covariance matrixOff-diagonal element or conditional number obtain the coefficient u of described linear combination,Wherein, $U=\left(\begin{array}{cccccccc}1& 0& 0& \mathrm{...}& u_{101}& 0& \mathrm{...}& 0\\ 0& 1& 0& \mathrm{...}& 0& u_{102}& \mathrm{...}& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& \mathrm{...}& u_{111}& 0& \mathrm{...}& 0\\ 0& 0& 0& \mathrm{...}& 0& u_{112}& \mathrm{...}& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& \mathrm{...}& 0& 0& \mathrm{...}& u_{PPK}\end{array}\right),$

Basic function ψ_pkExpansion on time shaft, 0≤p≤P, 1≤k≤K, K is described predetermined quantity, P is each heightThe quantity of the basic function that has time delay in predistorter, in the time of p=0, ψ_pkThe basic function without time delay, in the time of p ≠ 0, ψ_pkIt is nothingThe time delay pattern of the basic function of time delay,It is the basic function that has time delayExpansion on time shaft, 1≤i≤P, 1≤M≤K, U is the matrix that described linear combination coefficient u forms.

2. a power amplification device, comprising:

Predistorter, for original input signal is carried out to predistortion, output predistorted input signal;

Digital to analog converter, is converted to analog signal for the predistorted input signal that predistorter is exported;

Upconverter, for up-converting to radiofrequency signal from the analog signal of digital to analog converter output; And

Power amplifier, for carrying out the signal after power amplification power output are amplified to the radiofrequency signal of upconverter outputAs output signal;

Wherein, the knot of the structure of described predistorter and the predistorter for power amplifier according to claim 1Structure is identical.

3. for a pre-distortion method for power amplifier, comprise the steps:

Use the sub-predistortion module of predetermined quantity to process input signal, and by the output of each sub-predistortion module itWith export to power amplifier;

Wherein, described in each, sub-predistortion module comprises without time delay module, one or more has time delay module, described processingComprise:

Described calculate without time delay module the result that acts on input signal without the basic function of time delay as described without time delay moduleOutput;

The described result that has time delay module to calculate to have the basic function of time delay to act on input signal has a time delay module as describedOutput; And

The described output without time delay module and described one or more that calculate in described sub-predistortion module have time delay moduleThe linear combination of output as the output of described sub-predistortion module;

It is characterized in that, the basic function without time delay in every sub-predistortion module with have the basic function of time delay orthogonal;Wherein, the basic function that has time delay in every sub-predistortion module is the base letter without time delay in same sub-predistortion moduleThe linear combination of the time delay pattern of number and the described basic function without time delay, the coefficient of described linear combination makes every height pre-The basic function without time delay in distortion module with have the basic function of time delay orthogonal; Wherein, by minimization covariance squareBattle arrayOff-diagonal element or conditional number obtain the coefficient u of described linear combination, wherein, $U=\left(\begin{array}{cccccccc}1& 0& 0& \mathrm{...}& u_{101}& 0& \mathrm{...}& 0\\ 0& 1& 0& \mathrm{...}& 0& u_{102}& \mathrm{...}& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& \mathrm{...}& u_{111}& 0& \mathrm{...}& 0\\ 0& 0& 0& \mathrm{...}& 0& u_{112}& \mathrm{...}& 0\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ .& .& .& & .& .& & .\\ 0& 0& 0& \mathrm{...}& 0& 0& \mathrm{...}& u_{PPK}\end{array}\right),$

Basic function ψ_pkExpansion on time shaft, 0≤p≤P, 1≤k≤K, K is described predetermined quantity, P is each heightThe quantity that has time delay module in predistortion module, in the time of p=0, ψ_pkThe basic function without time delay, in the time of p ≠ 0, ψ_pkBe without timeThe time delay pattern of the basic function prolonging,It is the basic function that has time delayExpansion on time shaft, 1≤i≤P, 1≤m≤ K, U is the matrix that described linear combination coefficient u forms.

4. a power-magnifying method, comprising:

Original input signal is carried out to predistortion, output predistorted input signal;

Predistorted input signal is converted to analog signal;

Analog signal is up-converted to radiofrequency signal; And

Radiofrequency signal is carried out to signal after power amplification power output are amplified as output signal;

Wherein, described predistortion step adopts pre-distortion method according to claim 3.