CN203014828U - Digital rectification apparatus for radiofrequency signal - Google Patents
Digital rectification apparatus for radiofrequency signal Download PDFInfo
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- CN203014828U CN203014828U CN 201320007998 CN201320007998U CN203014828U CN 203014828 U CN203014828 U CN 203014828U CN 201320007998 CN201320007998 CN 201320007998 CN 201320007998 U CN201320007998 U CN 201320007998U CN 203014828 U CN203014828 U CN 203014828U
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Abstract
The utility model relates to a digital rectification apparatus for radiofrequency signals, comprising the components as following: a radio frequency modulation module, which is used for modulating input signals and outputting corresponding signals; a rectification information storage module, which includes an address shift register and a memory, wherein the address of the memory comprises a set of data registers, input data is sent to the address shift register in a serial mode, and the information stored in the memory cells of the memory includes predistortion information to be corrected; a rectification processing module, which provides rectification process and outputs corresponding signals according to the information input by the radio frequency modulation module and the rectification information storage module; and a power amplification module, which is used for carrying out power amplification output to the signals output by the rectification processing module and feeding back the output signals to the rectification information storage module.
Description
Technical field
The utility model relates to a kind of digital apparatus for correcting of radiofrequency signal.
Background technology
Now, in the transmission equipment of radio communication emission system, the operating characteristic of high-power amplifier module (HPA) has the decision meaning to performance, signal quality and the cost of whole wireless communication system.For system given power and performance index, the performance characteristics of power amplifier module will worsen along with the expansion of input signal linear work scope, and its price also will significantly rise along with the expansion of its linear working range.Therefore, adopt the pre-distortion technology of extended power amplification module linear working range to replace the Research Significance of buying more high-grade HPA device great.Research and application for the extended power amplification module range of linearity, namely adopt pre-distortion technology, chip and algorithm product that a lot of maturations have been arranged abroad, it is as around-France in: digital look-up table, Descartes etc. that a variety of Digital adaptive pre-distortion technology have appearred, although the practical application of these methods and technology is also in continuous expansion, the effect of practical application is not very good.Its reason is the dissimilar power amplifier module that uses in digital algorithm and wireless system, there are differences in coupling and the characteristic of input signal, causes the different-effect to non-linear correction.
The utility model content
Technical problem to be solved in the utility model is, can mate preferably to adapt to dissimilar power amplifier module in the transmission equipment of radio communication emission system, causes the better effects if to non-linear correction.
At first the utility model provides a kind of digital apparatus for correcting of radiofrequency signal, comprises following hardware module:
The rf modulations module is used for corresponding signal is modulated and exported to the signal of input;
Correct information storage module, comprise: address shift register and memory, the address of described memory is to be made of one group of data register, the input data are sent into address shift register by serial mode, and the information that stores in the memory cell of described memory comprises the predistortion information of proofreading and correct;
The correction process module is used for according to described rf modulations module and corrects the information that information storage module is inputted, and carries out correction process and exports corresponding signal; And,
Power amplifier module is used for the signal of described correction process module output is carried out power amplification output, and its output signal is fed back to described rectification information storage module.
Accordingly, the utility model also provides a kind of antidote that adopts the digital apparatus for correcting of described radiofrequency signal, comprises the steps:
Corresponding signal is modulated and exported to described rf modulations module to the signal of input;
Described rectification information storage module by the signal of described rf modulations module and power amplifier module output, is exported corresponding predistortion information to described correction process module according to respectively;
Described correction process module, is carried out correction process and exports corresponding signal and carry out power amplification output to described power amplifier module by the signal of described rectification information storage module and the output of rf modulations module according to respectively.
Compared with the prior art, the utility model has the advantage of, be to adopt the pre-distortion algorithms of store-memory to correct the power amplifier module with memory characteristic, and this processing directly can be applied in radio frequency domains.Adopt the pre-distortion algorithms of stored digital memory in the application of RF application, purpose is not only to reach the power amplifier module nonlinear characteristic with memory function is better corrected, and the rectification information after digital processing directly can be corrected radio frequency amplifier in radio frequency domains.This digitized processing method, future realize the digitlization radio-frequency technique and system vital.
Description of drawings
Fig. 1 is the structured flowchart of a kind of embodiment of digital apparatus for correcting of the utility model radiofrequency signal;
Fig. 2 is further concrete structured flowchart of part of module embodiment illustrated in fig. 1;
Fig. 3 is the nonlinear characteristic AM-AM(amplitude-amplitude of power amplifier module) the distorted characteristic schematic diagram;
Fig. 4 is the nonlinear characteristic AM-PM(amplitude-phase place of power amplifier module) the distorted characteristic schematic diagram.
Embodiment
Below in conjunction with accompanying drawing, embodiment of the present utility model is described further.
As depicted in figs. 1 and 2, a kind of digital apparatus for correcting of radiofrequency signal comprises following hardware module:
The rf modulations module is used for corresponding signal is modulated and exported to the signal of input;
Correct information storage module, comprise: address shift register and memory, the address of described memory is to be made of one group of data register, the input data are sent into address shift register by serial mode, and the information that stores in the memory cell of described memory comprises the predistortion information of proofreading and correct;
The correction process module is used for according to described rf modulations module and corrects the information that information storage module is inputted, and carries out correction process and exports corresponding signal; And,
Power amplifier module is used for the signal of described correction process module output is carried out power amplification output, and its output signal is fed back to described rectification information storage module.
Preferably, in described rectification information storage module, the nonlinear characteristic of the corresponding described power amplifier module of described predistortion information, and according to by described rf modulations module institute input signal, complete the address to the mapping of corresponding information.
Wherein, the predistortion information in described rectification information storage module comprises that first corrects component (PD-I in) and the second rectification component (PD-Q in);
Described correction process module comprises following hardware cell:
Quadrature modulator is used for and will carries out angular transition by the signal of described rf modulations module input;
The first multiplier is used for correcting component (PD-I in) with described first and carries out multiplication process and output with the signal of being inputted by described rf modulations module;
The second multiplier is used for correcting component (PD-Q in) with described second and carries out multiplication process and output with the signal of being inputted by described quadrature modulator; With,
Signal synthesizer, be used for will described the first multiplier and the signal exported of the second multiplier synthesize and output to described power amplifier module.
Accordingly, adopt the antidote of the digital apparatus for correcting of described radiofrequency signal, comprise the steps:
Corresponding signal is modulated and exported to described rf modulations module to the signal of input;
Described rectification information storage module by the signal of described rf modulations module and power amplifier module output, is exported corresponding predistortion information to described correction process module according to respectively;
Described correction process module, is carried out correction process and exports corresponding signal and carry out power amplification output to described power amplifier module by the signal of described rectification information storage module and the output of rf modulations module according to respectively.
In an embodiment, adopting the purpose of digital pre-distortion method, is the linearity that will improve power amplifier module.And the assessment of the power amplifier linearity is assessed with this index of ACPR.Therefore, the digital pre-distortion purpose is exactly to improve the ACPR index of power amplifier.Analyze the nonlinear characteristic of power amplifier, weigh exactly its various distorted characteristics, mainly concentrate on AM-AM(amplitude-amplitude) distorted characteristic and AM-PM(amplitude-phase place) distorted characteristic, as shown in Fig. 3 and Fig. 4.Wherein, AM-AM amplitude-amplitude distortion characteristic is exactly the gain compression phenomenon of amplifier, has produced the AM-AM distortion.Its characteristic can adopt nonlinear multinomial to characterize this specific character of amplifier:
The numerical value of output signal Y in formula is amplitude (AM) decision by input signal.Under the certain condition of rf gain, in, can according to the amplitude (power) of input signal, can calculate this kind nonlinear distortion component by a multinomial.For the AM-PM distorted characteristic of amplitude-phase place, with the AM-AM distortion, many similarities are arranged, be also the amplitude decision by input signal.Suppose that as shown in Figure 3 input signal is:
When adding the AM-AM distortion, can be expressed as:
Wherein ω m is the modulation signal angular frequency.
The broadband high-speed wireless communication system of development in recent years has proposed stricter requirement to the characteristic of power amplifier module and the overall performance of system.In order to effectively utilize valuable frequency spectrum resource, power amplifier module should guarantee that high linearity to reduce the error rate with outer transmitting power and signal reception, has higher efficient again to reduce electrical source consumption.Although particularly the efficient linear modulation technique of development in recent years such as the multi-carrier modulations such as QPSK, QAM and OFDM etc. can provide good spectrum efficiency, but non-linear due to the high-power amplifier module in transmitter (HPA), after modulation, the fluctuation envelope signal of generation can cause all kinds of intermodulation distortion of HPA generation subsequently, and intermodulation distortion presents the adjacent interior interference phenomenon of frequently disturbing, be with more.In order to ensure the linear characteristic of HPA, need to use pre-distortion technology.Traditional pre-distortion method is that the baseband portion at modulator adds a nonlinear digital processing element, namely as the device digital pre-distortion (DPD) of non-linear correction, makes predistorter and power amplifier module do as a whole.Like this, the entire gain characteristic of emission path is linear.
Predistortion is divided into analog predistortion and digital pre-distortion, is all the envelope of power amplifier module is regulated.Analog predistortion occurs relatively early, and the technology comparative maturity.The analogue technique cost is relatively low, and it is better that the intermediate frequency predistortion circuit that only need manually adjust can be worked.And digital pre-distortion technology is the application along with transmission of digital signals, constantly progressively grows up on the basis of expansion, suppresses the distortion of HPA with adaptive digital pre-distortion technology, can play than the better effect of analogy method.In numerous power amplifier linearization high efficiency technology, digital pre-distortion technology is considered to the most effective solution, receives increasing concern.
Yet, pre-distortion technology that uses in wireless communication field at present and products thereof, characteristic for the existence of actual power amplification module, needing to introduce Memory algorithm processes power amplifier module, yet because the complexity of Memory algorithm increases, caused again the amount of calculation when processing obviously to increase, cause thus this type of pre-distortion method practical application in the operand, device cost that cause contradiction between power consumption extremely.The method that this patent proposes is exactly the problem for present existence, propose a kind of solution at algorithm operation quantity, device from the contradiction between cost and system power consumption.
The present embodiment is based on traditional digital pre-distortion principle, has added memory function on the method for digital processing, the nonlinear distortion that causes with the memory characteristic that solves power amplifier module.In this memory pre-distortion algorithms and characteristic come from information table in system, the predistortion component of storing in this table and reading has memory characteristic.The information combination of the information of these information and current input and former some moment inputs consists of, and has therefore formed a kind of information mapping that memory characteristic is arranged.The output signal of the pre-distortion unit that forms has thus had the effect of memory.The below introduces the formation mechanism of this memory effect.
The complex envelope of power amplifier module output signal can be expressed as
Here vQ is the output of quadrature modulator, and vp is pre-distorted signals, and the H supposition is the transfer function of quadrature modulator, and G is the gain of power amplifier module.Therefore, the output of memory digital pre-distortion system can be expressed as following equation
Wherein, F is the mapping function of predistortion table, and it can be mapped to a real number output vr to N n dimensional vector n Vm, and vm is the RF radio frequency complex signal of input.Non-linear impact analysis to radio system from power amplifier, IM3 and IM5 are larger on the impact of high power amplifier, and IM3 (three intermodulation components) and IM5 can be by IM2 and IM4 and former baseband signal modulation generations, therefore as long as control the reverse nonlinear characteristic that predistorter produces, IM3 and IM5 single spin-echo that itself and high power amplifier and the modulation of former baseband signal are produced, can very large or fully cancel whole IM3 and IM5, make high power amplifier present linearisation, thereby significantly inhibition zone is launched, reduce inband distortion outward.
In order to correct the non-linear of power amplifier module, can non-linear feature extracton and the memory of power amplifier module be got up at first by a store-memory information table, then according to input signal, complete the address to the mapping of corresponding information.The nonlinear transformations of storing in the store-memory digital watch, that computing by algorithm obtains and upgrades in time, and by algorithm with decent Information Read-Out, be used for compensating and correcting the input signal of power amplifier module, thereby the nonlinear characteristic of power amplifier module proofreaied and correct.
For the pre-distortion system of memory function, the address of memory table is generated by the input data, and the store-memory digital watch is different from traditional predistortion look-up table.Storage and memory function that digital watch is introduced are that the serial signal input structure by digital watch determines.Consisting of each output signal corresponding to information of store-memory table address, not only comprise current incoming symbol, and comprised several input messages of front, is therefore a N n dimensional vector n.This just means, each is to the non-linear correction signal of correcting of power amplifier module, be not only to be determined by the input signal of current time, but determined by the combination of the input signal in front some moment.The store-memory digital watch that consists of is so not only introduced storage and memory mechanism, and has greatly improved the dynamic effect of whole pre-distortion system.This N dimension input signal vector is one group of N bit addresses code of predistortion table namely, and can be expressed as
(5)
Each symbol sgi in this vector can be defined by following formula
The orthogonal signalling structure of base what mobile radio system, the predistortion table that corresponds respectively to I and Q two-way can be shone upon all binary system input data vectors to I component and the Q component of signal output, and can be expressed as:
The structure of predistortion memory table
Predistortion memory table is to be made of address shift register and memory, and the address of memory is to be made of one group of data register, and the input data are sent into address shift register by serial mode.Corresponding memory table element has been determined in the address that address shift register forms, and the information that namely stores in memory cell is namely to the non-linear predistortion information of proofreading and correct of power amplifier module.Suppose that each predistortion table address is a N-bit register, predistortion table has just comprised so
Individual memory cell.Obviously, each output of predistortion table is the combination of function of past N institute's the transmission of data.That is to say, the gamma correction amount of information that can store in predistortion table is
Individual.And to using each input, only have and choose a predistortion valuation to come the nonlinear characteristic of corrected power amplification module as output.The description of base above what, we can be with the explanation of following mathematic(al) representation.At first, with the k address vector representation of predistortion table constantly be:
In the table, all the Input Address vectors corresponding to M predistortion table memory cell can be expressed as so
(9)
The rectification information that is equivalent to store in predistortion table is
In each moment of processing in real time, there is a predistortion valuation to read from table, namely
In formula, subscript iq (k)=Vm (k) expression is by N as enter binary character determined address.The mapping function F of predistortion table just can be expressed as
It is to carry out signal in the base band of system to process that traditional digital pre-distortion is processed, and the predistortion correcting signal that therefore forms in the base-band digital system also must be simulated upconversion process, and delivers to power amplifier module and launch.The method that this patent proposes is with the digital pre-distortion processing signals that numeric field is realized, directly to correct the input signal of radio frequency power amplification module.
The radiofrequency signal that enters power amplifier is to be made of the amount part, and a part is established high-frequency carrier signal, and a part is the signal envelope that modulation intelligence consists of.Correcting the input radio frequency signal of power amplifier module with the pre-distorted signals of base band, is exactly in fact the modulation envelope of correcting in radiofrequency signal.The advantage of the processing of digital pre-distortion directly being moved radio frequency domains is that the combination of processing in radio frequency domains for digitlization and the digital pre-distortion of radio system provides great convenience.Simultaneously, the predistortion structure with memory characteristic has more distortion correction and the signal controlling of great dynamic range, is more suitable for the application to multichannel, the transmission of multi-carrier-wave wireless signal.
It is to carry out signal in the base band of system to process that traditional digital pre-distortion is processed, and the predistortion correcting signal that therefore forms in the base-band digital system also must be simulated upconversion process, and delivers to power amplifier module and launch.The method that this patent proposes is with the digital pre-distortion processing signals that numeric field is realized, directly to correct the input signal of radio frequency power amplification module.
Fig. 1 and Fig. 2 show the hardware block diagram of the antidote of radio frequency distortion.In figure, the processing of digital pre-distortion is placed on radio-frequency front-end, the baseband signal correcting signal after digital pre-distortion is processed, directly the analog signal with the radio frequency power amplification module input multiplies each other, with the envelope of adjustment radio-frequency input signals.
The rf modulations module is used for corresponding signal is modulated and exported to the signal of input;
Correct information storage module, comprise: address shift register and memory, the address of described memory is to be made of one group of data register, the input data are sent into address shift register by serial mode, and the information that stores in the memory cell of described memory comprises the predistortion information of proofreading and correct;
The correction process module is used for according to described rf modulations module and corrects the information that information storage module is inputted, and carries out correction process and exports corresponding signal; And,
Power amplifier module is used for the signal of described correction process module output is carried out power amplification output, and its output signal is fed back to described rectification information storage module.
Signal PD_i in and PD_q in represent respectively the information in storage list of predistortion, after this signal is read from storage list, deliver to respectively correction process modules A M/AM, AM/BM correcting unit, and the radiofrequency signal of input is corrected;
Wherein, each signal component is all corresponding to the signal component of Fig. 1.Need to prove, the radiofrequency signal RFin of input first was divided into I component and Q component before entering multiplier, and multiplied each other with signal component PD_i and the PD_q of predistortion memory table, and the complex signal that consists of after predistortion is multiple, and is input in power amplifier module.This memory pre-distortion method and structure can use the method for software and hardware to realize, and combine with existing wireless communication system, consist of the emission system of a complete wireless signal.
Other need to prove:
1. the design philosophy of above-described embodiment proposition is suitable for all wireless telecommunication systems, and the modulation system of the method and system (as QAM, QPSK, OFDM and other modulation system) and the power amplifier module that uses are irrelevant.
2. above-described embodiment major advantage is, will store compensate function and introduce pre-distortion system.Like this, predistortion will be with the store-memory function, thereby can regulate all kinds of amplifier nonlinearity distortions in wider dynamic range.
3. in above-described embodiment, the store-memory method about predistortion is, the output calibration signal of each predistortion determined by current input, and it is the products by current and in the past a plurality of input signals combinations.
In above-described embodiment about pre-distortion method and structure, can be in radio frequency domains directly correct the input signal of power amplifier module, with realize to the non-linear of power amplifier module with correct.
Above content is further detailed description of the utility model in conjunction with specific embodiments, can not assert that concrete enforcement of the present utility model is confined to these explanations.For the utility model person of an ordinary skill in the technical field, without departing from the concept of the premise utility, can also make some simple deduction or replace, all should be considered as belonging to protection range of the present utility model.
Claims (3)
1. the digital apparatus for correcting of a radiofrequency signal, is characterized in that, comprises following hardware module:
The rf modulations module is used for corresponding signal is modulated and exported to the signal of input;
Correct information storage module, comprise: address shift register and memory, the address of described memory is to be made of one group of data register, the input data are sent into address shift register by serial mode, and the information that stores in the memory cell of described memory comprises the predistortion information of proofreading and correct;
The correction process module is used for according to described rf modulations module and corrects the information that information storage module is inputted, and carries out correction process and exports corresponding signal; And,
Power amplifier module is used for the signal of described correction process module output is carried out power amplification output, and its output signal is fed back to described rectification information storage module.
2. the digital apparatus for correcting of radiofrequency signal as claimed in claim 1, it is characterized in that, in described rectification information storage module, the nonlinear characteristic of the corresponding described power amplifier module of described predistortion information, and according to by described rf modulations module institute input signal, complete the address to the mapping of corresponding information.
3. the digital apparatus for correcting of radiofrequency signal as claimed in claim 1, is characterized in that,
Predistortion information in described rectification information storage module comprises that first corrects component (PD-I in) and the second rectification component (PD-Q in);
Described correction process module comprises following hardware cell:
Quadrature modulator is used for and will carries out angular transition by the signal of described rf modulations module input;
The first multiplier is used for correcting component (PD-I in) with described first and carries out multiplication process and output with the signal of being inputted by described rf modulations module;
The second multiplier is used for correcting component (PD-Q in) with described second and carries out multiplication process and output with the signal of being inputted by described quadrature modulator; With,
Signal synthesizer, be used for will described the first multiplier and the signal exported of the second multiplier synthesize and output to described power amplifier module.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106849880A (en) * | 2016-12-29 | 2017-06-13 | 中国电子科技集团公司第五十研究所 | Efficient linear digital radio frequency power signal generating method based on polar coordinates treatment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106849880A (en) * | 2016-12-29 | 2017-06-13 | 中国电子科技集团公司第五十研究所 | Efficient linear digital radio frequency power signal generating method based on polar coordinates treatment |
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