CN100449938C - Error loop self-adaptive cancellation control method for feedforward linear power amplifier - Google Patents
Error loop self-adaptive cancellation control method for feedforward linear power amplifier Download PDFInfo
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Abstract
The present invention relates to an error loop self-adaptive cancellation control method for a feedforward linear power amplifier, which at least comprises the steps that an amplitude difference A and a phase difference P of an output signal and an input signal of an error magnifying passage are detected; gain control voltage C#-A and phase control voltage C#-P of the error magnifying passage are calculated; the positions of good cancellation of nonlinear distortion signals from the C#-A and the C#-P to a central frequency point are tuned; the positions of good cancellation of the nonlinear distortion signals from K#-A and K#-P to a full band are tuned. In the method suggested by the present invention, the gain characteristic and the phase-shift characteristic of an active component in the error magnifying passage can be dynamically stabilized by an added adaptive control link and are approached to the linear transmission performance of a passive device, and the error magnifying passage has the gain characteristic and the phase-shift characteristic which are matched with the gain characteristic and the phase-shift characteristic of an output delaying passage of a main power amplifier through quiet tuning by inserting fixed offset (introducing offset interference voltage) in a closed-loop control link. Thus, a root purpose of error loop self-adaptive cancellation control is realized.
Description
Technical field:
The present invention relates to a kind of personal radio communication technology; Be specifically related to a kind of feedforward linear power amplifier error loop self-adaptive and offset control method, belong to the wireless signal processing technology field.
Background technology:
Broadband, digital development along with Modern Mobile Communications Systems, more and more Duo digital modulation means are used to improve the availability of frequency spectrum, for the user provides higher service quality and wider range of application, correspondingly also brought non-constant envelope modulation, big dynamic amplitude changes and the peak-all than etc. characteristics of signals, these all require transmission channel to have high transparency, with regard to the radio-frequency channel, require the high linearity exactly.Simultaneously, polynary Vector Modulation and demodulating process also require the extremely low transmission error of link, as an important step in the transmission link, radio-frequency power amplifier must keep the characteristic of approximate ideal---and except that the increase of input signal being made amplitude (multiply by fixing gain coefficient), do not change other any characteristic of signal, just need have enough linear power amplification characteristics.Therefore linear power amplifier (Linear Power Amplifier is called for short LPA) is essential in Modern Mobile Communications Systems.
Feedforward linearized mode is improved effect with the linear process scope in its broadband, good linearity and is very extensively adopted, and appears in the present overwhelming majority's the overloading frequency LPA product and correlation technique document.It is that the nonlinear distortion Signal Separation that main power amplifier (being called for short main power amplifier) produces is come out, gain again, the coupling adjustment of phase place, time-delay, add to main power amplifier output, offset the distortion component in the power amplifier output signal, improve index to obtain maximum linearity.
Present feedforward LPA comprises two signal cancellation loops at least: main ring and error loop.Main ring offsets the carrier frequency composition of eliminating in the main power amplifier output sampled signal, obtains only to comprise the error signal of main power amplifier non-linear distortion products; Error loop then is adjusted to the level that equates with nonlinear distortion component amplitude in the main power amplifier output signal, the anti-phase then distortion components that eliminates in the main power amplifier output signal that offsets with the error signal amplification.So-called signal cancellation is exactly a two-way with relevant and have that amplitude equates, the signal of 180 ° of characteristics of phase phasic difference is offseting a process of amplitude addition frequently.Owing to all comprise active amplifying circuit in two signal cancellation loops of feedforward LPA: the main power amplifier of main ring, the error amplifier of error loop, and their gain and phase-shift phase all can change along with factors such as operating frequency, ambient temperature, power output, device agings, so be difficult to guarantee that with static mode optimum signal all the time offsets effect, promptly needs to increase gain and the phase shift variations that the adaptive cancellation controlling unit is come the active amplifying circuit of dynamic tracking.
In main ring, because the carrier component amplitude is much larger than nonlinear distortion component in the main power amplifier output sampled signal, directly detecting main ring, to offset output be that carrier frequency in the error signal is offset residue, and the amplitude in the closed-loop control main ring and phase control parts (such as variable attenuator and adjustable phase shifter) can realize the process of its adaptive cancellation control, and many patents and technical literature all have the introduction of main ring adaptive cancellation control method.
Error loop is the core component of whole feed forward linearization systems, and the effect that system linearization improves directly is decided by the final result of error loop signal cancellation.Yet, what error loop realized is the cancellation process of a small-signal, that is: main ring being offseted the nonlinear distortion sampled signal that obtains amplifies and the phase place adjustment through amplitude, offset the nonlinear distortion component of eliminating in the system output signal in the loop exit, obtain pure high-power carrier signal output.And the residual nonlinear distorted signal amplitude among the result of offseting is much smaller than the outgoing carrier signal.To directly influence error loop like this and offset detection sensitivity (for nonlinear distortion offsets the residual signal testing circuit, CF signal after the amplification is an extremely strong interference source), and then influence the adaptive cancellation control precision of error loop, also improve effect with regard to the linearisation that has influenced feed-forward technique.
In some documents, recommend to adopt pilot tone tracking adaptive control mode to improve the adaptive control precision (such as U.S. Pat 6081156) of error loop.It is by introducing the error pilot tone in main power amplifier, detect the error pilot tone at System Outlet (after the nonlinear distortion signal cancellation) then and offset effect, and the amplitude of closed-loop control error loop and phase control parts (such as variable attenuator and adjustable phase shifter), guarantee that the best of error pilot tone offsets; Because the transmission path of error pilot tone and nonlinear distortion signal fits like a glove, and can think that the best that can realize the nonlinear distortion signal simultaneously offsets.
Referring to Fig. 1, it realizes block diagram for the pilot tone that U.S. Pat 6081156 provides with reference to error loop self-adaptive control feedforward LPA.The error pilot signal that pilot signal generator (PILOT SIGNAL GENERATOR) 130 produces enters main power amplification passage by coupler 135, and by after main power amplifier 140 amplifications, through coupler 145 samplings and straight-through output, through connect signal enters error canceller 185 through delay line (DELAY) 150, sampled signal then enters subtracter 165 and offsets elimination carrier frequency composition wherein with input carrier frequency sampled signal through delay line 160 time-delays, only stays nonlinear distortion and the error pilot component enters error loop as error signal; Error signal is through coupler 170 samplings, sampled signal enters control detection unit (CONTROL/DETECT DEVICE) 195 participation main rings and error loop offsets detection, after through connect signal then carries out the adjustment in real time of amplitude, phase place by error loop amplitude-phase modulator 175, amplify through error amplifier 180 again and export to error canceller 185, offset elimination nonlinear distortion and error pilot signal wherein with the main power amplifier output of time-delay through connect signal, at last through coupler 190 straight-through outputs.The system output signal of coupler 190 sampling (residue that offsets that has wherein comprised CF signal after being exaggerated and error pilot tone and nonlinear distortion signal) is sent into control detection unit 195 and is offseted effect with sampling error combined signal detection error pilot tone, and the gain and the phase-shift phase of the control voltage close loop departure amplification channel of generated error ring amplitude-phase modulator 175, offset error pilot tone in the signal (because the error weight of pilot frequency in the two paths of signals can keep enough signal levels all the time to guarantee that error canceller 185 place's two-way are participated in, in addition, error pilot signal amplitude in the sampling error signal is also much larger than residual CF signal, detection and control procedure are not disturbed by CF signal can, so it is benchmark that the error loop self-adaptive control procedure offsets with the tracking error pilot tone) maintenance amplitude always equates, 180 ° of phase phasic differences, thereby reach the good effect that offsets, and then guarantee stable the offseting of nonlinear distortion signal.
But, the shortcoming of this mode is: this method to the error amplification channel in various ambient temperatures, the gain flatness under the power output condition (the circuit gain amplifier is with the variable quantity of frequency) and the phase shift linearity (the circuit phase-shift phase departs from the value with the frequency change linear gradient) require high, otherwise can't guarantee that error loop is in the total temperature scope, whole power output dynamically down, the strict counterpoint of amplitude of all Frequency points (comprising the error pilot tone) and phase place in the working band (when error pilot tone point on time), also just can not guarantee well offseting in the full range band, the linearity of realizing ideal is improved effect.In actual design and production debug process, the error amplification channel of feedforward LPA includes the amplitude-phase modulator 175 that control characteristic changes with ambient temperature, operating frequency, and the active circuits such as error amplifier 180 that require of broadband, high-gain.Under total temperature scope, certain dynamic output condition, remain the good gain flatness and the phase shift linearity and then have great design difficulty and produce debugging work load in batches.Therefore, the actual operating performance of this scheme is poor, and the linearity that can realize is improved index and also is difficult near ideal value.
Also have some documents to propose: to offset the adaptive cancellation control (such as U.S. Pat 4389618) that loop is realized error loop by increasing a new carrier frequency.Outside two signal cancellation loops of feed forward linearization systems, use the 3rd signal cancellation loop and adaptive cancellation controlling mechanism thereof, utilization input carrier frequency sampled signal offsets the carrier frequency composition in the elimination system output sampled signal, obtain the remaining information that offsets of nonlinear distortion signal, and utilize its closed-loop adaptation that produces error loop to control voltage, dynamic tracking nonlinear distortion signal cancellation process guarantees that it well offsets effect.
Referring to Fig. 2, it is that U.S. Pat 4389618 disclosed additional carrier frequency compensating error loop self-adaptive control feedforward LPA realize block diagram.Main ring realizes that scheme is basic identical shown in principle and the U.S. Pat 6081156, repeats no more here.Error loop is taken a sample the error signal (wherein comprising main power amplifier 211 exports the nonlinear distortion signal in the sampling and offset remaining CF signal) that main ring offsets output by coupler 231, sampled signal enters detector (DETECTOR) 259 participation error loop and offsets effect detection and automatic control process; Through connect signal then passes through variable modulator (ADJUSTABLEMODULATOR) 229 to carry out after amplitude, phase place adjust in real time, export to error canceller 235 by error amplifier 233 amplifications, offset elimination nonlinear distortion composition wherein with main power amplifier output through connect signal through delay line 237 time-delays, obtain the system output signal after linearity is improved, and lead directly to output 239 through coupler 241 sampling backs.The system output signal of coupler 241 samplings is not participated in error loop directly and is offseted detection and control, but enter accumulator (SUMMER) 253, with 243 samplings of process coupler, delay line 251 time-delays, system's input CF signal 245 that variable modulator 247 amplitudes and phase place are adjusted in real time offsets elimination carrier frequency composition wherein, only contained the signal that system output nonlinear distortion offsets remaining information and sent into detector 259, detect error loop by it and offset effect, and the control voltage of generation variable modulator 229, closed-loop control error loop signal cancellation process, the adaptive cancellation controlled target of realization feedforward LPA error loop.
Though this scheme has adopted actual completely nonlinear distortion signal trace mode, thoroughly broken away from the adaptive tracing deviation that the pilot tone reference pattern brings, and to the also decrease to some degree of performance requirement of error amplification channel, but still there is very big defective:
At first, for guaranteeing to offset a little two-way and participate in the carrier component amplitude offset signal and equate increasing loop signals newly, must use directional coupler (or coupler adds attenuator) 241 sampler output signals 239 with very big coupling loss value, (input CF signal 245 has been passed through sampling coupler 214 with input carrier frequency sampling passage to eliminate carrier frequency amplification channel (input CF signal 245 has been passed through main power amplifier 211 and delay line 237), delay line 251 and variable modulator 247) gain inequality, like this in the system output sampled signal available nonlinear distortion to offset amplitudes of residual signal very little, directly influence the detection sensitivity of detector 259, and then influence the adaptive cancellation control precision of error loop;
Secondly, because the carrier component amplitude in the system output signal that sampling comes is much larger than offseting remaining nonlinear distortion component, the CF signal that increases newly offsets loop must keep fabulous signal cancellation effect in the full range band, could guarantee that its CF signal amplitude that offsets in the output is not more than the nonlinear distortion signal; Otherwise,, can't guarantee the detection sensitivity of detector 259 equally, and then influence the adaptive cancellation control precision of error loop owing to offset the interference of residual carrier frequency signal.But the carrier frequency cancellation process can not reach ideal effect (nothing offsets residue), so the actual realization difficulty of this scheme is very big; Moreover this method is owing to additionally increased a signal cancellation loop and adaptive cancellation controlling mechanism, and it is further complicated that system is constituted, and design and production cost improve, risk strengthens.
Summary of the invention:
Main purpose of the present invention is to propose a kind of by error amplification channel gain of closed-loop control feedforward LPA error loop and phase-shift phase, dynamically keep constant gain amplifier amount and the input and output phase difference of error amplification channel, and then guarantee that nonlinear distortion offsets effect, realize that feedforward LPA error loop self-adaptive offsets control.
Another object of the present invention is to: all participate in the nonlinear distortion extraction signal after the input signal that detects is the carrier frequency counteracting, the adaptive tracing testing process is not disturbed by CF signal, detection sensitivity and control precision height make the linearization process performance better.
Another purpose of the present invention is: error loop self-adaptive control dynamically round-off error amplifier changes because of ambient temperature and operating state, and the aging performance index variation of drifting about and bringing of amplifier tube, need in circuit design, not adopt extra indemnifying measure;
A further object of the present invention is: system constitutes simple, neither need to increase extra pilot tone generation circuit, do not need to add new signal cancellation loop yet, make feedforward LPA system not only have adaptation function completely, and hardware constitutes extremely simple, with low cost, there is very little risk for exploitation and batch process.
Technical scheme of the present invention is achieved in that
A kind of feedforward linear power amplifier error loop self-adaptive offsets control method, which comprises at least following steps:
Step 1: the amplitude difference A and the phase difference P that detect the output of error amplification channel, input signal;
Step 2: the gain-controlled voltage C of error of calculation amplification channel
AWith phase control voltage C
P
Step 3: tuning A
1And P
1To the position that center frequency points nonlinear distortion signal well offsets;
Step 4: tuning K
AAnd K
PThe position that the nonlinear distortion signal well offsets to the full range band.
The concrete operations step of above-mentioned steps 1 is:
Step 11: the input and output signal of sampling error amplification channel;
Step 12: utilize amplitude detection circuit and subtracter, obtain error amplification channel output sampled signal and the amplitude difference A that imports sampled signal;
Step 13 is utilized phase discriminator, detects error amplification channel output sampled signal and the phase difference P that imports sampled signal.
The concrete operations step of above-mentioned steps 2 is:
Step 21: calculated gains control voltage C
A, and will export, its inverting input of amplitude difference A value feed-in of input signal;
Step 22: calculate phase control voltage C
P, and will export, its inverting input of phase of input signals difference P value feed-in;
Step 23: with gain-controlled voltage C
AThe control end of threshold voltage feed-in error loop amplitude modulator is with phase control voltage C
PThe control end of threshold voltage feed-in error loop phase-modulator.
The concrete operations step of above-mentioned steps 3 is:
Step 31: set K
A=K
P=1;
Step 32: tuning A
1Value makes center frequency points nonlinear distortion signal cancellation respond well;
Step 33: tuning P
1Value makes center frequency points nonlinear distortion signal cancellation effect further perfect.
The concrete operations step of above-mentioned steps 4 is:
Step 41: tuning K
AValue makes the interior nonlinear distortion signal cancellation of full range band respond well;
Step 42: tuning K
PValue makes the interior nonlinear distortion signal cancellation effect of full range band further perfect.
The method that the present invention proposes, gain and phase-shift phase by closed-loop control feedforward LPA error loop error amplification channel, constant gain amplifier amount of error amplification channel and input and output phase difference have dynamically been kept, and then guaranteed that nonlinear distortion offsets effect, realized that feedforward LPA error loop self-adaptive offsets control.
The method that the present invention proposes is exactly the adaptive control link by adding, the gain and the phase-shift characterisitc of active parts in the middle of the dynamic stability error amplification channel, make it to reach the linear transfer performance of approximate passive device, and by in the closed-loop control link, inserting constant offset amount (introducing bias reference voltage), the static tuning error amplification channel that makes has the gain and the phase characteristic of mating with main power amplifier output time-delay passage, realizes that error loop self-adaptive offsets the basic goal of control.
In sum: the present invention has following characteristics:
The first, the linearization process performance is better.Because all participate in the nonlinear distortion extraction signal after the input signal that detects is the carrier frequency counteracting, CF signal amplitude wherein is very little, and therefore, the adaptive tracing testing process can not be subjected to CF signal and disturb, and detection sensitivity and control precision are very high; Simultaneously, method provided by the invention based on adaptive control active circuit simulation, approach the passive linear circuit characteristic and realize, therefore, adopt the linearity improvement amount of the feed forward linearization systems that the method realizes higher, to handle bandwidth wideer.
The second, the requirement of error amplifier design performance index is further reduced.The error amplifier that uses among the present invention has good AGC and APC function owing to system to it, so, very low to the requirement of its gain flatness and the phase shift linearity.Because the error loop self-adaptive control method provided by the invention dynamically round-off error amplifier performance index that drift brings because ambient temperature and operating state change and amplifier tube wears out changes, so need not consider to adopt extra indemnifying measure in circuit design.
The 3rd, system constitutes simple.Error loop self-adaptive nonlinear distortion provided by the invention offsets machine-processed need constitute increase by one cover AGC and APC detection control loop in the hardware in basic error loop, in addition, neither need to increase extra pilot tone generation circuit, do not need to add new signal cancellation loop yet, make feedforward LPA system not only have adaptation function completely, and the hardware formation is extremely simple, with low cost, and there is very little risk for exploitation and batch process.
Description of drawings:
Fig. 1 is that the disclosed pilot tone of one of prior art is with reference to error loop self-adaptive control feedforward LPA theory diagram.
Fig. 2 is two disclosed additional carrier frequency compensating error loop self-adaptive control feedforward LPA theory diagrams of prior art.
Fig. 3 is a method overview flow chart of the present invention.
Fig. 4 is the flow chart of the inventive method step 1.
Fig. 5 is the flow chart of the inventive method step 2.
Fig. 6 is the flow chart of the inventive method step 3.
Fig. 7 is the flow chart of the inventive method step 4.
Fig. 8 is that the error loop self-adaptive control feedforward LPA that the invention provides method realizes theory diagram.
Fig. 9 is that the error loop self-adaptive that the invention provides in the method offsets controller realization theory diagram.
Embodiment:
The present invention is described in further detail below in conjunction with accompanying drawing and specific embodiment:
Referring to Fig. 3, in a specific embodiment of the present invention, need carry out following step:
Step 1: the amplitude difference A and the phase difference P that detect the output of error amplification channel, input signal.The inlet that only detects the signal amplification channel could carry out self-adapting tuning control to it to amplitude difference that exports and phase difference, and this is first step that method provided by the invention realizes;
Step 2: according to formula C
A=-K
AA+A
1And C
P=-K
PP+P
1The gain-controlled voltage C of error of calculation amplification channel
AWith phase control voltage C
PAfter channel transfer amplitude that detection is obtained and phase difference value carried out the adjustment of certain slope and skew, amplitude in the negative feedback control channel and phase-correcting part were to realize the closed-loop stabilization balance of gain of error amplification channel and phase shift;
Step 3: tuning A
1And P
1To the position that center frequency points nonlinear distortion signal well offsets.The initial controlled quentity controlled variable of the amplitude of tuning negative feedback control loop and phase place finding the control balance point of system at the center frequency points place, and guarantees the optimum efficiency that offsets in this Frequency point error loop nonlinear distortion;
Step 4: tuning K
AAnd K
PThe position that the nonlinear distortion signal well offsets to the full range band.The voltage transmission slope of tuning negative feedback control loop makes it to fit with the amplitude-frequency and the phase-frequency characteristic quadrature of error amplification channel, realizes that error loop guarantees all that in the full range band good nonlinear distortion offsets the basic goal of effect.
Feedforward LPA error loop comprises two signal transmission passages: error amplification channel and main power amplifier output time-delay passage.Main power amplifier output time-delay passage is made up of two directional couplers and a delay line, it is the linear passive parts, its gain and phase-shift characterisitc can not change with ambient temperature with by power (when having enough power capacities) parameter, the time aging factor is also smaller, and their gain is all relatively good with the frequency change linearity with frequency change slope and phase shift.Therefore, as long as by automatic gain control (AGC) and automatic phase control (APC) circuit, self adaptation guarantees that the error amplification channel has stable gain and phase-shift characterisitc, and, make it to have gain and phase place (the differing 180 °) characteristic that is complementary with main power amplifier output time-delay passage by adding the constant offset amount; Just can guarantee that error loop all keeps the good effect that offsets in the full range band.And, because AGC and APC circuit automatically in the compensating error amplification channel active circuit because gain and the phase shift variations that factors such as temperature drift, dynamic power output, device aging bring, remain constant gain and phase-shift phase, so as long as static tuning assurance error loop well offset characteristic, just can under various conditions of work, stablize maintenance, what reach error loop self-adaptive offsets the control effect, realizes that the linearity of feedforward LPA approximate ideal is improved target.
Referring to Fig. 4, the concrete operations step of present embodiment step 1 comprises:
The first step, the input and output signal of sampling error amplification channel; Specifically can be by the input and output signal of two directional couplers difference sampling error amplification channels;
Second step, utilize amplitude detection circuit and subtracter, obtain error amplification channel output sampled signal and the amplitude difference A that imports sampled signal;
In the 3rd step, utilize phase discriminator to detect error amplification channel output sampled signal and the phase difference P that imports sampled signal.
Referring to Fig. 5, the concrete operations step of present embodiment step 2 comprises:
The first step, the amplitude difference A that step 1 is obtained carries out-K
AGain adjustment and A doubly
1The skew of value obtains the negative feedback gain-controlled voltage C of error loop
AAnd with its inverting input of A value feed-in.
In second step, the phase difference value P that step 1 is obtained carries out-K
PGain adjustment and P doubly
1The skew of value obtains the negative feedback phase control voltage C of error loop
PAnd with its inverting input of P value feed-in.
The 3rd step is with C
AThe control end of threshold voltage feed-in error loop amplitude modulator is with C
PThe control end of threshold voltage feed-in error loop phase-modulator.
Referring to Fig. 6, the concrete operations step of present embodiment step 3 comprises:
The first step, set K
A=K
P=1, the slope that makes gain and phase control feedback path is zero;
Second step, tuning A
1Value makes offseting of center frequency points nonlinear distortion signal respond well.Under the beneficial situation of-1 multiplication, tuning gain FEEDBACK CONTROL side-play amount, the amplitude that makes the error loop two-way participation of center frequency points place offset signal equate, thereby guarantee that center frequency points place nonlinear distortion signal keeps well offseting;
The 3rd step, tuning P
1Value, make center frequency points nonlinear distortion signal to offset effect further perfect.Under the beneficial situation of-1 multiplication, tuning phase feedback control side-play amount, 180 ° of the phase phasic differences that center frequency points place error loop two-way is participated in offset signal, thus guarantee that center frequency points place nonlinear distortion signal reaches best.
Referring to Fig. 7, the concrete operations step of present embodiment step 4 comprises:
The first step, tuning K
AValue makes the interior nonlinear distortion signal cancellation of full range band respond well; The multiplication factor K of tuning gain FEEDBACK CONTROL passage
AThe amplitude-versus-frequency curve quadrature of gain-controlled voltage change curve and error amplification channel is fitted, thereby realize the AGC function, dynamically guarantee the gain flatness that the error amplification channel is good, keep the good gain coupling of error amplification channel and main power amplifier output time-delay passage; And the gain bias-tuned result of integrating step 3, make the participation of error loop two-way offset signal maintenance amplitude in the full range band and equate that the nonlinear distortion signal that reaches in the full range band well offsets;
Second step, tuning K
PValue makes the interior nonlinear distortion signal cancellation effect of full range band further perfect.The multiplication factor K of tuning phase feedback control channel
PThe phase-frequency characteristic orthogonal curve of phase control voltage change curve and error amplification channel is fitted, thereby realize the APC function, dynamically guarantee the good phase shift linearity of error amplification channel, keep the good phase shift coupling of error amplification channel and main power amplifier output time-delay passage, and the tuning result of the phase bias of integrating step 3, make the participation of error loop two-way offset signal and in the full range band, keep 180 ° of phase phasic differences, reach the interior nonlinear distortion signal the best of full range band and offset.
Referring to Fig. 8, feedforward LPA is made up of two unit modules: main ring 81 and error loop 82.In main ring 81, radio-frequency input signals (only containing CF signal) is divided into two paths of signals through splitter 811; The main power amplifier 812 of leading up to carries out power amplification.Because main power amplifier 812 exists linear amplification and nonlinear modulating characteristic simultaneously, the CF signal and the nonlinear distortion signal that are exaggerated have been comprised in its output signal, these signals are by coupler A 821 samplings, directly enter error loop 82 and participate in offseting of nonlinear distortion signal, sampled signal then enters with road device 822 participation CF signal and offsets.Another road input CF signal is through delay line A 813 time-delays, (sampled signal enters main ring adaptive cancellation controller 816 in coupler B 814 samplings, the participation carrier frequency offsets the detection and the adaptive control process of effect) and straight-through, main ring amplitude-phase modulator 815 real-time gain and phase place adjustment, enter with road device 822 and main power amplifier output sampled signal and carry out signal cancellation, eliminate carrier frequency composition wherein, the error signal that is only comprised main power amplifier nonlinear distortion sampling enters error loop 82, and through coupler C 817 samplings, give main ring adaptive cancellation controller 816 detection main ring carrier frequency and offset effect, and the closed-loop control voltage of generation main ring amplitude-phase modulator, automatic control and the good result that keeps carrier frequency to offset, the adaptive control process of realization main ring signal cancellation.
In error loop 82, (send into error loop self-adaptive and offset controller 829 by sampled signal by coupler D 823 samplings for error signal, participate in the adaptive control process of error amplification channel performance), through connect signal is through the real-time gain adjustment of electrically controlled attenuator 824 and the real-time phase adjustment of voltage controlled phase shifter 825, entering error amplifier 826 amplitude of carrying out amplifies, then, take a sample (after sampled signal process delay line C 828 time-delays through coupler E 827 again, enter error loop self-adaptive and offset the adaptive control process that controller 829 participates in error amplification channel performance), through connect signal is sent into coupler F 831 and is offseted elimination nonlinear distortion signal wherein with coupler A 821 main power amplifier output signals straight-through and that delay time through delay line B 830, obtain high linear high-power CF signal output, the linearity that reaches feedforward linearized scheme is improved target.
As shown in Figure 8, the error loop of feedforward LPA comprises two signal transmission passages:
Main power amplifier output time-delay passage and error amplification channel.Main power amplifier output time-delay passage comprises coupler A 821, delay line B 830 and coupler F 831, be the linear passive device, its gain (is negative gain here, promptly insert loss) and phase shift very good with the linear index of frequency change, and performance with the aging change amount of temperature and time seldom, with this passage is benchmark, the performance of tuning correction error amplification channel and self adaptation keep, the good passband and the power dynamic performance index of error loop signal cancellation can be realized, and the good adaptive tracking performance can be kept.
The error amplification channel comprises coupler A 821, with road device 822, coupler C 817, coupler D 823, electrically controlled attenuator 824, voltage controlled phase shifter 825, error amplifier 826, coupler E 827, coupler F 831 etc., wherein be positioned at the coupler A 821 at passage two ends, with road device 822, coupler C 817 and coupler F 831 are the linear passive parts, have and the similar linear transfer performance of main power amplifier output time-delay passage, only be positioned at the middle parts of passage and (comprise coupler D 823, electrically controlled attenuator 824, voltage controlled phase shifter 825, error amplifier 826, coupler E 827) electrically controlled attenuator 824 in, contain active circuit in voltage controlled phase shifter 825 and the error amplifier 826, its gain and phase-shift characterisitc will change with condition of work, and poor with the linear index of frequency change.
Because coupler D 823 is to there being a fixing signal propagation delay time amount between the coupler E 827, so offset insertion delay line C 828 between the controller 829 in coupler E 827 sampling outputs and error loop self-adaptive, to compensate this section time delay error, keep error loop self-adaptive to offset the two-way input detection signal E of controller 829
IAnd E
OBe in same one-period, to guarantee the correctness of its phase-detection.
Referring to Fig. 9, it is that the error loop self-adaptive that the invention provides in the method offsets controller realization theory diagram.Two-way sampling input signal E
OAnd E
IPass through earlier the amplitude detection of wave detector 901 and 902 respectively, on behalf of the d. c. voltage signal of their amplitude characteristics, obtain two send into subtracter 903, obtain amplitude difference (being the gain amplification quantity of the detected control section of the error amplification channel) A of two paths of signals, and then through an algorithm C
A=-K
AA+A
1Realize that circuit 904 obtains the gain-controlled voltage C of electrically controlled attenuator 924
A, the gain-adaptive process of closed-loop control error amplification channel; Simultaneously, two-way sampling input signal E
OAnd E
IBe admitted to phase discriminator 905, detect phase difference (being the phase-shift phase of the detected control section of the error amplification channel) P between them, and then through an algorithm C
P=-K
PP+P
1Realize that circuit 906 obtains the phase shift control voltage C of voltage controlled phase shifter 825
P, the phase adaptation process of closed-loop control error amplification channel.
It should be noted last that: above embodiment is the unrestricted technical scheme of the present invention in order to explanation only, although the present invention is had been described in detail with reference to the foregoing description, those of ordinary skill in the art is to be understood that: still can make amendment or be equal to replacement the present invention, and not breaking away from any modification or partial replacement of the spirit and scope of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.
Claims (5)
1, a kind of feedforward linear power amplifier error loop self-adaptive offsets control method, it is characterized in that: which comprises at least following steps:
Step 1: the amplitude difference A and the phase difference P that detect the output of error amplification channel, input signal;
Step 2: the gain-controlled voltage C of error of calculation amplification channel
AWith phase control voltage C
P, with gain-controlled voltage C
AThe control end of feed-in error loop amplitude modulator is with phase control voltage C
PThe control end of feed-in error loop phase-modulator, wherein, C
A=-K
AA+A
1, C
P=-K
PP+P
1, K wherein
AFor amplitude difference is adjusted coefficient, K
PFor phase difference is adjusted coefficient, A
1For amplitude difference is adjusted parameter, P
1For phase difference is adjusted parameter;
Step 3: tuning A
1And P
1, make the two-way of center frequency points place error loop participate in the signal offset and have gain and the phase characteristic that is complementary;
Step 4: tuning K
AAnd K
P, the voltage of negative feedback control loop and the amplitude-frequency and the phase frequency quadrature of error amplification channel are fitted.
2, feedforward linear power amplifier error loop self-adaptive according to claim 1 offsets control method, it is characterized in that: the concrete operations step of described step 1 is:
Step 11: the input and output signal of sampling error amplification channel;
Step 12: utilize amplitude detection circuit and subtracter, obtain error amplification channel output sampled signal and the amplitude difference A that imports sampled signal;
Step 13 is utilized phase discriminator, detects error amplification channel output sampled signal and the phase difference P that imports sampled signal.
3, feedforward linear power amplifier error loop self-adaptive according to claim 1 offsets control method, it is characterized in that: the concrete operations step of described step 2 is:
Step 21: will export, the amplitude difference A value feed-in gain-controlled voltage C of input signal
AAlgorithm is realized the inverting input of circuit (904), comes calculated gains control voltage C
A
Step 22: will export, phase of input signals difference P value feed-in phase control voltage C
PAlgorithm is realized the inverting input of circuit (906), calculates phase control voltage C
P
4, feedforward linear power amplifier error loop self-adaptive according to claim 1 offsets control method, it is characterized in that: the concrete operations step of described step 3 is:
Step 31: set K
A=K
P=1;
Step 32: tuning A
1Value, the amplitude that makes the two-way of center frequency points place error loop participate in the signal offset equates;
Step 33: tuning P
1Value makes the two-way of center frequency points place error loop participate in 180 ° of the phase phasic differences of the signal offset.
5, feedforward linear power amplifier error loop self-adaptive according to claim 1 offsets control method, it is characterized in that: the concrete operations step of described step 4 is:
Step 41: tuning K
AValue fits the amplitude-versus-frequency curve quadrature of gain-controlled voltage change curve and error amplification channel;
Step 42: tuning K
PValue fits the phase-frequency characteristic orthogonal curve of phase control voltage change curve and error amplification channel, and the signal that the two-way participation of error loop is offseted keeps 180 ° of phase phasic differences in the full range band.
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Citations (4)
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|---|---|---|---|---|
| US6232837B1 (en) * | 1999-05-14 | 2001-05-15 | Electronics And Telecommunications Research Institute | Optimal control method for adaptive feedforward linear amplifier |
| CN1345482A (en) * | 1999-04-06 | 2002-04-17 | 艾利森公司 | Method and apparatus for reducing oscillator noise by noise-feedforward |
| US6400223B1 (en) * | 2000-06-12 | 2002-06-04 | Nokia Networks Oy | Double carrier cancellation in wide band multi-carrier feed forward linearized power amplifier |
| WO2002052717A2 (en) * | 2000-12-22 | 2002-07-04 | Paradigm Wireless Communications Llc | Feed-forward amplifier loop control utilizing if signal processing |
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2002
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| CN1345482A (en) * | 1999-04-06 | 2002-04-17 | 艾利森公司 | Method and apparatus for reducing oscillator noise by noise-feedforward |
| US6232837B1 (en) * | 1999-05-14 | 2001-05-15 | Electronics And Telecommunications Research Institute | Optimal control method for adaptive feedforward linear amplifier |
| US6400223B1 (en) * | 2000-06-12 | 2002-06-04 | Nokia Networks Oy | Double carrier cancellation in wide band multi-carrier feed forward linearized power amplifier |
| WO2002052717A2 (en) * | 2000-12-22 | 2002-07-04 | Paradigm Wireless Communications Llc | Feed-forward amplifier loop control utilizing if signal processing |
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| 教学新技术---自适应干扰抑制研究. 刘翔.四川师范大学. 2002 |
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