A kind of digital loop control implementation method and equipment of feed forward power amplifier
Technical field
The present invention relates to amplifier, relate in particular to digital loop control implementation method and equipment in a kind of amplifier.
Background technology
Continuous development along with present mobile communication technology, the linearity of radio-frequency power amplifier is required to be increased sharply, based on the independent power amplifier of power synthetic technique with can't satisfy the integration requirement of the factors such as performance, power consumption, cost of mobile communication base station Radio Frequency Subsystem fully based on the high power amplifier of back-off technology.Main in the industry at present the employing based on the class AB power amplifier of LDMOS (metal-oxide semiconductor extending transversely) technology is auxiliary realized high-power linear power amplifier with the linearisation means, and wherein the feedforward linear method is a kind of linearization technique that extensively adopts.
Feedforward linearized method is that the distorted signal that power amplifier produces is separated, gain again, the coupling adjustment of phase place, time-delay, add to the power amplifier output, eliminate the distortion component in the power amplifier output signal, to obtain maximum linearisation index.It is less that this method is influenced by factors such as ambient temperature, operating voltage, and the linearisation index is higher, the bandwidth of operation broad.And, be of wide application owing to technology maturation.
Present feed forward type linear power amplifier generally comprises two signal cancellation loops: 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 signal amplitude in the main power amplifier output signal with the error signal amplification, carries out anti-phase offseting then, eliminates the distortion component in the main power amplifier output signal.For the intermodulation that obtains maximum main ring carrier cancellation and error loop is offset, carry out control on amplitude and the phase place to main ring and error loop.What generally adopt is the method for simulation control, promptly obtain respectively on the signal amplitude by radio-frequency signal detection and phase place on difference signal, carry out adaptive control to reach the effect that loop is regulated from motion tracking by analog circuit then, make main ring produce the carrier signal with opposite magnitude and phase place, error loop produces the intermodulation signal with opposite magnitude and phase place.But because a lot of radiofrequency signal trim for example vector modulator, electrically controlled attenuator etc. all have non-linearly, control with analog circuit, be very limited to the nonlinear compensation of device, cause control precision limited like this.And adopt simulation control to carry out loop control, and in case Circuit Design is good, control algolithm can't be changed, control strategy is simple, is unfavorable for the upgrading of system.Simultaneously, the difficulty complexity of analog circuit implementation algorithm is limited.At present, also do not retrieve the correlation technique patent and the data document of basic this type of problem of solution.
Summary of the invention
The invention provides a kind of digital loop control implementation method and equipment of feed forward power amplifier, to solve complex structure and the high problem of cost in the existing Analogical Circuit Technique.
The technical solution adopted in the present invention is: the digital loop control appliance of this feed forward power amplifier, comprise main power amplifier, and two corresponding signal cancellation rings---main ring and error loop, main ring is eliminated working signal, extract distortion information, error loop is eliminated the distortion component in the power amplifier output, also comprise digital loop control appliance 112, this digital loop control appliance 112 is by main ring radiofrequency signal processing module 21, error loop radiofrequency signal processing module 22 and digital signal processing module 23 are formed, main ring radiofrequency signal processing module 21 detects the amplitude of main rings and phase information and it is transported to digital signal processing module 23, simultaneously, error loop radiofrequency signal processing module 22 detects the amplitude of error loop and phase information and it is transported to digital signal processing module 23, and 23 pairs of digital signal processing modules carry out after the digital processing for information about to main ring and error loop output control signal;
Digital signal processing module 23 comprises digital signal processor DSP 231, the 1D/A transducers 232, the 1 isolation amplifications 233, the 1A/D transducers 234, the 2 isolation amplifications 235, the 2A/D transducer 236 and 2D/A transducers 237; The 1st isolate to amplify 233 links to each other with 1A/D transducer 234, and the 2nd isolate to amplify 235 and link to each other with 2A/D transducer 236, imports the amplitude and the phase information of main ring radiofrequency signal processing module 21 and error loop radiofrequency signal processing module 22 respectively to digital signal processor DSP 231; Digital signal processor DSP 231 is exported control signals to main ring radiofrequency signal processing module 21 and error loop radiofrequency signal processing module 22 respectively by 1D/A transducer 232 and 2D/A transducer 237;
Described main ring radiofrequency signal processing module 21 comprises coupler 211, electrically controlled attenuator 212 and voltage controlled phase shifter 213, and link to each other successively, comprise that also amplitude-phase testing circuit 215 receives two-way radio frequency input in the main rings, isolate by the 1st in the 1st filter 216 and the digital signal processing module 23 and amplify 233 and link to each other with 1A/D transducer 234; Digital signal processing module 23 is exported control signals by 1D/A transducer 232 to electrically controlled attenuator 212 and voltage controlled phase shifter 213;
Described amplitude-phase testing circuit 215 adopts chip AD8302;
Described error loop radiofrequency signal processing module 22 comprises vector modulator 221, and the error pilot tone produces circuit 222, quadrature mixting circuit 223, frequency mixer 224, frequency mixer 225, the 2 filters 226 and the 3rd filter 227; The amplitude of error loop and phase signal are isolated amplification 235 through the 2nd filter 226 and the 3rd filter 227 by the 2nd in the digital signal processing module 23,2A/D transducer 236 supplied with digital signal processing modules 23, digital signal processing module 23 is exported control signals by 2D/A transducer 237 to vector modulator 221.
This digital loop control implementation method that is used for the feed forward power amplifier of above-mentioned digital loop control appliance, it adopts following steps:
Step 1: the amplitude and the phase information that detect main ring;
Step 2: the amplitude and the phase information that detect error loop;
Step 3: the information of 23 pairs of detections of digital signal processing module is carried out digital processing;
Step 4: the control signal of digital signal processing module 23 outputs is controlled main ring and error loop.
Described step 1 comprises following control procedure:
At first, import the signal that sampled signal 214 that main rings participate in the signal 217 of carrier cancellations and the output of main power amplifier promptly participates in carrier cancellation by coupler 211, deliver to amplitude-phase testing circuit 215 with this signal with as the input of two-way radio frequency, this two paths of signals is carried out the detection of amplitude difference and phase difference by the amplitude-phase testing circuit;
Secondly, by the 1st filter 216 amplitude difference and the phase signal of the two paths of signals of carrier cancellation in the main ring of amplitude-phase testing circuit 215 outputs carried out filtering, the direct current signal of output is delivered to digital signal processing module 23.
Described step 2 comprises following control procedure:
At first, the error pilot tone produces the error pilot signal of circuit 222 outputs and delivers to quadrature mixting circuit 223 from the sampled signal 228 of intermodulation counteracting output as input and carry out the quadrature mixing, the signal of output two-way quadrature; Before delivering to main power amplifier, the pilot signal that produces circuit 222 outputs with the time error pilot tone together amplifies with signal;
Secondly, the two paths of signals of quadrature mixting circuit 223 outputs is passed through frequency mixer 224,225 respectively sneak into a lower local oscillation signal of frequency that produces by local oscillator 2211, downconvert to lower frequency ranges;
Then, will be sent to the 2nd filter 226 and the 3rd filter 227 respectively through the two paths of signals of local oscillator mixing output, the direct current signal of output two-way reflection error loop phase place and amplitude is input to digital signal processing module 23 with this two-way direct current signal.
Described step 3 comprises following control procedure:
At first, the 1st isolate to amplify 233 will isolate amplification from the reflection main ring amplitude of main ring radiofrequency signal processing module 21 inputs and the direct current signal of phase signal, be input to 1A/D transducer 234 and carry out the A/D conversion and the amplitude of main ring and phase information are converted to digital signal are sent to digital signal processor DSP 231;
Secondly, the 2nd isolate to amplify 235 will isolate amplification from the reflection error loop amplitude of error loop radiofrequency signal processing module 22 inputs and the direct current signal of phase signal, be input to 2A/D transducer 236 and carry out the A/D conversion and the amplitude of main ring and phase information are converted to digital signal are sent to digital signal processor DSP 231;
Then, digital signal processor DSP 231 calls adaptive control algorithm main ring and error loop is reflected that the digital quantity of main ring and error loop phase place and amplitude carries out computing, generate control main ring and error loop digital controlled signal, the main ring digital controlled signal is delivered to 1D/A transducer 232 convert analog quantity to, the error loop digital controlled signal is delivered to 2D/A transducer 237 convert analog quantity to.
Described step 4 comprises following control procedure:
At first, the voltage controlled phase shifter 213 of main ring radiofrequency signal processing module 21 and electrically controlled attenuator 212 receives and from the control signal of 1D/A transducer 232 control phases and amplitude the radiofrequency signal 219 that is used for signal cancellation in the main ring carried out amplitude and phase control and generate the radiofrequency signal 2110 of participating in carrier cancellation and deliver to power amplifier carrier cancellation circuit and carry out carrier cancellation;
Secondly, the vector modulator 221 of error loop radiofrequency signal processing module 22 receives from 2D/A transducer 237 control signal vectors the radiofrequency signal 229 of participating in intermodulation in the error loop and offsetting is carried out vector control with the phase place that reaches conditioning signal and the purpose of amplitude, the error amplifier that generation participation radiofrequency signal 2110 is delivered in the power amplifier amplifies, and amplifies the back and participates in the intermodulation counteracting.
Beneficial effect of the present invention is: full-fledged along with the digital signal processor DSP technology, the commercial digital signal processor DSP chip of a large amount of excellent performances in the application of communication field more and more widely, the present invention is based on the digital loop controlled function that the digital signal processor DSP technology realizes feedforward linear power amplifier, and its concrete beneficial effect is as follows:
The first, the present invention adopts directly amplitude and the phase place to main ring to detect, and has simplified main ring control principle and control method greatly, design difficulty of Jian Shaoing and debugging difficulty simultaneously, the integrated level of the system of increase.
Second, adopt digital signal processor DSP to realize adaptive loop control algolithm, more flexibly the loop of feed forward power amplifier is adjusted, on algorithm, can also change and carry out adaptive compensation the parameter of system, the stability of raising system adopts the digital signal processor DSP technology to make and improves a lot on processing speed, and is simultaneously also very convenient for the upgrading of system, can accomplish only need not change circuit, reduce the cost of system upgrade software upgrading.
The 3rd, the Development and Production standardization.The present invention has adopted digital integrated circuit to carry out the loop control of Feed Forward Power Amplifier, has simplified the formation of system, and has accomplished high integrated level in the radiofrequency signal processing section of main ring, is very significant to exploitation, debugging and the production standardization of system.
In a word, adopt method and apparatus provided by the invention to realize the digital loop control of feedforward linear power amplifier, system is constituted simplify, technical difficulty reduces, and the R﹠D cycle shortens, and exploitation and production cost also can significantly reduce, production technology standard, simple helps large-scale mass production, therefore, the present invention is simple in structure and cost is low, can be used for the power amplifier in the mobile communication.
Description of drawings
Fig. 1 is an application principle schematic diagram of the present invention;
Fig. 2 is digital loop control appliance structural representation among the present invention;
Fig. 3 is a control flow schematic diagram of the present invention.
Embodiment
With embodiment the present invention is described in further detail with reference to the accompanying drawings below:
According to Fig. 1 and Fig. 2, the present invention includes main power amplifier 12, and two corresponding signal cancellation rings---main ring and error loop, main ring is eliminated working signal, extract distortion information, error loop is eliminated the distortion component in the power amplifier output, also comprise digital loop control appliance 112, this digital loop control appliance 112 is by main ring radiofrequency signal processing module 21, error loop radiofrequency signal processing module 22 and digital signal processing module 23 are formed, main ring radiofrequency signal processing module 21 detects the amplitude of main rings and phase information and it is transported to digital signal processing module 23, simultaneously, error loop radiofrequency signal processing module 22 detects the amplitude of error loop and phase information and it is transported to digital signal processing module 23, and 23 pairs of digital signal processing modules carry out after the digital processing for information about to main ring and error loop output control signal.
Digital signal processing module 23 comprises digital signal processor DSP 231, the 1D/A transducers 232, the 1 isolation amplifications 233, the 1A/D transducers 234, the 2 isolation amplifications 235, the 2A/D transducer 236 and 2D/A transducers 237; The 1st isolate to amplify 233 links to each other with 1A/D transducer 234, and the 2nd isolate to amplify 235 and link to each other with 2A/D transducer 236, imports the amplitude and the phase information of main ring radiofrequency signal processing module 21 and error loop radiofrequency signal processing module 22 respectively to digital signal processor DSP 231; Digital signal processor DSP 231 is exported control signals to main ring radiofrequency signal processing module 21 and error loop radiofrequency signal processing module 22 respectively by 1D/A transducer 232 and 2D/A transducer 237.
Main ring radiofrequency signal processing module 21 comprises coupler 211, electrically controlled attenuator 212 and voltage controlled phase shifter 213, and link to each other successively, comprise that also amplitude-phase testing circuit 215 receives two-way radio frequency input in the main rings, isolate by the 1st in the 1st filter 216 and the digital signal processing module 23 and amplify 233 and link to each other with 1A/D transducer 234; To electrically controlled attenuator 212 and voltage controlled phase shifter 213 output control signals, wherein, amplitude-phase testing circuit 215 can adopt chip AD8302 to digital signal processing module 23 by 1D/A transducer 232.
Error loop radiofrequency signal processing module 22 comprises vector modulator 221, and the error pilot tone produces circuit 222, quadrature mixting circuit 223, frequency mixer 224, frequency mixer 225, the 2 filters 226 and the 3rd filter 227; The amplitude of error loop and phase signal are isolated amplification 235 through the 2nd filter 226 and the 3rd filter 227 by the 2nd in the digital signal processing module 23,2A/D transducer 236 supplied with digital signal processing modules 23, digital signal processing module 23 is exported control signals by 2D/A transducer 237 to vector modulator 221.
As shown in Figure 1, input signal is through output such as power splitter 11 branches such as grade, and one road signal is sent into main power amplifier 12 and carried out power amplification, and back input coupler 19 is regulated through the 2nd delay line 6, electrically controlled attenuator 212, voltage controlled phase shifter 213 in another road; After the signal of main power amplifier 12 outputs is taken a sample through sampling coupler 13, enter another input with road device 19, carry out signal cancellation with the input signal of time-delay branch road, eliminate the input signal component in the main power amplifier output sampled signal, obtain the representation signal of power amplification distortion information---error signal, and send into error amplifier 111 through vector modulator 221; Error signal after the amplification enters the power amplifier output channel by directional coupler 15, carry out signal cancellation with the main power amplifier output signal of delaying time through the 1st delay line 14, eliminate the distortion product in the main power amplifier output signal, obtain the very high high-power signal of the linearity at the power amplifier output.
As seen from Figure 1, feed forward type linear power amplifier comprises two basic signal cancellation rings---main ring and error loop, and each encircles the separate function separately of finishing: main ring is eliminated working signal, extracts distortion information; Error loop is eliminated the distortion component in the power amplifier output, reaches the linearisation target.Digital loop control appliance 112 is mainly adjusted reaching best carrier wave and intermodulation neutralization effect main ring and error loop, thereby farthest improves the linearity of power amplifier output signal; Be input to digital loop control appliance 112 from the coupler 19 preceding two paths of signals that carries out carrier cancellation is taken a sample, this two paths of signals is carried out amplitude and phase-detection and controls according to the result who detects, adjust by control electrically controlled attenuator 212,213 pairs of main rings of voltage controlled phase shifter; The signal after intermodulation is offset of carrying out to directional coupler 15 output is taken a sample and is input to digital loop control appliance 112 and detects and control vector modulator 221 and carry out the adjustment of error loop.
As shown in Figure 2, the two paths of signals of carrier cancellation will be carried out before the coupler 19, promptly the sampled signal 2110 before the sampled signal 214 of main power amplifier output signal and the signal cancellation is delivered to main ring radiofrequency signal processing module 21, be directly inputted to amplitude-phase testing circuit 215 this two paths of signals is detected, the direct current signal of output this two paths of signals amplitude difference of reflection and phase difference is fed into the 1st filter 216; Simultaneously, the error pilot tone is produced the error pilot signal of circuit 222 outputs and is sent to quadrature mixting circuit 223 the radiofrequency signal processing module 22 from the sampled signal 228 that intermodulation is offset output, the two paths of signals of quadrature mixting circuit 223 outputs is sneaked into a lower local oscillation signal of frequency that is produced by local oscillator 2211 through frequency mixer 224,225 respectively, downconvert to lower frequency ranges, again this two-way output signal is input to the 2nd filter 226 and the 3rd filter 227 respectively; The reflection main ring amplitude of the 1st filter 216 outputs and the two-way direct current signal of phase place are sent to the isolation of the 1st in the digital signal processing module 23 and amplify 233, and the reflection error loop amplitude of while the 2nd filter 226 and 227 outputs of the 3rd filter and the direct current signal of phase information are input to the 2nd and isolate amplification 235; 1A/D transducer 234 sampling is isolated the signals that amplify 233 outputs from the 1st and is input to 236 samplings of digital signal processor DSP 231, the 2A/D transducers and isolates the signals that amplify 235 outputs from the 2nd and be input to digital signal processor DSP 231; The main ring after 231 pairs of samplings of digital signal processor DSP and the amplitude of error loop and phase signal call adaptive control algorithm respectively and calculate, obtain the control signal (digital quantity) of main ring and error loop, digital signal processor DSP 231 outputs to 1D/A transducer 232 with the control signal of main ring respectively, and the control signal of error loop outputs to 2D/A transducer 237 and carries out analog-to-digital conversion; The electrically controlled attenuator 212 and the voltage controlled phase shifter 213 that are input to main ring radiofrequency signal processing module 21 respectively from the main ring amplitude and the phase control amount of 1D/A transducer 232 output carry out the adjustment of main ring, and the signal 2110 that the radiofrequency signal 219 that is used for signal cancellation in the main ring is carried out after the adjustment output of amplitude and phase place carries out carrier cancellation with the sampled signal of the output of main power amplifier; Be input to vector modulator 221 the error loop radiofrequency signal processing module 22 from the control signal of the error loop of 2D/A transducer 237 output, the radiofrequency signal 229 of participating in the intermodulation counteracting in the error loop is carried out the adjustment of amplitude and phase place, and adjusted output signal 2210 is participated in intermodulations and is offset.
As shown in Figure 3, the present invention adopts following control flow step:
Step 1: the amplitude and the phase information that detect main ring;
Step 1 comprises following concrete control procedure:
At first, import the signal that sampled signal 214 that main rings participate in the signal 217 of carrier cancellations and the output of main power amplifier promptly participates in carrier cancellation by coupler 211, deliver to amplitude-phase testing circuit 215 with this signal with as the input of two-way radio frequency, this two paths of signals is carried out the detection of amplitude difference and phase difference by the amplitude-phase testing circuit;
Secondly, by the 1st filter 216 amplitude difference and the phase signal of the two paths of signals of carrier cancellation in the main ring of amplitude-phase testing circuit 215 outputs carried out filtering, the direct current signal of output is delivered to digital signal processing module 23.
Step 2: the amplitude and the phase information that detect error loop;
Step 2 comprises following concrete control procedure:
At first, the error pilot tone produces the error pilot signal of circuit 222 outputs and delivers to quadrature mixting circuit 223 from the sampled signal 228 of intermodulation counteracting output as input and carry out the quadrature mixing, the signal of output two-way quadrature; Before delivering to main power amplifier, the pilot signal that produces circuit 222 outputs with the time error pilot tone together amplifies with signal;
Secondly, the two paths of signals of quadrature mixting circuit 223 outputs is passed through frequency mixer 224,225 respectively sneak into a lower local oscillation signal of frequency that produces by local oscillator 2211, downconvert to lower frequency ranges;
Then, will be sent to the 2nd filter 226 and the 3rd filter 227 respectively through the two paths of signals of local oscillator mixing output, the direct current signal of output two-way reflection error loop phase place and amplitude is input to digital signal processing module 23 with this two-way direct current signal.
Step 3: the information of 23 pairs of detections of digital signal processing module is carried out digital processing;
Step 3 comprises following concrete control procedure:
At first, the 1st isolate to amplify 233 will isolate amplification from the reflection main ring amplitude of main ring radiofrequency signal processing module 21 inputs and the direct current signal of phase signal, be input to 1A/D transducer 234 and carry out the A/D conversion and the amplitude of main ring and phase information are converted to digital signal are sent to digital signal processor DSP 231;
Secondly, the 2nd isolate to amplify 235 will isolate amplification from the reflection error loop amplitude of error loop radiofrequency signal processing module 22 inputs and the direct current signal of phase signal, be input to 2A/D transducer 236 and carry out the A/D conversion and the amplitude of main ring and phase information are converted to digital signal are sent to digital signal processor DSP 231;
Then, digital signal processor DSP 231 calls adaptive control algorithm main ring and error loop is reflected that the digital quantity of main ring and error loop phase place and amplitude carries out computing, generate control main ring and error loop digital controlled signal, the main ring digital controlled signal is delivered to 1D/A transducer 232 convert analog quantity to, the error loop digital controlled signal is delivered to 2D/A transducer 237 convert analog quantity to.
Step 4: the control signal of digital signal processing module 23 outputs is controlled main ring and error loop.
Step 4 comprises following concrete control procedure:
At first, the voltage controlled phase shifter 213 of main ring radiofrequency signal processing module 21 and electrically controlled attenuator 212 receives and from the control signal of 1D/A transducer 232 control phases and amplitude the radiofrequency signal 219 that is used for signal cancellation in the main ring carried out amplitude and phase control and generate the radiofrequency signal 2110 of participating in carrier cancellation and deliver to power amplifier carrier cancellation circuit and carry out carrier cancellation;
Secondly, the vector modulator 221 of error loop radiofrequency signal processing module 22 receives from 2D/A transducer 237 control signal vectors the radiofrequency signal 229 of participating in intermodulation in the error loop and offsetting is carried out vector control with the phase place that reaches conditioning signal and the purpose of amplitude, the error amplifier that generation participation radiofrequency signal 2110 is delivered in the power amplifier amplifies, and amplifies the back and participates in the intermodulation counteracting.
Like this, the main ring control figure semaphore after digital signal processor DSP will calculate converts the digital signal amount to by 1D/A transducer 232 that analog control signal is delivered to main ring electrically controlled attenuator 212 and voltage controlled phase shifter 213 carries out the adjustment of main ring; Then, the error loop control figure semaphore after digital signal processor DSP will calculate by 2D/A transducer 236 just the digital signal amount convert analog control signal to and deliver to error loop vector modulator 221 and carry out the adjustment of error loop.