CN101136641A - Multi-stage transmitter with nonlinear components to achieve linear amplification - Google Patents

Abstract

A multi-stage transmitter for linear amplification with nonlinear components (LINC) includes a multi-stage demultiplexer including a multi-stage scaler and converting an input signal into a plurality of phase signals, a phase modulator module coupled to the multi-stage demultiplexer, and a radio frequency module including a plurality of power amplifiers coupled to the phase modulator module and the multi-stage scaler, and a power combiner coupled to the power amplifiers. The LINC multi-stage transmitter of the invention has the multi-stage scaler in the multi-stage signal separator, and the multi-stage scaler dynamically adjusts the scaling factor according to the input signal, so the reverse phase angle can be adjusted, and high power efficiency and linearity can be achieved. The invention can meet the linear requirement and improve the use efficiency of the power supply.

Description

Reach the multilevel transmitter of linear amplification with non-linear component

Technical field

The invention relates to non-linear component and reach linear amplification (linear amplificationwith nonlinear components, hereinafter to be referred as LINC) transmitter, particularly relevant for LINC multilevel transmitter (multilevel LINC transmitter).

Background technology

In order to prolong the battery life of portable hand-held device, the power-efficient of mobile radio system is more important, generally speaking, the assembly of wasted work rate is exactly the power amplifier with nonlinear characteristic in transceiver (transceiver), in addition, the modulation of constant amplitude envelope (non-constant envelope) signal does not need the power amplifier of high linearity, so just must make choice between the linearity of Wireless Transmitter and power-efficient.

The linearization technique of different power amplifiers has been used to improve the linearity and the power-efficient of Wireless Transmitter, the transmitter framework of LINC can increase the linearity and the power-efficient of Wireless Transmitter, because digital LINC transmitter has signal processing performance accurately, and be difficult for producing the characteristic drift, so it is suitable for being used in the existing technology with the technology variation.

Fig. 1 is the schematic diagram of the transmitter framework of traditional LINC, as shown in Figure 1, the input signal S (t) of LINC transmitter 100 is constant amplitude envelope (varying envelope) signal not, demultiplexer ll0 receives and input signal S (t) is divided into two constant amplitude envelopes (constant envelope) signal S1 and S2, then, two power amplifier PA1 and PA2 amplify constant amplitude envelope signal S1 and S2 respectively, because nonlinear power amplifier can amplify the constant amplitude envelope signal linearly, this framework has used the nonlinear power amplifier of two power savings.At last, two signals that are exaggerated are again by power combiner 120 combinations in addition, so the output of power combiner 120 can obtain the signal of linear amplification.

The input signal of LINC system is constant amplitude envelope signal not

, wherein, the envelope of A (t) representation signal, and

Be the phase place of signal, in the phasor diagram shown in Fig. 2 A, constant amplitude envelope signal S (t) is not separable is one group of constant amplitude envelope signal S ₁(t) and S ₂(t), and

$S\left(t\right)=\frac{1}{2}\left[S_1\right(t)+S_2\left(t\right)]$

And anti-phase parallactic angle (out-phasing angle) θ (t) is expressed as $\text{\θ}\left(t\right)={\cos }^{-1}\left(\frac{A\left(t\right)}{r_0}\right)$ , S ₁(t) and S ₂(t) be r all at a radius ₀Circle on, in traditional LINC transmitter, r ₀Be the fixedly scaling factor (scale factor) that system designer was predetermined, because the input value of an inverse cosine function (inverse consinefunction) is between-1 and 1, r ₀Selection need satisfy formula r ₀〉=max (A (t)).

Fig. 2 B has illustrated the schematic diagram of the signal after amplifying, and the signal indication after the amplification is G S ₁(t) with G S ₂(t), wherein G is the power gain of power amplifier, and power combiner can obtain two amplifying signals combinations

, it is the linear amplification of input signal S (t), utilizes anti-phase parallactic angle technology (out-phasing technique), LINC can use the nonlinear power amplifier of two power savings to reach linear amplification.

Summary of the invention

Therefore, need the problem that the proposition solution exists needs balance linearity and power-efficient in wireless launcher.

Multilevel transmitter according to a kind of LINC of the embodiment of the invention, transmitter comprises multistage demultiplexer, phase-modulator module and radio-frequency module, multistage demultiplexer comprises multistage scaler (multilevel scaler), and convert input signal to a plurality of phase signals, the phase-modulator module is coupled to multistage demultiplexer, radio-frequency module comprises a plurality of power amplifiers that are coupled to phase-modulator module and multistage scaler, and the power combiner that is coupled to these power amplifiers.

The present invention discloses the multilevel transmitter of a kind of LINC, and its multistage demultiplexer has multistage scaler, and multistage scaler is dynamically adjusted zoom factor according to input signal, and therefore anti-phase parallactic angle can be adjusted, so, can reach the power-efficient high and the linearity.

The present invention can improve the service efficiency of power supply when satisfying linear the requirement.

Description of drawings

Fig. 1 is the schematic diagram of traditional LINC transmitter framework.

Fig. 2 A and Fig. 2 B be respectively signal and component thereof before amplification with amplify after phasor diagram.

Fig. 3 is the schematic diagram according to a kind of LINC multilevel transmitter of the embodiment of the invention.

Fig. 4 A and Fig. 4 B are respectively the phasor diagram of the anti-phase parallactic angle in single-order and the multistage zoom technology.

Fig. 5 A and Fig. 5 B are respectively the detailed phasor diagram and the broad sense phasor diagram of the anti-phase parallactic angle that shows multistage zoom technology.

Figure 6 shows that the envelope distribution map of WCDMA.

Fig. 7 is the module map of multistage scaler 313 shown in Figure 3.

Fig. 8 is the module map of envelop modulator 340 shown in Figure 3.

Fig. 9 A is the schematic diagram that causes the VDD-PM deviation of linearity deterioration.

Fig. 9 B is the schematic diagram of the characteristic of digital deflection compensator 350 shown in Figure 3.

Fig. 9 C is the schematic diagram of stationary phase of output signal of multilevel transmitter that shows the LINC of different power amplifier supply voltage.

Embodiment

Fig. 3 is the schematic diagram according to a kind of LINC multilevel transmitter of the embodiment of the invention, transmitter 300 comprises multistage demultiplexer 310, phase-modulator module 320 and radio-frequency module 330, the phase calculator 317 that multistage demultiplexer 310 comprises polar converter (polar convener) 311, is coupled to the multistage scaler (multilevel scaler) 313 of polar converter 311, is coupled to the anticosine module 315 of multistage scaler 313 and is coupled to polar converter 311 and anticosine module 315.Polar converter 31l receiving inputted signal S (t) also converts thereof into polar form, the envelope A (t) of signal carries out convergent-divergent via multistage scaler 313 then, and anticosine module 315 produces anti-phase parallactic angle θ ' (t), and thereafter, phase calculator 317 produces phase signal

With

, in other words, multistage demultiplexer 310 converts input signal S (t) to phase signal

With

Phase-modulator module 320 comprises two phase- modulators 321 and 322 that are coupled to multistage demultiplexer 310, radio-frequency module 330 comprises a plurality of power amplifiers (PA) 331 that are coupled to phase-modulator module 320 and multistage scaler 313, and a power combiner 333 that is coupled to these power amplifiers (PA) 331.

In one embodiment of the invention, the LINC multilevel transmitter adopts Wilkinson power combiner (wilkinson power combiner), but scope of the present invention is not limited thereto, and other hybrid coupler, low-loss Wilkinson power combiner, strange Li Kahua antiphase synthesizer (Chireix-outphasingcombiner) or person like that all can be applicable among the present invention.With the Wilkinson power combiner is example,

Its efficiency eta (t) may be defined as η/(t)=cos ²θ (t) can find that when θ (t) was very little, efficiency eta (t) was very high, and as anti-phase parallactic angle θ (t) during with the formula substitution that discloses previously, efficiency eta (t) can be used $\mathrm{\θ}\left(t\right)={\cos }^{-1}\left(\frac{A\left(t\right)}{r_0}\right)$ Expression, so, in order to utilize the power-efficient high of Wilkinson power combiner, r ₀Value must try one's best near but be not more than the maximum of envelope A (t).

With use single-order r ₀Traditional zoom technology difference, multistage scaler 313 shown in Figure 3 can reduce θ (t), makes the Wilkinson power combiner can obtain higher power-efficient, Fig. 4 B is the design example of a second order, when envelope A (t) more than r ₀Hour, multistage scaler can be with zoom factor by r ₀Be adjusted to r ₁, and the anti-phase parallactic angle θ ' of Fig. 4 B (t) can be much smaller than the anti-phase parallactic angle θ (t) of Fig. 4 A, and therefore multistage zoom technology can increase the efficient of Wilkinson power combiner, and multistage zoom technology can extend to the N rank shown in Fig. 5 A, R _NBe the broad sense representation of the multistage zoom technology shown in Fig. 5 B, wherein, R _N=r _k, for r _K+1＜A (t)≤r _kK=0,1 ..., N-1, and r _N=0, r ₀=max (A (t)), and the definition of the anti-phase parallactic angle of multistage zoom technology is modified to $\text{\θ\′}\left(t\right)={\cos }^{-1}\left(\frac{A\left(t\right)}{R_N}\right)$

In order to make the efficient optimization of Wilkinson power combiner, just need each rank r of decision earlier _kZoom factor because the LINC multilevel transmitter uses multistage zoom factor, the effectiveness formula of Wilkinson power combiner is modified to $\mathrm{\η}\left(\text{t}\right)={\left(\frac{\mathrm{\&Agr;}\left(\text{t}\right)}{{\text{R}}_{\mathrm{\Ν}}}\right)}^2,$ Figure 6 shows that the envelope distribution map of WCDMA, wherein envelope A (t) is a probability function, and in order to obtain the desired value of η (t), shown in Fig. 5 A, Fig. 5 B, envelope A (t) is cut into several zones.Then, each regional desired value is added up with derivation E (η (t)) again, $E\left(\mathrm{\η}\left(t\right)\right)\text{=}\underset{k=0}{\overset{k=N-1}{\mathrm{\Σ}}}{\∫}_{r_k}^{r_k}+1P\left(A\left(t\right)\right)\·{\left(\frac{A\left(t\right)}{r_k}\right)}^2\text{dA}\left(t\right)$ Wherein p (A (t)) is the probability density function of envelope A (t), r _kBe the values of zoom factor on k rank, N is total exponent number of zoom factor, and max (A (t)) is the maximum of the envelope of input signal, in order to make the efficient optimization of Wilkinson power combiner, E (η (t)) can be given differential and make $\frac{\∂E\left(\mathrm{\η}\left(t\right)\right)}{\∂P_k\′\left(t\right)}=0,$ K=0 wherein, 1 ..., N is so can obtain the R of one group of the best _N, this group R has been arranged _N, multistage scaler just can dynamically be adjusted R _N, make it near envelope A (t), but be not less than envelope A (t).

Fig. 7 is the module map of multistage scaler 313 shown in Figure 3, and multistage scaler 313 comprises cutter (slicer) 510 and the read-only memory 530 that is coupled to cutter 510.Cutter 510 is used to select and export specific r _kGive anticosine module 315.Preferable, cutter 510 comprises comparator (not indicating), and comparator judges which interval range envelope A (t) falls within, and selects which rank r according to the interval range decision _k, read-only memory 530 is with one group of R of the best _NStore.

Moreover, a kind of LINC multilevel transmitter according to the embodiment of the invention more comprises the envelop modulator 340 that is coupled to multistage scaler 313 and these power amplifiers (PA) 331, as shown in Figure 8, Fig. 8 is the module map of envelop modulator 340 shown in Figure 3, envelop modulator 340 comprises the digital analog converter (DAC) 341 that is coupled to multistage scaler 313, be coupled to the low pass filter 343 of digital analog converter 341 and be coupled to low pass filter 343 and power amplifier (PA) 331 between low dropout voltage regulator (low drop-out is hereinafter to be referred as LDO) 345.The input signal of digital analog converter 341 is the digital controlled signal from multistage scaler 313, digital analog converter 341 is converted to analog control signal with digital controlled signal, analog control signal is by low pass filter 343 then, at last, high-power LDO 345 guarantees that supplying voltage with stable power offers power amplifier 331.Because RC late effect, the group delay in the group delay in control signal path and phase signal path is different, extra delay compensator need be assigned in the phase signal path (between phase modulated module and radio-frequency module), to compensate the deviation that is produced because of the RC late effect.In another embodiment, can add ldo regulator (LDO regulator) 347 to resist influences such as temperature, noise.

In addition, multilevel transmitter according to a kind of LINC of the embodiment of the invention also comprises the deviation compensator 350 that is coupled between multistage demultiplexer 310 and the envelop modulator 340, because the adjustment of the supply voltage of two radio-frequency power amplifiers 331 can be introduced another deviation (VDD-PM deviation, different supply voltages cause a kind of deviation of out of phase), add deviation compensator LINC multilevel transmitter with compensation VDD-PM deviation.Fig. 9 A is the schematic diagram that causes the VDD-PM deviation of linearity deterioration.In order to revise the VDD-PM deviation, the digital deflection compensator 350 that will have characteristic shown in Fig. 9 B is bonded in the multilevel transmitter of LINC, even if therefore different power amplifier supply voltage arranged, shown in Fig. 9 C, the phase place of output signal still remains unchanged.

Moreover, multilevel transmitter according to a kind of LINC of the embodiment of the invention also comprises temperature sensor 360 (Fig. 3), because temperature variations can cause different VDD-PM deviations, add the multilevel transmitter of temperature sensor 360 to LINC, make the VDD-PM deviation to be compensated.

The present invention discloses a kind of LINC multilevel transmitter, and its multistage demultiplexer has multistage scaler, and multistage scaler is dynamically adjusted zoom factor according to input signal, and therefore anti-phase parallactic angle can be adjusted, so, can reach the power-efficient high and the linearity.

In sum; though the present invention discloses as above with preferred embodiment; right its is not in order to restriction the present invention; anyly have the knack of this operator; without departing from the spirit and scope of the present invention; when can doing various changes and retouching, so protection scope of the present invention should be as the criterion with the desired scope of claims.

Claims (10)

1. reach the multilevel transmitter of linear amplification with non-linear component for one kind, it is characterized in that described multilevel transmitter comprises:

Multistage demultiplexer, described multistage demultiplexer comprises multistage scaler, and converts input signal to a plurality of phase signals;

The phase-modulator module is coupled to described multistage demultiplexer; And

Radio-frequency module, described radio-frequency module comprise a plurality of power amplifiers that are coupled to described phase-modulator module and described multistage scaler, and the power combiner that is coupled to described a plurality of power amplifiers.

2. according to claim 1ly reach the multilevel transmitter of linear amplification, it is characterized in that the read-only memory that described multistage scaler comprises cutter and is coupled to described cutter with non-linear component.

3. according to claim 2ly reach the multilevel transmitter of linear amplification, it is characterized in that described cutter comprises comparator with non-linear component.

4. the multilevel transmitter of reaching linear amplification with non-linear component according to claim 1, it is characterized in that the described multilevel transmitter of reaching linear amplification with non-linear component also comprises the envelop modulator that is coupled to described multistage scaler and described power amplifier.

5. the multilevel transmitter of reaching linear amplification with non-linear component according to claim 4, it is characterized in that described envelop modulator comprises digital analog converter that is coupled to described multistage scaler and the low pass filter that is coupled to described digital analog converter.

6. according to claim 1ly reach the multilevel transmitter of linear amplification, it is characterized in that described envelop modulator also comprises the low dropout voltage regulator that is coupled between described low pass filter and the described power amplifier with non-linear component.

7. the multilevel transmitter of reaching linear amplification with non-linear component according to claim 6, it is characterized in that the described multilevel transmitter of reaching linear amplification with non-linear component also comprises the delay compensator that is coupled between described phase modulated module and the described radio-frequency module.

8. the multilevel transmitter of reaching linear amplification with non-linear component according to claim 4, it is characterized in that the described multilevel transmitter of reaching linear amplification with non-linear component also comprises the deviation compensator that is coupled between described multistage demultiplexer and the described envelop modulator.

9. according to claim 8ly reach the multilevel transmitter of linear amplification with non-linear component, it is characterized in that, the described multilevel transmitter of reaching linear amplification with non-linear component also comprises the temperature sensor that is coupled to described deviation compensator.

10. according to claim 1ly reach the multilevel transmitter of linear amplification, it is characterized in that described power combiner is the Wilkinson power combiner with non-linear component.

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