CN100452645C - power amplifier - Google Patents

Abstract

The present invention discloses a power amplification device which comprises a decomposer (101), a first digital to analog (D/A) converter (102), a second D/A converter (103), a first power amplifier (105), a second power amplifier (106), a signal synthesizer (107) and a vertical and horizontal switcher (108) for converting decomposed digital signals. The power amplifier device has no need of a complicated network to compensate the amplification unbalance, and also has no need of a complicated measuring device to measure the absolute performance of each component.

Description

Power amplifier device

Technical field

The present invention relates generally to the power amplifier device field, relate more specifically to be used to improve the linearity of power amplifier device and/or the technology of efficient.

Background technology

In cellular basestation, satellite communication system and current other communications and broadcast system, the final step of transmitter always relates to low-power signal is amplified to transmission medium power demand level.For example, in wireless communication transmitter, source signal has the power level of about 1 milliwatt, and wireless channel needs 10,000 times of about through-put powers of 10 watts of source signal.Such low-power signal is amplified to high-power process is called power amplification, and by using power amplifier to realize.

Power amplifier has some very high requirements.It must accurately amplify source signal, can not make source signal produce distortion, energy can not be transmitted into outside the source signal frequency range, must act on the whole bandwidth of source signal, and must satisfy above-mentioned requirements in effectively mode.For fixing architecture and treatment technology, traditional method is to weigh between bandwidth, efficient and linearity.Improve the performance that a parameter must reduce another parameter.

In the past, avoid (unresolved) Designing power amplifier problem by modulating information signal, consequently modulation result is easy to amplify.For example, can be used cheap and effective C class A amplifier A to be amplified to high power levels by the source signal of frequency modulation (FM) modulation.Unfortunately, the modulation scheme that is easy to now amplify is out of favour, because these modulation schemes spectrum efficiency low (as FM) or efficient is low when being used for through-put power (as amplitude modulation (AM)) typically.

Modern modulation scheme for example QAM (quadrature amplitude modulation) is not used any skill, can not avoid the power amplification problem.Modern transmitter must receive wide bandwidth signal, and wherein the amplitude of transmission signals and phase place are all carried information.

Proposed that several generations are efficient, wide bandwidth, the system configuration of linear amplifier, such system configuration is called LINC, and the linear amplification of non-linear components system configuration is used in its expression.This amplifier is " Chireix amplifier " or " Outphasing amplifier " by name also.

Fig. 1 is the schematic block diagram of power amplifier device in the conventional LINC system configuration.As shown in Figure 1, power amplifier device 100 comprises decomposer 101, a pair of D/A converter 102,103, modulator 104, a pair of power controller 105,106 and synthesizer 107.

Decomposer 101 is used for phase place and am signals s (n) are divided into two signal s1 (n) and s2 (n).Digital signal s1 (n) and s2 (n) that D/ A converter 102 and 103 is used for obtaining are converted to analog signal s1 (t) and s2 (t).Modulator 104 usefulness carrier frequency fc modulate the first analog signal s1 (t) and the second analog signal s2 (t) respectively.For example, under the situation of 3GPP, the carrier frequency that is about 2GHz will be moved on on the information.Power amplifier 105,106 amplifies the analog signal of modulation to generate amplifying signal x1 (t) and x2 (t).Synthesizer 107 synthesizes amplifying signals then, and by antenna emission results x (t).

The basic principle of such power amplifier device is that source signal s (n) is decomposed into two component signal s1 (n) and s2 (n), makes s (n)=s1 (n)+s2 (n).Each component signal has for all values n, the character of its constant magnitude.In other words, the source signal that comprises amplitude and phase change resolves into two signals that phase change is only arranged.

Signal decomposition operation is described in following equation (1) and (2), and hypothesis s (n) is limited, and its amplitude is less than or equal to 1.

$s1\left(n\right)=\frac{s\left(n\right)}{2}+j\frac{s\left(n\right)\sqrt{{1-\left|s\left(n\right)\right|}^2}}{2\left|s\left(n\right)\right|}---\left(1\right)$

$s2\left(n\right)=\frac{s\left(n\right)}{2}-j\frac{s\left(n\right)\sqrt{{1-\left|s\left(n\right)\right|}^2}}{2\left|s\left(n\right)\right|}---\left(2\right)$

Wherein, s (n) is a digital source signal, and s1 (n) is the first decomposition digital signal, and s2 (n) is the second decomposition digital signal, and n is a markers.

The attractive reason of this system configuration is, although it needs two power amplifiers, the power amplifier in this system configuration is easier to structure than single power amplifier, has the character that is easier to amplify because enter the signal of these power amplifiers.

This system configuration is very restricted in actual use, because it is very responsive to gain between two amplifiers and phase imbalance.

Fig. 2 a is the output pattern that is illustrated in the broadband noise that causes owing to 0.25dB gain imbalance between two power amplifiers in the conventional method.X-axis is represented frequency, and scope is from-fs/2 to+fs/2.Fs is the sampling frequency of D/A converter 102,103, also equals the sampling frequency of digital source signal s (n) and two component signal s1 (n) and s2 (n).Y-axis is represented the signal power with the dB measurement, the measurement that is used to be correlated with.

Fig. 2 b is amplification result's the figure of the passband of presentation graphs 2a.Two figures among Fig. 2 a and Fig. 2 b are the results that describe identical data, but the ratio difference.

Can find out that from Fig. 2 a and Fig. 2 b the 0.25dB gain imbalance between two power amplifiers 105,106 causes out-of-band noise to begin to appear at below the about 30dB of passband.

And for given gain imbalance, the noise of introducing and the power of input are disproportionate.For example, in above-mentioned conventional system structure, for the total power input signal, the outer output of band is the 30dB below passband.If input power reduces 12dB (for example), be with the outer output 12dB that can't descend.They can remain on fixing absolute power level.

Sensitivity to gain imbalance often solves with complicated network building out power imbalances.Or the performance of measuring each parts with complex measurement device is only used the device of similar performance with assurance.

A large amount of out-of-band noises that amplifier is introduced cause the interference in the adjacent channel.This interference influences performance many-sidedly.

The first, interference can cause the error in the transmission.These errors must be proofreaied and correct, and need to retransmit or other forms of error correction.This error correction expends time in, and it seems to be exactly delay or slow response from system from the user.

The second, for overcoming interference,, other transmitters add power consumption automatically thereby must increasing power output.The mobile subscriber can observe the power consumption of increase, because the user uses the time quantum of mobile phone to be restricted before the running down of battery, fixing operator also can observe the increase of power consumption, because need heavy cable stimulated emission machine, also need when active force is failed, use reserve battery.

Summary of the invention

The objective of the invention is by providing a kind of power amplifier device to solve the above-mentioned problems in the prior art, in this device, do not need complicated network to come compensate for amplifier imbalance, do not need complex measurement device to measure the absolute performance of each parts, wherein, improved subscriber response time, extending battery life, and do not need heavy cable and reserve battery.

For realizing above-mentioned target, provide a kind of power amplifier device.This power amplifier device comprises:

Decomposer is used for digital source signal is decomposed into first digital component signal and second digital component signal;

First D/A converter is used for converting first conversion digital signal to first analog signal;

Second D/A converter is used for converting second conversion digital signal to second analog signal;

First power amplifier is used to amplify first analog signal to obtain first amplifying signal;

Second power amplifier is used to amplify second analog signal to obtain second amplifying signal;

Signal synthesizer is used for synthetic first amplifying signal and second amplifying signal to obtain output signal;

Wherein, described power amplifier device also comprises crossbar switch (crossbar), is used to switch the digital component signal of decomposition and exports first conversion digital signal to first D/A converter, exports second conversion digital signal to second D/A converter.

According to the present invention, do not need complicated network to come compensate for amplifier imbalance.Do not need complex measurement device to measure the absolute performance of each power amplifier yet.Improved the battery life of mobile unit.In addition, do not need heavy cable and reserve battery yet.

Description of drawings

The accompanying drawing that constitutes a specification part is described embodiments of the present invention, and explains principle of the present invention together with description.

Fig. 1 is the schematic block diagram of power amplifier device in the conventional LINC system configuration;

Fig. 2 a is because the figure of the out-of-band noise that the gain imbalance of two power amplifiers causes in the expression conventional method;

The amplification result's that the band of Fig. 2 b presentation graphs 2a is logical figure;

Fig. 3 is the schematic block diagram of power amplifier device according to the embodiment of the present invention;

Fig. 4 a is expression because the figure of the out-of-band noise that causes according to the gain imbalance of two power amplifiers of the present invention;

Fig. 4 b is the logical amplification result's of the band of presentation graphs 4a a figure;

Fig. 5 a is expression because the figure of the out-of-band noise that causes according to the gain imbalance of two power amplifiers of the present invention;

Fig. 5 b is the logical amplification result's of the band of presentation graphs 5a a figure.

Embodiment

Preferred implementation of the present invention will be described in detail with reference to the accompanying drawings.The schematic construction of the power amplifier device 300 of this execution mode of the present invention is described with reference to Fig. 3, and Fig. 3 is the schematic block diagram of power amplifier device according to the embodiment of the present invention.

Preferably, the digital source signal of this power amplifier device is the total power input signal.For example, if the peak power of digital source signal is assumed to be 0dB, peak-average ratio is assumed to be 10dB, and the maximum of Mean Input Power will be-10dB.With such Mean Input Power, the gain of selective amplifier is so that with the watt be the aspiration level that the power output of unit equals power output.For example, if the desired output power level is 10 watts or 40dBm, when input signal power can produce the power of this quantity during for-10dB.

As shown in Figure 3, power amplifier device 300 according to the present invention comprises decomposer 101, the first D/A converters 102, the second D/A converters 103, modulator 104, the first power amplifiers, 105, the second power amplifiers 106 and synthesizer 107.Power amplifier 300 also comprises crossbar switch 108.

In this special execution mode, decomposer 101 is to be used for digital source signal s (n) is divided into two component signals, i.e. the first digital component signal k1 (n) and the second digital component signal k2 (n).Decomposer 101 is connected to crossbar switch 108.According to different examples, crossbar switch 108 judges whether to exchange the digital component signal k1 (n) of decomposition, the value of k2 (n).

From the digital component signal k1 (n) of the decomposition of decomposer 101 output, k2 (n) sends to first D/A converter 102 and second D/A converter 103 by crossbar switch 108.To arbitrary markers n, crossbar switch 108 specifies s1 (n) to equal k1 (n), and s2 (n) equals k2 (n).Or specify s1 (n) to equal k2 (n), and s2 (n) equals k1 (n), and promptly based on different examples, crossbar switch 108 can generate the value that s1 (n) and s2 (n) exchange k1 (n) and k2 (n) before.

As shown in Figure 3, first D/A converter 102 is converted to the first analog signal s1 (t) with the first conversion digital signal s1 (n).Similarly, second D/A converter 103 is converted to the second analog signal s2 (t) with the second conversion digital signal s2 (n).

First D/A converter 102 and second transducer 103 are connected to modulator 104.Modulator 104 usefulness carrier frequency fc modulate the first analog signal s1 (t) and the second analog signal s2 (t) respectively.Therefore, the first modulation signal m1 (t) and the second modulation signal m2 (t) be can obtain and first power amplifier 105 and second power amplifier 106 also are input to respectively.The output of power amplifier is respectively x1 (t) and x2 (t).

What deserves to be explained is that modulator 104 is optional.Even the carrier frequency fc of expectation is zero, power amplifier device is still worked.In other words, modulation treatment does not influence any character of amplifying power device, its for carrier frequency be 0Hz with for carrier frequency, such as, for 2GHz effective comparably.

With reference to Fig. 3, first power amplifier 105 amplifies the first modulation signal m1 (t) to obtain the first amplifying signal x1 (t).

According to the present invention, crossbar switch 108 can be used for the unbalance noise that causes of power magnitude is carried out shaping.The noise shaping process can make the adjacent channel noise energy decreases, thereby reduces the requirement to the gain imbalance between the power amplifier 105,106.For example, system configuration originally requires power amplifier 105, the gain balance of 0.25dB reduces to out-of-band noise-30dBc between 106, and can out-of-band noise be reduced to-30dBc (Decibels Relating to Carrier is with respect to the decibels of carrier wave) with the gain balance of 1dB only according to power amplifier device 300 of the present invention.

As shown in Figure 3, after crossbar switch 108, the digital component signal k1 (n) of decomposition, k2 (n) is converted to digital signal s1 (n), s2 (n), it is input to first D/A converter 102 and second D/A converter 103 respectively.From above-mentioned equation (1) and (2), the digital signal that is input to first and second D/ A converters 102 and 103 can be defined as:

$s1\left(n\right)=\frac{s\left(n\right)}{2}+p\left(n\right)j\frac{s\left(n\right)\sqrt{{1-\left|s\left(n\right)\right|}^2}}{2\left|s\left(n\right)\right|}---\left(3\right)$

$s2\left(n\right)=\frac{s\left(n\right)}{2}-p\left(n\right)j\frac{s\left(n\right)\sqrt{{1-\left|s\left(n\right)\right|}^2}}{2\left|s\left(n\right)\right|}---\left(4\right)$

Wherein, s (n) is a digital source signal, and s1 (n) is first conversion digital signal that is input to first D/A converter 102, and s2 (n) is second conversion digital signal that is input to second D/A converter 103; P (n) value+1 or-1, n is a markers.

Shown in equation (3) and (4),, do not switch if p (n) is 1.If p (n) is-1, the exchange digital component, wherein the first digital component signal k1 (n) sends to second D/A converter, 103, the second digital component signal k2 (n) and sends to first D/A converter 102.Depend on how p (n) selects, can carry out shaping the adjacent channel noise that produces.

Fig. 4 a, Fig. 4 b are the examples for the output of the present invention of p (n) function, and wherein the value of function is determined at random, equal+1 or-1 probability is identical.Fig. 4 b is the logical amplification result's of the band of presentation graphs 4a a figure.Two figures among Fig. 4 a and Fig. 4 b are the results that describe identical data.But ratio difference.

In Fig. 4 a and Fig. 4 b,, can see that the noise ratio noise of the prior art of introducing is smooth for the gain imbalance of 0.25dB.The original system structure of representing among this smooth noise and Fig. 1 is that 30dBc compares, and has the better adjacent channel performance that is about 31dBc.

Fig. 5 a, Fig. 5 b are that wherein p (n) function changes between+1 and-1 for each n value, i.e. p (n)=(1) for another example of the present invention's output of p (n) function ⁿFig. 5 b is the logical amplification result's of the band of presentation graphs 5 a figure.Two figures among Fig. 5 a and Fig. 5 b are the results that describe identical data, but the ratio difference.

In Fig. 5 a, can see that most of noise energy moves to away from the logical place of band, and can observe adjacent channel noise and reduce greatly that adjacent channel noise is reduced to-55dBc.

Though the present invention has provided several examples of p (n) function, can produce the function that more noise is carried out shaping, so that it follows some design standard.For example, can expect to produce certain species stage form of noise, can make p (n) function produce the noise of this specific noise form.

And, can generate p (n) function and come direct analytic signal s (n), s1 (n) and s2 (n) are also true

And, can generate p (n) function and come direct analytic signal s (n), s1 (n) and s2 (n) also determine whether to exchange.That is, this function will consider current markers n, before the current markers, among and the value of digital source signal s afterwards, and before the current markers, among and the value of the first conversion digital signal s1 and the second conversion digital signal s2 afterwards.

And main application of the present invention is in the RF field.But be not limited to only amplify wireless signal.Also can use this technology amplifying optical signals or another to carry the energy of signal.

Though when source signal is amplitude and phase modulated signal, can realize most advantages of this system configuration, when source signal only for amplitude modulation(PAM) or only when the phase modulated the present invention still have advantage.

Can make many other changes and remodeling not breaking away from design of the present invention and scope.Should be appreciated that to the invention is not restricted to specific execution mode, scope of the present invention is defined by the following claims.

Claims (7)

1. power amplifier device comprises:

Decomposer (101) is used for digital source signal (s (n)) is decomposed into first digital component signal (k1 (n)) and second digital component signal (k2 (n));

First D/A converter (102) is used for converting first conversion digital signal (s1 (n)) to first analog signal (s1 (t));

Second D/A converter (103) is used for converting second conversion digital signal (s2 (n)) to second analog signal (s2 (t));

First power amplifier (105) is used to amplify first analog signal (s1 (t)) to obtain first amplifying signal (x1 (t));

Second power amplifier (106) is used to amplify second analog signal (s2 (t)) to obtain second amplifying signal (x2 (t));

Signal synthesizer (107) is used for synthetic first amplifying signal (x1 (t)) and second amplifying signal (x2 (t)) to obtain output signal (x (t));

Wherein, described power amplifier device also comprises crossbar switch (108), be used to switch the digital component signal (k1 (n) of decomposition, k2 (n)) and output first conversion digital signal (s1 (n)) to first D/A converter (102), export second conversion digital signal (s2 (n)) to second D/A converter (103).

2. power amplifier device according to claim 1, wherein said power amplifier device also comprises and is used for modulating respectively first analog signal (s1 (t)) that sends to first power amplifier (105) and second power amplifier (106) respectively and the modulator (104) of second analog signal (s2 (t)), with the carrier frequency (fc) that reaches expectation.

3. power amplifier device according to claim 1 and 2, the digital signal that wherein is input to first D/A converter (102) and second D/A converter (103) can be defined as:

$s1\left(n\right)=\frac{s\left(n\right)}{2}+p\left(n\right)j\frac{s\left(n\right)\sqrt{1-{\left|s\left(n\right)\right|}^2}}{2\left|s\left(n\right)\right|}$

$s2\left(n\right)=\frac{s\left(n\right)}{2}-p\left(n\right)j\frac{s\left(n\right)\sqrt{1-{\left|s\left(n\right)\right|}^2}}{2\left|s\left(n\right)\right|}$

Wherein, s (n) is a digital source signal, and s1 (n) is first conversion digital signal that is input to first D/A converter (102), and s2 (n) is second conversion digital signal that is input to second D/A converter (103); P (n) value+1 or-1, n is a markers.

4. power amplifier device according to claim 3, wherein the value of p (n) is determined at random, equal+1 or-1 probability is identical.

5. power amplifier device according to claim 3, wherein p (n)=(1) ⁿ, wherein n is a markers.

6. power amplifier device according to claim 3, wherein the value of p (n) only depends on value n, wherein n is a markers.

7. power amplifier device according to claim 3, wherein the value of p (n) depends on markers (n) and digital source signal (s (n)), before first conversion digital signal (s1 (n)) and second conversion digital signal (s2 (n)), current and value in the future.

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