CN101494439B - Amplifier - Google Patents
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- CN101494439B CN101494439B CN2009101264218A CN200910126421A CN101494439B CN 101494439 B CN101494439 B CN 101494439B CN 2009101264218 A CN2009101264218 A CN 2009101264218A CN 200910126421 A CN200910126421 A CN 200910126421A CN 101494439 B CN101494439 B CN 101494439B
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Abstract
There is provided an amplifier for combining outputs of a plurality of amplifying circuits to generate an amplifier output. The amplifier includes a first amplifying circuit for operating a first amplifying device in class-AB, wherein the first amplifying circuit is one among the plurality of the amplifying circuits; a second amplifying circuit for operating a second amplifying device in class-B or class-C, wherein the second amplifying circuit is one among the plurality of the amplifying circuits; and a summing node at which an output of the first amplifying circuit is combined with an output of the second amplifying circuit via a first impedance transformer containing a transmission line of an electrical length other than lambda/4. The second amplifying device is connected to the summing node via an output matching circuit and a second impedance transformer containing a transmission line.
Description
The application be that November 17, application number in 2005 are 200510116297.9 the applying date, denomination of invention divides an application for the application of " amplifier ".
Technical field
The present invention relates to amplifier; And more particularly; Relate to improved Doherty (Doherty) amplifier; Especially when using the amplifying device in traditional Doherty amplifier, be difficult to carry out impedance matching or the like, improved Doherty amplifier can strengthen its performance, perhaps can strengthen its power efficiency.
Background technology
Traditionally; When the such power amplification radio frequency signals of for example CDMA signal or multi-carrier signal is exaggerated; Increase the distortion compensation unit to common amplifier, make the working range of base amplifier to expand to and comprise the saturation region, to realize low power consumption.Although feedback distortion compensation or the such distortion compensating method of pre-distortion compensated before for example existing, these methods have realizing the restriction of said low power consumption.Therefore, Doherty amplifier is recently as candidate's high-efficiency amplifier and arouse attention.
Fig. 1 has shown the structure chart of traditional Doherty amplifier.The signal that is input to input 1 is assigned with device and opened in 2 minutes.One of them of the said signal that separates is imported in the carrier wave amplifying circuit 4.Carrier wave amplifying circuit 4 comprises the input matching circuit 41 of the impedance matching of the input side that is used to realize amplifying device 42, the output matching circuit 43 of impedance matching that comprises for example one or more transistorized amplifying devices 42 and be used to realize the outlet side of amplifying device 42.λ/4 converters 61 are connected to the output of carrier amplifier 4, with its output impedance of conversion.
Another signal that separates is imported into peak value amplifying circuit 5 after its phase place is postponed 90 ° by phase converter 3.Be similar to carrier wave amplifying circuit 4, peak value amplifying circuit 5 comprises input matching circuit 51, includes for example one or more transistorized amplifying devices 52 and output matching circuit 53.
λ/output the signal of 4 converters 61 and the output signal of peak value amplifying circuit 5 combine at summing junction 62.In conjunction with signal by λ/4 converters, 7 conversion, make that the output impedance of amplifier and output loading 9 (are Z
0) coupling.The combination of λ/4 converters 61 and summing junction 62 is called as Doherty combiner 6.The output of λ/4 converters 7 is applied to output loading 9 via amplifier out 8.
The difference of carrier wave amplifying circuit 4 and peak value amplifying circuit 5 is: amplifying device 42 is according to the biasing of AB class, yet amplifying device 52 is according to category-B or the biasing of C class.Therefore, amplifying device 42 works independently, and reaches the zone that beginning is saturated and amplifying device 52 is started working up to the incoming level of amplifier.That is, when the linearity of amplifying device 42 began to worsen fast, amplifying device 52 was started working, so that the output signal of amplifying device 52 is applied to load, to drive it together with amplifying device 42.At this moment, although the load line of output matching circuit 43 transfers Low ESR like what will describe after a while to from high impedance, because amplifying device 42 is in the saturation region, so the efficient of amplifying device 42 is higher.
When the incoming level from input 1 to amplifier further increased, amplifying device 52 also began saturated.Yet even at this moment, amplifier also keeps high efficiency, because amplifying device 42 and 52 is all saturated.
Fig. 2 describes the collector efficiency of the Doherty amplifier that shows among Fig. 1 or the theoretical prediction value of drain efficiency.Said collector efficiency is defined as the product of the DC electric current that is provided divided by the dc voltage that is applied to collector electrode from power supply and this power supply by the radio frequency power output of the collector electrode of amplifier transistor output.Equally, said drain efficiency is defined as the product of the DC electric current that is provided divided by the dc voltage that is applied to this drain electrode from power supply and this power supply by the radio frequency power output of the drain electrode output of amplifier transistor.
The trunnion axis of Fig. 2 is represented amplifier offset, that is, the dB ratio when compression point is set to 0dB between the incoming level of this compression point and amplifier, wherein said compression point is defined as the minimum incoming level that amplifying device 42 and 52 all reaches capacity.
In Fig. 2, dotted line is represented the efficient of traditional class-b amplifier, and the efficient of the Doherty amplifier that shows in the solid line presentation graphs 1.
When the incoming level of amplifier was in scope A, the carrier wave amplifying circuit worked independently basically.When amplifier offset reached about 6dB, carrier wave amplifying circuit circuit 4 began to reach capacity, and the efficient of Doherty amplifier reaches the maximal efficiency of about traditional B class A amplifier A.At this moment, the power output of carrier wave amplifying circuit 4 is approximately Po/4, and wherein Po is the peak power output of said Doherty amplifier.
At said amplifier offset is that 0dB is in the scope B between the 6dB; Increase along with the incoming level of Doherty amplifier; The power output of carrier wave amplifying circuit 4 is increased to 0.5Po from about 0.25Po, and the power output of peak value amplifying circuit 5 increases to 0.5Po from 0Po.In addition, in scope B, the power output sum of the power output of carrier wave amplifying circuit 4 and peak value amplifying circuit 5 is with the proportionality constant identical with scope A, and is proportional with the input power of Doherty amplifier.When peak value amplifying circuit 5 was started working, the efficient of Doherty amplifier is temporary transient to be reduced a bit.Yet the efficient of Doherty amplifier begins to increase once more, so that the compression point that begins to reach capacity at peak value amplifying circuit 5 reaches its peak value.In compression point, the power output of carrier wave amplifying circuit 4 is substantially equal to the power output of peak value amplifying circuit 5.
Usually, CDMA signal and multi-carrier signal have the peak value coefficient, that is, and and the ratio of peak power and average power.Yet traditional amplifier has operating point under compression point, so that corresponding to the peak factor of scope from 7dB to 12dB.
Below, with reference to figure 1, with assembly in the description Doherty amplifier and their impedance.Because the impedance of said output loading Zo is a constant, it is set to reference value.If the input impedance of λ/4 converters 7 that we will see from node 62 is defined as Z
7, and the characteristic impedance of λ/4 converters 7 is defined as Z
2, then following equality is set up:
The input impedance Z of the λ that therefore, sees/4 converters 61 from output matching circuit 43
4Can obtain as follows.In scope A, be infinitely great owing to the output impedance of output matching circuit 53 is actual, Z
4And Z
5Can obtain by following equality:
Z
5=∞ (in scope A) equality 3
Z wherein
1It is the characteristic impedance of λ/4 converters 61.
Yet incoming level is higher than among the scope C of compression point therein, Z
7Can be considered to the output impedance of the parallel a pair of λ that sees from node 62/4 converters 61 and the output impedance of output matching circuit 53, wherein said output impedance equates.Therefore, in scope C, Z
4And Z
5Can obtain be:
Z
5=2Z
7(in scope C) equality 5
In scope B, Z
4And Z
5In scope A and scope C, change in those boundaries.
Above result can description below.When in high-frequency operation, using Doherty amplifier, the Z of (, in scope C) when output level is higher relatively
4Value be the Z of when output level is relatively low (, in scope A)
4Value half the.For example, if Z
7=25 Ω and Z
1=50 Ω, Z
4In the scope of 100～50 Ω, change.Therefore, the impedance of amplifying device 42 also changes according to it.
Except that above-mentioned traditional Doherty amplifier, known a kind of improved Doherty amplifier, it can be through compensating its characteristic distorition (for example, referring to the open co-pending application No.2004-260232 of Japan Patent) based on leakage current control gate bias voltage.
In addition, also known a kind of improved Doherty amplifier, therein, all amplifying circuits all are configured to two-stage or multistage (for example, referring to the open co-pending application No.2004-173231 of Japan Patent).
In addition, also known a kind of improved Doherty amplifier, therein, all harmonic are all combined, thereby are compensated for (for example, referring to the open co-pending application No.H6-82998 of Japan Patent).
Yet; When in high-frequency operation, using traditional Doherty amplifier through use semiconductor amplifying device; Because the load line of seeing from amplifying device 42 changes according to the behavior of output matching circuit 43; So can not easily be adjusted from the impedance that amplifying device 42 is seen, so that it is consistent with the value that obtains based on the Doherty theory.
Fig. 3 is the Smith chart of the typical change of performance load impedance.Z
A, Z
BAnd Z
CIt is the load impedance of amplifying device 42.These impedances all at 2 Ω between 20 Ω or littler (with Z
4Compare obviously little), and be not fully resistive.This Smith chart is by at Z
AAnd Z
CBetween optional impedance normalization.Center at them comprises Z
AThe curve of three closures are constant output curves of representing 0.9P, 0.5P and 0.25P respectively, it has shown that power output becomes inaccurate along with impedance matching and reduces.Shown in wherein, when the load impedance of amplifying device 42 is Z
AThe time can obtain peak power output P.
In addition, four dot-dash curve of passing said constant output curve all are the constant efficiency curves, represent efficient a, b, c and d (descending in proper order with this) respectively.
Because along with the increase of output level, Z
4From Z
0Z
1 2/ Z
2 2, i.e. Z
4(A), be reduced to Z
0Z
1 2/ 2Z
2 2, i.e. Z
4(C), if Z
4(C) matched Z
AObtain the peak power output in scope C, then Z
4(A) and Z
BCoupling.Yet, changing on constant output curve in view of needing only impedance corresponding to 0.25Po, any impedance all will produce the power output of 0.25Po, should be noted that: with Z
CThe situation of coupling will be higher than and Z on efficient
BThe situation of coupling.That is, when the load impedance of amplifying device 42 along with the increase of incoming level from Z
CDrop to Z
AThe time, amplifying device 42 the most effectively carries out work.
More than describing is for the situation of only considering power output and efficient.Yet, usually not only the performance of amplifier is described but also through gaining and distortion is described through power output and efficient.Even consider the impedance matching of the particular condition of this power output, efficient, gain and the distortion of satisfying particular type amplifying device 42; Also there is certain situation; Wherein, Along with the increase of incoming level, the load impedance of amplifying device 42 is better than inside variation with respect to outside variation the in the center of Smith chart.In addition, also have certain situation, wherein, preferably impedance changes to Z from the arbitrfary point with superperformance
A
Yet traditional match circuit is difficult to the Z that inwardly changes with respect to the center of Smith chart sometimes
4Two dashed curves in the impedance conversion path in the presentation graphs 3 are transformed to the outwards impedance of variation of center, so can intersect each other with respect to Smith chart.Therefore, in traditional Doherty amplifier, along with impedance at Z
BAnd Z
ABetween change, output matching circuit 43 has increased improving the restriction of performance only to realize this impedance matching thus.
In addition, in traditional Doherty amplifier, when being connected in series a plurality of amplifiers with realization high-gain common amplifier, the separation loss of distributor 2 uprises, and power efficiency or power added efficiency step-down.
Figure 10 is the structure chart of traditional two-stage common amplifier.Be assigned with device 2 by preamplifier 20 amplifying signals and be separated into two signals, this means the loss that produces 3dB with the mode that separated signal has identical efficient.That is, be impossible, so use all electrical power of the signal that separates effectively because input impedance changes according to the mode of incoming level with complicacy.
At least, in scope A, all electrical power that are assigned to peak value amplifying circuit 5 are wasted.That is, the major part that is assigned to the electrical power of peak value amplifying circuit 5 is reflected, and reflected wave for example is being wasted in the insulator (not shown) usually, if perhaps distributor 2 is Wilkinson (Wilkinson) types, in the dummy resistor (not shown), is wasted.In addition, in scope B, the electrical power that is assigned to peak value amplifying circuit 5 is by partial reflection.Yet,,, can carry out summation at the node 62 of Figure 10 when the gain (that is, linearity) of scope A when being held because the power output of category-B or C class amplification circuit little by little increases and reflection power reduces.
Therefore, we need consider the loss of above-mentioned about 3dB, and it will be called as " separation loss ".
Figure 11 describes carrier amplifier 4, peak amplifier 5 and both the standardized input powers and the chart of power output.It is as the supposition power output of the carrier amplifier 4 of monomer under zero the situation that Figure 11 is also shown in separation loss.Shown in wherein, the power output of peak value amplifying circuit 5 increases near the amplifier offset of 6dB fast, and therefore, in amplifier offset was 6dB or littler scope B, carrier wave amplifying circuit 4 was shared said load together with peak value amplifying circuit 5.In addition, we can find out: for example, compare with the carrier wave amplifying circuit as monomer, because separation loss, gain reduces very big.
After this, under the situation with the actual specification that is described in supposition preamplifier 20 and Doherty amplifier 10, how to calculate the power added efficiency of common amplifier.Amplifier offset is set to standard value (7dB is to 10dB), make the input power of peak value amplifying circuit 5 owing to reflection is wasted, and preamplifier 20 is chosen to be traditional class ab ammplifier, rather than Doherty amplifier.
The specification of Doherty amplifier 10 is following:
Power output: 20W
Gain: 9dB (comprising separation loss)
Collector efficiency: 35%
Input power: 2.5W
The specification of preamplifier 20 is following:
Power output: 2.5W (than the little 9dB of 20W)
Input power: 0.156W
Gain: 12dB (comprising separation loss)
Collector efficiency: 20%
Therefore, we obtain following result:
The power consumption of Doherty amplifier is 20/0.35=57.1W;
The power consumption of preamplifier is 2.5/0.2=12.5W; And
The power added efficiency of common amplifier is (20-0.156)/(57.1+12.5)=27.5%.
Can see as above, although it is the collector efficiency of Doherty amplifier increases to the same with 35% high, be reduced to 27.5% as the overall power efficiency of common amplifier.
In addition, although also can be connected in series a plurality of Doherty amplifiers, the casacade multi-amplifier structure can cause the performance distortion, because Doherty amplifier comprises phase converter 3 and Doherty combiner 6, and its characteristic is along with frequency changes greatly.
Summary of the invention
Therefore, target of the present invention provides a kind of improved Doherty amplifier, wherein through realizing that the suitable resistance coupling makes its performance be superior to traditional Doherty amplifier.
Another object of the present invention provides a kind of improved Doherty amplifier, and wherein its gain is bigger, with and power added efficiency the same high with traditional Doherty amplifier at least basically.
According to an aspect of the present invention, a kind of amplifier is provided, has been used to make up the output of a plurality of amplifier circuits; To produce amplifier output, comprising: first amplifying circuit is used for first amplifying device of operation A category-B; Wherein, first amplifying circuit is one of in a plurality of amplifying circuits; Second amplifying circuit is used to operate category-B or C class second amplifying device, and wherein, second amplifying circuit is one of in a plurality of amplifying circuits; And summing junction, at this place, the output of first amplifying circuit is via the output combination of first impedance transformer and second amplifying circuit, and said first impedance transformer includes electrical length and is not the transmission line of λ/4.
Best, second amplifying device is connected to summing junction via the output matching circuit and second impedance transformer that comprises transmission line.
Best, amplifier also comprises distributor, is used for the input signal of amplifying circuit is separated into the signal more than a separation; First preamplifier is used for through operating one of signal that amplifies a plurality of separation according to the AB class, amplifying signal is sent to first amplifying circuit; And second preamplifier, be used for through operating one of signal that amplifies a plurality of separation, amplifying signal is sent to second amplifying circuit according to AB class, category-B or C class.
According to a further aspect in the invention, a kind of amplifier is provided, comprises: distributor is used for the input signal of amplifying circuit is separated into the signal of at least two separation; First preamplifier is used to one of signal that amplifies separation, and second preamplifier, is used for amplifying another of signal of separation; The carrier wave amplifying circuit, the output that is used to amplify first preamplifier; The peak value amplifying circuit if the output of second preamplifier is higher than threshold level, then is used to amplify the output of second preamplifier; And the Doherty combiner, be used for the output of carrier wave amplifying circuit and the output of peak value amplifying circuit are made up.
According to another aspect of the invention, a kind of amplifier is provided, comprises: distributor is used for the input signal of amplifying circuit is separated into two essentially identical separation signals of electrical power; First preamplifier is used to one of signal that amplifies separation, and wherein, first amplifier is setovered according to the AB class; Second preamplifier is used for amplifying another of signal of said separation, and wherein second amplifier is setovered according to the C class; The carrier wave amplifying circuit, the output that is used to amplify first preamplifier, wherein the carrier wave amplifying circuit is setovered according to the AB class; The peak value amplifying circuit if the output of second preamplifier is equal to or higher than threshold level, then is used to amplify the output of second preamplifier, and wherein the peak value amplifying circuit is according to category-B or the biasing of C class; And the Doherty combiner, be used for the output of carrier wave amplifying circuit and the output of peak value amplifying circuit are made up.
Best; Threshold level is corresponding with the level of the compression point 6dB that is lower than amplifier; The amount distortion of first preamplifier is different from the amount distortion of second preamplifier; The peak value amplifying circuit comprises semiconductor device; The carrier wave amplifying circuit comprise with the peak value amplifying circuit in another identical semiconductor device of configuration of semiconductor device, the saturated output level of peak value amplifying circuit and carrier wave amplifying circuit basic identical, and the Doherty combiner is not realized impedance conversion for the transmission line of λ/4 through utilizing electrical length.
According to another aspect of the invention, a kind of amplifier is provided, comprises: distributor is used for the input signal of amplifying circuit is separated into n signal that separates; First preamplifier is used to amplify one of them of signal of separation, and wherein first amplifier is setovered according to the AB class; Second to the n preamplifier, be used for amplifying separation signal other signal, wherein second setover according to the C class to the n amplifier; The carrier wave amplifying circuit, the output that is used to amplify first preamplifier, wherein the carrier wave amplifying circuit is setovered according to the AB class; Second to n peak value amplifying circuit, if second output to the n preamplifier is equal to or higher than threshold level, then is used to amplify second output to the n preamplifier, wherein second to n peak value amplifying circuit according to the biasing of category-B or C class; And the Doherty combiner, be used for the output of carrier wave amplifying circuit and second is made up to the output of n peak value amplifying circuit each other.
According to another aspect of the invention, a kind of amplifier is provided, comprises: distributor is used for the input signal of amplifying circuit is separated into the signal of two or more separation; One or more first preamplifiers are used to amplify one of them of signal of said separation, and wherein at least one first amplifier is setovered according to the AB class; Second preamplifier of one or more groups cascade is used to amplify the signal of other separation, and wherein second preamplifier of each group cascade is configured to make of front end in second preamplifier to setover according to the C class; The carrier wave amplifying circuit, the output that is used to amplify first preamplifier; One or more peak value amplifying circuits if the output of above-mentioned one or more groups second preamplifier is higher than threshold level, then are used to amplify the output of second preamplifier of above-mentioned one or more groups cascade; And the Doherty combiner, be used for the output of carrier wave amplifying circuit and the output of above-mentioned one or more peak value amplifying circuits are made up.
Best, a plurality of first preamplifiers all are connected in series, and of the front end in first preamplifier setovers according to the C class.
The accompanying drawing summary
Through the description of the preferred embodiment that provides below in conjunction with accompanying drawing, above-mentioned and other purpose of the present invention, characteristic will become more obvious, wherein:
Fig. 1 has shown the structure chart of traditional Doherty amplifier;
Fig. 2 has described the collector efficiency of the Doherty amplifier that shows among Fig. 1 or the theoretical prediction value of drain efficiency;
Fig. 3 is the Smith chart of the typical change of expression load impedance;
Fig. 4 has described the structure chart of the amplifier of first embodiment according to the present invention;
Fig. 5 is the Smith chart of describing through using output matching circuit 43 and impedance transformer 64 to carry out impedance matching.
Fig. 6 is that the electrical length that is presented at impedance transformer is the allocation plan of the amplifier of first embodiment according to the present invention under zero the situation;
Fig. 7 has described the structure chart of the amplifier of second embodiment according to the present invention;
Fig. 8 provides the structure chart of the amplifier of the 3rd embodiment according to the present invention;
Fig. 9 has shown the structure chart of the amplifier of the 4th embodiment according to the present invention;
Figure 10 is the structure chart of traditional two-stage common amplifier;
Figure 11 is the figure that describes carrier amplifier 4, peak amplifier 5 and both power outputs;
Figure 12 has described the structure chart of the common amplifier of the 5th embodiment according to the present invention; And
Figure 13 has described the structure chart of the common amplifier of the 6th embodiment according to the present invention.
Embodiment
Hereinafter, with reference to accompanying drawing, the preferred embodiments of the present invention will be described.
(embodiment 1)
Fig. 4 has described the structure chart of the amplifier of first embodiment according to the present invention.The difference of the amplifier that shows among the amplifier that shows among Fig. 4 and Fig. 1 is: λ/4 converters 61 are replaced by the impedance transformer 64 of the transmission line that any electric power length is installed, and phase converter 3 is replaced by phase converter 31.Maybe difference except that the specification of some assemblies, the amplifier that shows among other configuration of the amplifier that shows among Fig. 4 and Fig. 1 identical.
Input signal is imported into input 1.Input signal is assigned with device 2 to be separated, and distributor 2 for example is the coupler of 3dB or the T type branch line that on terminal block, forms.Phase converter 31 is a transmission line substantially, and it can produce and the corresponding delay of the delay of impedance transformer 64.When the output signal at the output signal of node 62 combined impedance converters 64 and output matching circuit 53, phase converter 31 makes the phase place of output signal of impedance transformer 64 equal the phase place of the output signal of output matching circuit 53.Because the phase difference that is caused by impedance transformer 64 and must be calculated by the phase difference that carrier wave amplifying circuit 4 and peak value amplifying circuit 5 cause is so the delay of phase converter 31 maybe be different with the delay of impedance transformer 64.
Carrier wave amplifying circuit 4 comprises: input matching circuit 41 is used to realize the impedance matching with the input side of amplifying device 42; Amplifying device 42, it comprises, for example, one or more transistors; And output matching circuit 43, be used to realize impedance matching with the outlet side of amplifying device 42.Impedance transformer 64 is connected to the output of carrier amplifier 4, with its output impedance of conversion.The amplifying device 42 that is used for amplifying signal is setovered according to the AB class.In scope A, output matching circuit 43 and impedance transformer 64 are transformed to the load impedance of amplifying device 42 therein that the heart partly comprises Z together
AThe curve of sub-circular on impedance.In scope C, output matching circuit 43 is transformed to Z with the load impedance of amplifying device 42 together with impedance transformer 64
A
The signal of other separation is imported into peak value amplifying circuit 5 after its phase place is postponed by phase converter 31.Be similar to carrier wave amplifying circuit 4, peak value amplifying circuit 5 comprises input matching circuit 51; Comprise, for example, one or more transistorized amplifying devices 52; And output matching circuit 53.Amplifying device 52 is according to category-B or the biasing of C class.Usually, amplifying device 42 and 52 all is a semiconductor device, for example LD-MOS (Lateral Double-diffusedMOS, lateral direction bilateral diffusion MOS), GaAs-FET, HEMT or HBT.In scope A, output matching circuit 53 is transformed to Z with the load impedance of amplifying device 52
5In scope C, output matching circuit 53 is transformed to the load impedance of amplifying device 52 and is essentially infinitely-great value. Input matching circuit 41 and 51 and output matching circuit 43 and 53 can be configured to lumped constant circuit, distributed constant circuit or its combination.In addition, output matching circuit 43 and 53 can include perhaps inductance of stray electrical.
The output signal of impedance transformer 64 and the output signal of output matching circuit 53 are in summing junction 62 combinations.Impedance transformer 64 is that an electrical length l is 0～λ/2 or longer transmission line.Be under zero the situation in the electrical length of impedance transformer 64, it with Fig. 6 in the ideal wire that shows identical.Z
1, that is, the characteristic impedance of impedance transformer 64 equals 2Z
7=2Z
2 2/ Z
0
Signal in node 62 combinations is imported into λ/4 converters 7, and it is with Z
7, that is, the input impedance of λ/4 converters 7 of seeing from node 62 is transformed to Z
0, i.e. output load impedance.The printed circuit that λ/4 converters 7 can be configured on terminal block, form, width and characteristic impedance Z
2Corresponding and length is corresponding with electrical length λ/4.Although through using λ/4 converters also can use the miscellaneous equipment except that λ/4 converters, as long as can realize impedance matching realizing impedance matching in the wider frequency relatively.
Fig. 5 is the Smith chart of describing through using output matching circuit 43 and impedance transformer 64 to carry out impedance matching.Output matching circuit 43 is configured to feasible load impedance Z when output matching circuit 43
9Equal Z
1The time, its power output is Po (it is the maximum power as the carrier amplifier 4 of monomer).That is, in scope C, the load resistance of amplifying device 42 and Z
AEquate that wherein impedance transformer 64 is as a transmission line.
In scope A, the output impedance of output matching circuit 53 is infinitely great basically.Therefore, Z
9Under the situation of l=0 or λ/2, be transformed to the Z that representes by an a
7, and under the situation of l=λ/4, be transformed to the Z that representes by a b
1 2/ Z
7In addition, if l 0 and λ/2 between scope in change Z then
9Along with Z
1Round clockwise direction variation for the center.
By with Z
1The impedance of representing for the circle at center is mapped to Z through output matching circuit 43
ABe included on the curve of sub-circular of its center.A, b are corresponding with an a ', b ' and c ' respectively with c for point, and it means that through changing l can be a ', b ' and c ' with impedance conversion.Therefore, preferably set l, make that c ' is the best point of performance of carrier wave amplifying circuit or amplifier.The optimal value of l be by, for example, repetition test is confirmed.Can carry out test and observe performance as the carrier wave amplifying circuit of monomer.Yet, more preferably, carry out the performance that whole amplifier is observed in test.
According to embodiment 1, though when optimum point along with Z
AWhen wrapping in the curvilinear motion of sub-circular of its center, only just can realize impedance matching through changing l, and regardless of the type of amplifying device or the like.
The electrical length l that Fig. 6 is presented at impedance transformer is under zero the situation, the structure chart of the amplifier of first embodiment according to the present invention.Can when being zero, the loss in preferably making impedance transformer 64 use the structure that shows among Fig. 6 according to the situation of device.
In addition, although electrical length l is 0 to λ/2 in above description, l can be longer than λ/2.In addition, Z
1Not fully to equal 2Z
7, sometimes can be slightly different.
(embodiment 2)
Fig. 7 describes the structure chart of the amplifier of second embodiment according to the present invention.The difference of the amplifier that shows among the amplifier that shows among Fig. 7 and Fig. 4 is: impedance transformer 65 is connected between output matching circuit 53 and the node 62, and phase converter 31 is replaced by phase converter 33.Maybe difference except that the specification of some assemblies, other configuration of the amplifier that shows among Fig. 7 all with Fig. 4 in the amplifier that shows identical.
When amplifying device 52 was not worked because its incoming level is low, impedance transformer 65 was with the output impedance Z of output matching circuit 53
20Be transformed to bigger value Z
21Suppress to flow into the signal of carrier wave amplifying circuit 4 thus.Impedance transformer 65 for example has the random length transmission line identical with impedance transformer 64.
According to first embodiment, the output impedance of traditional output matching circuit 53 hour can not become enough big at incoming level, causes the power loss in the carrier wave amplifying circuit 4 thus.Yet, according to second embodiment, can make the output impedance of the peak value amplifying circuit of seeing from node 62 5 become big, power loss that therefore can suppressed carrier amplifying circuit 4 through adding impedance transformer 65.
(embodiment 3)
Fig. 8 provides the structure chart of the amplifier of the 3rd embodiment according to the present invention; The difference of the amplifier that shows among the amplifier that shows among Fig. 8 and Fig. 4 is: wherein be provided with a plurality of carrier wave amplifying circuits or a plurality of peak value amplifying circuits; Distributor 2 is replaced by distributor 21, and λ/4 converters 7 are replaced by impedance transformer 71.Maybe difference except that the specification of some assemblies, other configuration of the amplifier that shows among Fig. 8 all with Fig. 4 in the amplifier that shows identical.This embodiment is preferred, especially when two amplifiers can not provide the power output of enough big needs.
The Signal Separation that distributor 21 will be input to input 1 is n.4-1,4-2 ... (0＜k＜n) is a k carrier wave amplifying circuit corresponding to the carrier wave amplifying circuit 4 among Fig. 4 to 4-k.5-1,5-2 ... 5-m is a m peak value amplifying circuit corresponding to the peak value amplifying circuit 5 among Fig. 4.4-1 to 4-k and 5-1 to 5-m also can be connected to Fig. 7 in the same impedance transformer that shows 65 or phase converter 33.Although not shown among Fig. 8, the phase place of the output of carrier wave amplifying circuit 4-1 to 4-k and peak value amplifying circuit 5-1 to 5-m is all adjusted, so that these outputs can be combined with identical phase place at summing junction.Impedance transformer 71 is transformed to Z with the output impedance of amplifier
0Impedance transformer 71 is λ/4 converters for example.
According to the 3rd embodiment; Input signal is assigned with device 21 and is separated into n; K wherein is all amplified by the class ab ammplifier of in the scope that is input to the large-signal input from small-signal, working, and m wherein is all amplified by category-B of in the large-signal input range, working or C class A amplifier A.The peak value amplifying circuit can be started working at identical incoming level.Yet the peak value amplifying circuit also possibly have different bias levels, and along with the increase of incoming level is started working one by one.
(embodiment 4)
Fig. 9 shows the structure chart of the amplifier of the 4th embodiment according to the present invention.The difference of the amplifier that shows among the amplifier that shows among Fig. 9 and Fig. 8 is: preamplifier is connected in series carrier wave amplifying circuit or peak value amplifying circuit.This embodiment can improve power efficiency.
Usually, amplifier uses a plurality of amplifying devices, to obtain sufficiently high gain.For example, preamplifier can be connected to serial the amplifier that shows among Fig. 4,6 or 7.Yet, because the amplifier that shows among Fig. 4,6 and 7 comprises distributor 2, so be sent under the situation of amplifier in the idle scope C of peak value amplifying circuit that the electrical power of peak value amplifying circuit shows in Fig. 4,6 and 7 not by effective use.That is, although be imported into input 1 by the preamplifier amplifying signal, input power wherein is 3dB under the worst situation by the part waste.The power added efficiency of traditional Doherty amplifier is owing to this separation loss reduces.
In Fig. 9,44-1 to 44-k and 54-1 to 54-m are preamplifiers, and it is connected respectively between distributor 21 and amplifying circuit 4-1 to 4-k and the 5-1 to 5-m.If desired, these preamplifiers can have input matching circuit or output matching circuit.These preamplifiers can have identical structure, perhaps according to dissimilar biasings.In addition, these preamplifiers can be connected with multistage mode.A plurality of preamplifiers (for example, 44-1 is to 44-k) also can be joined together as common amplifier.
According to the 4th embodiment, input signal is assigned with device 21 when input signal is little level separates, and reduces separation loss thus to improve the power efficiency of amplifier.This is conspicuous, and especially for example the gain of amplifying device 42 hour.
Compare with traditional Doherty amplifier, can strengthen the property through suitably adjusting impedance matching according to the amplifier of first to the 4th embodiment.
(embodiment 5)
Figure 12 has described the structure chart of the common amplifier of the 5th embodiment according to the present invention.The difference of the common amplifier that shows among the common amplifier that shows among Figure 12 and Figure 10 is: two preamplifiers 91 and 92 all are arranged between distributor 2 and amplifying circuit 4 and 5.In Figure 12, the specification with these assemblies among assembly and Figure 10 of the reference number identical with Figure 10 is identical.
10 ' be the part after the leaning on of traditional Doherty amplifier.Wherein, except that distributor 2 and phase converter 3 all were not included in wherein, the part after the leaning on of traditional Doherty amplifier was identical with the structure of traditional Doherty amplifier.Input signal is assigned with device 2 to be separated, and distributor 2 is the Wilkinson distributors that for example on terminal block, form.Phase converter 3 can produce corresponding time delay or the phase delay with λ/4 converters 61.The phase difference that phase converter 3 adjustment are caused by impedance transformer 64, carrier wave amplifying circuit 4 and peak value amplifying circuit 5.When at the node 62 combination λ/output signals of 4 converters 61 and the output signal of peak value amplifying circuit 5, phase converter 31 makes the phase place of output signal of λ/4 converters 61 equal the phase place of the output signal of peak value amplifying circuit 5.Because time difference or phase difference not only can cause by λ/4 converters 61, and can by preamplifier 91 and 92 and amplifying circuit 4 and 5 cause.So the time delay of phase converter 31 or phase delay maybe be different with the time delay or the phase delay of λ/4 converters 61.Phase converter 3 can be configured and make time delay or phase delay to be effectively controlled.
One of the signal that is used to receive separation with the preamplifier 91 that amplifies the signal that is received according to the biasing of AB class, the enough linearity that need with the input signal of keeping carrier wave amplifying circuit 4.The amplifier offset of preamplifier 91 for example is designated as, with the basic identical of carrier wave amplifying circuit 4 or big slightly.
The signal that is used to receive another separation with the preamplifier 92 that amplifies the signal that is received according to the biasing of C class, the enough linearity that need with the input signal of keeping peak value amplifying circuit 5.What therefore, the output signal of preamplifier 91 maybe be with preamplifier 92 is different.
The output signal of carrier wave amplifying circuit 4 receiving preamplifiers 91, amplifying the signal received, and the output signal of peak value amplifying circuit 5 receiving preamplifiers 92, to amplify the signal that is received.Usually, preamplifier 91 and 92 and the amplifier installation that uses of amplifying circuit 4 and 5 all be semiconductor device, for example LD-MOS (LateralDouble-diffused MOS, lateral direction bilateral diffusion MOS), GaAs-FET, HEMT or HBT.The amplifying device that carrier wave amplifying circuit 4 uses can have substantially the same configuration with peak value amplifying circuit 5 employed amplifying devices.
λ/4 converters 61 comprise the transmission line that is used to realize impedance matching.Replace λ/4 converters 61, the impedance transformer of being processed with the mode that is similar to Fig. 4 by transmission line can be used to realize impedance matching, and wherein said transmission line has 0～λ/2 or longer electrical length l, and characteristic impedance wherein is Z
1=2Z
2 2/ Zo.
λ/output the signal of 4 converters 61 and the output signal of peak value amplifying circuit 5 are combined at summing junction 62, and the signal that makes up at node 62 is imported into λ/4 converters 7, and λ/4 converters 7 are with Z
7, that is, the input impedance of λ/4 converters 7 of seeing from node 62 is transformed to Z
0, that is, and output load impedance.The printed circuit that λ/4 converters 7 can be configured on terminal block, form, width and characteristic impedance Z
2Corresponding and length is corresponding with electrical length λ/4.Although, also can use other device except that λ/4 converters, as long as can realize impedance matching through using λ/4 converters in whole relative wider frequency, to realize impedance matching.
After this, with the power added efficiency of the common amplifier of estimating to show among Figure 12.Wherein the characteristic of each assembly be assumed that with Figure 10 in corresponding assembly identical, and as long as incoming level be constant, the output level of common amplifier just is assumed that constant.Preamplifier 91 and 92 is configured to respectively according to AB class and the biasing of C class.The configuration of preamplifier 91 is identical with the configuration of preamplifier 92. Preamplifier 91 and 92 efficient and gain all with Figure 10 in amplifier 20 identical, but the output level of preamplifier 91 and 92 is lower than the output level of preamplifier 20.It is identical with the incoming level and the output level of the common amplifier that shows among Fig. 5 that the incoming level of the common amplifier that shows among Fig. 3 and output level all are set to.
Power output: 20W
Gain: 12dB (increasing 3dB) owing to lacking distributor
Collector efficiency: 35%
The specification of preamplifier 91 is following:
Power output: 1.25W
Input power: 0.078W
Amplification degree: 12dB
Collector efficiency: 20%
Therefore, we obtain following result:
The power consumption of Doherty amplifier is 20/0.35=57.1W;
The power consumption of preamplifier is 1.25/0.2=6.25W; And
The power added efficiency of common amplifier is (20-0.156)/(57.1+6.25)=31.3%.
Can see as above, compare, increase 2.8% according to the power efficiency of the common amplifier of the 5th embodiment with the traditional common amplifier that shows among Figure 10.
The saturated output of carrier wave amplifying circuit 4 can be identical or different with peak value amplifying circuit 5.In addition, although above-mentioned common amplifier has two-layer configuration, can have n level (n＞2) structure according to the common amplifier of present embodiment, so when keeping efficient, can improve gain.In this case, the preamplifier that amplifies for peak value although all can be according to the biasing of C class, also can have only on the front end one to setover according to the C class.
In addition; Common amplifier according to this embodiment can comprise a control circuit; Be used to control the gain or the phase place of peak value amplifying circuit 4 and peak value amplifying circuit 5; So that the Doherty amplifier performance is perhaps optimized in the suitably influence of distributed load impedance between carrier wave amplifying circuit 4 and peak value amplifying circuit 5.In this case, more preferably, control circuit is installed in the preamplifier of forward level in the middle of a string preamplifier.By this way, can improve the performance of Doherty amplifier, suppress the power loss in the control circuit simultaneously.Control circuit for example can use, PIN diode or varicap electric power ride gain or phase place.
Figure 13 has described the structure chart of the common amplifier of the 6th embodiment according to the present invention.The difference of the common amplifier of the common amplifier of the 6th embodiment and the 5th embodiment is: its configuration makes the output of three amplifying circuits output that all is combined.In Figure 13, with assembly that Figure 12 has a same reference numbers have with Figure 12 in the identical specification of these assemblies.
Although it is not shown in the accompanying drawing; If the configuration of the 6th embodiment and supposition is compared; Through shown in figure 13; Before each amplifying circuit 4,5 and 55, insert preamplifier 91 to 93 respectively, the absolute value of separation loss is reduced and power added efficiency is enhanced, and the configuration of said supposition is: the common amplifier that includes three amplifying circuits has preamplifier before being input to peak value amplifying circuit or drive circuit in that input signal is separated with the mode that is similar to Figure 10.With reference to the description of the 6th embodiment, although do not describe in detail, this result is conspicuous to those skilled in the art.
The structure of peak value amplifying circuit 55 structure with peak value amplifying circuit 5 basically is identical, removes its working point of setting it is being started working than peak value amplifying circuit 5 higher incoming levels.Impedance transformer 64 comprises transmission line, and its configuration is similar to the configuration of λ/4 converters 61.As long as can realize impedance matching, also can use the equipment of other kind to replace λ/4 converters 61 or impedance transformer 64.
After this, with the work of describing the common amplifier that shows among Figure 13.When wherein incoming level is not high enough to make 55 work of peak value amplifying circuit, basic identical in the common amplifier that shows among the output signal of the carrier wave amplifying circuit 4 in the common amplifier that shows among Figure 13 and Figure 12.Therefore, in this case, the signal of node 63 combinations in Figure 13 is basic identical with the signal of node 62 combinations in Figure 12.In addition, the load impedance of peak value amplifying circuit 55 is actual is infinitely great.The output impedance that impedance transformer 64 conversion are seen from node 63 is to transfer to node 66 with its influence.Therefore, when preamplifier 92 and/or 93 was not worked, separation loss reduced.
When incoming level was high enough to make peak value amplifying circuit 55 saturated, the input impedance of seeing from impedance transformer 64 increased, and the output impedance of therefore seeing from node 63 becomes and makes that the power of supply can be by transmission effectively.Therefore, the power output of common amplifier is assigned to amplifying circuit 4,5 and 55 almost equally.
Amplifying circuit 4 and 5 assembly through the carrier wave amplifying circuit 4 in the common amplifier that resembles Figure 12 in the common amplifier of operation Figure 13, the common amplifier that can easily understand among Figure 13 makes the behavior that peak value amplifying circuit 55 is started working at incoming level.
Although Doherty amplifier wherein also can use other configuration by constituting according to the λ of sixth embodiment of the invention/4 converter 61, impedance transformer 64 and node 63 and 66, for example, only comprise the configuration of single node.In addition, can be by the number of the separation signal of Doherty combiner combination greater than 3.In addition, also can a plurality of preamplifiers be combined into independent one, and let the signal that separates share it.Just as described above, through before amplifying circuit 4,5 and 55, inserting preamplifier 91 to 93 respectively, when peak value amplifying circuit 5 and 55 was not worked, the absolute value of separation loss reduced, and made and had improved power added efficiency.
According to the casacade multi-amplifier of the 5th and the 6th embodiment,,, can make the power efficiency of amplifier approach the collector efficiency of Doherty amplifier through separating input signal when incoming level is low when suppressing separation loss.
The term that in explanation, uses " category-A ", " AB-class ", " category-B " and " C class " should be interpreted as the bias condition that only defines based on idle current, and with class of operation (for example F class) compatibility based on the configuration of output matching circuit.
The present invention can be realized by any device, any circuit or any equipment.A plurality of circuit can be used to realize single function, and single circuit can be realized a plurality of functions.In addition, the function of the present invention's preferred embodiment or structure should not be interpreted as essence of the present invention.
Though the said preferred embodiment of reference is showed the present invention and is described, and those skill in the art will appreciate that, in not breaking away from like following claim, under the situation of defined the spirit and scope of the present invention, can carry out various changes and modifications.
Claims (2)
1. amplifier, the output that is used to make up a plurality of amplifying circuits is to produce amplifier output, and said amplifier comprises:
First amplifying circuit is used for first amplifying device of operation A category-B, and wherein, said first amplifying circuit is one of in said a plurality of amplifying circuit;
Second amplifying circuit is used to operate second amplifying device of category-B or C class, and wherein, said second amplifying circuit is one of in said a plurality of amplifying circuit; And
Summing junction, at this summing junction, the output of said first amplifying circuit is via comprising the output combination of first impedance transformer and said second amplifying circuit that electrical length is equal to or less than the transmission line of λ/2,
Wherein when the load impedance value of said first amplifying circuit equaled the resistance value of said first impedance transformer, the power output of said first amplifying circuit was the maximum power of said first amplifying circuit,
The resistance value of wherein said first impedance transformer is two times of resistance value of the said amplifier output seen from said summing junction,
Wherein the electrical length of said transmission line is regulated, make that the performance of said first amplifying circuit is best.
2. amplifier as claimed in claim 1, wherein, said second amplifying circuit is connected to said summing junction via second impedance transformer that comprises transmission line.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004322092 | 2004-11-05 | ||
| JP322092/2004 | 2004-11-05 | ||
| JP362826/2004 | 2004-12-15 | ||
| JP2004362826 | 2004-12-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2005101162979A Division CN1770622B (en) | 2004-11-05 | 2005-11-07 | Amplifier |
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| CN101494439A CN101494439A (en) | 2009-07-29 |
| CN101494439B true CN101494439B (en) | 2012-03-28 |
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| CN2009101264218A Expired - Fee Related CN101494439B (en) | 2004-11-05 | 2005-11-07 | Amplifier |
| CN2005101162979A Expired - Fee Related CN1770622B (en) | 2004-11-05 | 2005-11-07 | Amplifier |
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| CN2005101162979A Expired - Fee Related CN1770622B (en) | 2004-11-05 | 2005-11-07 | Amplifier |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100749870B1 (en) * | 2006-06-07 | 2007-08-17 | (주) 와이팜 | Doherty amplifier |
| CN101409532B (en) * | 2007-10-12 | 2011-07-13 | 瑞昱半导体股份有限公司 | Mixed output stage circuit and correlation method |
| CN101534093B (en) * | 2009-04-14 | 2011-08-10 | 武汉正维电子技术有限公司 | Final three-route power synthesizing amplifying circuit applied to power amplifier of mobile communication base station system |
| CN102130657A (en) * | 2010-09-14 | 2011-07-20 | 华为技术有限公司 | Power amplifier, asymmetric Doherty power amplifier equipment and base station |
| US8193857B1 (en) * | 2011-03-01 | 2012-06-05 | Infineon Technologies Ag | Wideband doherty amplifier circuit |
| US8339201B1 (en) * | 2011-06-17 | 2012-12-25 | Infineon Technologies Ag | Wideband doherty amplifier circuit having a constant impedance combiner |
| CN106257827B (en) * | 2015-06-17 | 2020-08-18 | 南京中兴新软件有限责任公司 | Symmetrical Doherty power amplifier circuit device and power amplifier |
| US11233483B2 (en) | 2017-02-02 | 2022-01-25 | Macom Technology Solutions Holdings, Inc. | 90-degree lumped and distributed Doherty impedance inverter |
| US11245363B2 (en) * | 2017-04-24 | 2022-02-08 | Macom Technology Solutions Holdings, Inc. | Efficiency, symmetrical Doherty power amplifier |
| EP3616320B1 (en) | 2017-04-24 | 2023-11-08 | MACOM Technology Solutions Holdings, Inc. | Inverted doherty power amplifier with large rf and instantaneous bandwidths |
| CN110785926B (en) | 2017-04-24 | 2023-10-03 | 麦克姆技术解决方案控股有限公司 | Reverse doherty power amplifier with large RF fraction and instantaneous bandwidth |
| CN109286377A (en) * | 2017-07-21 | 2019-01-29 | 中兴通讯股份有限公司 | The linearization process circuit and method of radiofrequency signal |
| EP3692631A1 (en) | 2017-10-02 | 2020-08-12 | MACOM Technology Solutions Holdings, Inc. | No-load-modulation, high-efficiency power amplifier |
| WO2020072898A1 (en) | 2018-10-05 | 2020-04-09 | Macom Technology Solutions Holdings, Inc. | Low-load-modulation power amplifier |
| US11888448B2 (en) | 2019-12-30 | 2024-01-30 | Macom Technology Solutions Holdings, Inc. | Low-load-modulation broadband amplifier |
| CN111384901B (en) * | 2020-03-14 | 2023-02-24 | 电子科技大学 | Broadband high-efficiency three-way Doherty power amplifier based on post-matching network |
| US12028022B2 (en) | 2020-12-10 | 2024-07-02 | Macom Technology Solutions Holdings, Inc. | Hybrid power amplifier with GaN-on-Si and GaN-on-SiC circuits |
| CN113746434A (en) * | 2021-07-26 | 2021-12-03 | 杭州电子科技大学 | Broadband Doherty power amplifier based on load modulation network |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5568086A (en) * | 1995-05-25 | 1996-10-22 | Motorola, Inc. | Linear power amplifier for high efficiency multi-carrier performance |
| EP1032121A1 (en) * | 1999-02-26 | 2000-08-30 | Koninklijke Philips Electronics N.V. | Electronic apparatus with a power amplifier |
| KR20040079597A (en) * | 2003-03-08 | 2004-09-16 | 학교법인 포항공과대학교 | The microwave doherty amplifier apparatus by using adaptive bias control technique |
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2005
- 2005-11-07 CN CN2009101264218A patent/CN101494439B/en not_active Expired - Fee Related
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| CN1770622A (en) | 2006-05-10 |
| CN101494439A (en) | 2009-07-29 |
| CN1770622B (en) | 2012-04-04 |
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