CN100420157C - Method for eliminating mirror image interference in low-intermediate frequency receiver and relevant apparatus - Google Patents
Method for eliminating mirror image interference in low-intermediate frequency receiver and relevant apparatus Download PDFInfo
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- CN100420157C CN100420157C CNB031037895A CN03103789A CN100420157C CN 100420157 C CN100420157 C CN 100420157C CN B031037895 A CNB031037895 A CN B031037895A CN 03103789 A CN03103789 A CN 03103789A CN 100420157 C CN100420157 C CN 100420157C
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Abstract
The present invention provides a method for eliminating amplitude mismatches and phase mismatches between a pair of quadrature signals to eliminate image interference, wherein the quadrature signals comprise an in-phase signal and a quadrature-phase signal; the method comprises the steps of compensating a part of the in-phase signal for the quadrature-phase signal so as to make the difference between the phase of the quadrature-phase signal and the phase of the in-phase signal 90 degrees to eliminate the mismatches of the quadrature signals; adjusting the amplitude of the in-phase signal and the quadrature-phase signal to be equal so as to eliminate the amplitude mismatches of the quadrature signals.
Description
Technical field
The invention provides a kind of novel lens as interference analysis and bearing calibration, be meant a kind of be used for eliminating the amplitude difference (Amplitude Mismatch) in the pair of orthogonal signal (Quadrature Signal) and the method for phase difference (Phase Mismatch) especially, disturb with the mirror image of eliminating in the low intermediate frequency receiver.
Background technology
In the radio frequency transmission structure of current wireless communication system, can reach Highgrade integration and multimodal receiver structure at present two big classes are arranged, a kind of is Low Medium Frequency (Low IF) receiver, another kind is direct conversion (Direct Conversion), or be called zero intermediate frequency (Zero IF) receiver, both have pluses and minuses mutually, also all are subjected to paying attention to widely an application in industrial circle.The former can avoid the problem of direct current offset and low-frequency noise, but can be subjected to the interference of image signal (Image Signal).The latter is then just in time opposite, does not have the problem of image signal interference, but has the problem of direct current offset and low-frequency noise.
Up to the present, the structure of Low Medium Frequency has obtained to use widely on the transmission of radio communication and receiving terminal, and therefore, in the structure of low intermediate frequency receiver, how solving the mirror image interference problem becomes the subject under discussion that industrial circle and academia's emphasis are inquired into.Present stage, the most general way was in the structure of Low Medium Frequency or ultralow intermediate-frequency receiver, with radio frequency signal after antenna receives, utilize one group of frequency mixer that this radiofrequency signal is done frequency reducing, and output pair of orthogonal signal, utilize complex filter structure (ComplexFilter Architecture) to handle this quadrature signal again.The structure of this low intermediate frequency receiver can be done the suitable division of labor with simulation process and digital operation aspect.For example people such as H.Tsurumi is at IEICETransaction of Communication., Vol.E83-B, No.6, " the Broadband and flexible receiver architecture for softwaredefined radio terminal using direct conversion and low-IF principle " that delivers among the pp.1246-1253, mode (the Analog System-Selection/DigitalChannel-Selection that just shows the analog-and digital-division of labor, ASS/DCS) be the mode of the most normal employing at present, reception of various criterion system signal just and transmission are handled with simulated mode, and the channel under the particular system is chosen and then adopted digitized compute mode.
Under the structure of the Low Medium Frequency of taking the analog digital division of labor like this or ultralow intermediate-frequency receiver, important notion is exactly that whole channel is chosen and the function of image cancellation (Image Rejection) etc. is to go to finish with the structure of complex filter, that is to say, the structure that is to use complex operation about the process and the mode of operation of signal processing is in the hope of doing accurate control to the part of signal phase.The structure of the low intermediate frequency receiver 10 of common technique please see Figure 1, radio frequency signal RF is after antenna receives, making a frequency band through the filter 12 of peripheral hardware earlier selects, through low noise noise amplifier 14 (Low NoiseAmplifier, LNA) after, utilize one group of frequency mixer 16 that this radiofrequency signal RF is downconverted to characteristic frequency and exports pair of orthogonal signal I, Q, this quadrature signal I, Q has comprised an in-phase signal (In-PhaseSignal, I) and a quadrature phase signal (Quadrature-Phase Signal, Q), utilize complex filter 18 to realize this quadrature signal I afterwards, the image cancellation of Q, at last with this quadrature signal I, Q delivers to analog-digital converter 20 (Analog-to-digital Converter, ADC) in, convert the form of digital signal to, and deliver to next stage digital signal processor 22 and deal with, please note, wherein document and the patent about complex filter 18 and complex signal processing structure has many, as people such as Pietro Andreani in " the A CMOS gm-C Polyphase Filterwith High Image Band Rejection " that ESSCIRC delivered, showed in polyphase filters (PolyphaseFilter), be used for a kind of circuit synthetic method (Gm-Ccircuit synthesis method) of LC staged (LC-ladder) complex filter.Same, people such as Svante Signell also propose the notion of " Implementation of an efficient lattice Digital Ladder Filter forup/down conversion in an OFDM-WLAN system ", on the basis of the notion of polyphase filters, a kind of novel wave filter model (lattice digital ladderfilter is proposed, LDLF), finish the function of image cancellation and frequency reducing in numerically controlled mode.And people such as Chun-Chyuan Chen and Chia-Chi Huang calendar year 2001 is at IEEE J.Select.AreasCommun., Vol.19, propose among the pp.1029-1040 " On the Architecture andPerformance of A Hybrid Image Rejection Receiver ", pair of orthogonal signal after the frequency reducing delivered to respectively in two analog-digital converters be converted to digital signal, again by novel phasing mechanism, eliminate not matching that analog element was caused with digital mode, finish the function of image cancellation and frequency reducing.Be in harmonious proportion in the patent of the Low Medium Frequency of image cancellation mechanism or ultralow if architectures about digital separating, US Patent 6 as people such as Mostafa proposition, 373,422, " Method andapparatus employing decimation filter for down conversion in areceiver ", and the US Patent 6 that proposes of people such as Brown, 366,622, all describe pair of orthogonal (Quadrature) signal that to receive in " Apparatus andmethod for wireless communications " and delivered to analog-digital converter (Analog-to-digital Converter earlier, ADC) be converted to digital signal form in, finish the function of image cancellation and frequency reducing again with digital mode.
Eliminate in the common patent of mirror image mainly utilizing digital form to go to proofread and correct not matching of pair of orthogonal signal, people such as Glas are at US Patent 6,330,290, in " Digital I/Q imbalancecompensation ", proposed to utilize test signal (Test Signal) and compensation (Compensation) mechanism the phase place (Phase) and the amplitude (Amplitude) of pair of orthogonal signal to be proofreaied and correct respectively in numerically controlled mode, the mode of its correction is a preset value that the pair of orthogonal signal be multiply by a plural number respectively with the phase place of fine adjustment signal and amplitude to identical, reach the purpose of eliminating mirror image, just, under the structure of above-mentioned common technique, on the one hand, mechanism about image cancellation mostly still is based upon in the complicated analysis and algorithm, moreover, the unmatched correction of orthogonal signalling can't can be finished with the simple and easy element that combines of receiver system at an easy rate with a small amount of, and the mechanism of the complex calculation of adding for the problem of handling image cancellation and too much add ons cause as energy consumption to wait other problem on the contrary easily.
Summary of the invention
Therefore, the invention provides under a kind of complex filter structure that is used in the low intermediate frequency receiver (Low-IF Receiver), be used for eliminating the amplitude difference (Amplitude Mismatch) in the pair of orthogonal signal (Quadrature Signal) and the method for phase difference (Phase Mismatch), to address the above problem.
In the present invention, proposition comprises the low intermediate frequency receiver structure of programmable amplitude adjuster and programmable phase adjuster, and with the analysis and the penalty method of amplitude disclosed by the invention and phase place, the mirror image that amplitude difference and phase difference caused that is used for eliminating respectively this quadrature signal disturbs (ImageCross-Talk).
The purpose of this invention is to provide a kind of be used for eliminating the amplitude difference in the pair of orthogonal signal and the method for phase difference, wherein, this quadrature signal (Quadrature Signal) comprises an in-phase signal (In-Phase Signal) and a quadrature phase signal (Quadrature-Phase Signal), this method comprises: the in-phase signal of a part is compensated to quadrature phase signal, make the phase place of the quadrature phase signal after compensating spend with the phasic difference mutually 90 of in-phase signal, to eliminate the phase difference of this quadrature signal, with the amplitude of adjusting in-phase signal and quadrature phase signal identical value extremely, to eliminate the amplitude difference of this quadrature signal.
Another object of the present invention provides a kind of method that mirror image disturbs (Image Cross-Talk) that is used for eliminating in low intermediate frequency receiver, wherein, low intermediate frequency receiver comprises: frequency mixer (Mixer), be used for received RF (RF) signal, and output pair of orthogonal signal; The programmable amplitude adjuster is electrically connected with one of them output of frequency mixer, is used for eliminating the amplitude difference of this quadrature signal, and wherein, this amplitude difference is one of principal element that causes the mirror image interference; With the programmable phase adjuster, be electrically connected with frequency mixer, be used for eliminating the phase difference of this quadrature signal, wherein, phase difference is one of principal element that causes the mirror image interference.This method comprises: use frequency mixer that radiofrequency signal is done frequency reducing and exported this quadrature signal; Use the programmable phase adjuster to eliminate the phase difference of this quadrature signal, wherein, the two-end-point of programmable phase adjuster is connected to two outputs of frequency mixer; With use the programmable amplitude adjuster and eliminate the amplitude difference of this quadrature signal.
Another object of the present invention provides a kind of method that mirror image disturbs that is used for eliminating in low intermediate frequency receiver, wherein, low intermediate frequency receiver comprises: frequency mixer, be used for received RF signal, and output pair of orthogonal signal, wherein, this quadrature signal comprises an in-phase signal and a quadrature phase signal; Two programmable amplitude adjusters are electrically connected in frequency mixer respectively, are used for eliminating the amplitude difference of this quadrature signal; With at least one programmable phase adjuster, wherein, the two-end-point of programmable phase adjuster is connected to two outputs of frequency mixer, is used for eliminating the phase difference of this quadrature signal.This method comprises: use frequency mixer that radiofrequency signal is done mixing and exported this quadrature signal; Use the programmable phase adjuster that the in-phase signal of a part is compensated to quadrature phase signal, make the phase place of the quadrature phase signal after compensating spend, to eliminate the phase difference of this quadrature signal with the phasic difference mutually 90 of in-phase signal; Adjust the amplitude of this quadrature signal respectively to identical value, to eliminate the amplitude difference of this quadrature signal with two programmable amplitude adjusters of use.
Another object of the present invention provides a kind of low intermediate frequency receiver, and this low intermediate frequency receiver comprises: frequency mixer, be used for received RF signal, and output pair of orthogonal signal, wherein, this quadrature signal comprises an in-phase signal and a quadrature phase signal; At least one programmable amplitude adjuster is electrically connected in frequency mixer respectively, is used for eliminating the amplitude difference of this quadrature signal; With at least one programmable phase adjuster, wherein, the two-end-point of programmable phase adjuster is connected to two outputs of frequency mixer, is used for eliminating the phase difference of this quadrature signal.Wherein, when frequency mixer is done mixing and is exported this quadrature signal to radiofrequency signal after, use the programmable phase adjuster that the in-phase signal of a part is compensated to quadrature phase signal, make the phase place of the quadrature phase signal after compensating spend with the phasic difference mutually 90 of in-phase signal, and use the programmable amplitude adjuster to adjust the amplitude of this quadrature signal to identical value, to eliminate the amplitude difference of this quadrature signal.
From as can be seen last, in the present invention, we propose a kind of novel lens and remove to analyze the phase difference and the amplitude difference of pair of orthogonal signal as the interference analysis method, and quantize its mirror image that causes interference.Simultaneously, we more propose a kind of novel lens and remove compensation of phase difference and correction amplitude difference respectively as the interference correction method, and programmable amplitude adjuster in low intermediate frequency receiver structure of the present invention and programmable phase adjuster, under need not situation via the analysis of complexity and algorithm, with a small amount of can with the simple and easy element that combines of receiver system, reach the purpose that the mirror image that amplitude difference and phase difference caused of eliminating this quadrature signal disturbs.
Description of drawings
Fig. 1 is the schematic diagram of common low intermediate frequency receiver.
Fig. 2 is the schematic diagram according to an embodiment of low intermediate frequency receiver of the present invention.
Fig. 3 (a) and (b) are the schematic diagrames according to analysis phase difference of the present invention.
Fig. 3 (c), (d) are the schematic diagrames according to compensation correction phase difference of the present invention.
Fig. 4 (a) and (b) are the schematic diagrames according to analysis amplitude difference of the present invention.
Fig. 4 (c), (d) are the schematic diagrames according to correction amplitude difference of the present invention.
Fig. 5 is a schematic diagram of analyzing amplitude difference and phase difference simultaneously according to of the present invention.
Fig. 6 is under different phase differences and amplitude difference, the analogous diagram of mirror image annoyance level.
Fig. 7 is to use the subelement among Fig. 2 embodiment to implement the schematic diagram of correction mechanism.
Embodiment
With reference to figure 2, Fig. 2 is the schematic diagram according to an embodiment of low intermediate frequency receiver 30 of the present invention.Low intermediate frequency receiver 30 comprises: additional filter 32, low noise amplifier (Low NoiseAmplifier, LNA) 34, frequency mixer (Mixer) 36, programmable amplitude adjuster 44,46 (the first programmable amplitude adjuster 44 and the second programmable amplitude adjusters 46), programmable phase adjuster 48, complex filter 38, and analog to digital converter (Analog-to-digital Converter, ADC) 40, wherein, Fig. 2 and the Fig. 1 that describes common technique are compared afterwards as can be known, additional filter 32 among Fig. 2 embodiment, low noise amplifier 34, frequency mixer 36, complex filter 38, all similar with analog to digital converter 40 elements such as grade and basic structure to common low intermediate frequency receiver 30, wherein, low intermediate frequency receiver 30 has also comprised frequency synthesizer 50, be used to provide certain negative frequency (Negative Frequency) and give frequency mixer 36, make frequency mixer 36 and to export pair of orthogonal signal I with the radiofrequency signal RF frequency reducing that receives, Q, this quadrature signal I, Q has comprised an in-phase signal and a quadrature-phase.Then, the low intermediate frequency receiver 30 of Fig. 2 embodiment utilizes complex filter 38 structures (Complex FilterArchitecture) to handle this quadrature signal I, Q equally.As from the foregoing, the maximum differential of embodiments of the invention and common technique is in low intermediate frequency receiver 30, has used programmable amplitude adjuster 44,46 and programmable phase adjuster 48, is used for handling in-phase signal I and quadrature phase signal Q.
The roughly operational circumstances of Fig. 2 embodiment is as follows, radiofrequency signal RF is after antenna receives, making a frequency band through additional filter 32 earlier selects, after passing through low noise amplifier 34 again, utilize frequency mixer 36, can be referred to as radio-frequency (RF) mixer (RF Mixer) again, the negative frequency that provides with frequency synthesizer 50 together, RF mixes down to characteristic frequency with radiofrequency signal, and output pair of orthogonal signal I, Q, just in-phase signal I and quadrature phase signal Q, then, in-phase signal I and quadrature phase signal Q are respectively by two programmable amplitude adjusters 44,46, wherein, the first programmable amplitude adjuster 44 is corresponding to in-phase signal I, and the second programmable amplitude adjuster 46 is corresponding to quadrature phase signal Q, programmable amplitude adjuster 44,46 can be used to eliminate this quadrature signal I, the amplitude difference of Q (AmplitudeMismatch).Simultaneously, the two-end-point of programmable phase adjuster 48 is connected to two outputs of two programmable amplitude adjusters 44,46, also promptly be connected with quadrature phase signal Q, can be used to eliminate the phase difference (Phase Mismatch) of this quadrature signal I, Q with in-phase signal I.Then, handled this quadrature signal I, Q later can further carry out image cancellation and the selection of raising channel again through complex filter 38 efficient by programmable amplitude adjuster and programmable phase adjuster 48.At last, pass through again after the frequency reducing of Low Medium Frequency frequency mixer 54, this quadrature signal I, Q can reach respectively in the analog-digital converter 40 and be converted to digital signal form, being sent to next stage digital signal processor 42 deals with, in addition, the low intermediate frequency receiver 30 of Fig. 2 also comprises AFE (analog front end) controller (Analog Frontend Controller, AFE Controller) 52, it and two programmable amplitude adjusters 44,46 and programmable phase adjuster 48 be electrically connected, be used for controlling programmable amplitude adjuster 44,46 and programmable phase adjuster 48, orthogonal signalling I can be accurately eliminated in hope, the amplitude of Q and phase difference.
Note that at first the low intermediate frequency receiver 30 of this example is to be applied in GSM or the wireless lan (wlan) communication system.In addition, when reality is implemented, the programmable amplitude adjuster can be programmable gain amplifier (Programmable Gain Amplifier, PGA), and programmable phase adjuster 48 can be intersection programmable gain amplifier (Cross Programmable Gain Amplifier, XPGA), just, the number of programmable amplitude adjuster need not be as Fig. 2 embodiment, be defined as two, as long as can reach correction of orthogonal signal I, the purpose of the amplitude difference of Q, no matter be only to use a programmable amplitude adjuster to be connected to this quadrature signal I, one of them of Q, even use above three programmable amplitude adjusters, all be included in the scope of present embodiment.In like manner, the number of programmable phase adjuster 48 need not be as Fig. 2 embodiment, be defined as one, but because the cause of its function design, it must be connected to in-phase signal I and quadrature phase signal Q simultaneously, could proofread and correct this quadrature signal I, the phase difference of Q, at last, the relative position of programmable amplitude adjuster and programmable phase adjuster 48 and on-fixed, that is to say, this quadrature signal I, Q can handle through programmable phase adjuster 48 through the programmable amplitude adjuster earlier shown in Fig. 2 embodiment again, perhaps handles through programmable phase adjuster 48 earlier again and handles through the programmable amplitude adjuster.In fact, can find that in ensuing analysis disclosed in this invention the mirror image that phase difference caused disturbs more serious than amplitude difference.
As from the foregoing, the topmost technical characterictic of the embodiment of the invention is, has used programmable amplitude adjuster and programmable phase adjuster to handle in-phase signal I and quadrature phase signal Q, to eliminate amplitude and the phase difference of this quadrature signal I, Q.Therefore, after roughly understanding the spendable Filter Structures of the present invention, in order to understand technical characterictic of the present invention in further detail is amplitude and phase difference how to resolve and eliminate this quadrature signal I, Q, just must describe a kind of novel lens picture proposed by the invention in detail disturbs (Image Cross-Talk) analytical method and novel lens as the interference correction method, and, come intactly to disclose technical characterictic of the present invention with the design of the hardware configuration of programmable amplitude adjuster of the present invention and programmable phase adjuster.
See also Fig. 3 (a) and Fig. 3 (b), Fig. 3 (a) and Fig. 3 (b) adopt novel lens proposed by the invention phase difference schematic diagram as interference analysis method gained.Novel lens proposed by the invention as the interference analysis method in, ideal situation is that in-phase signal I and quadrature phase signal Q should lay respectively on lineups and the quadrature phase axle, both amplitudes are identical, and the phase difference of two signals is 90 degree, thus, in-phase signal I is positioned at the forward component of lineups and the forward component that quadrature phase signal Q is positioned at the quadrature phase axle, and its both synthetic quantity can be positioned on the axle of positive frequency (Positive Frequency) fully.In-phase signal I is positioned at the negative sense component of lineups and the negative sense component that quadrature phase signal Q is positioned at the quadrature phase axle, and both synthetic quantities also can be positioned on the axle of positive frequency fully.And in-phase signal I is positioned at the synthetic quantity of the forward component and the negative sense component that quadrature phase signal Q is positioned at the quadrature phase axle of lineups, or in-phase signal I is positioned at the negative sense component of lineups and the synthetic quantity that quadrature phase signal Q is positioned at the forward component of quadrature phase axle, all can be positioned at fully on the axle of negative (Negative Frequency) frequently.Therefore, in the ideal case, when the phasic difference mutually 90 of in-phase signal I and quadrature phase signal Q is spent, frequently positive and negative composition frequently can not interfere with each other, because 38 of complex filters among Fig. 2 can allow the composition of positive frequency pass through, the negative composition frequently of filtering does not have the generation that mirror image disturbs fully, if but in-phase signal I and the phasic difference mutually of quadrature phase signal Q are not 90 when spending, and represent that then two signals have so-called phase difference (Phase Mismatch).Hypothesis in-phase signal I is positioned on the lineups among Fig. 3 (a), but quadrature phase signal Q is not positioned on the quadrature phase axle, under the situation of the forward of consideration quadrature phase axle, quadrature phase signal Q is inclined in second quadrant with quadrature phase axle difference angle Δ ψ, in-phase signal I is not 90 degree with the phasic difference mutually of quadrature phase signal Q, phase difference has appearred, by Fig. 3 (a) as can be known, thus, the synthetic quantity of two signals just can not be positioned on the axle of positive frequency fully, a spot of component can projection disturb (Crosstalk) to go up (as shown in the figure to negative axle frequently, the value of supposing in-phase signal I and quadrature phase signal Q is 1, it is ((1-sin Δ ψ-cos Δ ψ)/√ 2) that projection interferes with the negative amount of axle frequently, but because the negative composition frequently of complex filter 38 meeting filterings is lower to the influence of final signal quality as the situation of Fig. 3 (a).Ask for an interview Fig. 3 (b) simultaneously, same hypothesis in-phase signal I is positioned on the lineups, quadrature phase signal Q is not positioned on the quadrature phase axle, but under the situation of the negative sense of consideration quadrature phase axle, quadrature phase signal Q is inclined in the four-quadrant with quadrature phase axle difference angle Δ ψ, thus, the synthetic quantity of two signals just can not be positioned on the negative axle frequently fully, a spot of component can projection disturb (Crosstalk) to go up (as shown in the figure to the axle of positive frequency, the value of supposing script in-phase signal I and quadrature phase signal Q is 1, the amount that projection interferes with positive frequency axle is ((1+sin Δ ψ-cos Δ ψ)/√ 2), but because the complex filter 38 of Fig. 2 can only filtering be born composition frequently, in the situation as Fig. 3 (b), the component that these projections interfere with positive frequency axle can aggravate the influence of final signal quality, and the component that these projections interfere with positive frequency axle is and angle delta ψ positive correlation, the phase difference of in-phase signal I and quadrature phase signal Q is big more, just angle delta ψ is bigger, and the situation that mirror image disturbs will be serious more.
For proofreading and correct as the in-phase signal I of Fig. 3 (b) demonstration and the phase difference of quadrature phase signal Q, novel lens proposed by the invention is to utilize the in-phase signal I of a part to compensate to quadrature phase signal Q as the interference correction method, and the phase place of the quadrature phase signal Q after the feasible compensation and the phase place of in-phase signal I are at a distance of 90 degree.Later with reference to the programmable phase adjuster 48 among figure 2 embodiment, this programmable phase adjuster 48 (when reality is implemented, can be the intersection programmable gain amplifier) is exactly to be used for finishing the operation that the in-phase signal I of a part is compensated to quadrature phase signal Q.With reference to figure 3 (c) and Fig. 3 (d), Fig. 3 (c) and Fig. 3 (d) are novel lens proposed by the invention schematic diagrames as the interference correction method.Fig. 3 (c) continues to adopt the situation of Fig. 3 (a) and Fig. 3 (b), be the phase place that makes quadrature phase signal Q 90 degree of phasic difference mutually with in-phase signal I, the in-phase signal I of a part is compensated to quadrature phase signal Q (in Fig. 3 (c), under quadrature phase signal Q deflects into situation with quadrature phase axle difference angle Δ ψ, size is compensated to quadrature phase signal Q for the in-phase signal I of the part of (sin Δ ψ)), make the quadrature phase signal Q after the compensation can be positioned on the quadrature phase axle, thus, in-phase signal I is positioned at the synthetic quantity of the forward component and the negative sense component that quadrature phase signal Q is positioned at the quadrature phase axle of lineups, the capital is positioned on the negative axle frequently fully, and do not have on the axle that the negative frequency component projection interferes with positive frequency the situation that causes mirror image to disturb.But when eliminating the mirror image interference, some positive semaphores of composition have frequently also been sacrificed, shown in Fig. 3 (d), under quadrature phase signal Q is inclined to situation with quadrature phase axle difference angle ψ, and at in-phase signal I the composition of size for the part of (sin Δ ψ) compensated to quadrature phase signal Q, make the positive semaphore of composition frequently be reduced to (√ 2 (1-tan Δ ψ)) by 2 of ideal value.This shows, novel lens proposed by the invention as the interference correction method under, when proofreading and correct the phase difference of in-phase signal I and quadrature phase signal Q, what all can sacrifice gains (Gain) of some positive frequency compositions.Yet, under the little situation of angle delta ψ, the value of tan Δ ψ is still very small, the reduction that aligns the gain of composition frequently is very limited, moreover, and these reductions that align the gain of composition frequently are and angle delta ψ positive correlation, unless the phase difference of in-phase signal I and quadrature phase signal Q is very serious, just angle delta ψ is very big, otherwise the amplitude that the semaphore of positive composition frequently reduces still can maintain very little scope.
With reference to figure 4 (a) and Fig. 4 (b), Fig. 4 (a) and Fig. 4 (b) are the amplitude difference schematic diagrames that adopts novel lens proposed by the invention to obtain as the interference analysis method about the analytical method of the amplitude difference of positive in-phase signal I and quadrature phase signal Q.Novel lens proposed by the invention as the interference analysis method in, ideal situation is to lay respectively at in-phase signal I on lineups and the quadrature phase axle and phase difference 90 degree of quadrature phase signal Q, and the value of both amplitudes is identical.Thus, in-phase signal I is positioned at the forward component of lineups and the forward component that quadrature phase signal Q is positioned at the quadrature phase axle, and both synthetic quantities can be positioned on the axle of positive frequency fully.In-phase signal I is positioned at the negative sense component of lineups and the negative sense component that quadrature phase signal Q is positioned at the quadrature phase axle, and its both synthetic quantity also can be positioned on the positive frequency axle fully.And in-phase signal I is positioned at the synthetic quantity of the forward component and the negative sense component that quadrature phase signal Q is positioned at the quadrature phase axle of lineups, or in-phase signal I is positioned at the negative sense component of lineups and the synthetic quantity that quadrature phase signal Q is positioned at the forward component of quadrature phase axle, all can be positioned at fully on the negative axle frequently.Therefore, in the ideal case, when the amplitude of in-phase signal I and quadrature phase signal Q is identical, frequently positive and negative composition frequently can not interfere with each other, if with reference to Fig. 2, because 38 of complex filters among Fig. 2 can allow the composition of positive frequency pass through, composition is frequently born in filtering fully, therefore do not have the generation that mirror image disturbs, if but the amplitude of in-phase signal I and quadrature phase signal Q not simultaneously, show that then two signals have so-called amplitude difference (Amplitude Mismatch).In Fig. 4 (a), suppose that in-phase signal I and quadrature phase signal Q lay respectively on lineups and the quadrature phase axle, the value of in-phase signal I is 1, but the value of quadrature phase signal Q is not 1, under the situation of the forward of consideration quadrature phase axle, quadrature phase signal Q and in-phase signal I amplitude differ and are Δ A, shown in figure, the amplitude of quadrature phase signal Q is (1+ Δ A), amplitude difference has appearred in two signals, by Fig. 4 (a) as can be known, and thus, the synthetic quantity of two signals just can not be positioned on the positive frequency axle fully, a spot of component meeting projection interference (Crosstalk) upward (as shown in the figure, supposes originally that it is (Δ A/ √ 2) that projection interferes with the negative amount of axle frequently to negative axle frequently, but because complex filter 38 can filtering be born composition frequently, the situation in Fig. 4 (a) is lower to the influence of last signal quality.Ask for an interview Fig. 4 (b), consider the situation of the negative sense of quadrature phase axle, the amplitude of quadrature phase signal Q still is (1+ Δ A), the synthetic quantity of two signals not exclusively is positioned on the negative axle frequently, shown in Fig. 4 (b), there is a spot of component can projection to interfere with that (projection interferes with the amount of positive frequency axle and disturbs (Crosstalk) identical to the amount of negative axle frequently with projection on the positive frequency axle, all be (Δ A/ √ 2), but because complex filter 38 can only filtering be born composition frequently, the component that interferes with positive frequency axle as these projections in the situation of Fig. 4 (b) is then very big to the influence of last signal quality, and the component that these projections interfere with positive frequency axle is and amplitude difference Δ A positive correlation, if the amplitude difference of in-phase signal I and quadrature phase signal Q is big more, just Δ A is bigger, and then the situation of mirror image interference is just serious more.
With reference to figure 4 (c) and Fig. 3 (d), Fig. 4 (c) and Fig. 4 (d) are novel lens proposed by the invention schematic diagrames as the interference correction method.To will be proofreaied and correct as the in-phase signal I of Fig. 4 (b) demonstration and the amplitude difference of quadrature phase signal Q, realization on hardware device, later with reference to the programmable amplitude adjuster 44 or 46 among figure 2 embodiment, this programmable amplitude adjuster 44 or 46 (when reality is implemented, can be programmable gain amplifier) is exactly to be used for in-phase signal I is adjusted to identical value with the amplitude of quadrature phase signal Q.As described above, programmable amplitude adjuster 44 or 46 number need not be as Fig. 2 embodiment, be defined as two, if with in Fig. 4 (c), use amplitude to be adjusted into the method identical with the amplitude of in-phase signal I with quadrature phase signal Q, then can use a programmable amplitude adjuster 46 to be connected to circuit, only with the operation elimination amplitude difference that amplifies or dwindle quadrature phase signal Q corresponding to quadrature phase signal Q.Certainly, also can only use a programmable amplitude adjuster 44 to be connected to circuit corresponding to in-phase signal I, the amplitude of in-phase signal I is adjusted into the identical value of amplitude with quadrature phase signal Q, even use two programmable amplitude adjusters 44,46 to connect this quadrature signal I, Q respectively, perhaps more programmable amplitude adjuster is as long as it is just passable to identical value accurately to adjust the amplitude of this quadrature signal I, Q.Thus, in-phase signal I is positioned at the synthetic quantity of the forward component and the negative sense component that quadrature phase signal Q is positioned at the quadrature phase axle of lineups, will be positioned at fully on the negative axle frequently, can projection not interfere with on the positive frequency axle, cause mirror image to disturb and do not have negative frequency component.And when eliminating the mirror image interference, also adjust projection and interfered with the component of bearing on the frequency axle, shown in Fig. 4 (d), in Fig. 4 (c), consider under the situation of negative sense of quadrature phase axle, the amplitude of quadrature phase signal Q is reduced to amplitude with in-phase signal I identical the time, when later considering the situation of forward of quadrature phase axle, it is identical with the amplitude of in-phase signal I that the amplitude of quadrature phase signal also is reduced to, this expression, novel lens proposed by the invention can be eliminated the component on axle that interferes with negative frequency and the axle that interferes with positive frequency simultaneously as the interference correction method.
After having analyzed phase difference and amplitude difference respectively, when reality is implemented, it is that the different and amplitude difference of potential difference occurs simultaneously that the most normal appearance also needs most what overcome, therefore, we are discussed the situation that the projection simultaneously of phase difference and amplitude difference interferes with on the positive frequency axle, with reference to figure 5, Fig. 5 adopts the amplitude that novel lens proposed by the invention obtains as the interference analysis method and the schematic diagram of phase difference.In-phase signal I is positioned on the lineups, and quadrature phase signal Q is not positioned on the quadrature phase axle, under the situation of the negative sense of consideration quadrature phase axle, quadrature phase signal Q is inclined in the four-quadrant with quadrature phase axle difference angle Δ ψ, in addition, the value of in-phase signal I is 1, quadrature phase signal Q and in-phase signal I amplitude differ and are Δ A, by shown in Figure 5, the amplitude of quadrature phase signal Q is made as (1-Δ A), two signals have phase difference and amplitude difference, under these circumstances, the synthetic quantity of two signals not exclusively is positioned on the negative axle frequently, the composition that projection interferes with on the positive frequency axle is (√ 2+ (1-Δ A) (sin (Δ ψ-π/4))), as described above, because 38 of complex filters can filtering be born composition frequently, the component that these projections interfere with positive frequency axle is then very big to the influence of last signal quality, and the component that these projections interfere with positive frequency axle is simultaneously relevant with amplitude difference Δ A with angle delta ψ, if can't eliminate phase place and the amplitude difference of in-phase signal I and quadrature phase signal Q, mirror image disturbs signal quality and systematic function had and seriously influences, and the application novel lens that the invention described above proposed eliminates phase place as the interference correction method and amplitude difference is still best solution, with reference to figure 6, Fig. 6 is presented under the different phase difference and amplitude difference, the analogous diagram of the order of severity that mirror image disturbs, phase difference is to serve as to analyze benchmark with angle delta ψ, and the ratio value of amplitude difference Δ A for comparing with ideal value, the degree that mirror image disturbs also is the percent value of comparing with ideal value, it is 0 that the mirror image of ideal situation disturbs, can find out that in the analysis that Fig. 6 shows the mirror image that phase difference caused disturbs serious than amplitude difference.Therefore, with novel lens proposed by the invention as the interference correction method, with programmable phase adjuster 48 and the programmable amplitude adjuster 44 among Fig. 2 embodiment, 46 together, can use programmable phase adjuster 48 to adjust angle delta ψ earlier, obtain the minimum value that mirror image disturbs under this situation, re-use programmable amplitude adjuster 44,46 adjust amplitude difference Δ A obtains the minimum value that mirror image disturbs under this situation, such correction mechanism can be before actual signal enters, utilize default signal simulation truth earlier, and utilize circulation (Loop) operation to carry out repeatedly, constantly adjust amplitude difference and phase difference respectively, till obtaining minimum mirror image interference.With reference to figure 7, Fig. 7 is the schematic diagram that shows above-mentioned correction mechanism.Fig. 7 has also shown the element of part among Fig. 2 embodiment, comprise frequency mixer 36, be connected to the second programmable amplitude adjuster 46 of the quadrature phase signal Q of practical operation situation, programmable phase adjuster 48, with complex filter 38, in addition in order to carry out above-mentioned correction mechanism, allow novel lens proposed by the invention improve the situation that mirror image disturbs as interference analysis and correction method, but the embodiment additive correction detector 56 of Fig. 7, be used for transmitting negative correction signal frequently to frequency mixer 36, the situation of in-phase signal I and quadrature phase signal Q is truly exported in emulation, then use the programmable phase adjuster 48 and the second programmable amplitude adjuster 46 to adjust angle delta ψ and adjustment amplitude difference Δ A respectively, calibration detector 56 is in parallel with two outputs of complex filter 38, be used for detecting corrected signal after programmable phase adjuster 48 and the second programmable amplitude adjuster, 46 repeatable operation, just stop whole trimming process up to reaching minimum mirror image interference.In addition, the function of this calibration detector 56 also can be arranged in the AFE (analog front end) controller 52 among Fig. 2 and finish.
In the present invention, we propose a kind of novel lens and remove to analyze the phase difference and the amplitude difference of pair of orthogonal signal as the interference analysis method, and quantize its mirror image that causes interference.Simultaneously, we more propose a kind of novel lens and remove compensation of phase difference and correction amplitude difference respectively as the interference correction method, and programmable amplitude adjuster in low intermediate frequency receiver structure of the present invention and programmable phase adjuster, under need not situation via the analysis of complexity and algorithm, with a small amount of can with the simple and easy element that combines of receiver system, reach the purpose that the mirror image that amplitude difference and phase difference caused of eliminating this quadrature signal disturbs.
The above only is the preferred embodiments of the present invention, and every claim is made according to the present invention equal variation and modification all should belong to the scope of patent of the present invention.
Claims (24)
1. one kind is used at low intermediate frequency receiver, the amplitude difference in the elimination pair of orthogonal signal and the method for phase difference, this quadrature signal comprises an in-phase signal and a quadrature phase signal, wherein, low intermediate frequency receiver comprises at least one programmable phase adjuster, at least one programmable amplitude adjuster, with an AFE (analog front end) controller, be electrically connected with programmable amplitude adjuster and programmable phase adjuster, and be used for controlling programmable amplitude adjuster and programmable phase adjuster, to eliminate the amplitude and the phase difference of orthogonal signalling
This method comprises:
The in-phase signal of a part is compensated to quadrature phase signal, make the phase place of the quadrature phase signal after compensating spend, eliminate the phase difference of this quadrature signal with the phasic difference mutually 90 of in-phase signal; With
The amplitude of adjusting in-phase signal and quadrature phase signal is identical value extremely, eliminates the amplitude difference of this quadrature signal.
2. the method for claim 1, wherein also comprise and use the programmable phase adjuster that a part of in-phase signal is compensated to quadrature phase signal, to eliminate the phase difference of this quadrature signal.
3. the method for claim 1, wherein also comprise and use the programmable amplitude adjuster that in-phase signal is adjusted to identical value with the amplitude of quadrature phase signal, to eliminate the amplitude difference of this quadrature signal.
4. the method for claim 1, wherein the programmable amplitude adjuster is a programmable gain amplifier.
5. the method for claim 1, wherein the programmable phase adjuster is the intersection programmable gain amplifier.
6. the method for claim 1, wherein low intermediate frequency receiver is applied in GSM or the wireless lan communication system.
One kind in low intermediate frequency receiver, be used for eliminating the method that mirror image disturbs, wherein, low intermediate frequency receiver comprises:
Frequency mixer is used for received RF signal, and output pair of orthogonal signal;
The programmable amplitude adjuster is electrically connected with one of them output of frequency mixer, is used for eliminating the amplitude difference of this quadrature signal, and wherein, amplitude difference is one of principal element that causes the mirror image interference; With
The programmable phase adjuster is electrically connected with frequency mixer, is used for eliminating the phase difference of this quadrature signal, and wherein, phase difference is the one of the main reasons that causes mirror image to disturb; With
The AFE (analog front end) controller is electrically connected and is used for controlling programmable amplitude adjuster and programmable phase adjuster with programmable amplitude adjuster and programmable phase adjuster, to eliminate the amplitude and the phase difference of orthogonal signalling;
This method comprises:
Use frequency mixer that radiofrequency signal is done frequency reducing and exported this quadrature signal;
Use the programmable phase adjuster, eliminate the phase difference of this quadrature signal, wherein, the two-end-point of programmable phase adjuster is connected to two outputs of frequency mixer; With
Use the programmable amplitude adjuster to eliminate the amplitude difference of this quadrature signal.
8. method as claimed in claim 7, wherein, this quadrature signal comprises an in-phase signal and a quadrature phase signal.
9. method as claimed in claim 8, also comprise and use the programmable phase adjuster that the in-phase signal of a part is compensated to quadrature phase signal, make the phase place of the quadrature phase signal after compensating spend, to eliminate the phase difference of this quadrature signal with the phasic difference mutually 90 of in-phase signal.
10. method as claimed in claim 8 also comprises the amplitude identical size extremely of using the programmable amplitude adjuster to adjust in-phase signal and quadrature phase signal, to eliminate the amplitude difference of this quadrature signal.
11. method as claimed in claim 7, wherein, the programmable amplitude adjuster is a programmable gain amplifier.
12. method as claimed in claim 7, wherein, the programmable phase adjuster is the intersection programmable gain amplifier.
13. method as claimed in claim 7, wherein, low intermediate frequency receiver is to utilize the complex filter structure to handle this quadrature signal.
14. method as claimed in claim 7, wherein, low intermediate frequency receiver is applied in GSM or the wireless lan communication system.
15. one kind in low intermediate frequency receiver, be used for eliminating the method that mirror image disturbs, wherein, low intermediate frequency receiver comprises:
Frequency mixer is used for received RF signal, and output pair of orthogonal signal, and wherein, this quadrature signal comprises an in-phase signal and a quadrature phase signal;
The programmable amplitude adjuster is electrically connected in frequency mixer respectively, is used for eliminating the amplitude difference of this quadrature signal; With
At least one programmable phase adjuster, wherein, the two-end-point of programmable phase adjuster is connected to two outputs of frequency mixer, is used for eliminating the phase difference of this quadrature signal; With
The AFE (analog front end) controller is electrically connected and is used for controlling programmable amplitude adjuster and programmable phase adjuster with programmable amplitude adjuster and programmable phase adjuster, to eliminate the amplitude and the phase difference of orthogonal signalling;
This method comprises:
Use frequency mixer that radiofrequency signal is done mixing and exported this quadrature signal;
Use the programmable phase adjuster that the in-phase signal of a part is compensated to quadrature phase signal, make the phase place of the quadrature phase signal after compensating spend, to eliminate the phase difference of this quadrature signal with the phasic difference mutually 90 of in-phase signal; With
Use the programmable amplitude adjuster to adjust the amplitude of this quadrature signal respectively to identical value, to eliminate the amplitude difference of this quadrature signal.
16. method as claimed in claim 15, wherein, the programmable amplitude adjuster is a programmable gain amplifier.
17. method as claimed in claim 15, wherein, the programmable phase adjuster is the intersection programmable gain amplifier.
18. method as claimed in claim 15, wherein, low intermediate frequency receiver is to utilize the complex filter structure to handle this quadrature signal.
19. method as claimed in claim 15, wherein, low intermediate frequency receiver is applied in GSM or the wireless lan communication system.
20. a low intermediate frequency receiver, this low intermediate frequency receiver comprises:
Frequency mixer is used for received RF signal, and output pair of orthogonal signal, and wherein, this quadrature signal comprises in-phase signal and quadrature phase signal;
At least one programmable amplitude adjuster is electrically connected with frequency mixer respectively, is used for eliminating the amplitude difference of this quadrature signal; With
At least one programmable phase adjuster, wherein, the two-end-point of programmable phase adjuster is connected to two outputs of frequency mixer, is used for eliminating the phase difference of this quadrature signal; With
The AFE (analog front end) controller is electrically connected with programmable amplitude adjuster and programmable phase adjuster, and is used for controlling programmable amplitude adjuster and programmable phase adjuster, to eliminate the amplitude and the phase difference of orthogonal signalling;
Wherein, when frequency mixer is done mixing and is exported this quadrature signal to radiofrequency signal after, use the programmable phase adjuster that the in-phase signal of a part is compensated to quadrature phase signal, make the phase place of the quadrature phase signal after compensating spend with the phasic difference mutually 90 of in-phase signal, and use the programmable amplitude adjuster to adjust the amplitude of this quadrature signal to identical value, to eliminate the amplitude difference of this quadrature signal.
21. low intermediate frequency receiver as claimed in claim 20, wherein, the programmable amplitude adjuster is a programmable gain amplifier.
22. low intermediate frequency receiver as claimed in claim 20, wherein, the programmable phase adjuster is the intersection programmable gain amplifier.
23. low intermediate frequency receiver as claimed in claim 20, it utilizes the complex filter structure to handle this quadrature signal.
24. low intermediate frequency receiver as claimed in claim 20, it is applied in GSM or the wireless lan communication system.
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| US7590190B2 (en) * | 2004-11-10 | 2009-09-15 | Powerwave Technologies, Inc. | System and method for forward path gain control in a digital predistortion linearized transmitter |
| TWI398166B (en) * | 2009-04-07 | 2013-06-01 | Himax Media Solutions Inc | Digital receiver and related method thereof |
| CN101873446B (en) * | 2009-04-22 | 2012-05-16 | 承景科技股份有限公司 | Digital receiver and related method thereof |
| CN101547014B (en) * | 2009-04-24 | 2013-04-24 | 锐迪科科技有限公司 | Digital low intermediate frequency AM signal receiver and signal receiving method |
| CN102104369B (en) * | 2009-12-17 | 2013-11-27 | 雷凌科技股份有限公司 | Complex filter and correction method |
| CN101958861B (en) * | 2010-09-21 | 2013-08-07 | 何伟 | Virtual image inhibiting method and circuit |
| CN102694560B (en) * | 2011-03-25 | 2014-06-11 | 鼎桥通信技术有限公司 | Mirror image elimination method |
| US8831549B2 (en) * | 2012-09-18 | 2014-09-09 | Mediatek Inc. | Receiver circuit and associated method |
| CN109995387B (en) * | 2019-03-01 | 2021-03-30 | 电子科技大学 | Method for inhibiting image interference of broadband receiver |
| CN114944845B (en) * | 2022-06-16 | 2023-03-10 | 北京大有半导体有限责任公司 | Image interference suppression method and device, electronic equipment and low/zero intermediate frequency receiver |
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| CN1244315A (en) * | 1997-09-25 | 2000-02-09 | 皇家菲利浦电子有限公司 | Improvements in or relating to phase receivers |
| CN1348654A (en) * | 1999-01-19 | 2002-05-08 | 交互数字技术公司 | Correction of amplitude and phase imbalance in PSK receivers |
| WO2002041595A2 (en) * | 2000-11-06 | 2002-05-23 | Qualcomm Incorporated | Method and apparatus for adjusting the phase of a received signal |
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| CN1244315A (en) * | 1997-09-25 | 2000-02-09 | 皇家菲利浦电子有限公司 | Improvements in or relating to phase receivers |
| CN1348654A (en) * | 1999-01-19 | 2002-05-08 | 交互数字技术公司 | Correction of amplitude and phase imbalance in PSK receivers |
| WO2002041595A2 (en) * | 2000-11-06 | 2002-05-23 | Qualcomm Incorporated | Method and apparatus for adjusting the phase of a received signal |
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