CN100369383C - DC maladjustment eliminating method and device in wireless receiving system - Google Patents
DC maladjustment eliminating method and device in wireless receiving system Download PDFInfo
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- CN100369383C CN100369383C CNB2004101012642A CN200410101264A CN100369383C CN 100369383 C CN100369383 C CN 100369383C CN B2004101012642 A CNB2004101012642 A CN B2004101012642A CN 200410101264 A CN200410101264 A CN 200410101264A CN 100369383 C CN100369383 C CN 100369383C
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- maladjustment
- corner frequency
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Abstract
The present invention relates to a DC maladjustment eliminating method and a device thereof in a wireless receiving system. The present invention uses the technique of AC coupling to eliminate DC maladjustment, and has the kernel that a high-pass filter with many corner frequencies is adopted for eliminating DC maladjustment. More specifically, the corner frequency of the high-pass filter is switched according to proper time points from high to low orderly so as to rapidly eliminate the DC component in signals. Thus, the present invention can shorten the consumption time of eliminating DC maladjustment, and avoid the problem that the time of eliminating DC maladjustment is long in the prior art; thereby, the requirement of the relevant standard of a high performance communication system is satisfied commendably.
Description
Technical field
The present invention relates to wireless communication technology field, relate in particular to removing method, the Apparatus and system of DC maladjustment in a kind of wireless receiving system.
Background technology
Along with the fast development of integrated circuit processing technique, give the wireless transceiver system height the integrated possibility that provides.And the transceiver (perhaps being called the zero intermediate frequency transceiver) of direct transformational structure has become the main flow and the inevitable choice of present transceiver system integrated circuit (IC) design.But the topmost problem that runs in the design of zero intermediate frequency transceiver is exactly the problem of DC maladjustment.
Described DC maladjustment is meant and is subjected to The noise, self-mixing phenomenon or owing to not matching of receiver itself introduced DC component, the introducing of DC component will make the signal that receives with expect between the signal that receives bigger error is arranged, thereby have influence on the performance of whole wireless receiving system.
Need to adopt corresponding method that the DC component in the received signal is eliminated for this reason, promptly eliminate DC maladjustment, to guarantee the reliability of received signal.
At present, the method for eliminating DC maladjustment mainly contains three kinds of AC coupled, digital calibration and feedback calibration.Wherein, digital calibrating method needs more high performance analog circuit to cooperate and complicated digital signal processing algorithm, therefore realize comparatively difficulty, and cost is higher.And existing AC coupled and feedback calibration method be not in order to influence the frequency spectrum of signal as far as possible, so adopted lower corner frequency that the frequency signal that receives is carried out Filtering Processing; Owing to adopted lower corner frequency to make signal response time longer, can't satisfy the requirement of some high performance communication system standards, and then influence the performance of communication system.
Summary of the invention
In view of above-mentioned existing in prior technology problem, the purpose of this invention is to provide removing method, the Apparatus and system of DC maladjustment in a kind of wireless receiving system, to guarantee to eliminate fast the DC component in the received signal, improve the communication performance of communication system.
The objective of the invention is to be achieved through the following technical solutions:
The removing method of DC maladjustment in a kind of wireless receiving system comprises:
A, the signal that will need to eliminate DC maladjustment are introduced high pass filter;
B, set up some switching time of one group of corner frequency correspondence;
C, when meeting described switching time during point value, the corner frequency of described high pass filter is switched to the corresponding corner frequency value of described some switching time;
D, described high pass filter utilize described corner frequency that described signal is carried out Filtering Processing.
Described step D comprises: described high pass filter utilizes one group of frequency that has nothing in common with each other from high to low as corner frequency successively, and described signal is carried out Filtering Processing.
Described corner frequency comprises: the corner frequency value more than two or two.
The embodiment of the invention also provides the cancellation element of DC maladjustment in a kind of wireless receiving system, comprising:
High pass filter: its input is introduced pending signal, and utilizes the corner frequency adjusting module to determine that current corner frequency carries out DC maladjustment to described signal and eliminates and handle, and is output as the signal of eliminating after the DC maladjustment;
Corner frequency adjusting module: be used for the relation corresponding with described corner frequency, the corner frequency of described high pass filter switched to the corner frequency of described switching time of some correspondence according to switching time point.
Described corner frequency adjusting module can be the corresponding digital control processing circuit.
The embodiment of the invention also provides a kind of DC maladjustment of the cancellation element based on DC maladjustment in the wireless receiving system to eliminate system, comprising:
One group of DC maladjustment cancellation element, each DC maladjustment cancellation element that comprises is respectively arranged with some switching time of each corner frequency correspondence, each DC maladjustment cancellation element is connected in the output of receiving system module, and the output of described DC maladjustment cancellation element links to each other with next stage receiving system module;
Described receiving system module is the system module that contains the DC component that remains to be eliminated in the output signal.
Each DC maladjustment cancellation element that described one group of DC maladjustment cancellation element comprises is respectively arranged with the corner frequency value that one group of corresponding size has nothing in common with each other.
As seen from the above technical solution provided by the invention, the present invention at first carries out Filtering Processing with higher corner frequency to the frequency signal that receives owing to having adopted, and then with medium corner frequency and the lower corner frequency of setting signal is carried out Filtering Processing successively, thereby make that eliminating the time that DC maladjustment consumed shortens greatly, effectively avoided eliminating long problem of DC maladjustment time in the prior art, satisfied the requirement of high performance communication system respective standard well.
Description of drawings
Fig. 1 is the flow chart of method of the present invention;
Fig. 2 is the schematic diagram of high pass filter;
The apparatus structure schematic diagram of the elimination DC maladjustment when Fig. 3 is the multimode cascade;
Fig. 4 eliminates the effect schematic diagram of DC maladjustment for adopting prior art and the present invention.
Embodiment
Use the AC coupled technology to eliminate DC maladjustment among the present invention.In fact AC coupled is exactly high-pass filtering.In order to shorten the response time, core of the present invention is that the elimination of adopting the high pass filter with a plurality of corner frequencies to carry out DC maladjustment is handled.Be specially size, to realize eliminating fast DC maladjustment by the corner frequency that switches high pass filter in turn.
The specific implementation of method of the present invention specifically comprises as shown in Figure 1:
Step 11: be provided with frequency signal is carried out the corner frequency that several sizes of the high pass filter that DC maladjustment eliminate to handle have nothing in common with each other, the occurrence of described corner frequency need be determined according to the frequecy characteristic of frequency signal;
For example, the corner frequency that can be set to described high pass filter is followed successively by ω 1, ω 2, ω 3 from big to small;
Step 12: needs are carried out DC maladjustment eliminate the signal introducing high pass filter of handling, so that the processing of adopting the mode of AC coupled to remove DC component;
Step 13: high pass filter adopts the highest corner frequency of determining in the step 11 that the pending signal of introducing is carried out Filtering Processing;
Above example at first adopts ω 1 as the corner frequency of high pass filter the signal of introducing to be carried out Filtering Processing in this step, to remove the DC component in the signal fast;
Adopt higher corner frequency in the short period of time the DC component in the signal to be got rid of;
If but adopt higher corner frequency to carry out Filtering Processing always, then can be bigger to the power loss of useful signal, for this reason, go back execution in step 14 among the present invention;
Step 14: high pass filter adopts lower turning filtering that described pending signal is carried out Filtering Processing successively, and is minimum until the loss of useful signal is reduced to, and also the DC component in the described signal removed simultaneously;
Be specially the corner frequency value of switching high pass filter from high to low successively and being adopted, and described signal carried out Filtering Processing based on the corner frequency value after switching;
Still above example then adopts ω 2, ω 3 as the corner frequency of high pass filter the signal of introducing to be carried out Filtering Processing in this step successively.
The present invention passes through the corner frequency of descending switching high pass filter successively, make and to utilize the elimination that big corner frequency can very fast realization DC maladjustment, simultaneously, in follow-up process, also need to adopt successively less corner frequency to carry out Filtering Processing to reduce influence to the useful signal frequency spectrum.
To describe device of the present invention in conjunction with the accompanying drawings more below.
Understand for device of the present invention being had clearly, at first the basic realization principle to device of the present invention describes:
As shown in Figure 2, the high pass filter that simple resistance, electric capacity RC form be input as Eu (t), be output as Vout;
If the initial voltage value on the capacitor C is v0, wherein Eu (t) satisfies following expression:
Eu(t)＝0； t＜0；
Eu(t)＝E； t≥0；
Can get,
Wherein, E is a DC offset voltage, is time dependent amount in concrete the application, but for bag in the communication system sent the time that is continued, this value was bordering on constant; The magnitude of voltage at capacitor C two ends when v0 switches for the high pass filter corner frequency;
As shown in Figure 2, the switching from high to low of a plurality of corner frequencies can make in a short period of time that the value of v0 is increasing, thus the DC component E in the erasure signal.
It is as follows to utilize described Fig. 2 to carry out the detailed process of the DC component in the erasure signal:
With three time period qualitative analyses, three time points are respectively t3＞t2＞t1; As shown in Figure 2, be located at t1 constantly, the voltage v0 (t) on the electric capacity equals 0, and the bandwidth of high pass filter switches to maximum (promptly adopting maximum corner frequency value), and then in the moment of t1～t2, the voltage v0 on the electric capacity will charge with fast speeds; At t2 constantly, the voltage v0 on the electric capacity reaches v0 (t2), and greater than v0 (t1), at this moment, bandwidth with high pass filter switches to medium value (promptly adopting medium sized corner frequency value) again, and in the moment of t2～t3, the voltage v0 on the electric capacity will charge with the medium speed; The rest may be inferred, and the voltage v0 on electric capacity reaches E, also promptly eliminated DC maladjustment.
Another problem, if directly switch to little corner frequency from high corner frequency, purely from DC maladjustment elimination aspect, be fine, but, in order to improve data rate, usually in the DC maladjustment elimination time, also to be AGC (automatic gain control) and adjust, simultaneously because high corner frequency just causes decay to the signal less than this corner frequency, and AGC to adjust be that RMS (root mean square) value according to signal is calculated, thereby directly switched to low corner frequency by high corner frequency will be influential to the precision that AGC adjusts, so the removal of DC component is finished in common switching between need a plurality of corner frequencies of employing in the specific implementation process.This also is preferable selection.
Analysis by above-mentioned realization principle at device of the present invention as can be known, device of the present invention mainly comprises:
High pass filter: input is introduced pending signal, and according to the corner frequency of corner frequency adjusting module setting described signal is carried out Filtering Processing, is output as and eliminates signal without direct current component;
Corner frequency adjusting module: according to the time conditions of setting and size descending successively handover operation that carries out between each corner frequency of each corner frequency value;
Described corner frequency adjusting module can be realized by pure software, when corresponding process software judgement meets time conditions, then the corner frequency of high pass filter is switched to the corner frequency value of this time conditions correspondence, so that high pass filter carries out Filtering Processing based on different corner frequencies to pending signal, the final DC component that realizes removing in the pending signal;
Described corner frequency adjusting module can also adopt digital control treatment circuit to realize.
In addition, in communication system, because the dynamic range of signal is very big, corresponding gain ranging is also very big, therefore, if each cascade separately independently the DC offset voltage that produces of module can not in time eliminate, may make the circuit of back cascade that saturated or distortion phenomenon takes place.Device of the present invention is in concrete application process, can be respectively with each output signal of receiving system in comprise the DC component that remains to be eliminated standalone module be connected, concrete syndeton as shown in Figure 3, wherein, B1 and B2 are the circuit module that has DC maladjustment output; H1 and H2 then are that DC maladjustment is eliminated circuit, device promptly provided by the invention.Adopt connected mode shown in Figure 3, can eliminate the DC maladjustment of B1 and B2 module easily, thereby reduce circuit module B1 and B2 offset voltage designing requirement.
Simultaneously, because the gain of each circuit module B1 and B2 is different, it is different with the DC maladjustment amount to show as the amplitude that is input to signal among H1 and the H2, and signal amplitude also can influence the time that DC maladjustment is eliminated, if so make H1 carry out the switching of different corner frequencies in the different time with H2, then can eliminate DC offset voltage well, for this reason, can a total digital control treatment circuit be set for H1 and H2, so that control the switching that different DC maladjustment are eliminated the corner frequency of circuit (being H1, H2) respectively at reasonable time point.For example,, so, wish that this offset cancellation circuit is long slightly with the time that the highest corner frequency continued if the circuit module before the offset cancellation circuit has gain, or the like.The processing mode of concrete digital control treatment circuit can make up setting respectively according to the concrete condition of system.
Corresponding explanation has been carried out to devices and methods therefor of the present invention respectively in the front, in conjunction with the accompanying drawings the actual effect of the present invention in concrete application process is described below again.
As shown in Figure 4, the waveform of the top is the input of high pass filter among the figure, has very big DC maladjustment component;
Among Fig. 4, the output of the high pass bandpass filter of middle curve waveform when directly being set at low corner frequency, as can be seen, when adopting the low corner frequency of setting, eliminating this DC maladjustment needs long time;
Among Fig. 4, nethermost curve waveform is to be set at high corner frequency earlier, is set at medium corner frequency then, is set at the output of the high pass filter under the low corner frequency situation at last again, as can be seen, it is very short to adopt the present invention to remove the time that DC maladjustment consumes.
Therefore, effective effect of the present invention is apparent.
The above; only for the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, and anyly is familiar with those skilled in the art in the technical scope that the present invention discloses; the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.
Claims (7)
1. the removing method of DC maladjustment in the wireless receiving system is characterized in that, comprising:
A, the signal that will need to eliminate DC maladjustment are introduced high pass filter;
B, set up some switching time of one group of corner frequency correspondence;
C, when meeting described switching time during point value, the corner frequency of described high pass filter is switched to the corresponding corner frequency value of described some switching time;
D, described high pass filter utilize described corner frequency that described signal is carried out Filtering Processing.
2. the removing method of DC maladjustment is characterized in that in the wireless receiving system according to claim 1, and described step D comprises:
Described high pass filter utilizes one group of frequency that has nothing in common with each other from high to low as corner frequency successively, and described signal is carried out Filtering Processing.
3. the removing method of DC maladjustment is characterized in that in the wireless receiving system according to claim 1 and 2, and described corner frequency comprises:
Corner frequency value more than two or two.
4. the cancellation element of DC maladjustment in the wireless receiving system is characterized in that, comprising:
High pass filter: its input is introduced pending signal, and utilizes the corner frequency adjusting module to determine that current corner frequency carries out DC maladjustment to described signal and eliminates and handle, and is output as the signal of eliminating after the DC maladjustment;
Corner frequency adjusting module: be used for the relation corresponding with described corner frequency, the corner frequency of described high pass filter switched to the corner frequency of described switching time of some correspondence according to switching time point.
5. the cancellation element of DC maladjustment is characterized in that in the wireless receiving system according to claim 4, and described corner frequency adjusting module can be the corresponding digital control processing circuit.
6. the DC maladjustment based on the cancellation element of DC maladjustment in the wireless receiving system is eliminated system, it is characterized in that, comprising:
One group of DC maladjustment cancellation element, each DC maladjustment cancellation element that comprises is respectively arranged with some switching time of each corner frequency correspondence, each DC maladjustment cancellation element is connected in the output of receiving system module, and the output of described DC maladjustment cancellation element links to each other with next stage receiving system module;
Described receiving system module is the system module that contains the DC component that remains to be eliminated in the output signal.
7. DC maladjustment according to claim 6 is eliminated system, it is characterized in that, each DC maladjustment cancellation element that described one group of DC maladjustment cancellation element comprises is respectively arranged with the corner frequency value that one group of corresponding size has nothing in common with each other.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2004101012642A CN100369383C (en) | 2004-12-17 | 2004-12-17 | DC maladjustment eliminating method and device in wireless receiving system |
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2004101012642A CN100369383C (en) | 2004-12-17 | 2004-12-17 | DC maladjustment eliminating method and device in wireless receiving system |
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| CN1790924A CN1790924A (en) | 2006-06-21 |
| CN100369383C true CN100369383C (en) | 2008-02-13 |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101197581B (en) * | 2006-12-04 | 2011-01-19 | 北京六合万通微电子技术股份有限公司 | Method, device and system for eliminating DC disadjustment in wireless receiving system |
| CN102386857B (en) * | 2011-09-22 | 2014-11-05 | 佛山敏石芯片有限公司 | Limiting amplifier without direct current restorer |
| CN104380609B (en) * | 2012-06-28 | 2016-02-17 | 意法-爱立信有限公司 | A kind of direct current elimination method, device and receiver |
| CN109274627B (en) * | 2018-11-19 | 2021-05-11 | 上海航天测控通信研究所 | Ka frequency band QPSK direct modulation device and communication equipment |
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|---|---|---|---|---|
| CN1065762A (en) * | 1990-12-20 | 1992-10-28 | 莫托罗拉公司 | Method of DC offset correction for receiver and device |
| WO2001024352A1 (en) * | 1999-09-30 | 2001-04-05 | Analog Devices, Inc. | Direct conversion receivers and filters adapted for use therein |
| US6583746B2 (en) * | 2001-11-16 | 2003-06-24 | Mitsubishi Denki Kabushiki Kaisha | A/D converter with high speed input circuit |
| WO2003107547A1 (en) * | 2002-06-18 | 2003-12-24 | 株式会社豊田自動織機 | Low frequency attenuating circuit |
| CN1498457A (en) * | 2002-01-29 | 2004-05-19 | ���µ�����ҵ��ʽ���� | Direct conversion receiver and DC offset reducing method |
| WO2004107557A1 (en) * | 2003-05-21 | 2004-12-09 | Hyperband Communication, Inc. | Fast-settling dc offset removal circuits with continuous cutoff frequency switching |
-
2004
- 2004-12-17 CN CNB2004101012642A patent/CN100369383C/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1065762A (en) * | 1990-12-20 | 1992-10-28 | 莫托罗拉公司 | Method of DC offset correction for receiver and device |
| WO2001024352A1 (en) * | 1999-09-30 | 2001-04-05 | Analog Devices, Inc. | Direct conversion receivers and filters adapted for use therein |
| US6583746B2 (en) * | 2001-11-16 | 2003-06-24 | Mitsubishi Denki Kabushiki Kaisha | A/D converter with high speed input circuit |
| CN1498457A (en) * | 2002-01-29 | 2004-05-19 | ���µ�����ҵ��ʽ���� | Direct conversion receiver and DC offset reducing method |
| WO2003107547A1 (en) * | 2002-06-18 | 2003-12-24 | 株式会社豊田自動織機 | Low frequency attenuating circuit |
| WO2004107557A1 (en) * | 2003-05-21 | 2004-12-09 | Hyperband Communication, Inc. | Fast-settling dc offset removal circuits with continuous cutoff frequency switching |
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