CN1531215A - Analog demodulator for low and medium frequency receiver - Google Patents
Analog demodulator for low and medium frequency receiver Download PDFInfo
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- CN1531215A CN1531215A CNA031201865A CN03120186A CN1531215A CN 1531215 A CN1531215 A CN 1531215A CN A031201865 A CNA031201865 A CN A031201865A CN 03120186 A CN03120186 A CN 03120186A CN 1531215 A CN1531215 A CN 1531215A
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Abstract
An analog demodulator is used in low medium frequency receiver. It has the function taking frequency mixing and mirror image eliminating. The analog demodulator uses at least one calibrating device, DC displacement calibrating circuit and filter device to carry out DC potential shift collimation technology and filter technology for solving the problem, so that the analog demodulator will produce DC potential shift and upper harmonic.
Description
Technical field
The invention provides an a kind of analog demodulator (Analog Demodulator) that is used for a Low Medium Frequency receiver (Low-IF Receiver), refer in particular to a kind of correlation techniques such as DC potential offset calibration and filtering of utilizing, area oscillation leaks and the analog demodulator of high order harmonic component item to eliminate respectively.
Background technology
At the radio frequency transmission receiver of wireless communication system (RF Transceiver) now three kinds of structures are arranged, first kind is superhet (Super-heterodyne) with the longest history, because it receives and transmits signal with an intermediate frequency element, therefore has highly sensitive advantage in its work, but shortcoming need to be intermediate frequency surface acoustic wave filter more separate type elements such as (IF SAW Filter), makes that assembling selling at exorbitant prices and requisite space are excessive; Second kind is directly conversion (Direct Conversio), or is called zero intermediate frequency (Zero IF), and its technical characterictic is directly to reduce to fundamental frequency signal by the signal that radio frequency receives, and saves the intermediate frequency element, but also therefore causes sensitivity deficiency and noise excessive; The third is Low Medium Frequency (Low IF), or claim nearly zero intermediate frequency (NearZero IF), its characteristics are between above-mentioned two kinds of technology, Low Medium Frequency and superhet difference are that the Low Medium Frequency section processes of Low Medium Frequency technology is lower than the frequency of the intermediate-freuqncy signal of super-heterodyne architecture, even the frequency of Low Medium Frequency technology Low Medium Frequency part is near fundamental frequency, thus, both can economize except that separate type elements such as intermediate-frequency filter to save cost, space, be unlikely to cause the sensitivity of excessive deficiency and excessive noise again.
From the above, the structure of Low Medium Frequency has sizable advantage in the transmission and the application on the receiving terminal of radio communication, therefore its application is also quite extensive, such as at radio area network (Wireless LAN, WLAN), mobile phone (Cellular Telephone), and in the radio telephone systems such as (Cordless Telephone), the structure and the notion of all visible Low Medium Frequency, US Patent 5 as people such as Baltus proposition, 751,249, just propose to adjust the electromagnetic wave reception bundle of aerial array in " Radio transmission system and a radio apparatus for use in such a system " with a phase control array apparatus (Rhased-array Radio Apparatus), and the notion that cooperates a Low Medium Frequency or zero intermediate frequency receiver is made up the easier and perfect ground of whole system in a radio transmission system (Radio Transmission System).In addition, also begin to adopt the structure and the notion of Low Medium Frequency at the bluetooth system of wireless personal network, as " the A 2.4GHzCMOS Low-IF Receiver " of people such as YiLu in International Analog VLSI Workshop proposition in 1999, International Analog VLSI Workshop, and the documents such as " An FH-SS GFSK Low-IF Receiver for Bluetooth " that proposes in Proceedings of the 11 th VLSI/CADSymposium in 2000 of people such as Wei-Cherng Liao, all disclose in bluetooth system, adopt the change-over circuit of low-intermediate frequency, radio frequency is converted to earlier after the low-intermediate frequency signal of 1～4MHz, transfer the structure that fundamental frequency is handled again to.
The structure of Bu Fen Low Medium Frequency or ultralow intermediate frequency receiver is that the signal that will receive from antenna is directly via behind the analog-digital converter now, transferring to digital wireless signal processor (Digital RadioProcessor) handles, though so removed the analog element of the required frequency dependence of model configuration from, therefore increased the complexity in the radio frequency receiving terminal combination with simulation.Moreover this kind structure is except need have high frequency range, at a high speed and the analog-digital converter of high-res, and it is to the then aggravation thereupon of requirement of the operational capability of digital element line signal processor, and therefore with regard to client product, cost control is difficult for.Present stage, more general way was in the structure of Low Medium Frequency or ultralow intermediate frequency receiver, and simulation process and digital operation aspect are done the suitable division of labor.For example people such as H.Tsurumi is in IEICE Transaction ofCommunication., Vol.E83-B, No.6, " the Broadband andflexible receiver architecture for software defined radio terminal using directconversion and low-IF principle " that delivers among the pp.1246-1253, with regard to mode (the AnalogSystem-Selection/Digital Channel-Selection of display simulation with the numeral division of labor, ASS/DCS) be the mode of the most normal employing at present, the reception of various criterion system signal is just handled with simulated mode with transmission, and the passage under the particular system is chosen and then adopted digitized compute mode.Under the notion of the Low Medium Frequency of taking the analog digital division of labor like this or ultralow intermediate frequency receiver, the structure of separating mediation image cancellation (ImageRejection) with digital mode is still common general, in US Patent 5,802,463, in " Apparatus andmethod for receiving a modulated radio frequency signal by converting the radiofrequency signal to a very low intermediate frequency signal ", people such as Zuckerman propose the structure of a ultralow intermediate frequency (Very Low Intermediate Frequency) in radio area network or radio telephone, and finish the structure of this ultralow intermediate frequency in the mode of digital demodulation, the signal frequency of this ultralow intermediate frequency is very near fundamental frequency (Base-band), people such as Zuckerman also adds the technology of image cancellation (Image Rejection) in system, keep the signal quality after the frequency reducing.Afterwards, foundation and aforementioned US Patent 5,802, it is too numerous to enumerate that the similar notion of 463 known technology proposes the patent of the Low Medium Frequency of digital demodulator or ultralow if architectures, US Patent 6 as people such as Mostafa proposition, 373,422, " Method and apparatus employing decimation filter for down conversion in areceiver ", and the US Patent 6 that proposes of people such as Brown, 366,622, (Analog-to-digital Converter is converted to the form of digital signal in ADC), finishes the function of image cancellation and frequency reducing again with digital mode all pair of orthogonal (Quadrature) signal that receives to be delivered to an analog-digital converter in " A pparatus andmethod for wireless communications " earlier.And in the patent of digital Low Medium Frequency of numerous descriptions or ultralow if architectures, there are some known technologies to be conceived to utilize digital form to remove to eliminate mirror image especially, US Patent 6 as people such as Glas proposition, 330,290, in " Digital I/Qimbalance compensation ", utilize detection signal (Test Signal) and compensation (Compensation) technology to compensate respectively with the phase place (Phase) and the amplitude (Amplitude) of numerically controlled mode to the pair of orthogonal signal, with the phase place and the amplitude of fine adjustment signal, reach the purpose of eliminating mirror image.Just, under the structure of above-mentioned known technology, one will to be combined into the structure of digital demodulator in analog radio frequency receiving terminal comparatively numerous and diverse, moreover, because the structure of digital demodulator must need to add analog-digital converter, therefore derive relevant problems such as too much energy resource consumption.
Finish the configuration aspects of ultralow intermediate frequency as for using analog demodulator circuit, people such as Michiel Steyaert are in " RF Integrated Circuits in Standard CMOS Technologies ", with and and JanCrols at IEEE Transactions on Circuits and Systems-II:Analog andDigital Signal Processing in 1998, vol.45, No.3, existing mentioned in " Low-IFTopologies for High Performance Analog Front Enads of Fully IntegratedReceivers " that pp.269-282 delivers, and the structure of display simulation formula mixing with the combination of analog radio frequency receiving terminal on truly have many benefits, and this group research team comprises people such as Jan Crols and MichielSteyaert also at the Symposium of nineteen ninety-five on VLSI Circuits Digest of TechnicalPapers, pp.87-88, in " An Analog Integrated Polyphase Filter for a HighPerformance Low-IF Receiver ", be conceived to reduce the error of phase place for the improvement of the relevant issues of complete analog Low Medium Frequency or ultralow if architectures, and utilize a phase place to arrange device, go to reduce the error of phase place as a phase-locked loop circuit (Phase Locked Loop (PLL) circuit).
Even to this day, because advantages such as advantage that makes up with the analogue transmission receiving terminal and low energy expenditure, application simulation formula demodulator is more paid attention in the structure of Low Medium Frequency or ultralow intermediate frequency receiver, just, the radio frequency that receives in the receiving terminal to be downconverted to the ultralow intermediate frequency that is close to fundamental frequency, under the structure of analog demodulator, also cause other problem easily, except the phase error that aforementioned known technology is had in mind, also comprised the local oscillation leakage (LO leakage) that DC potential skew (DC Offset) is caused, and the problems such as high order harmonic component item that local oscillations generator (Local Oscillator Generator) is brought wait to solve.
Summary of the invention
Therefore the present invention mainly provides an a kind of analog demodulator and correlation technique that is used for a Low Medium Frequency receiver (Low-IF Receiver), to address the above problem.
In the present invention, we propose one and comprise the described analog demodulator of calibrating installation, direct current displacement calibration circuit and filter, with solve problems such as DC potential skew that this analog demodulator produces and high order harmonic component item in a Low Medium Frequency receiver.
Purpose of the present invention is for providing a kind of analog demodulator (Analog Demodulator) that is applicable in the Low Medium Frequency receiver (Low-IF Receiver).This analog demodulator includes at least one receiving circuit, is used for receiving respectively pair of orthogonal signal (Quadrature Signal); At least one calibrating installation is used for reducing the DC potential skew (DC Offset) of this quadrature signal; One oscillation source (Reference Source) is used to provide a reference clock; One local oscillations generator (Local Oscillator Generator) is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; At least one frequency mixer (mixer) is connected in this local oscillations generator, and is connected in after this calibrating installation, is used for respectively this quadrature signal being carried out mixing; And at least one direct current displacement calibration circuit (DC OffsetCalibration Circuit), be connected in this frequency mixer, be used for eliminating the DC potential skew that this frequency mixer itself is produced.Wherein after this receiving circuit received this quadrature signal that is transmitted by a front stage circuits respectively, this calibrating installation can reduce the DC potential skew (DC Offset) of this quadrature signal.Next when this frequency mixer cooperates this local oscillations generator respectively this quadrature signal to be carried out mixing, this direct current displacement calibration circuit can be eliminated the DC potential skew that this frequency mixer itself is produced, and exports this quadrature signal after the mixing at last respectively.
Another object of the present invention is for providing a kind of method that lowers local oscillation leakage (LOleakage) in analog demodulator.This analog demodulator includes at least one receiving circuit, is used for receiving respectively the pair of orthogonal signal; At least one calibrating installation is used for reducing the DC potential skew of this quadrature signal to avoid local oscillation leakage; One oscillation source is used to provide a reference clock; One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; At least one frequency mixer (mixer) is used for respectively this quadrature signal being carried out mixing; And at least one direct current displacement calibration circuit, be connected in this frequency mixer, be used for reducing DC potential skew that this frequency mixer itself produced to avoid local oscillation leakage.And this method includes and uses this receiving circuit to receive this quadrature signal that is transmitted by a front stage circuits respectively; Use this calibrating installation to reduce the DC potential skew of this quadrature signal; Use this frequency mixer respectively this quadrature signal to be carried out mixing; And use this direct current displacement calibration circuit to eliminate the DC potential skew that this frequency mixer itself is produced.
Another object of the present invention is for providing a kind of analog demodulator that is applicable in the Low Medium Frequency receiver.This analog demodulator includes at least one receiving circuit, is used for receiving the pair of orthogonal signal; At least one calibrating installation is used for reducing the DC potential skew of this quadrature signal; One oscillation source is used to provide a reference clock; One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; And at least one frequency mixer, be connected in this local oscillations generator, and be connected in after this calibrating installation, be used for respectively this quadrature signal being carried out mixing.Wherein after this receiving circuit receives this quadrature signal that is transmitted by a front stage circuits respectively, this calibrating installation can reduce the DC potential skew of this quadrature signal, then this frequency mixer cooperates this local oscillations generator to carry out mixing to this quadrature signal respectively, exports this quadrature signal after the mixing at last respectively.
Another object of the present invention uses a collimation technique to lower the method for the local oscillation leakage of this analog demodulator for providing a kind of in analog demodulator.Wherein this analog demodulator includes at least one receiving circuit, is used for receiving respectively the pair of orthogonal signal; At least one calibrating installation is used to provide this collimation technique, and to reduce the DC potential skew of this quadrature signal, wherein this DC potential skew is for causing the main cause of local oscillation leakage; One oscillation source is used to provide a reference clock; One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; And at least one frequency mixer, be connected in this local oscillations generator, and be connected in after this calibrating installation, be used for respectively this quadrature signal being carried out mixing.And this method includes and uses this receiving circuit to receive this quadrature signal that is transmitted by a front stage circuits respectively; Use this calibrating installation to reduce the DC potential skew of this quadrature signal; Use this frequency mixer respectively this quadrature signal to be carried out mixing; And this quadrature signal after the output mixing.
Another object of the present invention is for providing a kind of analog demodulator that is applicable in the Low Medium Frequency receiver.This analog demodulator includes at least one receiving circuit, is used for receiving respectively the pair of orthogonal signal; One oscillation source is used to provide a reference clock; One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; At least one frequency mixer is connected in this local oscillations generator, and is connected in after this receiving circuit, is used for respectively this quadrature signal being carried out mixing; And at least one direct current displacement calibration circuit, be connected in this frequency mixer.Be used for eliminating the DC potential skew that this frequency mixer itself is produced.Wherein after this receiving circuit receives this quadrature signal that is transmitted by a front stage circuits respectively, this frequency mixer cooperates this local oscillations generator to carry out mixing to this quadrature signal respectively, this direct current displacement calibration circuit can be eliminated the DC potential skew that this frequency mixer itself produced simultaneously, exports this quadrature signal after the mixing at last respectively.
Another object of the present invention is for providing a kind of method that is used for lowering local oscillation leakage in analog demodulator.Wherein this analog demodulator includes at least one receiving circuit, is used for receiving respectively the pair of orthogonal signal; One oscillation source is used to provide a reference clock; One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; At least one frequency mixer is connected in this local oscillations generator, and is connected in after this receiving circuit, is used for respectively this quadrature signal being carried out mixing; And at least one direct current displacement calibration circuit, be connected in this frequency mixer, be used for the DC potential skew that this frequency mixer itself produced, wherein this DC potential skew is for causing the main cause of local oscillation leakage.This method includes uses this receiving circuit to receive this quadrature signal that is transmitted by a front stage circuits respectively; Use this frequency mixer respectively this quadrature signal to be carried out mixing; Use this direct current displacement calibration circuit to eliminate the DC potential skew that this frequency mixer itself is produced; And this quadrature signal after the output mixing.
Another object of the present invention is for providing a kind of analog demodulator that is applicable in the Low Medium Frequency receiver.This analog demodulator is for an analog image cancellation demodulator (Image-Rejected AnalogDemodulator), has the function of image cancellation (Image-Rejection).This analog demodulator includes at least one receiving circuit, is used for receiving respectively the pair of orthogonal signal; One oscillation source is used to provide a reference clock; One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; At least one frequency mixer is connected in this local oscillations generator, is used for respectively this quadrature signal being carried out mixing; And at least one filter, be connected in this local oscillations generator, be used for eliminating the high order harmonic component item that this local oscillations produces.
Another object of the present invention is for providing a kind of use one filtering technique in analog demodulator, to eliminate the method for high order harmonic component item.Wherein this analog demodulator includes at least one receiving circuit, is used for receiving respectively the pair of orthogonal signal; One oscillation source is used to provide a reference clock; One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; Wherein the high order harmonic component item is produced by this local oscillations; At least one frequency mixer is connected in this local oscillations generator, is used for respectively this quadrature signal being carried out mixing; And a filter, be connected in after this local oscillations generator, be used to provide this filtering technique, to eliminate the high order harmonic component item that this local oscillations is produced.And this method includes this oscillation source generation reference clock of use; Use this local oscillations generator that the reference clock that this oscillation source produces is downconverted to a characteristic frequency, wherein the reference clock of this characteristic frequency can be used for respectively this quadrature signal being carried out mixing for this frequency mixer; And use this filter to eliminate the high order harmonic component item that this local oscillations produces.
The invention has the advantages that analog demodulator of the present invention can utilize at least one calibrating installation to go to reduce the DC potential skew of this quadrature signal, reduces area oscillation and leaks after receiving the pair of orthogonal signal that is transmitted by a front stage circuits.
The invention has the advantages that, analog demodulator of the present invention is when utilizing frequency mixer that the pair of orthogonal signal that receives is carried out mixing, can utilize at least one direct current displacement calibration circuit to go to eliminate the DC potential skew that this frequency mixer itself is produced, reduce area oscillation and leak.
The invention has the advantages that analog demodulator of the present invention can utilize at least one filter to go to eliminate the high order harmonic component item that a local oscillations is produced, avoid influencing the stable and accurate of signal.
Description of drawings
Fig. 1 is the schematic diagram of first embodiment of the analog demodulator of the present invention.
Fig. 2 is the schematic diagram of second embodiment of the analog demodulator of the present invention.
Fig. 3 is the schematic diagram of controllable type current mirror one embodiment of Fig. 2 direct current displacement calibration circuit.
Fig. 4 is the schematic diagram of another embodiment of controllable type current mirror of Fig. 2 direct current displacement calibration circuit.
Fig. 5 is the schematic diagram of the 3rd embodiment of the analog demodulator of the present invention.
Fig. 6 is the circuit diagram of the analog demodulator part of Fig. 5.
Fig. 7 (a) and (b) are another embodiment of Fig. 6 circuit structure.
Fig. 8 is the schematic diagram that adds a filter among Fig. 5 embodiment.
Fig. 9 is the schematic diagram of the 4th embodiment of the analog demodulator of the present invention.
The reference numeral explanation
10,30,60,90 analog demodulators
12,32,62,92 receiving circuits
14,34,64,94 receiving circuits
16,66,96 first calibrating installations
18,68,98 second calibrating installations
20,40,70,100 oscillation sources
22,42,72,102 local oscillations generators
24,44,74,104 frequency mixers
26,46,76,106 first programmable gain amplifiers
28,48,78,108 second programmable gain amplifiers
35,65,95 first direct current displacement calibration circuits
37,67,97 second direct current displacement calibration circuits
50,54 controllable type current mirrors
52 voltages are selected array
56 switch arrays
80,110 ripple filter devices
116,118 calibrating installations
126,128 amplifying devices
Embodiment
Analog demodulator disclosed in this invention (Analog Demodulator) is the analog demodulator in the second level that places a Low Medium Frequency receiver (Low-IF Receiver), that is, in the Low Medium Frequency receiver, before analog demodulator of the present invention, be provided with a first order demodulator earlier with radio frequency (the Radio Frequency that receives, RF) signal is done the operation of frequency reducing for the first time, next will deliver to mixing, the frequency reducing work of carrying out in the analog demodulator of the present invention again through the signal of a frequency reducing again.
Analog demodulator is applied under the structure in the Low Medium Frequency receiver, the problem that need overcome is exactly the influence to system effectiveness of the local oscillation leakage that caused of DC potential skew and high order harmonic component item, therefore, analog demodulator disclosed in this invention can utilize two direct current displacement collimation techniques and a filtering technique to solve problems such as DC potential skew and high order harmonic component item.
See also Fig. 1, Fig. 1 is the schematic diagram of first embodiment of the analog demodulator 10 of the present invention.The analog demodulator 10 of the present invention is an analog image cancellation demodulator (Image-Rejected AnalogDemodulator), has the function of eliminating mirror image.Analog demodulator 10 includes two receiving circuits 12,14, be used for receiving respectively the pair of orthogonal signal (QuadratureSignal) that is transmitted by above-mentioned previous stage demodulator, this quadrature signal comprises a same-phase signal (In-Phase Signal, I) and a quadrature phase signal (Quadrature-Phase Signal, Q).As shown in Figure 1, analog demodulator 10 has also comprised two calibrating installations 16,18, an oscillation source (Reference Source) 20, one local oscillations generator (LocalOscillator Generator) 22 and one groups of frequency mixers (mixer) 24.Two calibrating installations 16,18 are divided into first calibrating installation 16 and second calibrating installation 18, after being connected to two receiving circuits 12,14, make same-phase signal I and the quadrature phase signal Q of this quadrature signal I, Q pass through this two calibrating installation 16,18 respectively, this two calibrating installation 16,18 can be a band and prohibits filter (Notch Filter), a high pass filter (High Pass Filter), perhaps other devices of adjustable potential shift.In the present embodiment, calibrating installation the 16, the 18th is for the very low high pass filter of cut-off frequency, with the filtering direct current signal.Ask for an interview Fig. 1, first calibrating installation 16 corresponding to same-phase signal I second calibrating installation 18 corresponding to quadrature phase signal Q.Can be sent to frequency mixer 24 through same-phase signal I and quadrature phase signal Q after first calibrating installation 16 and 18 processing of second calibrating installation.In addition, oscillation source 20 can provide a reference clock to local oscillations generator 22, local oscillations generator 22 can be downconverted to a characteristic frequency with the reference clock that oscillation source 20 produces, and this characteristic frequency is between global system for mobile communications (GSM) or radio frequency (RF) signal of radio area network (WLAN) application and the arbitrary frequency between fundamental frequency (Base-Band) frequency.Then local oscillations generator 22 is connected to frequency mixer 24, thus, frequency mixer 24 just can utilize the reference clock of this characteristic frequency that same-phase signal I and quadrature phase signal Q are carried out mixing respectively, again same-phase signal Q after the mixing and quadrature phase signal Q is delivered to the next stage circuit at last.
Please continue to consult Fig. 1, the operative scenario of the first embodiment of the present invention is as follows, when two receiving circuits 12,14 receive the same-phase signal I and quadrature phase signal Q that is transmitted by a front stage circuits respectively after, first calibrating installation 16 and second calibrating installation 18 that are connected to behind same-phase signal I and the quadrature phase signal Q can reduce this quadrature signal I, the DC potential skew of Q, this quadrature signal I, it is exactly amplifying circuit from previous stage that the DC potential of Q is offset topmost source, and the skew of this kind DC potential is exactly one of main cause that causes local oscillation leakage.Then frequency mixer 24 cooperates the reference clock of this characteristic frequency of local oscillations generators 22 outputs to carry out mixing to same-phase signal I and quadrature phase signal Q respectively, exports this quadrature signal I, Q after the mixing at last more respectively.In the first embodiment of the present invention, analog demodulator 10 can comprise at least one amplifying device (Amplifier) (as shown in fig. 1 in addition, be connected to first programmable gain amplifier (the Programmable Gain Amplifier behind same-phase signal I and the quadrature phase signal Q, PGA) 26 and second programmable gain amplifier 28 can be used to amplify respectively same-phase signal I and quadrature phase signal Q).As from the foregoing, first programmable gain amplifier 26 and second programmable gain amplifier 28 remove to amplify this quadrature signal I because analog demodulator 10 comprises into, Q, if this quadrature signal I that the previous stage demodulator circuit is transmitted, Q has had a certain amount of DC potential skew, again after first and second programmable gain amplifier 28 amplifies signal, the amount of DC potential skew then will become very considerable, if do not add first calibrating installation 16 in the system and second calibrating installation 18 removes to reduce this quadrature signal I, the DC potential skew of Q, the area oscillation leakage that then huge DC potential skew causes can have a strong impact on the usefulness of system.Therefore, this two calibrating installation 16,18 and be the important techniques feature of first embodiment of the invention to the function of the DC potential offset correction of pair of orthogonal signal I, Q.
As described above, the analog demodulator 10 of first embodiment is to be used for a Low Medium Frequency receiver, and the Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.In addition, please note, when reality is implemented, the number of calibrating installation need not be as be defined as two of Fig. 1 embodiment, as long as can reach the DC potential skew of proofreading and correct this quadrature signal I, Q, no matter only use a calibrating installation in the same way even surpass calibrating installation more than three, be included in the scope of present embodiment.
Another factor that produces the DC potential skew in system is because the DC potential skew that frequency mixer is produced because of not matching of mixer core (Mixer Core) own in the system, see also Fig. 2, Fig. 2 is the schematic diagram of the second embodiment of the present invention, the analog demodulator 30 of Fig. 2 also is an analog image cancellation demodulator, be similar to previous embodiment, analog demodulator 30 includes two receiving circuits 32,34, an oscillation source 40, a local oscillations generator 42 and one group of frequency mixer 44.Two receiving circuits 32,34 are used for receiving respectively the pair of orthogonal signal (Quadrature Signal) that is transmitted by above-mentioned previous stage demodulator, this quadrature signal comprises a same-phase signal (In-Phase Signal, I) and a quadrature phase signal (Quadrature-Phase Signal, Q).In Fig. 2, comprise two direct current displacement calibration circuits 35 in the frequency mixer 44 on two circuit-lines of corresponding same-phase signal I and quadrature phase signal Q respectively, 37 (DC Offset Calibration Circuit) (first direct current displacement calibration circuit 35, the second direct current displacement calibration circuit 37 corresponds to a same-phase signal I and an orthogonal signalling Q respectively), this two direct currents displacement calibration circuit 35,37 can be a kind of controllable type current mirror (Controllable Current Mirror), wherein the controllable type current mirror is that voltage signal with same-phase signal I and quadrature phase signal Q is converted to current signal, and the bias current of the input stage circuit of adjustment frequency mixer 44 is to identical value, to eliminate the area oscillation leakage that frequency mixer 44 is produced.Ask for an interview Fig. 3.One embodiment of the controllable type current mirror of Fig. 3 displayed map 2 first direct current displacement calibration circuits 35 or the second direct current displacement calibration circuit 37.The controllable type current mirror 50 of Fig. 3 is to utilize metal-oxide semiconductor (MOS) (metal-oxide semiconductor, MOS) structure of transistor M1-M4 is finished, in fact, the controllable type current mirror of Fig. 3 mainly shows the structure division of control image current I ' size, then be general known technology as for the structure that voltage signal is converted to current signal, need not add to give unnecessary details and show.As shown in Figure 3, after electric current I enters controllable type current mirror 50, controllable type current mirror 50 utilizes a voltage to select array (Voltage Switch Array) 52, control is corresponding to the switch of each voltage V2-V4 of metal oxide semiconductor transistor M1-M4, with the size that determines to merge the area of the whole metal oxide semiconductor transistor in back and adjust image current I ' by the area that changes whole metal oxide semiconductor transistor.When reality was implemented, the number of metal oxide semiconductor transistor need not limit as Fig. 3 embodiment.The number of metal oxide semiconductor transistor the more, then the accuracy of Tiao Zhenging is then higher.See also Fig. 4, Fig. 4 has shown another embodiment of the controllable type current mirror of Fig. 2 direct current displacement calibration circuit.The controllable type current mirror 54 of Fig. 4 is to utilize the structure of resistance R0-R3 in bipolar transistor (Bipolar) the B0 cooperation to finish, identical with the embodiment of Fig. 3, the controllable type current mirror 54 main structure divisions that show the Control current size of Fig. 4 do not show the structure that voltage signal is converted to current signal.In Fig. 4, after electric current I entered controllable type current mirror 54, controllable type current mirror 54 utilized switch arrays 56, and control is corresponding to the connection of the connection of resistance R 0-R3 or open circuit, and adjusted the size of image current I ' with the size that merges the back all-in resistance.Similarly, when reality was implemented, the number of resistance need not limit as figure embodiment.The number of resistance the more, then the accuracy of Tiao Zhenging is then higher.
Please continue to consult Fig. 2, oscillation source 40 can provide a reference clock to local oscillations generator 42, local oscillations generator 42 can be downconverted to a characteristic frequency with the reference clock that oscillation source 40 produces, and this characteristic frequency is between global system for mobile communications or radio frequency (RF) signal of radio area network (WLAN) application and the arbitrary frequency between fundamental frequency (Base-Band) frequency.Then local oscillations generator 42 is connected to frequency mixer 44, provide the reference clock of this characteristic frequency to give calibrating installation, thus, frequency mixer 44 just can utilize the reference clock of this characteristic frequency that same-phase signal I and quadrature phase signal Q are carried out mixing respectively, again same-phase signal I after the mixing and quadrature phase signal Q is delivered to the next stage circuit at last.The second embodiment of the invention major technology is characterised in that utilizes the direct current displacement calibrating installation 35,37 that connects frequency mixer 44 to eliminate the DC potential skew that frequency mixer itself is produced, and eliminates the local oscillation leakage that the skew of this kind DC potential causes.In addition, in the second embodiment of the present invention, analog demodulator 30 can comprise at least one amplifying device (Amplifier) (as shown in fig. 1 in addition behind receiving circuit 32,34, be connected to first programmable gain amplifier (the Programmable Gain Amplifier behind same-phase signal I and the quadrature phase signal Q, PGA) 46 and second programmable gain amplifier 48 can be used to amplify respectively same-phase signal I and quadrature phase signal Q).
Identical with first embodiment is, the analog demodulator 30 of second embodiment also is used for a Low Medium Frequency receiver, and the Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.In addition, please note, when reality is implemented, the number of direct current displacement calibration circuit need not be as be defined as two of Fig. 2 embodiment, the setting of direct current displacement calibration circuit also need not be installed in respectively on two circuit-lines of corresponding same-phase signal I in the frequency mixer and quadrature phase signal Q as being defined as of Fig. 2 embodiment, promptly, even only install a direct current displacement calibration circuit in one of them of two circuit-lines of same-phase signal I and quadrature phase signal Q, eliminate the function that DC potential that frequency mixer itself produced is offset as long as can reach, also belong to the technical characterictic of present embodiment.
After the technical characterictic merging with the first embodiment of the invention and second embodiment, can more complete and comprehensively eliminate the DC potential that DC potential is offset and frequency mixer itself the is produced skew that the previous stage demodulator brings, make the DC potential skew of system and the local oscillation leakage that is caused thereof to reduce to minimum.See also Fig. 5, Fig. 5 is the schematic diagram of the third embodiment of the present invention, the analog demodulator 60 of Fig. 5 is the technical characterictic that has merged the analog demodulator of first and second embodiment, and the title of related elements and function are described identical with first and second embodiment in the structure.Analog demodulator 60 includes and is used for receiving respectively two receiving circuits 62,64 of same-phase signal I and quadrature phase signal Q, is used for reducing by two calibrating installations 66,68 (first calibrating installation 66 and second calibrating installation 68) of the DC potential skew of this quadrature signal I, Q; Be used to provide an oscillation source 70 of a reference clock; Be used for the reference clock that oscillation source 70 produces is downconverted to a local oscillations generator 72 of a characteristic frequency; Be used for respectively this quadrature signal I, Q being carried out one group of frequency mixer 74 of mixing; And the two direct current displacement calibration circuits 65,67 (the first direct current displacement calibration circuit 65, the second direct current displacement calibration circuit 67) that are used for eliminating the frequency mixer 74 DC potential skews that produced own.The analog demodulator 60 most important technical characterictics of Fig. 5 are connected in two calibrating installations 66,68 behind the receiving circuit and are connected in two direct current displacement calibration circuits 65,67 in the frequency mixer 74 for having comprised simultaneously, cause the reason of DC potential skew all to take in into all, therefore can will cause the DC potential skew of local oscillation leakage to reduce to minimum.
Please refer to Fig. 6, Fig. 6 is the circuit diagram of analog demodulator 60 parts of Fig. 5.The circuit diagram of Fig. 6 is for carrying out an embodiment of the analog demodulator 60 of Fig. 5, and signal is to import with current forms.The circuit diagram of Fig. 6 has comprised two calibrating installations 66,68 (first calibrating installation and second calibrating installation 66,68) of the analog demodulator 60 of Fig. 5, frequency mixer 74, the two direct current displacement calibration circuit 65,67 and the local oscillations generators 72 of part.The shown circuit of Fig. 6 embodiment mainly be utilize metal oxide semiconductor transistor, bipolar transistor, and the model configuration of other analog elements finish.It should be noted that at first first calibrating installation and second calibrating installation 66,68 are that the band that utilizes resistance R 1, R2 and capacitor C 1, C2 to constitute is respectively prohibited the effect that filter (Notch Filter) reaches the skew of elimination DC potential in Fig. 6.Described in first embodiment of the invention, the pattern of calibrating installation is not limited to band and prohibits filter, in other devices that comprise high pass filter (High Pass Filter) or adjustable potential shift also were included in, moreover the number and the pattern of direct current displacement calibration circuit also need not limit.At last, about showing the circuit part of local oscillations generator 72 among Fig. 6, because the analog demodulator 60 of the present invention is an analog image cancellation demodulator, mutually whether the quadrature (Quadrature Phase Difference) that the ability of its image cancellation is looked closely four input A, B in local oscillations generator 72, C, D signal gap 90 degree, and whether the amplitude (Amplitude) of four input A, B of local oscillations generator 72, C, D signal is identical.Please then refer to Fig. 7 (a) and Fig. 7 (b), Fig. 7 (a) and Fig. 7 (b) are another embodiment of Fig. 6 circuit structure, in fact, Fig. 7 (a) and Fig. 7 (b) are interconnective circuit structure, among Fig. 7 (a) circuit junction p and q promptly respectively correspondence be connected in circuit junction p and q among Fig. 7 (b).Please together see it with Fig. 6, the structure of Fig. 7 (a) is roughly corresponding to the shown frequency mixer 74 of Fig. 6, four terminal A, B, C, mutually whether the quadrature of D signal (Quadrature Phase Difference) gap 90 degree, and A, B, C, whether the amplitude of four signals of D the identical quality that has still determined the analog demodulator 60 image cancellation abilities of the present invention, the structure of Fig. 7 (b) is then roughly corresponding to the part except frequency mixer 74 in Fig. 6 circuit structure, but do not comprise two calibrating installations 66 among Fig. 6,68 (first calibrating installation and second calibrating installations 66,68) and two direct current displacement calibration circuits 65,67, therefore, shown pair of orthogonal signal I among Fig. 7 (b), Q should be considered as having passed through two shown calibrating installations 66 of Fig. 6,68 eliminate the pair of orthogonal signal I after the DC potential skew, Q.At first please note, Fig. 7 (a) and Fig. 7 (b) are with the most important different part of Fig. 6, signal among Fig. 7 (a) and Fig. 7 (b) embodiment is to import with voltage form, and the signal among Fig. 6 embodiment is to import with current forms, moreover, metal oxide semiconductor transistor M1, M2 and bipolar transistor B1～B4 shown among Fig. 7 (a) and Fig. 7 (b) embodiment are not the combination and the selection of the only qualification of this structure, and other can finish therewith that the structure of embodiment identical function is included in the middle of the technical characterictic of the present invention.
Under the structure of the analog demodulator of the present invention, the problem that need overcome is except the local oscillation leakage that the DC potential skew is caused, and the high order harmonic component item that local oscillations produced also has bad influence to system effectiveness.In the invention described above first to the 3rd embodiment, because the reference clock that oscillation source provides is a square-wave signal, harmonic term by different powers is formed, so be easy to generate the problem of high order harmonic component item, in the structure of the invention described above first to the 3rd embodiment, after its oscillation source and local oscillations generator, if a filter is set, connect after the local oscillations generator, then can be used for the high order harmonic component item that the filtering local oscillations produced, especially at three rank (3
Rd) and five rank (5
Th) harmonic term.See also Fig. 8, Fig. 8 is the schematic diagram that 72 backs of the local oscillations generator among Fig. 5 embodiment is added a filter 80.Note that ripple filter device 80 can be a polyphase filters (Poly-PhaseFilter), a low pass filter (Low Pass Filter) or digital filter (Digital Filter), is mainly used to filtering three rank (3
Rd) and five rank (5
Th) harmonic term.The structure of Fig. 8 schematic diagram is to be example with Fig. 5, and in fact, the structure that adds a filter so also is applicable among the embodiment of Fig. 1 and Fig. 2.
Thus, after the embodiment combination with the present invention first, second, third and Fig. 8, can all important techniques features of complete description the present invention.Ask for an interview Fig. 9, Fig. 9 is the schematic diagram of the 4th embodiment of the analog demodulator 90 of the present invention.In the analog demodulator 90 of the 4th embodiment is included in the main element of aforementioned all embodiment and function.As shown in Figure 9, analog demodulator 90 has comprised two receiving circuits 92,94, two calibrating installations 96,98 (first calibrating installation 96 and second calibrating installation 98), an oscillation source 100, a local oscillations generator 102, one group of frequency mixer 104, a filter 110 and two direct current displacement calibration circuits 95,97.After analog demodulator 90 has also comprised two amplifying devices 106,108 in addition and is connected in receiving circuit 92,94, be used for amplifying and receive pair of orthogonal signal I, the Q of advancing.Analog demodulator 90 has also comprised two amplifying devices 126,128 in the output of this quadrature signal I, Q, is used for amplifying this quadrature signal I, Q after the mixing.In the present embodiment, other comprises low pass filter (Low Pass Filter) 116,11 8, is connected in after the frequency mixer 104, is used for the high order harmonic component composition that further filtering previous stage demodulator circuit produced.Wherein after receiving circuit 92,94 received this quadrature signal I, the Q that is transmitted by a front stage circuits respectively, calibrating installation 96,98 can reduce the DC potential skew of this quadrature signal I, Q.Next when frequency mixer 104 cooperate local oscillations generators 102 respectively to this quadrature signal I, when Q carries out mixing, filter 110 can be eliminated the high order harmonic component item that local oscillations produced, and direct current displacement calibration circuit can be eliminated the DC potential skew that frequency mixer 104 itself is produced, and exports this quadrature signal I, Q after the mixing at last respectively.
The invention discloses the structure that an analog demodulator is applied to Low Medium Frequency or ultralow intermediate frequency receiver, with reach with analogue transmission receiving terminal combination on advantage and advantage such as low energy expenditure, moreover, analog demodulator of the present invention utilize at least one calibrating installation, direct current displacement calibration circuit, and filter carry out DC potential offset calibration technology and filtering technique, problems such as DC potential skew that can produce with the analog demodulator that solves in a Low Medium Frequency receiver and high order harmonic component item.
The above only is preferred embodiment of the present invention, and all equivalences of making according to claim of the present invention change and revise, and all should belong to covering scope of the present invention.
Claims (50)
1. analog demodulator that is used for a Low Medium Frequency receiver, this analog demodulator includes:
At least one receiving circuit is used for receiving respectively the pair of orthogonal signal;
At least one calibrating installation is used for reducing the DC potential skew of this quadrature signal;
One oscillation source is used to provide a reference clock;
One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency;
At least one frequency mixer is connected in this local oscillations generator, and is connected in after this calibrating installation, is used for respectively this quadrature signal being carried out mixing; And
At least one direct current displacement calibration circuit is connected in this frequency mixer, is used for eliminating the DC potential skew that this frequency mixer itself is produced;
Wherein after this receiving circuit receives this quadrature signal that is transmitted by a front stage circuits respectively, this calibrating installation can reduce the DC potential skew of this quadrature signal, next when this frequency mixer cooperates this local oscillations generator respectively this quadrature signal to be carried out mixing, this direct current displacement calibration circuit can be eliminated the DC potential skew that this frequency mixer itself produced, and exports this quadrature signal after the mixing at last respectively.
2. analog demodulator as claimed in claim 1, it is to be an analog image cancellation demodulator.
3. analog demodulator as claimed in claim 1, wherein this calibrating installation is to prohibit filter, a high pass filter, perhaps other devices of adjustable potential shift for a band.
4. analog demodulator as claimed in claim 1, it comprises at least one amplifying device in addition, is connected in after this receiving circuit, is used for amplifying this quadrature signal.
5. analog demodulator as claimed in claim 1, wherein this direct current displacement calibration circuit is to be a controllable type current mirror, wherein this controllable type current mirror is that voltage signal with this quadrature signal is converted to current signal, and the bias current of input stage circuit of adjusting this frequency mixer is to identical value, and the area oscillation that is produced when eliminating this quadrature signal by this frequency mixer leaks.
6. analog demodulator as claimed in claim 1, wherein the characteristic frequency that this local oscillations generator produced is between global system for mobile communications or the radiofrequency signal of radio area network (WLAN) application and the arbitrary frequency between the fundamental frequency.
7. analog demodulator as claimed in claim 1, wherein this Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.
8. method that in an analog demodulator, lowers local oscillation leakage, this analog demodulator includes:
At least one receiving circuit is used for receiving respectively the pair of orthogonal signal;
At least one calibrating installation is used for reducing the DC potential skew of this quadrature signal to avoid local oscillation leakage;
One oscillation source is used to provide a reference clock;
One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency;
At least one frequency mixer is connected in this local oscillations generator, and is connected in after this calibrating installation, is used for respectively this quadrature signal being carried out mixing; And
At least one direct current displacement calibration circuit is connected in this frequency mixer, is used for reducing DC potential skew that this frequency mixer itself produced to avoid local oscillation leakage; This method includes:
Use this receiving circuit to receive this quadrature signal that is transmitted by a front stage circuits respectively;
Use this calibrating installation to reduce the DC potential skew of this quadrature signal;
Use this frequency mixer respectively this quadrature signal to be carried out mixing; And
Use this direct current displacement calibration circuit to eliminate the DC potential skew that this frequency mixer itself is produced.
9. method as claimed in claim 8, wherein this analog demodulator is to be an analog image cancellation demodulator.
10. method as claimed in claim 8, wherein this analog demodulator is to be used for a Low Medium Frequency receiver.
11. as the method for claim 10, wherein this Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.
12. method as claimed in claim 8, wherein this calibrating installation is to prohibit filter, a high pass filter, perhaps other devices of adjustable DC potential shift for a band.
13. method as claimed in claim 8, wherein this direct current displacement calibrating installation is to be a controllable type current mirror, wherein this controllable type current mirror is that voltage signal with this quadrature signal is converted to current signal, and the bias current of input stage circuit of adjusting this frequency mixer is to identical value, and the area oscillation that is produced when eliminating this quadrature signal by this frequency mixer leaks.
14. method as claimed in claim 8, wherein this analog demodulator comprises at least one amplifying device in addition, is connected in after this receiving circuit, is used for amplifying this quadrature signal.
15. an analog demodulator that is used for a Low Medium Frequency receiver, this analog demodulator includes:
At least one receiving circuit is used for receiving the pair of orthogonal signal;
At least one calibrating installation is used for reducing the DC potential skew of this quadrature signal;
One oscillation source is used to provide a reference clock;
One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; And
At least one frequency mixer is connected in this local oscillations generator, and is connected in after this calibrating installation, is used for respectively this quadrature signal being carried out mixing;
Wherein after this receiving circuit receives this quadrature signal that is transmitted by a front stage circuits respectively, this calibrating installation can reduce the DC potential skew of this quadrature signal, then this frequency mixer cooperates this local oscillations generator to carry out mixing to this quadrature signal respectively, exports this quadrature signal after the mixing at last respectively.
16. analog demodulator as claimed in claim 15, it is to be an analog image cancellation demodulator.
17. analog demodulator as claimed in claim 15, wherein this calibrating installation is to prohibit filter, a high pass filter filter, perhaps other devices of adjustable DC potential shift for a band.
18. analog demodulator as claimed in claim 15, it comprises at least one amplifying device in addition, is connected in after this receiving circuit, is used for amplifying this quadrature signal.
19. analog demodulator as claimed in claim 15, wherein the characteristic frequency that this local oscillations generator produced is between global system for mobile communications or radio frequency (RF) signal of radio area network (WLAN) application and the arbitrary frequency between the fundamental frequency.
20. analog demodulator as claimed in claim 15, wherein this Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.
21. one kind in an analog demodulator, use a collimation technique to lower the method for the local oscillation leakage of this analog demodulator, wherein this analog demodulator includes:
At least one receiving circuit is used for receiving respectively the pair of orthogonal signal;
At least one calibrating installation is used to provide this collimation technique, and to reduce the DC potential skew of this quadrature signal, wherein this DC potential skew is for causing the main cause of local oscillation leakage;
One oscillation source is used to provide a reference clock;
One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency; And
At least one frequency mixer is connected in this local oscillations generator, and is connected in after this calibrating installation, is used for respectively this quadrature signal being carried out mixing;
This method includes:
Use this receiving circuit to receive this quadrature signal that is transmitted by a front stage circuits respectively;
Use this calibrating installation to reduce the DC potential skew of this quadrature signal;
Use this frequency mixer respectively this quadrature signal to be carried out mixing; And
This quadrature signal after the output mixing.
22. as the method for claim 21, wherein this analog demodulator is to be an analog image cancellation demodulator.
23. as the method for claim 21, wherein this analog demodulator is to be used for a Low Medium Frequency receiver.
24. as the method for claim 23, wherein this Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.
25. as the method for claim 21, wherein this calibrating installation is to prohibit filter, a high pass filter, perhaps other devices of adjustable DC potential shift for a band.
26. as the method for claim 21, wherein this analog demodulator comprises at least one amplifying device in addition, is connected in after this receiving circuit, is used for amplifying this quadrature signal.
27. one kind be used for a Low Medium Frequency receiver (an analog demodulator, this analog demodulator includes:
At least one receiving circuit is used for receiving respectively the pair of orthogonal signal;
One oscillation source is used to provide a reference clock;
One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency;
At least one frequency mixer is connected in this local oscillations generator, and is connected in after this receiving circuit device, is used for respectively this quadrature signal being carried out mixing; And
At least one direct current displacement calibration circuit is connected in this frequency mixer, is used for eliminating the DC potential skew that this frequency mixer itself is produced;
Wherein after this receiving circuit receives this quadrature signal that is transmitted by a front stage circuits respectively, this frequency mixer cooperates this local oscillations generator to carry out mixing to this quadrature signal respectively, this direct current displacement calibration circuit can be eliminated the DC potential skew that this frequency mixer itself produced simultaneously, exports this quadrature signal after the mixing at last respectively.
28. analog demodulator as claimed in claim 27, it is to be an analog image cancellation demodulator.
29. analog demodulator as claimed in claim 27, it comprises at least one amplifying device in addition, is connected in after this receiving circuit, is used for amplifying this quadrature signal.
30. analog demodulator as claimed in claim 27, wherein this direct current displacement calibrating installation is to be a controllable type current mirror, wherein this controllable type current mirror is that voltage signal with this quadrature signal is converted to current signal, and the bias current of input stage circuit of adjusting this frequency mixer is to identical value, and the area oscillation that is produced when eliminating this quadrature signal by this frequency mixer leaks.
31. analog demodulator as claimed in claim 27, wherein the characteristic frequency that this local oscillations generator produced is between global system for mobile communications or the radiofrequency signal of radio area network (WLAN) application and the arbitrary frequency between the fundamental frequency.
32. analog demodulator as claimed in claim 27, wherein this Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.
33. a method that is used for lowering local oscillation leakage in an analog demodulator, wherein this analog demodulator includes:
At least one receiving circuit is used for receiving respectively the pair of orthogonal signal;
One oscillation source is used to provide a reference clock;
One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency;
At least one frequency mixer is connected in this local oscillations generator, and is connected in after this receiving circuit, is used for respectively this quadrature signal being carried out mixing; And
At least one direct current displacement calibration circuit is connected in this frequency mixer, is used for eliminating the DC potential skew that this frequency mixer itself is produced, and wherein this DC potential skew is for causing the main cause of local oscillation leakage;
This method includes:
Use this receiving circuit to receive this quadrature signal that is transmitted by a front stage circuits respectively;
Use this frequency mixer respectively this quadrature signal to be carried out mixing;
The DC potential skew of using this direct current displacement calibrating installation circuit for eliminating this frequency mixer itself to be produced; And
This quadrature signal after the output mixing.
34. as the method for claim 33, wherein this analog demodulator is to be an analog image cancellation demodulator.
35. as the method for claim 33, wherein this analog demodulator is to be used for a Low Medium Frequency receiver.
36. as the method for claim 35, wherein this Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.
37. method as claim 33, wherein this direct current displacement calibrating installation is to be a controllable type current mirror, wherein this controllable type current mirror is that voltage signal with this quadrature signal is converted to current signal, and the bias current of input stage circuit of adjusting this frequency mixer leaks to eliminate the area oscillation that frequency mixer was produced to identical value.
38. as the method for claim 33, wherein this analog demodulator includes at least one amplifying device in addition, is connected in after this receiving circuit, is used for amplifying this quadrature signal.
39. one kind is used for the analog demodulator described in the Low Medium Frequency receiver, this analog demodulator is to be an analog image cancellation demodulator, has the function of image cancellation, and this analog demodulator includes:
At least one receiving circuit is used for receiving respectively the pair of orthogonal signal;
One oscillation source is used to provide a reference clock;
One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency;
At least one frequency mixer is connected in this local oscillations source generator, is used for respectively this quadrature signal being carried out mixing; And
One filter is connected in this local oscillations generator, is used for eliminating the high order harmonic component item that this local oscillations produces.
40. analog demodulator as claimed in claim 39, the ability of the image cancellation of this analog demodulator wherein, be to look closely, and whether the amplitude of four input end signals of this local oscillations generator is identical in the quadrature of four input end signals of this local oscillations generator gap 90 degree whether mutually.
41. analog demodulator as claimed in claim 39, wherein this filter is to be a polyphase filters, a low pass filter or digital filter.
42. analog demodulator as claimed in claim 39, wherein the characteristic frequency that this local oscillations generator produced is between global system for mobile communications or the radiofrequency signal of radio area network (WLAN) application and the arbitrary frequency between the fundamental frequency.
43. analog demodulator as claimed in claim 39, wherein this Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.
44. one kind is used a filtering technique in an analog demodulator, to eliminate the method for high order harmonic component item, wherein this analog demodulator includes:
At least one receiving circuit is used for receiving respectively the pair of orthogonal signal;
One oscillation source is used to provide a reference clock;
One local oscillations generator is connected in this oscillation source, is used for the reference clock that this oscillation source produces is downconverted to a characteristic frequency, and wherein the high order harmonic component item is produced by this local oscillations;
At least one frequency mixer is connected in this local oscillations generator, is used for respectively this quadrature signal being carried out mixing; And
One filter is connected in after this local oscillations generator, is used to provide this filtering technique, to eliminate the high order harmonic component item that this local oscillations is produced;
This method includes:
Use this oscillation source to produce reference clock;
Use this local oscillations generator that the reference clock that this oscillation source produces is downconverted to a characteristic frequency, wherein the reference clock of this characteristic frequency can be used for respectively this quadrature signal being carried out mixing for this frequency mixer; And
Use this filter to eliminate the high order harmonic component item that this local oscillations produces.
45. method as claim 44, wherein this analog demodulator is to be an analog image cancellation demodulator, function with image cancellation, the ability of the image cancellation of this analog demodulator wherein, be to look closely, and whether the amplitude of four input end signals of this local oscillations generator is identical in the quadrature of four input end signals of this local oscillations generator gap 90 degree whether mutually.
46. as the method for claim 44, wherein this filter is to be a polyphase filters, a low pass filter or digital filter.
47. as the method for claim 44, wherein this high order harmonic component item is to be primarily aimed at three rank and five order harmonics items.
48. analog demodulator as claimed in claim 44, wherein the characteristic frequency that this local oscillations generator produced is between global system for mobile communications or the radiofrequency signal of radio area network (WLAN) application and the arbitrary frequency between the fundamental frequency.
49. as the method for claim 44, wherein this analog demodulator is to be used for a Low Medium Frequency receiver.
50. analog demodulator as claimed in claim 49, wherein this Low Medium Frequency receiver is to be applied in global system for mobile communications or radio area network (WLAN) communication system.
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| CNB031201865A CN100486122C (en) | 2003-03-12 | 2003-03-12 | Analog demodulator and method for reducing local oscillation leakage and eliminating high order harmonic |
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| CNB031201865A CN100486122C (en) | 2003-03-12 | 2003-03-12 | Analog demodulator and method for reducing local oscillation leakage and eliminating high order harmonic |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN100426686C (en) * | 2005-06-01 | 2008-10-15 | 鼎芯通讯（上海）有限公司 | Low mid frequency wireless receiver of automatic calibration circuit with image suppression |
| CN103208978A (en) * | 2012-01-12 | 2013-07-17 | 上海创远仪器技术股份有限公司 | Broadband self-adaption harmonic elimination device based on method of images |
| CN103546404A (en) * | 2012-07-12 | 2014-01-29 | 创杰科技股份有限公司 | Direct conversion transceiver for compensating DC offset and operation method thereof |
| CN103607213A (en) * | 2013-11-06 | 2014-02-26 | 苏州磐启微电子有限公司 | Low and medium frequency receiver with high image rejection ratio |
| WO2014139409A1 (en) * | 2013-03-11 | 2014-09-18 | Huawei Technologies Co., Ltd. | Current conveyor circuit and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100426686C (en) * | 2005-06-01 | 2008-10-15 | 鼎芯通讯（上海）有限公司 | Low mid frequency wireless receiver of automatic calibration circuit with image suppression |
| CN103208978A (en) * | 2012-01-12 | 2013-07-17 | 上海创远仪器技术股份有限公司 | Broadband self-adaption harmonic elimination device based on method of images |
| CN103208978B (en) * | 2012-01-12 | 2016-08-03 | 上海创远仪器技术股份有限公司 | Broadband self adaptation harmonic elimination device based on image method |
| CN103546404A (en) * | 2012-07-12 | 2014-01-29 | 创杰科技股份有限公司 | Direct conversion transceiver for compensating DC offset and operation method thereof |
| CN103546404B (en) * | 2012-07-12 | 2016-09-07 | 密克罗奇普技术公司 | Direct conversion transceiver for compensating DC offset and operation method thereof |
| WO2014139409A1 (en) * | 2013-03-11 | 2014-09-18 | Huawei Technologies Co., Ltd. | Current conveyor circuit and method |
| US8928407B2 (en) | 2013-03-11 | 2015-01-06 | Futurewei Technologies, Inc. | Current conveyor circuit and method |
| CN105340185A (en) * | 2013-03-11 | 2016-02-17 | 华为技术有限公司 | Current conveyor circuit and method |
| CN103607213A (en) * | 2013-11-06 | 2014-02-26 | 苏州磐启微电子有限公司 | Low and medium frequency receiver with high image rejection ratio |
| CN103607213B (en) * | 2013-11-06 | 2016-04-13 | 上海磐启微电子有限公司 | A kind of low intermediate frequency receiver of high image rejection ratio |
| WO2021098718A1 (en) * | 2019-11-18 | 2021-05-27 | 深圳市中兴微电子技术有限公司 | Radio frequency receiving link and radio frequency transceiving device |
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| CN100486122C (en) | 2009-05-06 |
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