CN102497341A - Method and system for local oscillator leakage calibration - Google Patents
Method and system for local oscillator leakage calibration Download PDFInfo
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- CN102497341A CN102497341A CN2011103623937A CN201110362393A CN102497341A CN 102497341 A CN102497341 A CN 102497341A CN 2011103623937 A CN2011103623937 A CN 2011103623937A CN 201110362393 A CN201110362393 A CN 201110362393A CN 102497341 A CN102497341 A CN 102497341A
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Abstract
The invention discloses a method and a system for local oscillator leakage calibration, which are used for calibrating local oscillator leakage of existing hardware equipment, simplifying calibration of the local oscillator leakage, increasing calibration speed of the local oscillator leakage and improving the efficiency thereof and are adaptive to dynamic deviation of parameters including frequency, temperature and using time and the like. The method includes that a signal feedback circuit is coupled with to-be-transmitted signals of a transmitting antenna to obtain a coupled signal, and the coupled signal is fed back to a data processor after being filtered and subjected to analog-digital conversion and mixed with a local oscillator signal; the data processor confirms the present local oscillator leakage power according to the signals fed back by the signal feedback circuit, and the local oscillator leakage voltage adjusting width can be confirmed according to the present local oscillator leakage power and the target local oscillator leakage power, the present offset compensation voltage of an analog-digital converter is adjusted according to the local oscillator leakage voltage adjusting width until the difference of the present local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value.
Description
Technical Field
The present invention relates to the field of communications, and in particular, to a local oscillator leakage calibration method and system.
Background
At present, in a base station RRU (Radio Remote Unit) architecture, a modulator is often used in a base station transmitter, local oscillator leakage may be inevitably introduced due to a plurality of non-ideal factors in practical application, for example, non-ideal factors such as device discreteness, asymmetry of a differential circuit implementation, dispersion of filtering capacitance and the like may cause differential transmission to have a dc component, and the dc component may be introduced into local oscillator leakage by combining with frequency conversion of the modulator.
In order to reduce local oscillator leakage in the prior art, the following modes are mainly adopted: the modulator shown in fig. 1 comprises a Digital-to-Analog Converter (DAC) 11, a filter 12, a modulator 13, at least one rf filter 14, and an open-loop calibration instrument 15 connected in series, wherein:
the digital-to-analog converter 11 is used for completing digital-to-analog conversion of the intermediate frequency data and outputting an orthogonal signal and an in-phase signal;
a filter 12, configured to filter out mirror images of the quadrature signal and the in-phase signal output by the digital-to-analog converter 11, and output the filtered quadrature signal and the filtered in-phase signal;
a modulator 13 for modulating the quadrature signal and the in-phase signal output from the filter 12, respectively;
the radio frequency filter 14 is used for suppressing the local oscillation signal so as to achieve the purpose of reducing local oscillation leakage;
and the open-loop calibration instrument 15 is used for measuring the local oscillator leakage power, calibrating the direct current according to the minimum stepping open-loop cycle until the value measured by the open-loop calibration instrument reaches the position of the target local oscillator leakage power value, and determining the appropriate direct current offset.
Although the calibration of local oscillator leakage can be realized through the multistage radio frequency filter 14 and the open-loop calibration instrument 15, so that the local oscillator leakage power reaches an ideal local oscillator leakage power value, the following technical defects are also brought at the same time:
(1) at least one radio frequency filter needs to be added to an original base station transmitter, and especially more radio frequency filters need to be added under the condition of more antennas, so that larger hardware resources need to be consumed, and the cost is increased;
(2) an open-loop calibration instrument is introduced into a base station transmitter, so that a corresponding test tool needs to be developed for the whole round-robin calibration process of the open-loop calibration instrument, the calibration process tends to be complex, and longer production time is occupied in the calibration process, so that the production efficiency is reduced;
(3) under the change of three dimensions of frequency, temperature and service time, the calibration offset selected by open-loop round-robin calibration of the open-loop calibration instrument cannot adapt to the change, the optimal offset point is easy to generate dynamic drift, and the long-term work of equipment is not facilitated.
Disclosure of Invention
In view of the above technical problems in the prior art, embodiments of the present invention provide a method and a system for calibrating local oscillator leakage, so as to calibrate local oscillator leakage through existing hardware devices, simplify the complexity of local oscillator leakage calibration, improve the speed and efficiency of local oscillator leakage calibration, and adapt to dynamic drift of parameters such as frequency, temperature, and service time.
A local oscillator leakage calibration system comprises a data processor, a digital-to-analog converter, a first filter, a modulator and a transmitting antenna which are sequentially connected, wherein a signal feedback circuit is also connected between the transmitting antenna and the data processor and is coupled with the transmitting antenna;
the signal feedback circuit is used for coupling a signal to be transmitted of the transmitting antenna to obtain a coupled signal, mixing the coupled signal with a local oscillator signal, and feeding the coupled signal back to the data processor after filtering and analog-to-digital conversion;
the data processor is used for determining the current local oscillator leakage power according to the signal fed back by the signal feedback circuit; and determining the adjustment width of the local oscillator leakage voltage at this time according to the current local oscillator leakage power and the target local oscillator leakage power, and adjusting the current offset compensation voltage of the digital-to-analog converter according to the adjustment width of the local oscillator leakage voltage at this time until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value.
Preferably, the signal feedback circuit is connected with a mixer, a second filter and an analog-to-digital converter in sequence from the transmitting antenna to the data processor, wherein:
the frequency mixer is used for mixing the coupled signal obtained by coupling with the local oscillator signal to obtain a mixed frequency signal and outputting the mixed frequency signal;
the second filter is used for filtering the mixed signal output by the mixer and outputting a filtered signal;
and the analog-to-digital converter is used for performing analog-to-digital conversion on the filtering signal output by the second filter and feeding back the obtained digital signal to the digital processor.
Preferably, the data processor adjusts the current offset compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width, and the specific application is as follows:
and within the range of the adjustment width of the local oscillator leakage voltage, adjusting the current bias compensation voltage of the digital-to-analog converter step by step according to the set voltage step length.
Preferably, the first filter includes a first sub-filter and a second sub-filter, and the first sub-filter and the second sub-filter are connected in parallel between the digital-to-analog converter and the modulator, where the digital-to-analog converter, the first sub-filter, and the modulator form a quadrature link, and the digital-to-analog converter, the second sub-filter, and the modulator form an in-phase link;
the first sub-filter filters the orthogonal signal output by the digital-to-analog converter to obtain a filtered orthogonal signal;
and the second sub-filter filters the in-phase signal output by the digital-to-analog converter to obtain a filtered in-phase signal.
Preferably, the data processor adjusts the current offset compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width, and the specific application is as follows:
adjusting the current first offset compensation voltage corresponding to the orthogonal link in the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold; or,
and adjusting the current second offset compensation voltage corresponding to the in-phase link in the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold.
Preferably, the data processor is further configured to, when the current first offset compensation voltage is adjusted within the adjustment width range of the local oscillator leakage voltage, and the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than a set power threshold, adjust the current second offset compensation voltage according to the adjustment width of the current local oscillator leakage power until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold;
or, when the current second offset compensation voltage is adjusted within the adjustment width range of the local oscillator leakage voltage, and the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than the set power threshold, adjusting the current first offset compensation voltage according to the adjustment width of the local oscillator leakage voltage until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold.
Preferably, an amplifier is further connected between the modulator and the transmitting antenna, and the amplifier is configured to amplify a signal output by the modulator.
Preferably, the data processor determines the local oscillator leakage voltage adjustment width at this time, and the specific application is as follows:
and determining the local oscillator leakage voltage adjustment width corresponding to the current local oscillator leakage power from the preset corresponding relation among the local oscillator leakage power, the target local oscillator leakage power and the local oscillator leakage voltage adjustment width, and determining the determined local oscillator leakage voltage adjustment width as the local oscillator leakage voltage adjustment width at this time.
The embodiment of the present invention further provides a method for calibrating local oscillator leakage by using the local oscillator leakage calibration system, where the method includes:
the signal feedback circuit is coupled with a signal to be transmitted of the transmitting antenna to obtain a coupled signal, and the coupled signal and a local oscillator signal are subjected to frequency mixing, filtering and analog-to-digital conversion and then fed back to the data processor;
the data processor determines the current local oscillator leakage power according to the signal fed back by the signal feedback circuit; and determining the adjustment width of the local oscillator leakage voltage at this time according to the current local oscillator leakage power and the target local oscillator leakage power, and adjusting the current offset compensation voltage of the digital-to-analog converter according to the adjustment width of the local oscillator leakage voltage at this time until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value.
Preferably, the adjusting, by the data processor, the current offset compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width includes:
and within the range of the adjustment width of the local oscillator leakage voltage, adjusting the current bias compensation voltage of the digital-to-analog converter step by step according to the set voltage step length.
Preferably, the first filter of the system includes a first sub-filter and a second sub-filter, and the first sub-filter and the second sub-filter are connected in parallel and are connected between the digital-to-analog converter and the modulator, where the digital-to-analog converter, the first sub-filter and the modulator form a quadrature link, and the digital-to-analog converter, the second sub-filter and the modulator form an in-phase link;
the first sub-filter filters the orthogonal signal output by the digital-to-analog converter to obtain a filtered orthogonal signal;
and the second sub-filter filters the in-phase signal output by the digital-to-analog converter to obtain a filtered in-phase signal.
Preferably, the data processor adjusts the current offset compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width, and the specific application is as follows:
adjusting the current first offset compensation voltage corresponding to the orthogonal link in the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold; or,
and adjusting the current second offset compensation voltage corresponding to the in-phase link in the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold.
Preferably, the method further comprises: the data processor adjusts the current first offset compensation voltage within the adjustment width range of the current local oscillator leakage voltage, and adjusts the current second offset compensation voltage according to the adjustment width of the current local oscillator leakage voltage when the difference between the current local oscillator leakage power and the target local oscillator leakage power is larger than a set power threshold value until the difference between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value;
or, the data processor adjusts the current second offset compensation voltage within the local oscillator leakage voltage adjustment width range, and adjusts the current first offset compensation voltage according to the local oscillator leakage voltage adjustment width when the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than a set power threshold value until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold value.
Preferably, the determining, by the data processor, the local oscillator leakage voltage adjustment width at this time includes:
and determining the local oscillator leakage voltage adjustment width corresponding to the current local oscillator leakage power from the preset corresponding relation among the local oscillator leakage power, the target local oscillator leakage power and the local oscillator leakage voltage adjustment width, and determining the determined local oscillator leakage voltage adjustment width as the local oscillator leakage voltage adjustment width at this time.
In the embodiment of the invention, the current local oscillator leakage voltage is determined according to a signal fed back by a signal feedback circuit connected between a transmitting antenna and a data processor, and the local oscillator leakage voltage adjustment width is determined according to the current local oscillator leakage power and the target local oscillator leakage power; and adjusting the current bias compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold value. By adopting the technical scheme, on one hand, the calibration of the local oscillator leakage can be realized according to the existing hardware equipment, a plurality of radio frequency filters and open-loop calibration instruments do not need to be additionally arranged, the hardware resources are saved, and the cyclic measurement is not needed through the open-loop calibration instruments, so that the calibration of the local oscillator leakage is simplified, and the speed and the efficiency of the calibration of the local oscillator leakage are improved; on the other hand, the calibration of local oscillator leakage is realized by adopting a signal feedback mode, and the dynamic drift of parameters such as frequency, temperature, service time and the like can be adapted.
Drawings
Fig. 1 is a schematic structural diagram of a local oscillator leakage calibration system in the prior art;
fig. 2 is a schematic structural diagram of a local oscillator leakage calibration system in the embodiment of the present invention;
fig. 3 is a schematic structural diagram of a local oscillator leakage calibration system in practical application in the embodiment of the present invention;
fig. 4 is a second schematic structural diagram of a local oscillator leakage calibration system according to an embodiment of the present invention;
fig. 5 is a third schematic structural diagram of a local oscillator leakage calibration system in the embodiment of the present invention;
fig. 6 is a fourth schematic structural diagram of a local oscillator leakage calibration system in the embodiment of the present invention;
fig. 7 is a local oscillator leakage characteristic diagram of a certain modulator in an actual application scenario in the embodiment of the present invention;
fig. 8 is a flowchart of a method for calibrating local oscillator leakage according to an embodiment of the present invention.
Detailed Description
In view of the above technical problems in the prior art, embodiments of the present invention provide a method and a system for calibrating local oscillator leakage, so as to calibrate local oscillator leakage through existing hardware devices, simplify the complexity of local oscillator leakage calibration, improve the speed and efficiency of local oscillator leakage calibration, and adapt to dynamic drift of parameters such as frequency, temperature, and service time. The local oscillator leakage calibration system comprises a data processor, a digital-to-analog converter, a first filter, a modulator and a transmitting antenna which are sequentially connected, wherein a signal feedback circuit is also connected between the transmitting antenna and the data processor and is coupled with the transmitting antenna; the signal feedback circuit is used for coupling a signal to be transmitted of the transmitting antenna to obtain a coupled signal, mixing the coupled signal with a local oscillator signal, and feeding the coupled signal back to the data processor after filtering and analog-to-digital conversion; the data processor is used for determining the current local oscillator leakage power according to the signal fed back by the signal feedback circuit; and determining the adjustment width of the local oscillator leakage voltage at this time according to the current local oscillator leakage power and the target local oscillator leakage power, and adjusting the current offset compensation voltage of the digital-to-analog converter according to the adjustment width of the local oscillator leakage voltage at this time until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value. By adopting the technical scheme, on one hand, the calibration of the local oscillator leakage can be realized according to the existing hardware equipment, a plurality of radio frequency filters and open-loop calibration instruments do not need to be additionally arranged, the hardware resources are saved, and the cyclic measurement is not needed through the open-loop calibration instruments, so that the calibration of the local oscillator leakage is simplified, and the speed and the efficiency of the calibration of the local oscillator leakage are improved; on the other hand, the calibration of local oscillator leakage is realized by adopting a signal feedback mode, and the dynamic drift of parameters such as frequency, temperature, service time and the like can be adapted.
The technical scheme of the invention is described in detail in the following with reference to the attached drawings of the specification.
Referring to fig. 2, which is a schematic structural diagram of a local oscillator leakage calibration system in an embodiment of the present invention, the system may include: the digital-to-analog converter comprises a data processor 21, a digital-to-analog converter 22, a first filter 23, a modulator 24 and a transmitting antenna 25 which are connected in sequence, wherein a signal feedback circuit 26 is also connected between the transmitting antenna 25 and the data processor 21, and the signal feedback circuit 26 is coupled with the transmitting antenna 25; wherein:
a data processor 21 for processing the intermediate frequency signal and outputting the processed signal;
a digital-to-analog converter 22, configured to perform digital-to-analog conversion on the signal output by the data processor 21, and output an analog signal;
a filter 23, configured to filter an image signal from the analog signal output by the digital-to-analog converter 22, and output an analog signal after the image signal is filtered;
a modulator 24 for modulating the analog signal output from the filter 23 and transmitting the modulated analog signal through the transmitting antenna 24;
the signal feedback circuit 26 is configured to couple a signal to be transmitted of the transmitting antenna 25 to obtain a coupled signal, mix the coupled signal with a local oscillator signal, filter the frequency mixed signal, perform analog-to-digital conversion on the frequency mixed signal, and feed the frequency mixed signal back to the data processor;
the data processor 21 is configured to determine a current local oscillator leakage power according to the signal fed back by the signal feedback circuit 26; and determining the adjustment width of the local oscillator leakage voltage of the current time according to the current local oscillator leakage power and the target local oscillator leakage power, and adjusting the current offset compensation voltage of the digital-to-analog converter 22 according to the adjustment width of the local oscillator leakage voltage of the current time until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value. For example, the variation range of the offset compensation voltage before the digital-to-analog converter 22 performs digital conversion is-10 mA to 10mA at a resolution of 16 bit.
The data processor 21 in the embodiment of the present invention may be a DSP (Digital Signal Processing), an FPGA (Field Programmable Gate Array), or the like.
Preferably, in combination with practical applications, the signal feedback circuit 26 in the embodiment of the present invention may include, from the transmitting antenna 25 to the data processor 21: a mixer 261, a second filter 262 and an analog-to-digital converter 263 are connected in sequence, as shown in fig. 3, wherein:
the frequency mixer 261 is configured to mix the coupled signal obtained through coupling with the local oscillator signal to obtain a mixed frequency signal and output the mixed frequency signal;
a second filter 262 for filtering the mixed signal output from the mixer 261 and outputting a filtered signal;
an analog-to-digital converter 263, configured to perform analog-to-digital conversion on the filtered signal output by the second filter 262, and feed back the obtained digital signal to the digital processor 21.
Preferably, the data processor 21 adjusts the current offset compensation voltage of the digital-to-analog converter 22 according to the local oscillator leakage voltage adjustment width at this time, and may adopt the following method:
and within the range of the adjustment width of the local oscillator leakage voltage, adjusting the current bias compensation voltage of the digital-to-analog converter step by step according to the set voltage step length.
Preferably, for the case that the quadrature signal and the in-phase signal need to be output, the first filter 23 in the embodiment of the present invention may include a first sub-filter 231 and a second sub-filter 232, which may be as shown in fig. 4, the first sub-filter 231 and the second sub-filter 232 are connected in parallel and connected between the digital-to-analog converter 22 and the modulator 24, wherein the digital-to-analog converter 22, the first sub-filter 231 and the modulator 24 may form a quadrature link, and the digital-to-analog converter 22, the second sub-filter 232 and the modulator 24 may form an in-phase link;
the first sub-filter 231 filters the orthogonal signal output by the digital-to-analog converter 22 to obtain a filtered orthogonal signal;
the second sub-filter 232 filters the in-phase signal output by the digital-to-analog converter 22 to obtain a filtered in-phase signal.
Preferably, based on the system structure shown in fig. 4, the data processor 21 adjusts the current offset compensation voltage of the digital-to-analog converter 22 according to the local oscillator leakage voltage adjustment width, specifically, the following method may be adopted:
adjusting the current first offset compensation voltage corresponding to the orthogonal link in the digital-to-analog converter 22 according to the local oscillator leakage voltage adjustment width until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to a set power threshold; or,
and adjusting the current second offset compensation voltage corresponding to the in-phase link in the digital-to-analog converter 22 according to the local oscillator leakage voltage adjustment width until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold.
Preferably, to further ensure the success rate of calibrating the local oscillator leakage, the data processor 21 is further configured to, when the current first offset compensation voltage is adjusted within the local oscillator leakage voltage adjustment width, and the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than a set power threshold, adjust the current second offset compensation voltage according to the local oscillator leakage voltage adjustment width until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold;
or, when the current second offset compensation voltage is adjusted within the adjustment width range of the local oscillator leakage voltage, and the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than the set power threshold, adjusting the current first offset compensation voltage according to the adjustment width of the local oscillator leakage voltage until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold.
Preferably, to further improve the effect of calibrating the local oscillator leakage, an amplifier 27 is further connected between the modulator 24 and the transmitting antenna 25, wherein the amplifier 27 is configured to amplify the signal output by the modulator 24. I.e. an amplifier 27 may be connected between the modulator 24 and the transmitting antenna 25 in fig. 2, 3 and 4 as described above. As shown in fig. 5, an amplifier 27 is connected between the modulator 24 and the transmitting antenna 25 shown in fig. 4.
In the embodiment of the present invention, the specific structure of the signal feedback circuit 26 shown in fig. 4 and fig. 5 may be the structure of the signal feedback circuit 26 shown in fig. 3, and as shown in fig. 6, the signal feedback circuit 26 shown in fig. 5 includes a mixer 261, a second filter 262, and an analog-to-digital converter 263.
Preferably, the data processor 21 determines the local oscillator leakage voltage adjustment width at this time, and the specific application is as follows:
and determining the local oscillator leakage voltage adjustment width corresponding to the current local oscillator leakage power from the preset corresponding relation among the local oscillator leakage power, the target local oscillator leakage power and the local oscillator leakage voltage adjustment width, and determining the determined local oscillator leakage voltage adjustment width as the local oscillator leakage voltage adjustment width at this time. In the embodiment of the present invention, the corresponding relationship between the local oscillator leakage power, the target local oscillator leakage power, and the local oscillator leakage voltage adjustment width may be set according to an empirical value, as shown in table 1.
Table 1 is a table of correspondence between local oscillator leakage power, target local oscillator leakage power, and local oscillator leakage voltage adjustment width
| Local oscillator leakage power (dB) | Local oscillator leakage voltage regulating width (uv) | Target local oscillator leakage power (dB) |
| -30 | 8000 | -70 |
| -40 | 2000 | -70 |
| -50 | 800 | -70 |
| -60 | 200 | -70 |
The initial value of the local oscillator leakage power is about-40 dBm, typical leakage performance is as shown in fig. 7, the local oscillator leakage voltage adjustment width is set to Δ x (uv) (for example, Δ x is 2000uv, when the voltage step is 15uv, adjustment can be saved by (2000/15)) and the local oscillator leakage power variation range is about-50 dBm to-35 dBm, and the adjustment direction can be adjusted by ± Δ x on the in-phase link and the quadrature link.
In the embodiment of the present invention, in addition to determining the local oscillator leakage voltage adjustment width according to the correspondence shown in table 1, the local oscillator leakage voltage adjustment width may also be determined and obtained according to the following manner:
step 1, assuming that the maximum value of the local oscillator leakage power measured in the adjustment process is P2(dBm), the bias voltage corresponding to P2 is X2(uv), the current local oscillator leakage power measured is P1(dBm), and the bias voltage X1(uv) corresponding to P1 can be obtained according to the following formula (1):
20 log (X2) -20 log (X1) P2-P1 formula (1);
step 2, the target local oscillator leakage power P3(dBm) is-70 dBm, P3-P1 is Δ P is-30 dB, and the bias voltage corresponding to the target local oscillator leakage power P3 obtained according to the formula (2) is X3 (uV):
20 log (X2) -20 log (X1) P3-P1 formula (2);
according to the obtained X3 and X1, the adjustment width delta X of the local oscillator leakage voltage is (X3-X1), and the step length of each voltage is set to be 15uv, so that the step number needing to be adjusted is (X3-X1)/15. An embodiment of the present invention further provides a local oscillator leakage calibration method, where the method is based on the foregoing system, and the method is as shown in fig. 8, and includes:
Preferably, in the above step 803, the adjusting, by the data processor 21, the current offset compensation voltage of the digital-to-analog converter 22 according to the local oscillator leakage voltage adjustment width includes:
and within the adjustment width range of the local oscillator leakage voltage, adjusting the current bias compensation voltage of the digital-to-analog converter 22 according to the set voltage step length.
Preferably, the first filter 23 of the system includes a first sub-filter 231 and a second sub-filter 232, and the first sub-filter 231 and the second sub-filter 232 are connected in parallel and between the digital-to-analog converter 22 and the modulator 24, wherein the digital-to-analog converter 22, the first sub-filter 231 and the modulator 24 form a quadrature link, and the digital-to-analog converter 22, the second sub-filter 232 and the modulator 24 form an in-phase link;
the first sub-filter 231 filters the orthogonal signal output by the digital-to-analog converter 22 to obtain a filtered orthogonal signal;
the second sub-filter 232 filters the in-phase signal output by the digital-to-analog converter 22 to obtain a filtered in-phase signal.
Preferably, in the above step 803, the data processor 21 adjusts the current offset compensation voltage of the digital-to-analog converter 22 according to the local oscillator leakage voltage adjustment width, and the specific application is as follows:
adjusting the current first offset compensation voltage corresponding to the orthogonal link in the digital-to-analog converter 22 according to the local oscillator leakage voltage adjustment width until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to a set power threshold; or,
and adjusting the current second offset compensation voltage corresponding to the in-phase link in the digital-to-analog converter 22 according to the local oscillator leakage voltage adjustment width until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold.
Preferably, the flow step 803 further includes the steps of:
the data processor 21 adjusts the current first offset compensation voltage within the current local oscillator leakage voltage adjustment width range, and when the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than a set power threshold, adjusts the current second offset compensation voltage according to the current local oscillator leakage voltage adjustment width until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold;
or, the data processor 21 adjusts the current second offset compensation voltage within the present local oscillator leakage voltage adjustment width range, and when the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than a set power threshold, adjusts the current first offset compensation voltage according to the present local oscillator leakage voltage adjustment width until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold.
Preferably, in the above step 803, the determining, by the data processor 21, the local oscillator leakage voltage adjustment width includes:
and determining the local oscillator leakage voltage adjustment width corresponding to the current local oscillator leakage power from the preset corresponding relation among the local oscillator leakage power, the target local oscillator leakage power and the local oscillator leakage voltage adjustment width, and determining the determined local oscillator leakage voltage adjustment width as the local oscillator leakage voltage adjustment width at this time.
In the embodiment of the invention, on one hand, the calibration of the local oscillator leakage can be realized according to the existing hardware equipment, a plurality of radio frequency filters and open-loop calibration instruments do not need to be additionally and newly added, the hardware resource is saved, and the cyclic measurement is not needed through the open-loop calibration instruments, so that the calibration of the local oscillator leakage is simplified, and the speed and the efficiency of the calibration of the local oscillator leakage are improved; on the other hand, the calibration of local oscillator leakage is realized by adopting a signal feedback mode, and the dynamic drift of parameters such as frequency, temperature, service time and the like can be adapted.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (14)
1. A local oscillator leakage calibration system comprises a data processor, a digital-to-analog converter, a first filter, a modulator and a transmitting antenna which are sequentially connected, and is characterized in that a signal feedback circuit is further connected between the transmitting antenna and the data processor and coupled with the transmitting antenna;
the signal feedback circuit is used for coupling a signal to be transmitted of the transmitting antenna to obtain a coupled signal, mixing the coupled signal with a local oscillator signal, and feeding the coupled signal back to the data processor after filtering and analog-to-digital conversion;
the data processor is used for determining the current local oscillator leakage power according to the signal fed back by the signal feedback circuit; and determining the adjustment width of the local oscillator leakage voltage at this time according to the current local oscillator leakage power and the target local oscillator leakage power, and adjusting the current offset compensation voltage of the digital-to-analog converter according to the adjustment width of the local oscillator leakage voltage at this time until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value.
2. The system of claim 1, wherein the signal feedback circuit has a mixer, a second filter, and an analog-to-digital converter connected in sequence from the transmit antenna to the data processor, wherein:
the frequency mixer is used for mixing the coupled signal obtained by coupling with the local oscillator signal to obtain a mixed frequency signal and outputting the mixed frequency signal;
the second filter is used for filtering the mixed signal output by the mixer and outputting a filtered signal;
and the analog-to-digital converter is used for performing analog-to-digital conversion on the filtering signal output by the second filter and feeding back the obtained digital signal to the digital processor.
3. The system according to claim 1, wherein the data processor adjusts the current offset compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width, and the specific application is:
and within the range of the adjustment width of the local oscillator leakage voltage, adjusting the current bias compensation voltage of the digital-to-analog converter step by step according to the set voltage step length.
4. The system of claim 1, wherein the first filter comprises a first sub-filter and a second sub-filter, the first sub-filter and the second sub-filter being connected in parallel between the digital-to-analog converter and the modulator, wherein the digital-to-analog converter, the first sub-filter and the modulator form a quadrature link, and the digital-to-analog converter, the second sub-filter and the modulator form an in-phase link;
the first sub-filter filters the orthogonal signal output by the digital-to-analog converter to obtain a filtered orthogonal signal;
and the second sub-filter filters the in-phase signal output by the digital-to-analog converter to obtain a filtered in-phase signal.
5. The system according to claim 4, wherein the data processor adjusts the current offset compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width, and the specific application is:
adjusting the current first offset compensation voltage corresponding to the orthogonal link in the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold; or,
and adjusting the current second offset compensation voltage corresponding to the in-phase link in the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold.
6. The system according to claim 5, wherein the data processor is further configured to, when the current first offset compensation voltage is adjusted within the adjustment width of the current local oscillator leakage voltage and the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than a set power threshold, adjust the current second offset compensation voltage according to the adjustment width of the current local oscillator leakage voltage until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold;
or, when the current second offset compensation voltage is adjusted within the adjustment width range of the local oscillator leakage voltage, and the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than the set power threshold, adjusting the current first offset compensation voltage according to the adjustment width of the local oscillator leakage voltage until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold.
7. The system of claim 1, wherein an amplifier is further coupled between the modulator and the transmit antenna, the amplifier being configured to amplify the signal output by the modulator.
8. The system of claim 1, wherein the data processor determines the local oscillator leakage voltage adjustment width by:
and determining the local oscillator leakage voltage adjustment width corresponding to the current local oscillator leakage power from the preset corresponding relation among the local oscillator leakage power, the target local oscillator leakage power and the local oscillator leakage voltage adjustment width, and determining the determined local oscillator leakage voltage adjustment width as the local oscillator leakage voltage adjustment width at this time.
9. A method for calibrating local oscillator leakage using the system of claim 1, comprising:
the signal feedback circuit is coupled with a signal to be transmitted of the transmitting antenna to obtain a coupled signal, and the coupled signal and a local oscillator signal are subjected to frequency mixing, filtering and analog-to-digital conversion and then fed back to the data processor;
the data processor determines the current local oscillator leakage power according to the signal fed back by the signal feedback circuit; and determining the adjustment width of the local oscillator leakage voltage at this time according to the current local oscillator leakage power and the target local oscillator leakage power, and adjusting the current offset compensation voltage of the digital-to-analog converter according to the adjustment width of the local oscillator leakage voltage at this time until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value.
10. The method of claim 9, wherein the data processor adjusting the current offset compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width comprises:
and within the range of the adjustment width of the local oscillator leakage voltage, adjusting the current bias compensation voltage of the digital-to-analog converter step by step according to the set voltage step length.
11. The method of claim 9, wherein the first filter of the system comprises a first sub-filter and a second sub-filter, the first sub-filter and the second sub-filter being connected in parallel and between the digital-to-analog converter and the modulator, wherein the digital-to-analog converter, the first sub-filter and the modulator form a quadrature link, and the digital-to-analog converter, the second sub-filter and the modulator form an in-phase link;
the first sub-filter filters the orthogonal signal output by the digital-to-analog converter to obtain a filtered orthogonal signal;
and the second sub-filter filters the in-phase signal output by the digital-to-analog converter to obtain a filtered in-phase signal.
12. The method according to claim 11, wherein the data processor adjusts the current offset compensation voltage of the digital-to-analog converter according to the local oscillator leakage voltage adjustment width at this time, and the specific application is:
adjusting the current first offset compensation voltage corresponding to the orthogonal link in the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold; or,
and adjusting the current second offset compensation voltage corresponding to the in-phase link in the digital-to-analog converter according to the local oscillator leakage voltage adjustment width until the difference value between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to a set power threshold.
13. The method of claim 12, further comprising:
the data processor adjusts the current first offset compensation voltage within the adjustment width range of the current local oscillator leakage voltage, and adjusts the current second offset compensation voltage according to the adjustment width of the current local oscillator leakage voltage when the difference between the current local oscillator leakage power and the target local oscillator leakage power is larger than a set power threshold value until the difference between the current local oscillator leakage power and the target local oscillator leakage power is smaller than or equal to the set power threshold value;
or, the data processor adjusts the current second offset compensation voltage within the local oscillator leakage voltage adjustment width range, and adjusts the current first offset compensation voltage according to the local oscillator leakage voltage adjustment width when the difference between the current local oscillator leakage power and the target local oscillator leakage power is greater than a set power threshold value until the difference between the current local oscillator leakage power and the target local oscillator leakage power is less than or equal to the set power threshold value.
14. The method of claim 9, wherein the data processor determining the local oscillator leakage voltage adjustment width comprises:
and determining the local oscillator leakage voltage adjustment width corresponding to the current local oscillator leakage power from the preset corresponding relation among the local oscillator leakage power, the target local oscillator leakage power and the local oscillator leakage voltage adjustment width, and determining the determined local oscillator leakage voltage adjustment width as the local oscillator leakage voltage adjustment width at this time.
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