KR20150100032A - Apparatus and method for phase mismatch compensation in communication apparatus - Google Patents

Abstract

The present invention is to control a transmission rate in a communication apparatus. According to an embodiment of the present invention, the communication apparatus calibrates phase difference mismatch by using a mismatched control code value for a signal phase difference calibration, and calibrates the phase difference mismatch with respect to a predetermined phase difference value. Accordingly, signal transmission can be effectively performed by calibrating the signal phase mismatch in the communication apparatus.

Description

[0001] APPARATUS AND METHOD FOR PHASE MISMATCH COMPENSATION IN COMMUNICATION APPARATUS [0002]

The present invention relates to the calibration of phase difference disparities occurring in a communication device.

Radio frequency (RF) transceivers are widely used in modern wireless communications. The RF transceiver includes a receiver for converting and demodulating the received RF signal into a baseband I (Inphase) signal and a Q (quadrature phase) signal, and a transmitter for converting and modulating the baseband IQ signal into an RF signal. One of the important criteria for evaluating RF transmission efficiency in most existing wireless communication standards, namely General Packet Radio Service (GPRS), Wideband Code Multiple Access (WCDMA) / High Speed Packet Access (HSPA) and Long Term Evolution (LTE) (Error Vector Magnitude). The EVM is affected by signal to noise ratio (SNR), phase noise, linearity, IQ origin offset, IQ channel mismatch, and the like. Among these factors, IQ origin offset or IQ channel mismatch can occur in various forms due to defects in the RF manufacturing process. Therefore, a calibration process is required.

One embodiment of the present invention provides an apparatus and method for calibrating a phase mismatch of a signal in a communication device.

Another embodiment of the present invention provides an apparatus and method for determining a signal phase mismatch control value in a communication device.

Another embodiment of the present invention provides an apparatus and method for increasing transmission efficiency in a communication apparatus.

A communication apparatus according to an embodiment of the present invention includes a control unit for checking a mismatch control code value and a calibration unit for compensating for a phase mismatch between a plurality of signals using an mismatch control code value, And the phase mismatch is calibrated based on the value.

A method for calibrating a signal phase difference in a communication apparatus according to an exemplary embodiment of the present invention includes calibrating a phase mismatch using an mismatch control code value and transmitting a compensated signal through the calibration process, The calibration process compensates for the phase mismatch based on a predetermined phase difference value.

The communication apparatus can perform efficient signal transmission by calibrating the phase mismatch of the signal.

1 shows an example of a communication apparatus according to an embodiment of the present invention.
Figure 2 illustrates an example of operation of an apparatus for applying IQ mismatch calibration in a communication device according to an embodiment of the present invention.
FIG. 3 shows an example of the result of IQ cap code determination in the communication device according to the embodiment of the present invention.
FIG. 4 illustrates an example of a process of determining an IQ cap code in a communication apparatus according to an embodiment of the present invention.
FIG. 5 shows an example of a signal phase mismatch calibration process in a communication apparatus according to an embodiment of the present invention.
6 illustrates an example of multipath calibration by a modem and an RF stage in a communication apparatus according to an embodiment of the present invention.
FIG. 7 illustrates an example of RF-only single-path calibration according to an embodiment of the present invention.
FIG. 8 shows an example of a process for determining a cap code considering a temperature range according to an embodiment of the present invention.
FIG. 9 illustrates an example of a process of applying a cap code determined in consideration of a temperature range according to an embodiment of the present invention.
10 shows a block diagram of an apparatus for IQ mismatch calibration in a communication device according to an embodiment of the present invention.
Figure 11 shows the results of a simulation of the performance according to the proposed algorithm according to an embodiment of the present invention.

Hereinafter, the operation principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. The following terms are defined in consideration of the functions of the present invention, and these may be changed according to the intention of the user, the operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

The present invention will now be described in the context of a technique for calibrating phase difference disparity in a communication device.

Baseband Sinusoidal A single signal is generated from the modem. The single signal is transmitted to the RF and converted into an RF signal by the transmitter. An untransformed RF signal is detected by an envelope detector at the RF output and is converted back to the baseband signal. The converted baseband signal is retransmitted to the modem to check for IQ imperfection. In this way, the IQ mismatch of the RF stage is calibrated by the digital domain modem through the phase and amplitude adjustment of the baseband IQ signal. When calibration starts, the modem checks the envelope of the RF output signal. If the output signal envelope falls below a certain level, the modem detects that the calibration is complete and corrects the digital range calibration value.

As transmission without SAW filters becomes a major technology, only a single drive amplifier is allowed to reduce RX band noise in RF. However, single pass RF including the single drive amplifier is difficult to meet wide gain wide range. In this case, the digital domain IQ calibration can be performed in only one RF short path, i.e., a high gain RF short path. As a result, low EVM performance is performed on the non-calibrated RF short path. In order to obtain a good EVM in multipath RF transmission, it is necessary that IQ calibration takes place in all RF short paths. On the other hand, modems should be done on a single path, while others should be treated as RF itself.

Moreover, 16-QAM modulation is widely used, but 256-QAM modulation can be used to increase the communication data rate. The requirement for IQ mismatch calibration is more important when 256-QAM modulation is applied in extremely dense space with inter-symbol spacing. In this situation, if the IQ calibration is made only in the nominal condition, the data rate can be reduced by the temperature change of the IQ mismatch. Therefore, a calibration process including temperature calibration is also needed.

In general, signal mismatches are related to amplitude and phase. In theory, an In-Phase Quadrature (IQ) mismatch may be caused by a baseband (BB) signal and a local oscillation (LO) signal. Until the modem produces an ideal IQ signal through the Digital to Analog Converter (DAC), there is little additional amplitude and phase mismatch in the RF. Therefore, in practical situations, the IQ signal delivered from the baseband is ideal and can be considered to have no amplitude or phase mismatch. IQ mismatches occur primarily from the LO signal. In general, the frequency of the transmitter LO signal is very high. The phase mismatch between the I and Q LO paths can easily occur in high frequency situations, due to environmental changes, layout, and manufacturing defects. On the other hand, waveforms such as square waves are favored by the mixer to improve mixer linearity and reduce LO phase noise. LO is always designed with amplitude saturation. Therefore, the amplitude mismatch between I and Q is always negligible, and most of the unexpected IQ mismatches in RF arise from LO phase mismatches.

1 shows an example of a communication apparatus according to an embodiment of the present invention. 1 comprises an oscillator 100, a modem 130, an RF transceiver 140, and a receive path 150.

The oscillator includes a voltage controlled oscillator (VCO) 102, an LO 110, and IQ calibration units 122 and 124. The modem 130 includes a digital signal processor (DSP) 132 A digital-to-analog converter (DAC) 134 for converting a digital signal to an analog signal, and an analog-to-digital converter (ADC) 136 for converting an analog signal to a digital signal, and the RF transceiver 140 Includes an analog baseband (ABB) chip 142, a high gain transmit mixer (TXM_HG) 144, a low gain transmit mixer (ADC) 144, and a low gain transmit mixer (TXM_LG: Transmitting Mixer-Low Gain) 146, a high-gain digital amplifier (DA_HG) 148, and a low-gain digital amplifier (DA_LG) 149.

The major inconsistency that occurs in LO 110 is phase mismatch. The IQ calibration units 122 and 124 are connected directly to the LO 110 to control the IQ mismatch occurring in the LO 110. [ The IQ calibrator calibrates the phase difference by delaying the phase using a Cap code. The cap code refers to a code value used for determining the amount of capacitance for IQ calibration. The cap code determination process is described in detail in the process of determining the IQ cap code shown in FIG. 4, The method of calibrating IQ mismatch will be described in detail in the switch control operation procedure for the IQ mismatch calibration in FIG.

2 shows an example of the configuration of the IQ mismatch calibration unit 122, 124 in the communication apparatus according to the embodiment of the present invention.

Referring to FIG. 2, a capacitor 210 corresponding to the switch 220 is connected between the LO and the ground. The added capacitor 210 may delay the phase of the LO by a certain amount. When the communication device receives the stored cap code value and closes the switch, it generates a capacitance, and eventually delays the phase by a certain amount. Conversely, when the communication device opens the switch 220, it does not generate a capacitance and does not affect the LO signal. Since the phase between the I path and the Q path is a relative value, the phase adjustment can be performed by delaying one of the phases of the I path and the Q path. For example, if the phase of the I path precedes the phase of the Q path by 1 degree, then the amount of capacitance of the I path must be added as much as 1 degree. If the phase of the I path is one degree later than the phase of the Q path, the amount of capacitance of the Q path must be further delayed by an amount corresponding to 1 degree. The IP 230 in FIG. 2 is a positive voltage terminal Plus applied to the I path, the IN 240 is a negative voltage terminal applied to the I path, the QP 250 is a positive voltage terminal applied to the Q path, (Plus), and QN 260 denotes a negative voltage terminal (Negative) applied to the Q path.

3 shows an example of a change in IRR according to a determined IQ cap code in a communication apparatus according to an embodiment of the present invention.

The IRR (Image Rejection Ratio) is a measure of the ability to remove an image signal. By comparing the intensity of a prescribed signal with the intensity of an image signal, Which means that the recorded image signal cancellation performance is high. The optimal cap code can be determined individually for the I path and the Q path. 3, the optimum cap code for the I path is "7" because the IRR value is about 41 dB when the cap code is 7, and the IRR value at this time is "7" The optimum cap code for the cap code is "0" because the IRR value is about 34.2 dB when the cap code is 0, and the IRR value at this time is the highest. Examples of the above results may vary depending on the process.

4 illustrates an example of a process of determining an IQ cap code in a communication apparatus according to an embodiment of the present invention. Hereinafter, the entity that determines the IQ cap code is referred to as an IQ decision section.

Referring to FIG. 4, in step 410, the IQ determining unit initializes the IQ cap code. Accordingly, the cap code of the I path and the Q path is initialized to zero. The initialized cap code is stored temporarily.

In step 420, the IQ determining unit increments the cap code of the I path by one stage. The cap code value of the I path is incremented by one and the IRR value is checked.

In step 430, the IQ determining unit compares the IRR value before the cap code is increased and the IRR value after the cap code is increased. The IRR value before the cap code of the I path is increased by one step and the IRR value after the cap code of the I path by one step are compared with each other and if there is an improvement of the IRR value after the increase of the IRR value before the increase, In addition, it is checked whether there is a cap code value that can improve the IRR. If there is no improvement in the IRR value after the increase of the IRR value before the increase, the cap code value at the time when the IRR value is the highest is stored, and the flow advances to step 440.

In step 440, the IQ determining unit increments the cap code of the Q path by one step. Increase the cap code of the Q path by one step. The cap code value of the Q path is incremented by one and the IRR value is checked.

In step 450, the IQ determining unit compares the IRR value before the cap code is increased and the IRR value after the cap code is increased. If the IRR value before the increase of the cap code of the Q path is increased by one step and the IRR value after the increase of the cap code of the Q path by one step are compared with each other and if there is an improvement of the IRR value after the increase of the IRR value before the increase, In addition, it is checked whether there is a cap code value that can improve the IRR. If there is no improvement in the IRR value after the increase of the IRR value before the increase, finally, the cap code value having the highest IRR value is stored and the cap code determination process is terminated. The determined cap code value is stored in memory and used during the calibration process.

5 shows an example of a process of IQ mismatch calibration in a communication device according to an embodiment of the present invention.

Referring to FIG. 5, in step 510, the communication apparatus confirms the mismatch control code value generated by the process of FIG. The IQ cap code value when the IRR value is the highest, which is determined by the same procedure as in the IQ determination unit of FIG. 4, is determined as the optimal mismatch control code value, and the mismatch control code value is transmitted to the calibration unit of step 520. [

In step 520, the communication device calibrates the phase mismatch using the set mismatch control code value. The communication device controls the signal in accordance with the mismatch code to calibrate the phase mismatch. By controlling the signal according to the mismatch code, one of the phases is delayed to adjust the mismatched phase. And a switch control method using a capacitor as a method of controlling the signal.

When a signal is transmitted using a multipath, an amplifier in a range corresponding to the gain is used to increase the efficiency of the amplifier according to the degree of gain, so that the path varies depending on the distribution of the gain and the performance of the amplifier. When multipath is used, compensation can be performed in the modem and RF when the modem is present, and RF alone if the modem is present.

6 illustrates an example of multipath calibration by a modem and an RF stage in a communication apparatus according to an embodiment of the present invention.

 If the IQ calibration proposed in the present invention is used together with the digital domain calibration for multipath RF, the calibration is first performed by the modem, and the subsequent paths are calibrated by RF.

In step 610 of FIG. 6, the communication device performs calibration in the modem for the Nth path. The communication device selects the next path in step 620 and the RF is calibrated for the path selected in step 620 in step 630. [ In step 640, if the calibration is completed for all the paths, the process is terminated. If the calibration for all the paths is not completed, the RF is calibrated for the remaining paths. The Nth path starts from the initial 1 and is increased by the number N of paths at the time of completion. The calibration in the RF is performed until the calibration for all the paths is completed.

FIG. 7 illustrates an example of RF-only single-path calibration according to an embodiment of the present invention.

If the proposed IQ calibration is used as a multipath RF alone, then each calibration will be done per path by RF.

In step 710 of FIG. 7, RF calibration is performed on the Nth path. In step 720, the next path is selected. In step 730, the path selected in step 720 is calibrated in RF. In step 740, if the calibration is completed for all the paths, the process ends. If the calibration for all the paths is not completed, the RF is calibrated for the remaining paths. The Nth path starts from the initial 1 and is increased by the number N of paths at the time of completion. The calibration in the RF is performed until the calibration for all the paths is completed.

FIG. 8 shows an example of a process for determining a cap code considering a temperature range according to an embodiment of the present invention.

Referring to FIG. 8, the controller initializes the IQ cap code in step 810. Accordingly, the cap code of the I path and the Q path is initialized to zero. The initialized cap code is temporarily stored. Then, considering the temperature range, the cap code of the I and Q paths is increased until the IRR value is not improved and the cap code is determined.

In step 820, the cap code values are determined as the I and Q path cap code values in consideration of various temperature ranges until the IRR value is no longer improved for the remaining specified temperature range except the temperature range of step 810 And the IQ cap code values determined in consideration of various temperature ranges are stored in a memory in a table manner. The cap code determination is performed until the cap code value determination for all the specified temperature ranges is completed.

FIG. 9 illustrates an example of a process of applying a cap code determined in consideration of a temperature range according to an embodiment of the present invention. In step 910, the communication device measures the temperature. The actual temperature of the chip is measured. In step 920, it is determined whether there is a change in the temperature range. If there is a change in the temperature range, the process proceeds to step 930 where the combination of IQ cap codes is selected and applied by the previously stored IQ cap code value. If there is no change in the temperature range, the process proceeds to step 940 to maintain the cap code value.

5, the apparatus includes a radio frequency (RF) processor 1010, a baseband processor (not shown), and a baseband processor 1020, a storage unit 1030, a control unit 1040, and an update control unit 1042.

The RF processor 1010 performs a function of transmitting and receiving a signal through a wireless channel such as band conversion and amplification of a signal. That is, the RF processor 1010 upconverts the baseband signal provided from the baseband processor 1020 to an RF band signal, transmits the RF band signal through the antenna, and converts the RF band signal received through the antenna into a baseband signal . For example, the RF processor 1010 may include a transmit filter, a receive filter, an amplifier, a mixer, an oscillator, a digital to analog converter (DAC), an analog to digital converter . In FIG. 10, only one antenna is shown, but the transmitting terminal may include a plurality of antennas. In addition, the RF processor 1010 may include a plurality of RF chains. For the beamforming, the RF processor 1010 can adjust the phase and size of signals transmitted and received through a plurality of antennas or antenna elements.

According to an embodiment of the present invention, the RF processor 1010 includes a mismatch compensation unit 1012. [ The operation of the RF processor 1010 according to the embodiment of the present invention is as follows. To calibrate the phase mismatch, the cap code is fetched to create the capacitance and the mismatched phase is adjusted by delaying either phase.

The baseband processor 1020 performs conversion between a baseband signal and a bitstream according to a physical layer specification of the system. For example, at the time of data transmission, the baseband processing unit 1020 generates complex symbols by encoding and modulating transmission bit streams. Also, upon receiving the data, the baseband processor 1020 demodulates and decodes the baseband signal provided from the RF processor 1010 to recover the received bitstream. For example, in accordance with the OFDM scheme, when data is transmitted, the baseband processing unit 1020 generates complex symbols by encoding and modulating transmission bit streams, maps the complex symbols to subcarriers, The baseband processing unit 1020 forms an OFDM (Orthogonal Frequency Division Multiplexing) symbol through Fast Fourier Transform (OFDM) operations and a Cyclic Prefix (CP) insertion. Divides the band signal into OFDM symbol units, restores the signals mapped to the subcarriers through the FFT operation, and restores the received bitstream through demodulation and decoding. The baseband processing unit 1020 and the RF processing unit 1010 transmit and receive signals as described above. Accordingly, the baseband processing unit 1020 and the RF processing unit 1010 may be referred to as a transmitting unit, a receiving unit, a transmitting / receiving unit, or a communication unit.

The storage unit 1030 stores data such as a basic program, an application program, and setting information for operation of the rate control unit. In particular, the storage unit 1030 may store relevant information for inconsistency compensation in the communication device. The storage unit 1030 provides the stored data in response to the request of the controller 1040.

The controller 1040 controls overall operations of the apparatus for rate control. For example, the control unit 1040 transmits and receives signals through the baseband processing unit 1020 and the RF processing unit 1010. In addition, the controller 1040 writes data in the storage unit 1030 and reads the data. For example, the control unit 1040 controls the apparatus for rate control to perform the procedure shown in FIG. 3 and FIG. The control unit sets a mismatch control code value. In order to set the mismatch control code value, the control unit initializes the phase mismatch control code value. The control unit continuously increases the mismatch control code value until the IRR value is improved. If the IRR value is checked and there is no further improvement than the IRR value in the discrepancy control code value of the previous step, the discrepancy control code value in the immediately preceding step has the lowest intensity of the image signal, Set by control code value.

Figure 11 shows the results of a simulation of the performance according to the proposed algorithm according to an embodiment of the present invention.

In Fig. 11, the vertical axis indicates the intensity of a signal. Since the IRR means an image signal rejection ratio, the lower the intensity of the image signal, the more the image signal is removed. Therefore, the intensity of the low image signal eventually means a high IRR. In FIG. 11, reference numerals 1110 and 1130 denote image signals, and reference numerals 1120 and 1140 denote original output signals. The intensity 1110 of the image signal before applying the algorithm is -74.204 dB, which is the original output signal intensity (-30 dB) The difference was about -34.204dB. On the other hand, the intensity 1130 of the image signal after applying the algorithm showed -71.279 dB, which is about -41.279 dB different from the intensity of the original output signal (-30 dB). As a result, it can be seen that the IRR is increased due to the decrease of the intensity of the image signal after applying the algorithm.

Methods according to the claims or the embodiments described in the specification may be implemented in hardware, software, or a combination of hardware and software.

When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored on a computer-readable storage medium are configured for execution by one or more processors in an electronic device. The one or more programs include instructions that cause the electronic device to perform the methods in accordance with the embodiments of the invention or the claims of the present invention.

Such programs (software modules, software) may be stored in a computer readable medium such as a random access memory, a non-volatile memory including a flash memory, a ROM (Read Only Memory), an electrically erasable programmable ROM (EEPROM), a magnetic disc storage device, a compact disc-ROM (CD-ROM), a digital versatile disc (DVDs) An optical storage device, or a magnetic cassette. Or a combination of some or all of these. In addition, a plurality of constituent memories may be included.

In addition, the program may be transmitted through a communication network composed of a communication network such as the Internet, an Intranet, a LAN (Local Area Network), a WLAN (Wide LAN), or a SAN (Storage Area Network) And can be stored in an attachable storage device that can be accessed. Such a storage device may be connected to an apparatus performing an embodiment of the present invention via an external port. In addition, a separate storage device on the communication network may be connected to an apparatus that performs an embodiment of the present invention.

In the concrete embodiments of the present invention described above, the elements included in the invention are expressed singular or plural in accordance with the specific embodiment shown. It should be understood, however, that the singular or plural representations are selected appropriately according to the situations presented for the convenience of description, and the present invention is not limited to the singular or plural constituent elements, And may be composed of a plurality of elements even if they are expressed.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

Claims (23)

A communication device comprising:
A control unit for providing a mismatch control code value,
And a calibration unit for compensating for a phase mismatch between a plurality of signals using the mismatch control code value,
Wherein the calibration unit controls the plurality of signals to have a predetermined phase difference.
The method according to claim 1,
Wherein the mismatch control code value is determined by comparing an increased mismatch control code value with an Image Rejection Ratio (IRR) of the mismatch control code value before increment.
The method according to claim 1,
Wherein the phase mismatch is a phase mismatch between an I (In-phase) component and a Q (Quadrature phase) component output from a LO (Local Oscillator).
The method according to claim 1,
Wherein the calibration unit compensates for the phase mismatch through capacitance adjustment.
The method according to claim 1,
Wherein the calibration unit comprises at least one capacitor and at least one switch.
6. The method of claim 5,
Wherein the at least one capacitor is coupled to a path of the plurality of signals,
Said at least one switch being disposed between said at least one capacitor and ground.
6. The method of claim 5,
Wherein the at least one switch, in an On state, activates the at least one capacitor.
6. The method of claim 5,
Wherein the mismatch control code value indicates on / off of each of the at least one switch.
The method according to claim 1,
Wherein the calibration unit compensates for the phase mismatch between the plurality of signals using a mismatch control code value generated in consideration of various temperature range changes.
The method according to claim 1,
Wherein the control unit provides the calibration unit with a mismatch control code value corresponding to the current temperature among mismatch control code values corresponding to different temperature ranges.
A method of calibrating a phase mismatch of a communication device,
Checking the mismatch control code value,
And compensating phase mismatch between the plurality of signals so that the plurality of signals have a predetermined phase difference using the mismatch control code value.
12. The method of claim 11,
Wherein the mismatch control code is generated by comparing an increased mismatch control code value with an Image Rejection Ratio (IRR) of a mismatch control code value before increase to determine an mismatch control code.
12. The method of claim 11,
Wherein the mismatch is a discrepancy between an I (In-phase) component and a Q (Quadrature phase) component of the plurality of signals caused by the LO output.
12. The method of claim 11,
Wherein compensating the phase mismatch comprises compensating the phase difference through capacitance adjustment.
12. The method of claim 11,
Wherein compensating the phase mismatch is performed using at least one capacitor and at least one switch.
16. The method of claim 15,
Wherein compensating for the phase mismatch comprises activating the at least one capacitor by an on state of at least one switch.
16. The method of claim 15,
Wherein the at least one switch is turned on / off by the mismatch control code, respectively.
12. The method of claim 11,
Wherein the step of compensating for the phase mismatch compensates for a phase mismatch between a plurality of signals using a mismatch control code value generated in consideration of various temperature range changes.
12. The method of claim 11,
Wherein the step of verifying the mismatch control code value determines a mismatch control code value corresponding to a current one of mismatch control code values corresponding to different temperature ranges.
A method for determining an inconsistency control code value,
Comparing the corresponding IRR values of the mismatch control code values and determining the largest value of the corresponding IRR value among the mismatch control code values as the mismatch control code value for phase difference compensation, Methods of inclusion.
A method for determining a control code for compensating for a phase mismatch between a plurality of signals,
Determining a first control code value for sequentially increasing a first control code value for a first signal among the plurality of signals and minimizing the phase mismatch;
And sequentially increasing a second control code value for a second one of the plurality of signals and determining a second control code value that minimizes the phase discrepancy.
22. The method of claim 21,
Wherein the plurality of signals comprises an I signal and a Q signal generated in a local oscillator (LO).
22. The method of claim 21,
Wherein the minimization of the phase mismatch is determined based on an IRR (Image Rejection Ratio) measured for a mixed transmission signal using the plurality of signals.

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