JP2007235643A - Iq offset adjuster, program, and adjuster of quadrature modulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten adjustment time of IQ offset of a quadrature modulator, to attain higher precision and to reduce test costs. <P>SOLUTION: This IQ offset adjuster is attached to the quadrature modulator 14 which outputs an IQ signal as a transmission signal by performing quadrature modulation to the IQ signal, adjusts offset of the IQ signal and has a digital filter 151 as a carrier leakage component detection means and a DC component control means. The digital filter 151 is attained in a DSP by a computer program and detects carrier leakage components included in the transmission signal output from the quadrature modulator 14 via an RF circuit 12 and a detection circuit 13. The DC component control means changes DC components of the IQ signal input in the quadrature modulator 14 so that the carrier leakage components detected by the digital filter 151 are reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a modulator of a radio communication apparatus such as a mobile phone terminal. More specifically, the present invention relates to an IQ offset adjustment that is attached to a quadrature modulator that performs quadrature modulation on an IQ signal and outputs the signal as a transmission signal. It relates to devices. The “offset” here includes the amplitude of the IQ signal in addition to the DC component of the IQ signal.

Wireless communication devices such as mobile phone terminals include QPSK (Quadrature Phase Shift Keying), π / 4 shift QPSK, 8PSK, HPSK (Hybrid Phase).
A modulation scheme in which communication information is mapped on a so-called IQ plane of a modulation carrier, such as Shift Keying, is widely used. Such a cellular phone terminal or the like has a configuration in which an IQ signal is generated by a circuit on the baseband side and modulated by an orthogonal modulator to generate a radio signal.

  By the way, if a DC component remains in the IQ signal output from the baseband circuit or the IQ input circuit on the quadrature modulator side, the carrier component is superimposed on the modulated radio signal, so-called origin offset. Increases, resulting in problems such as deterioration in modulation accuracy (hereinafter referred to as “EVM: Error Vector Magnitude”) and an increase in errors on the demodulation side. Since these DC offset components have characteristics that vary depending on the device, they are not zero.

  If a DC component remains in the IQ input circuit of the quadrature modulator, the DC component is superimposed on the IQ input, and an unnecessary signal called “carrier leak” is generated. When the ratio of the carrier leak component to the signal component is large, the origin offset of the modulation output signal is increased, which causes the EVM to deteriorate or the demodulation error on the demodulation side to increase. As described above, since the offset component has a characteristic that varies depending on a device (for example, a semiconductor device including a quadrature modulator), it is not zero. However, when the allowable offset value is set narrow in a device or the like, the yield is lowered due to an offset defect in an inspection at the time of manufacturing the device or the like.

  For this reason, when manufacturing a radio | wireless communication apparatus, the mechanism which detects a residual offset component and cancels this is needed. These processes are called “IQ offset adjustment” and are essential processes (processes) for manufacturing a mobile phone terminal or the like using a quadrature modulator. In order to perform the IQ offset adjustment, an adjustment time is required and an instrument such as a measuring instrument is required because the spectrum analyzer is used to manually perform the adjustment many times.

  Here, a typical example of the conventional IQ offset adjustment method will be outlined. IQ offset adjustment is for detecting a residual offset value of each IQ signal and canceling it by intentionally adding a DC offset to the IQ signal. Since the I signal and the Q signal are two-dimensional signals, it is difficult to adjust both the I signal and the Q signal at the same time. Therefore, adjustment is performed by using the orthogonality of IQ so that one side of each of the I signal and the Q signal has an optimum offset cancellation amount.

  First, the offset amount on the I side is set to a fixed value, the offset amount on the Q side is changed, and several measurements are performed to find the offset on the Q side that minimizes the carrier leak. The best point. Similarly, the obtained Q-side offset amount is fixed at the best point, the I-side offset amount is changed, and a value that minimizes carrier leakage is set as the I-side best point. Again, fix the I side and change the Q side to find the best point. The IQ offset amount is adjusted by a procedure in which the above processing is repeated until the IQ offset value does not change.

  However, in such an adjustment method, since the IQ offset amount is obtained sequentially or empirically, many measurement / adjustments are necessary, and the time required for adjustment of one terminal (wireless communication apparatus) is also required. It is not stable and takes time.

  Patent Document 1 discloses a configuration for arithmetically calculating an IQ offset amount to be corrected by measuring the origin offset amount several times. However, this method does not measure the carrier leak amount, but directly measures the origin offset amount, and one IQ offset pair must be set every time.

JP 2000-124964 A (pages 4-5, FIG. 4) JP 2005-217911 A

  As described above, in the conventional IQ offset adjustment, the IQ offset amount varies for each device to be adjusted, and it is necessary to perform adjustment in two dimensions of the I signal and the Q signal using a spectrum analyzer. Requires operator skill and time. Further, in order to determine the IQ offset amount to be corrected, an adjustment method is generally used in which a DC offset is added to the IQ signal for a large number of times to reduce the amount of carrier leakage at that time. It is necessary to repeat the offset setting and the measurement of the amount of carrier leak, which takes time.

  According to Patent Document 1, although the number of times of measurement itself is greatly reduced, repeating measurement and setting a plurality of times is not changed, and adjustment takes time. The long adjustment time impairs productivity and makes it difficult to reduce manufacturing costs in mass production of mobile phone terminals and the like.

  In addition, if the sideband leak component included in the transmission signal is large, it may cause the EVM to deteriorate as in the case of the carrier leak component.

  Accordingly, an object of the present invention is to provide an apparatus and the like that achieve high accuracy and reduce test cost while particularly shortening the adjustment time of the IQ offset of the quadrature modulator of the transmission circuit.

  A first IQ offset adjustment apparatus according to the present invention is attached to a quadrature modulator that performs quadrature modulation on an IQ signal and outputs the signal as a transmission signal, and adjusts the offset of the IQ signal. Carrier leak component detection means, DC component control means is provided. The carrier leak component detection means detects a carrier leak component included in the transmission signal output from the orthogonal transformer. The direct current component control means changes the direct current component of the IQ signal input to the quadrature modulator so that the carrier leak component detected by the carrier leak component detection means decreases.

  When the DC component of the IQ signal increases, the carrier leak component included in the transmission signal increases, and as a result, EVM degradation and the like increase. Therefore, the DC component control means changes the DC component, and the carrier leak component detection means detects the carrier leak component and feeds it back to the DC component control means, so that the DC component is automatically reduced so that the carrier leak component is reduced. Can be changed.

  Further, the carrier leak component detection means may be a filter that extracts the frequency of the carrier leak component. Since the carrier leak component is lower than the transmission signal by the frequency of the baseband signal, it can be extracted by a filter.

  A second IQ offset adjustment apparatus according to the present invention is attached to a quadrature modulator that performs quadrature modulation on an IQ signal and outputs it as a transmission signal, and adjusts the offset of the IQ signal. Component control means is provided. The DC component output means uses only the DC component as the IQ signal input to the quadrature modulator. The direct current component control means changes the direct current component of the IQ signal input to the quadrature modulator so that the carrier leak component output from the quadrature modulator decreases.

  If the IQ signal input to the quadrature modulator is only a DC component, only the carrier leak component is output from the quadrature modulator. Therefore, the DC component control means changes the DC component and feeds back the carrier leak component output from the quadrature modulator to the DC component control means, so that the DC component is automatically changed so that the carrier leak component is reduced. be able to. In this case, the carrier leak component detection means is not necessary.

  A third IQ offset adjustment apparatus according to the present invention is attached to a quadrature modulator that performs quadrature modulation on an IQ signal and outputs the signal as a transmission signal, and adjusts the offset of the IQ signal. Sandband leak component detection means And amplitude control means. The sand band leak component detecting means detects a side band leak component included in the transmission signal output from the orthogonal transformer. The amplitude control means changes the amplitude of the IQ signal input to the quadrature modulator so that the sideband leak component detected by the sideband leak component detection means decreases.

  In accordance with the amplitude of the IQ signal, the sideband leak component included in the transmission signal increases, and as a result, EVM degradation and the like increase. Therefore, the amplitude control means changes the amplitude of the IQ signal, and the sideband leak component detection means detects the sideband leak component and feeds back to the amplitude control means, so that the amplitude is automatically reduced so that the sideband leak component is reduced. Can be changed.

  Further, the sideband leak component detection means may be a filter that extracts the frequency of the sideband leak component. Since the sideband leakage component is lower than the transmission signal by twice the frequency of the baseband signal, it can be extracted by a filter.

  The quadrature modulator adjustment device according to the present invention includes the first or third IQ offset adjustment device, the APC (Automatic Power Control) device, and the switching means according to the present invention. The APC device detects the power level of the transmission signal output from the quadrature converter, adjusts the gain of the amplifier included in the quadrature modulator so that the power level is constant, and has the configuration of the IQ offset adjustment device. Some are shared. The switching means selects either the IQ offset adjustment device or the APC device.

  A general wireless communication apparatus is already provided with an APC device. Since the IQ offset adjusting device is configured to share, for example, a detection circuit or an A / D converter of the APC device, the component parts can be effectively used, so that the size and the price can be reduced.

  The first IQ offset adjustment program according to the present invention is for causing a computer to function as the above-described carrier leak component detection means and DC component control means. The second IQ offset adjustment program according to the present invention is for causing a computer to function as the aforementioned DC component output means and DC component control means. A third IQ offset adjustment program according to the present invention is for causing a computer to function as the above-described sideband leak component detection means and amplitude control means.

  In other words, the present invention is characterized in that IQ offset adjustment is performed quickly and automatically in a radio communication device or mobile phone having a quadrature modulator. The present invention can also be configured as follows. (1). A system that enables IQ offset adjustment by extracting a carrier leak by providing a DSP with a filter function in a baseband circuit. (2). (1) In the system of (1), an IQ offset adjustment is automatically enabled by using an APC detection circuit and a feedback function used for normal operation. (3). An adjustment method for realizing the tracking by IQ offset adjustment by a program by a DSP in the baseband unit.

  According to the present invention, the IQ offset can be automatically adjusted by the radio communication device itself, so that the time required for adjusting the IQ offset can be greatly reduced, and the equipment required for adjusting the spectrum analyzer and the like can be reduced.

  In other words, the present invention has the following effects. (1). The IQ offset can be automatically adjusted by adding a filter that extracts only the carrier leak component in the DSP of the baseband unit. (2). Conventionally, since the measurement was performed with a spectrum analyzer, much adjustment time was required. On the other hand, in the present invention, since a part of the APC function is used, adjustment in a very short time is possible. Of course, it is possible to check with a spectrum analyzer whether or not the adjustment is possible. (3). By performing automatic adjustment by the terminal itself, it is possible to reduce capital investment in the manufacturing process because no measuring instrument for adjustment is required.

  FIG. 1 is a block diagram showing a first embodiment of an adjusting device according to the present invention. FIG. 2 [1] is a block diagram showing a part of the adjusting device of FIG. Hereinafter, description will be given based on this drawing.

  The adjustment device according to the present embodiment is provided as a part of the wireless communication device 10, and includes an APC device including the detection circuit 13, the LPF 17, the A / D converter 152, the CPU 16, the detection circuit 13, and the A / D converter 152. An IQ offset adjusting device including a digital filter 151, a CPU 16 and the like, and switching means including switches 153, 154 and 155. The APC device detects the power level of the transmission signal output from the quadrature converter 14, adjusts the gain of the amplifier 146 included in the quadrature modulator 14 so that the power level becomes constant, and detects the detection circuit 13, The A / D converter 152, the CPU 16, and the like are shared with the IQ offset adjusting device. The switching means selects either the IQ offset adjustment device or the APC device.

  The wireless communication device 10 includes an antenna 11, an RF circuit 12, a detection circuit 13, a quadrature modulator 14, a baseband circuit 15, a CPU 16, an LPF 17, and the like. The RF circuit 12 is provided between the quadrature modulator 14 and the antenna 11, and includes, for example, an amplifier and a power source. The RF circuit 12 amplifies the transmission signal output from the quadrature modulator 14 and supplies the amplified signal to the antenna 11. The detection circuit 13 includes a diode or the like, and performs envelope detection on the transmission signal output from the RF circuit 12. The LPF 17 removes an AC component from the output signal of the detection circuit 13 and outputs it to the baseband circuit 15.

The quadrature modulator 14 is composed of an RFIC, and includes mixers 141 and 142, an adder 145 that adds output signals of the mixers 141 and 142, a local oscillator 143 that generates a carrier wave (sinω _c t), and a local oscillator 143. A phase shifter 144 that supplies a carrier wave and a signal whose phase is shifted by 90 degrees to mixers 142 and 141, and an amplifier 146 that amplifies the output signal of adder 145 and outputs the amplified signal to RF circuit 12, respectively. The mixer 141 differentially inputs the complementary I signal (non-inverted) and IB signal (inverted) from the baseband circuit 15 and multiplies them by a carrier wave whose phase is shifted by 90 degrees. The mixer 142 differentially inputs complementary Q signals (non-inverted) and QB signals (inverted), and multiplies them by a carrier wave. The carrier wave from the local oscillator 143 may be supplied to the mixers 141 and 142 in the differential mode. As the mixers 141 and 142, for example, a well-known Gilbert multiplier is used. The gain of the amplifier 146 is controlled by the CPU 16.

The baseband circuit 15, IQ signal (baseband _{signal: sinω b t, cosω b t} ) In addition to the general configuration for outputting the digital filter 151, A / D converter 152, a switch 153 to 155, etc. ing.

  The IQ offset adjusting apparatus according to the present embodiment is attached to a quadrature modulator 14 that performs quadrature modulation on an IQ signal and outputs it as a transmission signal, and adjusts the offset of the IQ signal. The filter 151 and the DC component control means 30 shown in FIG. 2 [1] are provided. The digital filter 151 is realized by a computer program in the DSP and detects a carrier leak component included in a transmission signal output from the orthogonal transformer 14 via the RF circuit 12 and the detection circuit 13. The DC component control means 30 changes the DC component of the IQ signal input to the quadrature modulator 14 so that the carrier leak component detected by the digital filter 151 decreases.

The DC component control means 30 on the I signal side includes an amplifier 31 for amplifying the DC reference voltage Vdc and an output signal α of the amplifier 31 from the I signal (sinω _b t + A) before correction, as shown in FIG. And a control unit 33 that controls the gain of the amplifier 31 so that, for example, A-α is equal to or less than an allowable value in accordance with the carrier leak component. The amplifier 31 and the subtracter 32 are provided in the baseband circuit 15, for example. The control unit 33 is realized by a computer program in the CPU 16, for example. The DC component control means on the Q signal side has the same configuration as that in FIG. The entire direct current component control means 30 can be realized by a computer program.

  When the DC component of the IQ signal increases, the carrier leak component included in the transmission signal increases, and as a result, EVM degradation and the like increase. Therefore, the DC component control unit 30 changes the DC component α, and the digital filter 151 detects the carrier leak component and feeds it back to the DC component control unit 30 to automatically reduce the DC component α so that the carrier leak component is reduced. Can be changed.

  Further, in this embodiment, IQ offset adjustment is realized by using the detection function of an APC device that is already installed in a general wireless communication device, and providing the DSP of the baseband circuit 15 with a filter function. The APC device detects the transmission output power and controls the gain so as to keep the detection voltage constant, thereby obtaining a desired constant power. Hereinafter, the operation of the APC apparatus will be described with reference to FIG.

  An IQ signal is output from the baseband circuit 15, and the IQ signal is input to the quadrature modulator 14. The input IQ signals are mixed with local signals by mixers 141 and 142, respectively, and converted into RF signals. The converted RF signal is output by adding an I signal and a Q signal by an adder 145. Further, the output signal is amplified by the amplifier 146 and is output to the air as a transmission signal from the antenna 11 via the RF circuit 12.

  The transmission signal output from the RF circuit 12 is envelope-detected by the detection circuit 13 in another system, converted into a voltage value from which the AC component has been removed by the LPF 17, and fed back to the baseband circuit 15. The baseband circuit 15 converts the voltage value from an analog signal to a digital signal using an A / D converter 152 and reports the result to the CPU 16 as a detection value. The CPU 16 controls the gain of the amplifier 146 of the quadrature modulator 14 so that the transmission output power becomes a desired value while monitoring the detection value.

  Next, an IQ offset adjustment device that performs IQ offset adjustment using the detection function of the APC device will be described.

First, carrier leakage that occurs due to IQ offset adjustment will be described. Assuming that the offset values of the DC component of the IQ signal are A and B, respectively, the output signal _Pout of the quadrature modulator 14 is expressed by the following equation (1).

P _out = (sin ω _b t + A) cos ω _c t + (cos ω _b t + B) sin ω _c t

= Sin ω _b t · cos ω _c t + cos ω _b t · sin ω _c t + Acos ω _c t + Bsin ω _c t

_{= Sin (ω c + ω b} ) t + Acosω c t + Bsinω c t ··· (1)

_{Here, sin (ω c + ω b} ) t is the signal component, so that the A, B and a coefficient Acosω _c t + Bsinω _c t is generated as the carrier leak component. The waveform of the output signal is as shown in FIG. 3, and the component of ω _c is the carrier leak component. Since this carrier leak component causes the EVM to deteriorate, DC components α and β that cancel A and B are generated in the baseband circuit 15 and added to the IQ line, thereby reducing the amount of carrier leak. It needs to be minimized (FIG. 2 [1]).

  The carrier leak component generated here is amplified by the amplifier 146 and output from the antenna 11 via the RF circuit 12. The transmission signal is detected by the detection circuit 13 of the APC device, and the value is reported to the baseband circuit 15. Here, since the IQ adjustment uses only the detection function of the APC device, it is necessary to turn off the APC function of the CPU 16 so that the gain control signal from the CPU 16 does not go to the amplifier 146.

  When performing IQ adjustment, by operating switches 153 to 155 in the baseband circuit 15, the LPF 17 is excluded in the feedback loop from the detection circuit 13 to the CPU 16, and the digital filter 151 is inserted.

In the detection circuit 13, the transmission signal is envelope-detected by the diode. For this reason, the AC component output from the detection circuit 13 includes a carrier leak component separated by ω _b from the frequency component of the transmission signal and a sideband leak component separated by 2ω _b . The output signal of the detection circuit 13 is converted into a digital value by the A / D converter 152 in the baseband circuit 15. A digital filter 151 that extracts only the component of ω _b that is a carrier leak component is mounted on the DSP of the baseband circuit 15, and only the carrier leak component is extracted and reported to the CPU 16.

  The digital filter 151 is configured to be switched by switches 153 to 155 so as to be applied only at the time of IQ offset adjustment. During normal operation, the digital filter 151 is not inserted. That is, the contacts of the switches 153 to 155 are “2” during IQ offset adjustment and “1” during normal operation.

  When the DC component of the IQ signal is changed, only the carrier leak component changes from the equation (1). Therefore, it is possible to select an optimum DC component value by controlling the DC component of the IQ signal so that the detection value obtained by the CPU 16 is minimized. In this adjustment, the optimum DC component value of the IQ signal is obtained by executing the adjustment a plurality of times. Since the detection cycle of the APC device is very short (about 666 μs in the WCDMA system), the time required for one detection is very short. Therefore, in the present embodiment, the number of measurement points is not a big problem. This is a merit in using the APC apparatus.

  Here, an optimal value driving method will be described. In order to obtain the optimum combination of the DC component values of the IQ signal, it is necessary to obtain the combination of the minimum values after setting the plurality of times and filtering the detection signal.

  Since the I signal and the Q signal are two-dimensional signals, it is difficult to adjust both the I signal and the Q signal at the same time. Adjustment is performed by applying an estimation method such as the Newton method or the Newton method. These adjustment methods require many adjustments, but the adjustment method according to the present embodiment is not a big problem because the adjustment time required at one time is very short.

  By incorporating such a DC component value tracking program into the CPU 16 or the DSP in the baseband circuit 15, IQ offset adjustment can be automatically executed. An example is shown below. Since the I signal and the Q signal are orthogonal, adjustment is performed so that one side of each of the I signal and the Q signal has an optimum offset cancellation amount.

  First, the offset amount on the I side is set to a fixed value. Then, the amount of offset on the Q side is changed to find the TXQ offset that minimizes the value after filtering the detected signal, and set it as the best point on the Q side. Similarly, the obtained offset amount on the Q side is fixed at the best point, the offset amount on the I side is changed, and a value with the smallest detection value is set as the best point on the I side. Again, fix the I side and change the Q side to find the best point. The above procedure is repeated until the IQ offset value does not change, and the TXI and TXQ offset amounts are adjusted. The specified value can be arbitrarily changed, and the desired signal quality can be changed by setting the specified value.

  Further, as a follow-up method for reducing the number of measurement points, a method using three-point adjustment can be given. As shown in Patent Document 2, it is possible to obtain the distance from one measurement point to the optimum adjustment point on the IQ plane, and any three measurement points and the distance to the optimum point. It is possible to obtain the optimum adjustment point by obtaining. If this method is used, the number of measurement points can be reduced. However, in this embodiment, since a very short APC update cycle is used, the number of measurement points is not a big problem.

  FIG. 4 is a flowchart showing the operation of the adjusting device of FIG. Hereinafter, the operation of the adjusting device of the present embodiment will be described with reference to FIGS. 1 to 4.

  FIG. 4 is a flowchart of the IQ offset adjustment process. First, an IQ signal is output from the baseband circuit 15 by the transmission on control from the CPU 16, and a transmission signal converted into an RF signal by the quadrature modulator 14 is output from the antenna 11 (steps 100 and 101). In this embodiment, since only the detection function of the APC device is used, APC off for stopping the feedback operation of APC is performed (step 102). That is, the gain control from the CPU 16 to the amplifier 146 is not performed.

  Here, the baseband circuit 15 performs bypass of the LPF 17 and insertion of the digital filter 151 by the switches 153 to 155 in order to perform IQ offset adjustment (step 103). Then, IQ offset setting is performed on the I side and the Q side (step 104). The output carrier leak amount changes depending on the set IQ offset value. The transmission signal is subjected to envelope detection through the detection circuit 13 and input to the baseband circuit 15 (step 105). The input detection signal is A / D converted in the baseband circuit 15 (step 106), only the carrier leak component is extracted by the digital filter 151, and its value is reported to the CPU 16 (step 107).

  Since the amount of carrier leak varies depending on the set IQ offset value, the value reported to the CPU 16 through the detection circuit 13 and the baseband circuit 15 differs. Here, the CPU 16 compares the reported value with a predetermined specified value (step 108), and if the specified value is not satisfied, the CPU 16 returns to a new IQ offset value setting (step 104) and satisfies the specified value. If so, the IQ offset adjustment ends (step 109). This operation is repeated until the CPU report value is smaller than the prescribed value, that is, the carrier leak amount is smaller than the prescribed value.

  Next, a second embodiment of the adjusting device according to the present invention will be described. The present embodiment is different from the first embodiment (FIG. 1) only in part of the digital filter 151, the baseband circuit 15, and the CPU 16. That is, the gain is adjusted instead of the DC component of the IQ signal in the same way as in the first embodiment.

  Assuming that the gain on the I side is C and the gain on the Q side is D, the output power is as shown in equation (2), and it can be seen that an extra sideband leak component occurs.

P _out = C sin ω _b t cos ω _c t + D cos ω _b t sin ω _c t

= (C / 2) {sin (ω _b + ω _c ) t + sin (ω _b −ω _c ) t} + (D / 2) {sin (ω _b + ω _c ) t−sin (ω _b −ω _c ) t}

= (1/2) {(C + D) sin (ω _c + ω _b ) t + (D−C) sin (ω _c −ω _b ) t}
... (2)

Here, (C + D) sin (ω _c + ω _b ) t is a signal component, and (D−C) sin (ω _c −ω _b ) t is output as a sideband leak component. When the sideband leak component is generated, it causes the EVM to be deteriorated similarly to the carrier leak component.

The waveform of the output signal is as shown in FIG. 3, and the component ω _c −ω _b is a sideband leak component. In order to cancel this, it is necessary to adjust the gain of the IQ signal so as to obtain an optimum amplitude (for example, C = D).

  Here, since only the sideband leak component is extracted as in the case of the carrier leak component, the sideband leak component can be adjusted by mounting the digital filter 151 with a DSP. The adjustment method is the same as that for the carrier leak component.

  This will be described in more detail based on FIG. 1 and FIG. 2 [2]. The IQ offset adjustment apparatus according to the present embodiment is attached to a quadrature modulator 14 that performs quadrature modulation on an IQ signal and outputs it as a transmission signal, and adjusts the offset of the IQ signal. The filter 151 and the amplitude control means 40 (FIG. 2 [2]) are provided. The digital filter 151 detects a sideband leak component included in the transmission signal output from the orthogonal transformer 14. The amplitude control means 40 changes the amplitude of the IQ signal input to the quadrature modulator 14 so that the sideband leak component detected by the digital filter 151 decreases.

The amplitude control means 40 on the I signal side, for example, as shown in FIG. 2 [2], an amplifier 41 that amplifies the uncorrected I signal (sinω _b t + A) with a gain C, and D according to the sideband leak component, for example. And a control unit 42 that controls the gain C of the amplifier 41 so that −C becomes equal to or less than an allowable value. The amplifier 41 is provided in the baseband circuit 25, for example. The control unit 42 is realized by a computer program in the CPU 16, for example. The amplitude control means on the Q signal side has the same configuration as FIG. 2 [2]. The entire amplitude control means 40 can be realized by a computer program.

  In accordance with the amplitude of the IQ signal, the sideband leak component included in the transmission signal increases, and as a result, EVM degradation and the like increase. Therefore, the amplitude control means 40 changes the amplitude of the IQ signal, and the digital filter 151 detects the sideband leak component and feeds it back to the amplitude control means 40, so that the amplitude of the IQ signal is reduced so that the sideband leak component is reduced. Can be changed automatically.

  FIG. 5 is a block diagram showing a third embodiment of the adjusting device according to the present invention. FIG. 6 is a block diagram showing a part of the adjusting device of FIG. Hereinafter, description will be given based on these drawings.

In the present embodiment, IQ offset adjustment is performed by inputting only a DC component to the quadrature modulator 14 using the detection function of the APC device. If IQ signal inputted to the quadrature modulator 14 becomes only the DC component, the output signal P _out of the orthogonal modulator 14 is as deduced (3) from equation (1).

P _out = Acos ω _c t + B sin ω _c t (3)

  This value is the carrier leak component itself. The carrier leak component is reported as a detection value to the baseband circuit 25 via the detection circuit 13. Here, since the detection value of only the carrier leak component has already been obtained, it is not necessary to extract only the carrier leak component by the digital filter 151 (FIG. 1). The tracking is performed by changing the DC component of the IQ signal so that the carrier leak component output from the quadrature modulator 14 to which only the DC component is input is minimized. The DC component value of the IQ signal, which is the minimum combination of carrier leak components, becomes the final set value.

  This will be described in more detail with reference to FIGS. The IQ offset adjusting apparatus according to the present embodiment is attached to a quadrature modulator 14 that performs quadrature modulation on an IQ signal and outputs it as a transmission signal, and adjusts the offset of the IQ signal. Control means 60 is provided. The DC component output means 50 uses only the DC component as the IQ signal input to the quadrature modulator 14. The DC component control means 60 changes the DC component of the IQ signal input to the quadrature modulator 14 so that the carrier leak component output from the quadrature modulator 14 decreases.

DC component output unit 50 of the I signal side selects the LPF51 for removing an AC component from the uncorrected I signal (sinω _b t + A), whether through uncorrected I signal (sinω _b t + A) to LPF51 And switches 52 and 53. The DC component control means 60 on the I signal side includes an amplifier 61 that amplifies the DC reference voltage Vdc and the I signal (sinω _b t + A) before correction or the I signal (A) from which the AC component has been removed by the LPF 53. A subtractor 62 that subtracts the output signal α and a control unit 63 that controls the gain of the amplifier 61 so that, for example, A−α is equal to or less than an allowable value according to the carrier leak component. The components of the DC component output unit 50 and the DC component control unit 60 are realized in the baseband circuit 25 except for the control unit 33, for example. The control unit 33 is realized by a computer program in the CPU 26, for example. The direct current component output means and direct current component control means on the Q signal side have the same configuration as in FIG. The entire direct current component output means 50 and the entire direct current component control means 60 can also be realized by a computer program.

  At the time of IQ offset adjustment, the control unit 63 sets the contact points of the switches 52 and 53 to “2” so that the IQ signal input to the quadrature modulator 14 is only the DC component. Then, as described above, only the carrier leak component is output from the quadrature modulator 14. Therefore, the control unit 63 changes the DC component α through the gain of the amplifier 61 and feeds back the carrier leak component output from the quadrature modulator 14 to the control unit 63 so that the carrier leak component is reduced. The component α can be automatically changed. When the carrier leak component becomes equal to or less than the specified value, the control unit 63 fixes the direct current component α at that time and returns the contact points of the switches 52 and 53 to “1” to cope with the normal transmission operation.

It is a block diagram which shows 1st embodiment of the adjustment apparatus which concerns on this invention. FIG. 2 [1] is a block diagram showing a part (first embodiment) of the adjusting device of FIG. FIG. 2 [2] is a block diagram showing a part (second embodiment) of the adjusting device of FIG. It is a graph which shows each frequency component contained in a transmission signal. It is a flowchart which shows operation | movement of the adjustment apparatus of FIG. It is a block diagram which shows 3rd embodiment of the adjustment apparatus which concerns on this invention. It is a block diagram which shows a part of adjustment apparatus of FIG.

Explanation of symbols

10, 20 Wireless communication device 11 Antenna 12 RF circuit 13 Detection circuit 14 Quadrature modulator 15, 25 Baseband circuit 151 Digital filter (carrier leak component detection means, sideband leak component detection means)
152 A / D converter 153-155 Switch (switching means)
16, 26 CPU
17 LPF
30, 60 DC component control means 40 Amplitude control means 50 DC component output means

Claims (9)

In an IQ offset adjustment device that is attached to a quadrature modulator that performs quadrature modulation on an IQ signal and outputs the signal as a transmission signal, and adjusts the offset of the IQ signal,
Carrier leak component detection means for detecting a carrier leak component included in the transmission signal output from the orthogonal transformer;
DC component control means for changing the DC component of the IQ signal input to the quadrature modulator so that the carrier leak component detected by the carrier leak component detection means decreases,
An IQ offset adjusting device comprising: The carrier leak component detection means is a filter that extracts the frequency of the carrier leak component.
The IQ offset adjustment apparatus according to claim 1.
In an IQ offset adjustment device that is attached to a quadrature modulator that performs quadrature modulation on an IQ signal and outputs the signal as a transmission signal, and adjusts the offset of the IQ signal,
DC component output means for making the IQ signal input to the quadrature modulator only a DC component;
DC component control means for changing a DC component of the IQ signal input to the quadrature modulator so that a carrier leak component output from the quadrature modulator is reduced;
An IQ offset adjusting device comprising:
In an IQ offset adjustment device that is attached to a quadrature modulator that performs quadrature modulation on an IQ signal and outputs the signal as a transmission signal, and adjusts the offset of the IQ signal,
Sandband leak component detection means for detecting a sideband leak component included in the transmission signal output from the orthogonal transformer;
Amplitude control means for changing the amplitude of the IQ signal input to the quadrature modulator so that the sideband leak component detected by the sideband leak component detection means decreases;
An IQ offset adjusting device comprising: The sideband leak component detection means is a filter that extracts the frequency of the sideband leak component.
The IQ offset adjustment apparatus according to claim 4.
IQ offset adjusting device according to claim 1, 2, 4 or 5,
The power level of the transmission signal output from the quadrature converter is detected, the gain of the amplifier included in the quadrature modulator is adjusted so that the power level is constant, and the IQ offset adjustment device and the configuration are configured. APC device that shares a part,
Switching means for selecting one of the APC device and the offset adjusting device;
An apparatus for adjusting a quadrature modulator, comprising:
In an IQ offset adjustment program for adjusting an offset of the IQ signal, which is used in a quadrature modulator that performs orthogonal modulation on an IQ signal and outputs it as a transmission signal,
A carrier leak component detecting means for detecting a carrier leak component included in the transmission signal output from the orthogonal transformer;
And DC component control means for changing the DC component of the IQ signal input to the quadrature modulator so that the carrier leak component detected by the carrier leak component detection means decreases.
IQ offset adjustment program for causing a computer to function as In an IQ offset adjustment program for adjusting an offset of the IQ signal, which is used in a quadrature modulator that performs orthogonal modulation on an IQ signal and outputs it as a transmission signal,
DC component output means for making the IQ signal input to the quadrature modulator only a DC component;
And DC component control means for changing a DC component of the IQ signal input to the quadrature modulator so that a carrier leak component output from the quadrature modulator decreases.
IQ offset adjustment program for causing a computer to function as In an IQ offset adjustment program for adjusting an offset of the IQ signal, which is used in a quadrature modulator that performs orthogonal modulation on an IQ signal and outputs it as a transmission signal,
Sandband leak component detection means for detecting a sideband leak component included in the transmission signal output from the orthogonal transformer;
And amplitude control means for changing the amplitude of the IQ signal input to the quadrature modulator so that the sideband leak component detected by the sideband leak component detection means decreases,
IQ offset adjustment program for causing a computer to function as

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