JP5486613B2 - Signal generating apparatus and signal generating method - Google Patents

Description

  The present invention relates to a signal generation apparatus and a signal generation method for generating a test signal in a characteristic test for a mobile communication terminal such as a mobile phone or a mobile terminal.

  Conventionally, in a characteristic test of a mobile communication terminal or the like, a signal generator is used to supply a test signal to the mobile communication terminal or the like (see, for example, Patent Document 1).

  A signal generation device described in Patent Document 1 includes a baseband signal generation unit that generates an IQ baseband signal, quadrature modulation means that outputs a quadrature modulation signal obtained by modulating a local oscillation signal input from a local oscillator with an IQ baseband signal, and A level control circuit including a variable attenuator (ATT) for controlling the signal level of the quadrature modulation signal to a predetermined level, and a step ATT for attenuating and outputting the output signal of the level control circuit, specified by the tester A test signal having a radio frequency and a signal level can be output.

  In general, a conventional signal generator includes two attenuators in addition to the variable ATT and step ATT described in Patent Document 1, and has a configuration as shown in FIG.

  FIG. 9 is a block diagram showing a main part of a conventional signal generator. The conventional signal generator 1 includes a variable ATT 2, an amplifier 3, a level control (ALC) circuit 4, a step ATT 5, and an attenuation setting unit. 6 is provided. The ALC circuit 4 includes a variable ATT 4a, an amplifier 4b, a variable ATT 4c, an amplifier 4d, a detector 4e, and a level control unit 4f.

  The variable ATT2 is an attenuator in which the attenuation amount is varied by the attenuation amount setting unit 6 in a state where the attenuation amounts of the variable ATTs 4a and 4c and the step ATT5 and the output signal level of the ALC circuit 4 are fixed. This attenuator has a function of preventing the output signals from being out of synchronization at the moment of interruption when step ATT5 is switched.

  In the variable ATT 4a, the attenuation amount is varied by the level control unit 4f in accordance with the output signal level of the detector 4e, and fine adjustment of the attenuation amount can be performed. The variable ATT 4a also performs the interpolation of the attenuation amount in step ATT5 and the correction of the attenuation amount error.

  The variable ATT 4c operates as an auxiliary to the variable ATT 4a, and is used for coarse adjustment of attenuation.

  Step ATT5 is step-variable by a predetermined attenuation step (for example, 5 dB).

  The variable ATT2 to step ATT5 are usually composed of analog elements and thus have frequency characteristics. Therefore, the conventional signal generator has been adapted by changing the attenuation amount of the variable ATT 4a in order to correct the frequency characteristic.

JP 2008-205812 A

  However, in the conventional signal generator, the variable ATT 4a is configured to correct the frequency characteristic in addition to the interpolation of the attenuation amount and the correction of the attenuation amount error in step ATT5 as described above. The variable width of was relatively wide. When the variable width of the attenuation amount becomes wide, in the conventional signal generator, the distortion of the output signal deteriorates as the attenuation amount of the variable ATT 4a decreases, and the S / N of the output signal deteriorates as the attenuation amount of the variable ATT 4a increases. There was a problem to do.

  The present invention has been made to solve the conventional problems, and a signal generator and a signal generator capable of suppressing distortion of an output signal and deterioration of S / N while correcting frequency characteristics of the output signal. It aims to provide a method.

A signal generator according to claim 1 of the present invention attenuates a modulation signal generated by modulating a baseband signal in order to suppress at least one of distortion of the output signal and S / N deterioration of the output signal. A first attenuator (15), a second attenuator (21) for attenuating the output signal of the first attenuator, a third attenuator (23) for attenuating the output signal of the second attenuator, In the signal generator (10) comprising: the attenuation amounts of the first, second and third attenuators and the output signal level of the third attenuator are associated for each predetermined frequency. An attenuation table storage means (32) for storing an attenuation setting table (34), and the first, second and third attenuators with reference to the attenuation setting table An attenuation amount setting means (33) for setting each attenuation amount, and the attenuation amount setting table has a predetermined ratio of frequency characteristic correction values for correcting the frequency characteristic of the output signal level of the third attenuator. In other words, each attenuation value determined based on each division value divided into three is included.

  With this configuration, in the signal generator according to claim 1 of the present invention, the frequency characteristic correction value for correcting the frequency characteristic of the output signal level of the third attenuator is divided into each divided value divided into three by a predetermined ratio. Since each attenuation amount determined based on the first, second, and third attenuators is set, the difference in the output signal level between the first, second, and third attenuators can be reduced. While correcting the frequency characteristic of the output signal, distortion of the output signal and deterioration of S / N can be suppressed.

  In the signal generator according to claim 2 of the present invention, the attenuation setting table includes the output signal levels at predetermined frequencies of the first, second, and third attenuators within a predetermined range. As described above, the frequency characteristic correction value includes data of each attenuation determined based on each divided value obtained by dividing the frequency characteristic into three.

  With this configuration, the signal generator according to claim 2 of the present invention suppresses distortion of the output signal and deterioration of the S / N while correcting the frequency characteristic of the output signal by optimizing the level diagram. be able to.

The signal generation method according to claim 3 of the present invention attenuates the modulation signal generated by modulating the baseband signal in order to suppress at least one of the distortion of the output signal and the S / N deterioration of the output signal. A first attenuator (15), a second attenuator (21) for attenuating the output signal of the first attenuator, a third attenuator (23) for attenuating the output signal of the second attenuator, In the signal generation method using the signal generation device (10) comprising: the attenuation amounts of the first, second, and third attenuators and the output signal level of the third attenuator are predetermined. An attenuation table storing step (S14) for storing an attenuation setting table (34) associated with each frequency, and the first and second with reference to the attenuation setting table. And an attenuation amount setting step (S23) for setting each attenuation amount of the third attenuator, wherein the attenuation amount setting table corrects the frequency characteristic of the output signal level of the third attenuator. It has a configuration that includes data of each attenuation determined based on each divided value obtained by dividing the value into three by a predetermined ratio.

  With this configuration, in the signal generation method according to claim 3 of the present invention, the frequency characteristic correction value for correcting the frequency characteristic of the output signal level of the third attenuator is divided into each divided value divided into three by a predetermined ratio. Since the attenuation amounts of the first, second, and third attenuators are set by the attenuation amounts determined based on the attenuation amounts, the difference in the output signal level between the first, second, and third attenuators is reduced. It is possible to suppress the distortion of the output signal and the deterioration of the S / N while correcting the frequency characteristic of the output signal.

  In the signal generation method according to claim 4 of the present invention, in the attenuation setting table, each output signal level at a predetermined frequency of the first, second and third attenuators falls within a predetermined range. As described above, the frequency characteristic correction value includes data of each attenuation determined based on each divided value obtained by dividing the frequency characteristic into three.

With this configuration, the signal generation method according to claim 4 of the present invention suppresses the distortion of the output signal and the deterioration of the S / N while correcting the frequency characteristic of the output signal by optimizing the level diagram. be able to.
The signal generator according to claim 5 of the present invention includes a first amplifier (16) for amplifying an output signal of the first attenuator and outputting the amplified signal to the second attenuator, and an output signal of the second attenuator And a third amplifier (24) for amplifying and outputting the output signal of the third attenuator. Each division value is determined based on a level diagram representing a signal level from one attenuator to the third amplifier.
In the signal generation method according to claim 6 of the present invention, the signal generation device amplifies the output signal of the first attenuator and outputs the amplified signal to the second attenuator; A second amplifier (22) for amplifying the output signal of the second attenuator and outputting it to the third attenuator; a third amplifier (24) for amplifying and outputting the output signal of the third attenuator; And each division value is determined based on a level diagram representing a signal level from the first attenuator to the third amplifier.

  The present invention can provide a signal generation device and a signal generation method having an effect of suppressing distortion of an output signal and deterioration of S / N while correcting frequency characteristics of the output signal. .

It is a block block diagram in one Embodiment of the signal generator which concerns on this invention. It is explanatory drawing of f special correction value in one Embodiment of the signal generator which concerns on this invention. It is the figure which showed the various characteristics of each part from variable ATT15 to amplifier 24 in one Embodiment of the signal generator which concerns on this invention. 6 is a level diagram showing signal levels from a variable ATT 15 to an amplifier 24 in an embodiment of the signal generator according to the present invention. It is a figure which shows the attenuation amount setting table in one Embodiment of the signal generator which concerns on this invention. It is a figure which shows the procedure which calculates | requires the attenuation amount setting table in one Embodiment of the signal generator which concerns on this invention. It is a flowchart in one Embodiment of the signal generator which concerns on this invention. FIG. 8 is an explanatory diagram of the process in step S20 shown in FIG. 7 in the embodiment of the signal generator according to the present invention. It is a block block diagram which shows the principal part of the conventional signal generator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the configuration of an embodiment of a signal generator according to the present invention will be described.

  As shown in FIG. 1, the signal generator 10 in this embodiment includes a waveform storage unit 11, a digital analog converter (DAC) 12, a local oscillator 13, a quadrature modulator 14, a variable ATT 15, an amplifier 16, a step ATT 17, and an operation unit. 18, an ALC circuit 20 and a control circuit 30 are provided.

  The ALC circuit 20 includes a variable ATT 21, an amplifier 22, a variable ATT 23, an amplifier 24, a detector 25, a reference value output unit 27, and a comparator 28.

  The waveform storage unit 11 stores digital value waveform data, and previously stores baseband waveform data of an I-phase component and a Q-phase component prepared for testing a device under test (not shown). It comes to memorize. The baseband waveform data is generated by, for example, a DSP (Digital Signal Processor) or FPGA (Field Programmable Gate Array) (not shown).

  The DAC 12 converts the digital baseband signal waveform data output from the waveform storage unit 11 into an analog value and outputs the converted baseband signal waveform data to the quadrature modulator 14.

  The local oscillator 13 generates a local oscillation signal having a predetermined frequency based on the local oscillation control signal output from the control circuit 30 and outputs the local oscillation signal to the quadrature modulator 14.

  The quadrature modulator 14 orthogonally modulates the local oscillation signal from the local oscillator 13 with the baseband signal waveform data from the DAC 12 and converts the frequency into an RF signal, and outputs the frequency-converted orthogonal modulation signal to the variable ATT 15. It has become.

  The variable ATT 15 is an attenuator in which the attenuation amount is varied by the attenuation amount setting unit 33 while the attenuation amounts of the variable ATTs 21 and 23 and step ATT 17 and the output signal level of the ALC circuit 20 are fixed. In addition, the variable ATT 15 has a function of preventing the output signals from being out of synchronization at the moment of interruption when the step ATT 17 is switched. Here, the variable ATT 15 constitutes a first attenuator according to the present invention.

  The amplifier 16 amplifies the output signal of the variable ATT 15 and outputs the amplified signal to the variable ATT 21.

  The variable ATTs 21 and 23 set a control voltage for setting each attenuation amount in order to set a signal level of a reference point (hereinafter referred to as “reference point level”) provided at the output of the ALC circuit 20 to a predetermined value. Input is made from the comparator 28. Note that the variable ATTs 21 and 23 constitute second and third attenuators according to the present invention, respectively.

  The variable ATT 21 can set the attenuation amount continuously, for example, and can adjust the attenuation amount more finely than the variable ATT 23. The variable ATT 21 also performs interpolation of the attenuation amount in step ATT17 and correction of the attenuation amount error.

  The amplifier 22 amplifies the output signal level of the variable ATT 21 and outputs it to the variable ATT 23.

  The variable ATT 23 operates as an auxiliary to the variable ATT 21 and can set an attenuation amount in, for example, 0.25 dB steps, and is used for coarse adjustment of the attenuation amount.

  The amplifier 24 amplifies the output signal level of the variable ATT 23 and outputs it to the step ATT 17 and the detector 25.

  The detector 25 detects the output signal of the amplifier 24 and outputs it to the comparator 28.

  The reference value output unit 27 generates a control voltage whose reference point level becomes a desired power value (for example, −10 dBm) based on a control signal from the control circuit 30 and outputs the control voltage to the comparator 28.

  The comparator 28 compares the output signal level of the detector 25 with the output signal level of the reference value output unit 27, and sets the attenuation amount setting signal to a variable ATT 21 so that the reference point level becomes, for example, a power value of −10 dBm. To output.

  The step ATT17 is an ATT in which an attenuation amount is set in a step larger than the variable ATTs 21 and 23 (for example, a 5 dB step). The attenuation amount of step ATT17 is set by a setting signal from the control circuit 30.

  The operation unit 18 is operated by a tester in order to make settings relating to test conditions and test procedures, and includes, for example, an input device such as a keyboard, dial, or mouse, and a control circuit that controls these devices. . Test conditions set by the examiner include, for example, waveform data stored in the waveform storage unit 11, the output level of the RF test signal output by the step ATT17, the radio frequency, and the like.

  The control circuit 30 is configured by, for example, a microcomputer, and includes a setting unit 31, a table storage unit 32, and an attenuation amount setting unit 33, and controls the entire apparatus.

  The setting unit 31 outputs a signal indicating waveform data determined by the tester operating the operation unit 18 to the waveform storage unit 11, and sets the radio frequency of the RF test signal determined by the tester operating the operation unit 18. Based on this, a signal indicating the local oscillation frequency of the local oscillator 13 is output to the local oscillator 13.

  The table storage unit 32 stores an attenuation amount setting table in which each attenuation amount of the variable ATTs 15, 21, and 23 and the reference point level (in other words, the output signal level of the variable ATT 23) are associated for each predetermined frequency. It comes to memorize. The table storage unit 32 constitutes an attenuation table storage unit according to the present invention.

  The attenuation amount setting unit 33 sets the attenuation amounts of the variable ATTs 15, 21, and 23 with reference to the attenuation amount setting table based on the output level determined by the tester operating the operation unit 18. Yes. The attenuation amount setting unit 33 constitutes an attenuation amount setting unit according to the present invention.

  Next, the attenuation amount setting table will be described with reference to FIGS. The attenuation amount setting table is determined based on a frequency characteristic correction value (f special correction value) for correcting the frequency characteristic of the output signal level of the signal generator 10 at a predetermined frequency. The attenuation setting table is preferably determined in consideration of the level diagram of the output signal in addition to the f-specific correction value.

  First, the f special correction value will be described with reference to FIG.

  FIG. 2A shows the frequency characteristics of the output signal level of the signal generator 10. Among the frequencies f1 to f5 shown in the figure, the output signal level at the frequency f2 is the frequency characteristic reference level (f special reference level). The frequency characteristics at the frequencies f1, f3 to f5 are indicated by an increase / decrease with respect to the f special reference level.

  FIG. 2B shows the frequency characteristic (solid line) and the f characteristic correction value (dashed line) for correcting the frequency characteristic to the f characteristic reference level. For example, if the output signal level at the frequency f5 is −6 dB with respect to the f special reference level, the f special correction value at the frequency f5 is +6 dB. As will be described later, in the present embodiment, the f-special correction value is divided into three according to a predetermined ratio, the divided value obtained by dividing the three is obtained, and the respective divided values are attenuated by the variable ATTs 15, 21, and 23. Add to. For example, if the predetermined ratio is 1/3, each divided value is +2 dB, and the divided value +2 dB is added to the attenuation amounts of the variable ATTs 15, 21, and 23.

  Next, a level diagram of the ALC circuit 20 will be described with reference to FIGS.

  FIG. 3 shows various characteristics of each part from the variable ATT 15 to the amplifier 24 at a frequency of 3 GHz as an example. 3A shows a conventional configuration, FIG. 3B shows various characteristics in the state before the frequency characteristic correction in the present invention, and FIG. 3C shows various characteristics in the state after the frequency characteristic correction in the present invention.

  In the figure, Gain represents gain, OIP3 represents third-order intercept point, NF represents low noise figure, S represents signal level, N represents noise level, S / N represents signal level to noise level ratio, and IM3 represents third-order intermodulation distortion. . In the variable ATTs 15, 21, and 23, for example, a gain of −12 dB means an attenuation of 12 dB.

  Further, ACP (Adjacent Channel Power) indicates adjacent channel leakage power, and ALT (Alternate Channel Power) indicates next adjacent channel leakage power. In general, if the signal level becomes too high, signal distortion occurs in the amplifier, and if the signal level becomes too low, the S / N ratio decreases and the dynamic range becomes narrow. Therefore, in the signal generator, for example, performance may be expressed by characteristics in W-CDMA, which is a common communication standard in the world, and ACP characteristics are used for signal distortion evaluation and ALT characteristics are used for S / N evaluation. Here, the ACP characteristic is a characteristic that deteriorates as the signal distortion increases, and the ALT characteristic is a characteristic that deteriorates as the S / N decreases.

  In the conventional configuration shown in FIG. 3A, the gains of the variable ATTs 15, 21, and 23 are -8 dB, -23 dB, and -8 dB, respectively. The gains of the amplifiers 16, 22, and 24 are all 13 dB. Under this condition, when the input signal level of the variable ATT 15 is −10 dBm, the output signal level of the amplifier 24 is −10 dBm. That is, the output signal level of the ALC circuit 20 is −10 dBm.

  Next, in the state before the frequency characteristic correction of the present invention, when the f-special reference level of the output signal of the ALC circuit 20 is set to −10 dBm, as shown in FIG. 3B, the variable ATTs 15, 21, and 23 Assume that the output signal level of the ALC circuit 20 becomes −7 dBm when the gains are the same. That is, the ALC circuit 20 has a frequency characteristic of +3 dB with respect to −10 dBm which is the f special reference level.

  Here, the f characteristic correction value for matching the frequency characteristic to the f characteristic reference level is −3 dB. FIG. 3C shows a state in which the division value (= −3 / 3 dB) obtained by dividing the f-special correction value into three is added to the variable ATTs 15, 21 and 23, respectively.

  That is, the variable ATT 15 is added with a divided value of −1.0 dB and the gain is −13.0 dB, the variable ATT 21 is added with a divided value of −1.0 dB and the gain is −13.0 dB, and the variable ATT 23 is divided into a divided value of −1. 0 dB is added to obtain a gain of -13.0 dB. As a result, the output signal level of the ALC circuit 20 becomes −10 dBm, and the frequency characteristics are corrected. In this case, a better result than the conventional configuration of ACP = −73.9 dBc and ALT = −75.6 dBc is obtained.

  The above example is an example in which -3 dB of the f-special correction value is divided into three equal parts. Since -3 is divisible by 3, the above-mentioned distribution is used, but the three-part division of the f-special correction value is divided into three equal parts. The division ratio is not limited, and the division ratio may be determined based on a level diagram described later.

  Next, a level diagram representing signal levels from the variable ATT 15 to the amplifier 24 will be described with reference to FIG.

  A broken line shown in FIG. 4 represents a change in signal level in the conventional configuration shown in FIG. That is, the broken line shown in FIG. 4 has shown the level diagram in the conventional signal generator. Also, the solid line shown in FIG. 4 represents the change in the signal level after the correction of the frequency characteristics in the present embodiment shown in FIG.

  Comparing the change in the signal level after correcting the frequency characteristics in the present embodiment with the change in the signal level in the conventional configuration, the signal level in the conventional configuration changes between −28 dB and −5 dB. On the other hand, the change of the signal level in this embodiment changes between -23 dB and -10 dB. That is, in the present embodiment, it can be seen that the characteristic that the signal level does not decrease excessively and does not increase excessively (that is, the characteristic in which the change level of the signal level is small) is obtained compared to the conventional configuration.

  By adjusting (level diagram optimization) so that the signal level between the variable ATTs 15, 21, and 23 falls within a predetermined range, division values (attenuation amounts) to be added to the variable ATTs 15, 21, and 23, respectively. Is determined in advance to define an attenuation setting table. By optimizing the level diagram, the difference in the output signal level between the variable ATTs 15, 21 and 23 can be reduced at any frequency, and the signal distortion and S / N can be improved.

  Further, in this embodiment, when the overall gain of the system from the variable ATT 15 to the amplifier 24 is large (that is, when the reference point level is large), the signal distortion and S / N are improved, and the overall gain of the above-described system is improved. Is small (that is, when the reference point level is small), the margin of the ALC circuit 20 can be expanded.

  FIG. 5 shows an attenuation setting table 34 determined based on the contents shown in FIG. As shown in FIG. 5, the attenuation setting table 34 associates the reference point level with each attenuation set in the variable ATTs 15, 21, and 23 at each frequency.

  Next, a procedure for obtaining the attenuation setting table 34 will be described with reference to FIG. The attenuation amount setting table 34 is acquired at the time of factory shipment.

  As shown in FIG. 6, the control circuit 30 outputs, for example, a calibration tone signal from the waveform storage unit 11 (step S11).

  Subsequently, the control circuit 30 obtains an f-specific correction value for each frequency at which the reference point level becomes, for example, −10 dBm, −11 dBm, −12 dBm,... (Step S12).

  Then, the control circuit 30 creates the attenuation setting table 34 as shown in FIG. 5 (Step S13), and the table storage unit 32 stores the attenuation setting table 34 (Step S14).

  Next, the operation of the signal generator 10 in this embodiment will be described with reference to FIGS.

  The control circuit 30 sets test conditions set by the user operating the operation unit 18 (step S20). Here, the center frequency of the RF test signal designated by the user is 3 GHz, and the output signal level of the RF test signal is −30 dBm. The output signal level of the quadrature modulator 14 is -10 dBm. Hereinafter, the details of the process of step S20 will be described with reference to FIG.

  Since the control circuit 30 outputs the RF test signal having the output signal level of −30 dBm from the step ATT17, the control circuit 30 determines the attenuation amount of the step ATT17 to 20 dB, the output signal level of the ALC circuit 20 to −10 dBm, and the attenuation amount of the step ATT17. Is set to 20 dB (step S21).

  The control circuit 30 reads the attenuation amount data of the variable ATTs 15, 21, and 23 at the reference point level = −10 dBm from the table storage unit 32 (step S22). As shown in FIG. 5, at the reference point level = −10 dBm, the attenuation amounts of the variable ATTs 15, 21 and 23 are 13.0 dB, 13.0 dB and 13.0 dB, respectively.

  The control circuit 30 sets the attenuation amounts of the variable ATTs 15, 21, and 23 to 13.0 dB, 13.0 dB, and 13.0 dB, respectively (step S23).

  The control circuit 30 instructs the waveform data specified by the user to the waveform storage unit 11 (step S24).

  The control circuit 30 instructs the local oscillator 13 on the local oscillation frequency (step S25).

  Returning to FIG. 7, the waveform storage unit 11 outputs the baseband waveform data designated by the control circuit 30 to the DAC 12 (step S31).

  The DAC 12 converts the digital baseband waveform data into analog baseband waveform data, and outputs the analog baseband waveform data to the quadrature modulator 14 (step S32).

  The quadrature modulator 14 performs quadrature modulation and frequency conversion of the baseband waveform data based on the local oscillation signal output from the local oscillator 13 (step S33), and outputs an RF signal having a signal level of −10 dBm to the variable ATT 15. To do.

  The variable ATT 15 attenuates the RF signal by 13.0 dB, the amplifier 16 amplifies the attenuated RF signal by 13 dB (step S34), and outputs the RF signal to the ALC circuit 20.

  The ALC circuit 20 performs level control (step S35), and outputs an RF signal of −10 dBm to the step ATT17.

  Specifically, the reference value of the reference value output unit 27 is set by the control circuit 30 so that the variable ATT 21 has an attenuation amount of 13.0 dB, and the input RF signal is attenuated by 13.0 dB to be amplified. 22 for output. The amplifier 22 amplifies the input RF signal by 13 dB and outputs the amplified RF signal to the variable ATT 23. The variable ATT 23 attenuates the input RF signal by 13.0 dB and outputs it to the amplifier 24. The amplifier 24 amplifies the input RF signal by 13 dB and outputs it to the step ATT 17 and the detector 25. The detector 25 detects the input RF signal and outputs it to the comparator 28. The comparator 28 compares the output signal level of the detector 25 with the output signal level of the reference value output unit 27, and outputs an attenuation setting signal to the variable ATT 21 so that the reference point level becomes a power value of −10 dBm. To do.

  Step ATT17 attenuates the RF signal from the amplifier 24 by 20 dB (step S36). As a result, the 3 GHz RF test signal corrected so that the frequency characteristic of the output signal level matches the f-special reference level is output from the signal generator 10 (step S37).

  In the above example, the gains of the amplifiers 16, 22, and 24 are the same at 13 dB, and the attenuation amounts of the variable ATTs 15, 21, and 23 are the same at 13 dB. However, this is only an example, and the frequency and reference Depending on the point level, each may have a different value.

  As described above, in the signal generation device 10 according to the present embodiment, the attenuation amount setting unit 33 refers to the attenuation amount setting table 34, and the f characteristic correction value is divided into three divided values according to a predetermined ratio. Since the attenuation amounts of the variable ATTs 15, 21, and 23 are set according to the attenuation amounts determined on the basis of the attenuation amounts, the difference in the output signal level between the variable ATTs 15, 21, and 23 can be reduced, and the frequency of the output signal can be reduced. It is possible to suppress distortion of the output signal and deterioration of S / N while correcting the characteristics.

  As described above, the signal generation device and the signal generation method according to the present invention have an effect that the distortion of the output signal and the deterioration of the S / N can be suppressed while correcting the frequency characteristic of the output signal. The present invention is useful as a signal generation apparatus and a signal generation method for generating a test signal in a characteristic test for a mobile communication terminal such as a mobile phone or a mobile terminal.

DESCRIPTION OF SYMBOLS 10 Signal generator 11 Waveform memory | storage part 12 DAC
13 Local oscillator 14 Quadrature modulator 15 Variable ATT (first attenuator)
16, 22, 24 Amplifier 17 Step ATT
18 Operation unit 20 ALC circuit 21 Variable ATT (second attenuator)
23 Variable ATT (third attenuator)
25 detector 27 reference value output unit 28 comparator 30 control circuit 31 setting unit 32 table storage unit (attenuation amount table storage means)
33 Attenuation amount setting unit (Attenuation amount setting means)
34 Attenuation amount setting table

Claims (6)

In order to suppress at least one of distortion of the output signal and S / N deterioration of the output signal,
A first attenuator (15) for attenuating the modulated signal generated by modulating the baseband signal;
A second attenuator (21) for attenuating the output signal of the first attenuator;
A third attenuator (23) for attenuating the output signal of the second attenuator;
In a signal generator (10) comprising:
Attenuation storing an attenuation amount setting table (34) in which each attenuation amount of the first, second, and third attenuators and the output signal level of the third attenuator are associated with each other at a predetermined frequency. A quantity table storage means (32);
An attenuation amount setting means (33) for referring to the attenuation amount setting table and setting the attenuation amounts of the first, second and third attenuators;
With
The attenuation amount setting table includes a frequency characteristic correction value for correcting the frequency characteristic of the output signal level of the third attenuator, which is determined based on each division value obtained by dividing the frequency characteristic correction value into three by a predetermined ratio. A signal generator characterized by containing data.   In the attenuation amount setting table, each of the frequency characteristic correction values is divided into three so that output signal levels at predetermined frequencies of the first, second, and third attenuators are within a predetermined range. 2. The signal generator according to claim 1, comprising data of each attenuation determined based on the division value. In order to suppress at least one of distortion of the output signal and S / N deterioration of the output signal,
A first attenuator (15) for attenuating the modulated signal generated by modulating the baseband signal;
A second attenuator (21) for attenuating the output signal of the first attenuator;
A third attenuator (23) for attenuating the output signal of the second attenuator;
In a signal generation method using a signal generator (10) comprising:
Attenuation storing an attenuation amount setting table (34) in which each attenuation amount of the first, second, and third attenuators and the output signal level of the third attenuator are associated with each other at a predetermined frequency. A quantity table storage step (S14);
Attenuation amount setting step (S23) for setting each attenuation amount of the first, second and third attenuators with reference to the attenuation amount setting table,
Including
The attenuation amount setting table includes a frequency characteristic correction value for correcting the frequency characteristic of the output signal level of the third attenuator, which is determined based on each division value obtained by dividing the frequency characteristic correction value into three by a predetermined ratio. A signal generation method comprising data.   In the attenuation amount setting table, each of the frequency characteristic correction values is divided into three so that output signal levels at predetermined frequencies of the first, second, and third attenuators are within a predetermined range. 4. The signal generation method according to claim 3, comprising data of each attenuation determined based on the division value. A first amplifier (16) for amplifying an output signal of the first attenuator and outputting the amplified signal to the second attenuator;
A second amplifier (22) for amplifying an output signal of the second attenuator and outputting the amplified signal to the third attenuator;
A third amplifier (24) for amplifying and outputting the output signal of the third attenuator;
Further comprising
3. The signal generator according to claim 2, wherein each of the division values is determined based on a level diagram representing a signal level from the first attenuator to the third amplifier. The signal generator is
A first amplifier (16) for amplifying an output signal of the first attenuator and outputting the amplified signal to the second attenuator;
A second amplifier (22) for amplifying an output signal of the second attenuator and outputting the amplified signal to the third attenuator;
A third amplifier (24) for amplifying and outputting the output signal of the third attenuator;
Further comprising
5. The signal generation method according to claim 4, wherein each of the division values is determined based on a level diagram representing a signal level from the first attenuator to the third amplifier.

Images