JP7165766B2 - Signal generator and its attenuation correction method - Google Patents

Description

The present invention relates to a signal generator that generates a modulated wave in a desired frequency band.

As a signal generator for generating a modulated wave in a desired frequency band, for example, there is a signal generator that generates a modulated wave in a desired frequency band by frequency-converting an intermediate frequency signal generated by an arbitrary signal generator using a mixer or the like. Are known.

Such a signal generator is incorporated in, for example, a mobile terminal testing device for testing mobile communication terminals, and generates and outputs a signal for testing.

Patent Document 1 discloses a storage device that stores the relationship between the number of transmission slots, the attenuation setting value, and the terminal voltage control value, and an attenuation that controls the attenuation based on the attenuation setting value selected based on the number of transmission slots. and an amplifier that controls the transmission power of a transmission signal based on a terminal voltage control value selected based on the number of transmission slots, and uses the ambient temperature of the amplifier to adjust the attenuation setting value and the terminal voltage control value. Weighting is described.

As described above, some devices using semiconductor components such as attenuators and amplifiers have characteristics that change depending on the temperature.

Japanese Patent Application Laid-Open No. 2006-80992

For devices whose characteristics change with temperature, the temperature around the device is measured and the characteristics are selected based on the measured temperature. was taking a long time. In particular, equipment with non-linear characteristics requires time for adjustment.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a signal generator capable of correcting an output signal in a short period of time even if it is equipped with equipment whose characteristics change with temperature.

A signal generator according to the present invention comprises a signal generator that generates a test signal, a variable attenuator that attenuates the signal generated by the signal generator and whose characteristics change with temperature, and a signal attenuated by the variable attenuator. a level detection unit for detecting the level of the signal received by the variable attenuator ; a temperature detection unit for detecting the temperature around the variable attenuator ; is a control parameter of the variable attenuator at the reference temperature of the attenuation of the variable attenuator based on the ambient temperature of the variable attenuator and a control section for correcting the characteristic with respect to the control voltage , wherein the control section stores the slope for each predetermined voltage of the control voltage, which is the control parameter of the variable attenuator .

With this configuration, the characteristics of the attenuation amount of the variable attenuator with respect to the control voltage, which is the control parameter of the variable attenuator, at the reference temperature are corrected based on the temperature around the variable attenuator based on the slope that indicates the change in the attenuation amount with respect to temperature. be done. Therefore, even if a device whose characteristics change with temperature is provided, the output signal can be corrected in a short period of time.
Further, the characteristic of the attenuation amount of the variable attenuator with respect to the control voltage, which is the control parameter of the variable attenuator, at the reference temperature is corrected by changing the slope of the attenuation amount with respect to temperature according to the control voltage of the variable attenuator. Therefore, even a variable attenuator having nonlinear characteristics can accurately correct an output signal.

Further, in the signal generating device of the present invention, the control unit obtains the slope by a calculation formula using the frequency of the signal to be attenuated by the variable attenuator as a parameter for each of the predetermined control voltages of the variable attenuator. is.

With this configuration, the slope of the attenuation amount with respect to temperature is obtained according to the frequency of the signal to be attenuated by the variable attenuator, and the characteristics of the variable attenuator are corrected. Therefore, even a variable attenuator whose characteristics change according to the frequency can accurately correct the output signal.

Further, the attenuation amount correction method of the present invention includes a signal generation unit that generates a test signal, a variable attenuator that attenuates the signal generated by the signal generation unit and whose characteristics change depending on temperature, and the variable attenuator. and a temperature detector for detecting the temperature around the variable attenuator. a step of detecting ambient temperature; a characteristic of the attenuation amount of the variable attenuator with respect to a control voltage, which is a control parameter of the variable attenuator, at a reference temperature; and the temperature difference between the reference temperature and the ambient temperature of the variable attenuator . obtaining a correction amount of the characteristic of the control voltage, which is the control parameter of the attenuator; and obtaining the characteristic of the attenuation amount of the variable attenuator with respect to the control voltage, which is the control parameter of the variable attenuator, at the reference temperature based on the obtained correction amount. and a step of correcting the

With this configuration, the characteristics of the attenuation amount of the variable attenuator with respect to the control voltage, which is the control parameter of the variable attenuator, at the reference temperature can be changed from the reference temperature to the temperature around the variable attenuator by the slope showing the change in the attenuation amount with respect to temperature. Corrected based on temperature difference. Therefore, even if a device whose characteristics change with temperature is provided, the output signal can be corrected in a short period of time.
Further, the characteristic of the attenuation amount of the variable attenuator with respect to the control voltage, which is the control parameter of the variable attenuator, at the reference temperature is corrected by changing the slope of the attenuation amount with respect to temperature according to the control voltage of the variable attenuator. Therefore, even a variable attenuator having nonlinear characteristics can accurately correct an output signal.

INDUSTRIAL APPLICABILITY The present invention can provide a signal generator capable of correcting an output signal in a short period of time even if it is equipped with equipment whose characteristics change with temperature.

FIG. 1 is a block diagram of a signal generator according to one embodiment of the present invention. FIG. 2 is a flowchart for explaining the procedure of attenuation amount correction processing of the signal generator according to one embodiment of the present invention.

Hereinafter, signal generators according to embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, a signal generator 1 according to an embodiment of the present invention includes a signal generator 10 that generates a test signal, a variable attenuator 11 that attenuates the test signal generated by the signal generator 10, A level detector 12 for detecting the level of the test signal attenuated by the variable attenuator 11, an output port 13 for outputting the test signal attenuated by the variable attenuator 11, and a temperature around the variable attenuator 11 are measured. A temperature detection unit 14 for detecting temperature, a user interface unit 15 for accepting a user's operation and providing information to the user, and a control unit 16 for controlling each part of the device to execute processing as the signal generation device 1. consists of

The signal generation unit 10 is configured by a signal generator that generates test signals having the intensity and frequency set by the control unit 16 . The variable attenuator 11 is configured by, for example, a voltage control type variable attenuator.

The level detector 12 detects the level of the test signal attenuated by the variable attenuator 11 and outputs it to the controller 16 . The temperature detector 14 detects the temperature around the variable attenuator 11 and outputs it to the controller 16 .

The user interface unit 15 includes an input unit that receives an operation input from a user, and a display unit that displays a screen for setting parameters of test signals to be generated, various messages, and the like. The input unit is composed of a touch pad, keyboard, push buttons, rotary knob, and the like. The display unit is configured by a liquid crystal display device or the like.

The control unit 16 is configured by a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk device, and an input/output port (not shown).

The ROM and hard disk device of the computer unit store programs for causing the computer unit to function as the control section 16 along with various control constants, various maps, and the like. That is, the computer unit functions as the control unit 16 by the CPU executing programs stored in the ROM and the hard disk device. The hard disk device may be a CF (Compact Flash) card based on flash memory.

The input/output ports of the controller 16 are connected to the signal generator 10, the variable attenuator 11, the level detector 12, the temperature detector 14, and the user interface 15, so that the controller 16 and each part can transmit and receive signals. It has become.

In this embodiment, the variable attenuator 11 has nonlinear characteristics. Also, the variable attenuator 11 has different characteristics depending on the frequency of the signal to be attenuated.

Also, the characteristics of the variable attenuator 11 change depending on the temperature of the variable attenuator 11 . The hard disk device of the control unit 16 stores the characteristics of the variable attenuator 11 for each predetermined frequency at a predetermined reference temperature. As the characteristics of the variable attenuator 11, for example, a control voltage, which is a control parameter of the variable attenuator 11, is stored for each predetermined frequency and predetermined attenuation amount at a reference temperature.

The control unit 16 corrects the characteristics of the variable attenuator 11 based on the temperature around the variable attenuator 11 detected by the temperature detection unit 14 .

The control unit 16 stores, for example, the slope of the control voltage of the variable attenuator 11, which indicates the change in the amount of attenuation with respect to the change in temperature, for each predetermined voltage.

The control unit 16 stores, for example, a calculation formula for calculating the slope of the attenuation amount with respect to temperature for each predetermined control voltage of the variable attenuator 11, using the frequency of the signal to be attenuated as a parameter.

This calculation formula obtains, for example, a change in the amount of attenuation measured by changing the frequency of the signal to be attenuated, by polynomial approximation. The calculation formula is, for example, a third-order polynomial.

The control unit 16 calculates a correction value for the characteristics of the variable attenuator 11 based on the difference between the reference temperature and the temperature detected by the temperature detection unit 14, for example.

Based on the corrected characteristics, the control unit 16 sets the control voltage, which is the control parameter of the variable attenuator 11, causes the signal generation unit 10 to generate a signal of a predetermined level, and determines the signal level detected by the level detection unit 12. Therefore, it is preferable to detect the amount of attenuation by the variable attenuator 11 and change the control voltage of the variable attenuator 11 to finely adjust the corrected characteristics.

Further, the control unit 16 corrects the characteristics of the variable attenuator 11 based on the temperature around the variable attenuator 11 detected by the temperature detection unit 14, and provides a control voltage for the variable attenuator 11 that attenuates a predetermined amount of attenuation. can also be asked for.

For example, a case will be described in which the control voltage of the variable attenuator 11 is obtained so that the attenuation of a signal with a frequency of 0.4 GHz is -10.5 dB.

Based on the characteristics of the variable attenuator 11 at the reference temperature, the control unit 16 obtains a control voltage that makes -10.5 dB attenuation for a signal with a frequency of 0.4 GHz. If there is no matching attenuation amount, it can be obtained by linear interpolation from the previous and subsequent values. Here, it is assumed that the control voltage is 3.23V for the attenuation of a signal with a frequency of 0.4 GHz of -10.5 dB.

The control unit 16 obtains the slope indicating the change in the amount of attenuation with respect to the change in temperature when the control voltage is 3.23V. Here, using the frequency of the signal to be attenuated as a parameter, if the calculation formula for calculating the slope of the attenuation amount with respect to temperature is only for the control voltages of 3.20V and 3.30V, the slope for 3.20V and 3.30V is , find the slope at 3.23V by linear interpolation.

For example, assume that the formula for calculating the slope y at the frequency x when the control voltage is 3.20V and 3.30V is as follows. The following formulas are written in floating point format.
3.20V: y=-1.27000E-04 x ^x3 + 1.47100E-03 x x2 - 1.48300E ^- 03 x x - 1.73000E-02
3.30V: y=-1.20000E-04 x ^x3 + 1.42900E-03 x x2 - 1.94300E ^- 03 x x - 1.65000E-02

From this formula, each slope is obtained.
3.20V: y=-1.27000E-04×(0.4) ³ +1.47100E-03×(0.4) ² -1.48300E-03×(0.4)-1.73000E-02
=-1.766596800000000E-02
3.30V: y=-1.20000E-04×(0.4) ³ +1.42900E-03×(0.4) ² -1.94300E-03×(0.4)-1.65000E-02
=-1.705624000000000E-02
Here, the calculation is performed in double-precision floating point during the calculation.

From this value, determine the slope at 3.23V.
3.23V: y= ((3.23 - 3.20)/(3.30 - 3.20)) x ((-1.705624000000000E-02) - (-1.766596800000000E-02)) + (-1.766596800000000E-02)
= -1.748304960000000E-02

The control unit 16 obtains the level fluctuation amount at the temperature around the variable attenuator 11 from the difference between the reference temperature and the temperature around the variable attenuator 11 detected by the temperature detection unit 14 .

For example, when the reference temperature is 25.3° C. and the temperature around the variable attenuator 11 detected by the temperature detection section 14 is 45.0° C., the level fluctuation amount is as follows.
Level variation (dB) = (45.0 - 25.3) × (-1.748304960000000E-02)
= -3.444160771200000E-01

The control unit 16 obtains a control voltage for the variable attenuator 11 that attenuates a predetermined amount of attenuation at the ambient temperature of the variable attenuator 11 from the obtained slope.

If the amount of level fluctuation is negative, the control voltage is obtained by linear interpolation from the value of the control voltage with the smaller amount of attenuation in the characteristics of the variable attenuator 11 at the reference temperature.

When the amount of level fluctuation is positive, the control voltage is obtained by linear interpolation from the value of the control voltage with the greater amount of attenuation in the characteristics of the variable attenuator 11 at the reference temperature.

Here, since the amount of level fluctuation is negative, the control voltage is calculated to be 3.24 V at -10.1 dB, which is less attenuation than -10.5 dB, based on the characteristics of the reference temperature.

Control voltage = ((-3.444160771200000E-01)/((-10.5) - (-10.1))) x (3230 - 3240) + 3230
= 3221[mV]

The control voltage is shown in units of mV, and the final control voltage is an integer rounded off to the first decimal place.

By doing so, if the temperature around the variable attenuator 11 is known, the control voltage of the variable attenuator 11 that attenuates a predetermined amount of attenuation can be obtained by calculation.

Attenuation amount correction processing by the signal generator according to the present embodiment configured as described above will be described with reference to FIG. Note that the attenuation correction process described below is executed when the output level correction function is selected by operating the user interface unit 15 .

In step S<b>1 , the controller 16 detects the temperature around the variable attenuator 11 using the temperature detector 14 . After executing the process of step S1, the control unit 16 executes the process of step S2.

In step S2, the controller 16 calculates the temperature difference between the temperature detected by the temperature detector 14 and the reference temperature. After executing the process of step S2, the control unit 16 executes the process of step S3.

In step S<b>3 , the control unit 16 calculates the slope of the attenuation amount with respect to the temperature at the frequency to be measured and the control voltage of the variable attenuator 11 using a calculation formula. After executing the process of step S3, the control unit 16 executes the process of step S4.

In step S4, the control unit 16 calculates a correction amount for the characteristics of the variable attenuator 11 from the obtained slope of the attenuation amount and the temperature difference. After executing the process of step S4, the control unit 16 executes the process of step S5.

In step S5, the control unit 16 corrects the map of the characteristics of the variable attenuator 11 using the obtained correction amount. After executing the process of step S5, the control unit 16 executes the process of step S6.

In step S6, the control unit 16 sets the control voltage of the variable attenuator 11 to a predetermined voltage, causes the signal generation unit 10 to generate a signal of a predetermined level, and detects the level of the output signal by the level detection unit 12 to perform variable attenuation. Measure the attenuation of the device 11. After executing the process of step S6, the control unit 16 executes the process of step S7.

In step S7, the control unit 16 changes the control voltage based on the corrected map, and performs fine adjustment such as determining the control voltage corresponding to each 1 dB of attenuation. After executing the process of step S7, the control unit 16 ends the attenuation correction process.

Thus, in the above-described embodiment, the control unit 16 stores the characteristics of the variable attenuator 11 at the reference temperature and the slope indicating the change in the attenuation amount with respect to temperature, and based on the temperature around the variable attenuator 11, The characteristics of the variable attenuator 11 at the reference temperature are corrected.

As a result, the characteristic of the variable attenuator 11 at the reference temperature is corrected based on the ambient temperature of the variable attenuator 11 according to the slope indicating the change in attenuation with respect to temperature. Therefore, even if a device whose characteristics change with temperature is provided, the output signal can be corrected in a short period of time.

The control unit 16 also stores the slope of the attenuation amount with respect to the temperature for each predetermined voltage of the control voltage, which is the control parameter of the variable attenuator 11 .

As a result, the characteristic of the variable attenuator 11 is corrected by changing the slope of the attenuation amount with respect to temperature according to the control voltage of the variable attenuator 11 . Therefore, even if a device having non-linear characteristics is provided, it is possible to accurately correct the output signal.

Further, the control unit 16 obtains the slope by a calculation formula using the frequency of the signal to be attenuated by the variable attenuator 11 as a parameter for each predetermined control voltage of the variable attenuator 11 .

As a result, the slope of the attenuation amount with respect to temperature is obtained according to the frequency of the signal to be attenuated by the variable attenuator 11, and the characteristics of the variable attenuator 11 are corrected. Therefore, even if a device whose characteristics change according to the frequency is provided, the output signal can be corrected with high accuracy.

Although embodiments of the present invention have been disclosed, it will be apparent that modifications may be made by those skilled in the art without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

1 signal generator 10 signal generator 11 variable attenuator 12 level detector 14 temperature detector 16 controller

Claims (3)

a signal generator (10) for generating a test signal;
a variable attenuator (11) that attenuates the signal generated by the signal generator and whose characteristics change with temperature;
a level detector (12) for detecting the level of the signal attenuated by the variable attenuator;
a temperature detection unit (14) for detecting the temperature around the variable attenuator;
A characteristic of the attenuation amount of the variable attenuator at a reference temperature with respect to a control voltage, which is a control parameter of the variable attenuator, and a slope indicating a change in the attenuation amount with respect to temperature are stored, and based on the ambient temperature of the variable attenuator. a control unit (16) for correcting the characteristic of the attenuation amount of the variable attenuator with respect to the control voltage, which is the control parameter of the variable attenuator at the reference temperature ,
The control section stores the slope for each predetermined voltage of the control voltage, which is the control parameter of the variable attenuator . 2. The signal generating device according to claim 1 , wherein the control unit obtains the slope by a calculation formula using, as a parameter, the frequency of the signal to be attenuated by the variable attenuator for each predetermined control voltage of the variable attenuator. A signal generator (10) that generates a test signal, a variable attenuator (11) that attenuates the signal generated by the signal generator and whose characteristics change according to temperature, and a signal attenuated by the variable attenuator and a temperature detection unit (14) for detecting the temperature around the variable attenuator, comprising:
detecting the temperature around the variable attenuator;
A characteristic of the attenuation amount of the variable attenuator with respect to a control voltage, which is a control parameter of the variable attenuator, at a reference temperature, and a change in the attenuation amount with respect to temperature for each predetermined voltage of the control voltage, which is the control parameter of the variable attenuator. and a temperature difference between the reference temperature and the ambient temperature of the variable attenuator, the control voltage being a control parameter of the variable attenuator at the reference temperature of the attenuation amount of the variable attenuator a step of obtaining a characteristic correction amount for
and a step of correcting a characteristic of the attenuation of the variable attenuator at the reference temperature with respect to a control voltage, which is a control parameter of the variable attenuator, using the obtained correction amount.

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