JP7495092B2 - High frequency output device and high frequency output stabilization method - Google Patents

Description

The present invention relates to a high-frequency output device and a method for stabilizing high-frequency output.

For example, in devices that output high-frequency waves, also known as radio frequencies, such as wireless devices, it is essential to output a stable high-frequency wave that is independent of frequency, temperature, and output level. However, devices such as amplifiers and filters have frequency characteristics and temperature drift to some extent, and the more stages these devices are configured in, the greater the uncertainty of the output. For this reason, high-frequency output devices that output high frequencies often have a configuration for stabilizing the output.

Patent document 1 describes an example of a configuration that has a gain adjustment unit that adjusts the gain so that the detected power matches the reference power, thereby stabilizing the output.

JP 2001-217812 A

The disclosures of the above prior art documents are incorporated herein by reference. The following analysis was conducted by the present inventors.

However, even if a gain stabilization configuration is provided, the gain stabilization configuration itself needs to be calibrated to ensure that it functions accurately. In order to perform calibration that responds to all changes in frequency, temperature, and output level, the principle is to measure the effects of all these changes in advance.

However, while it is relatively easy to measure in advance the effects of changes in frequency and output level, it is not easy to measure in advance the effects of temperature changes. To calibrate for the effects of temperature changes, it is necessary to place the high-frequency output device in a thermostatic bath and perform calibration while varying the temperature. Furthermore, calibration using a thermostatic bath generally takes several hours or more, which puts a strain on production costs.

In view of the above-mentioned problems, the object of the present invention is to provide a high-frequency output device and a high-frequency output stabilization method that contribute to eliminating the time required for calibration in response to temperature changes.

The first aspect of the present invention provides a high-frequency output device comprising: a signal generating unit that generates a high-frequency signal; a variable amplifier that amplifies the high-frequency signal generated by the signal generating unit in such a way that the gain can be changed and inputs the signal to a high-frequency component; a directional coupler that splits the high-frequency signal traveling from the high-frequency component to an output end between the high-frequency component and the output end; an adjustment amount calculation unit that calculates the amount of gain adjustment in the variable amplifier based on the high-frequency signal split by the directional coupler; and a pair of switches that are disposed between the signal generating unit and the variable amplifier, and between the high-frequency component and the directional coupler, and that switch to a path that bypasses the variable amplifier and the high-frequency component.

The second aspect of the present invention is a high-frequency output stabilization method for stabilizing the output of a high-frequency output device while measuring a high-frequency signal near the output end, the method including the steps of calibrating the high-frequency output device with respect to frequency and output level, measuring the characteristics of a measurement system that measures the high-frequency signal near the output end with respect to frequency and output level at room temperature, measuring the characteristics of a measurement system that measures the high-frequency signal near the output end with respect to frequency and output level during use, and adjusting the output of the high-frequency output device based on the difference between the measurement results of the characteristics of the measurement system at room temperature and during use.

According to each aspect of the present invention, it is possible to provide a high-frequency output device and a high-frequency output stabilization method that contribute to eliminating the time required for calibration in response to temperature changes.

FIG. 1 is a diagram showing an overview of a high-frequency output device according to a first embodiment. FIG. 2 is a diagram showing a calibration process of the high frequency output device according to the first embodiment. FIG. 3 is a diagram showing the high frequency output device according to the first embodiment in use. FIG. 4 is a flow chart showing an overview of the high frequency output stabilization method according to the first embodiment. FIG. 5 is a diagram showing an outline of a high-frequency output device according to the second embodiment. FIG. 6 is a flow chart showing an overview of a high frequency output stabilization method according to the second embodiment. FIG. 7 is a flow chart showing an overview of a high frequency output stabilization method according to the second embodiment. FIG. 8 is a flow chart showing an overview of a high frequency output stabilization method according to the second embodiment. FIG. 9 is a flow chart showing an overview of a high frequency output stabilization method according to the second embodiment. FIG. 10 is a diagram showing an example of the slope and the intercept.

Below, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiment described below. In addition, in each drawing, the same or corresponding elements are appropriately assigned the same reference numerals. Furthermore, it should be noted that the drawings are schematic, and the dimensional relationships and ratios of each element may differ from the actual ones. There may also be parts in which the dimensional relationships and ratios differ between the drawings.

First Embodiment
Fig. 1 is a diagram showing an overview of a radio frequency output device according to the first embodiment. As shown in Fig. 1, a radio frequency output device 100 includes a signal generating section 10, a variable amplifier 20, a directional coupler 30, an adjustment amount calculating section 40, and a pair of switches 51 and 52.

The signal generating unit 10 is a unit that generates a high-frequency signal, and is located at the most upstream of the path of the high-frequency signal in the high-frequency output device 100. The signal generating unit 10 may include, but is not limited to, an oscillator that generates a high-frequency wave as a carrier wave. The signal generating unit 10 may suitably employ any device that generates a high-frequency wave whose frequency varies depending on the frequency, temperature, and output level of a downstream device.

The variable amplifier 20 amplifies the high-frequency signal generated by the signal generating unit 10 and then inputs it to the high-frequency component 21. The variable amplifier 20 can vary the gain when amplifying the high-frequency signal generated by the signal generating unit 10. The amount of gain adjustment in the variable amplifier 20 is configured to follow the output of the adjustment amount calculation unit 40.

The high-frequency component 21 may be any device that varies depending on temperature and output level. For example, it may be a filter such as a high-pass filter, low-pass filter, or band-pass filter, an amplifier, or a modulator that encodes a desired signal into a high-frequency signal, but is not limited to these. The high-frequency component 21 is a configuration that may be appropriately selected depending on the purpose of the high-frequency output device 100.

The directional coupler 30 splits the high-frequency signal traveling from the high-frequency component 21 to the output end 31. The directional coupler 30 is disposed between the high-frequency component 21 and the output end 31. In addition, since the switch 52 is disposed between the high-frequency component 21 and the directional coupler 30, the directional coupler 30 is also disposed between the switch 52 and the output end 31.

The adjustment amount calculation unit 40 calculates the amount of gain adjustment in the variable amplifier 20 based on the high-frequency signal branched by the directional coupler 30. The variable amplifier 20 adjusts the amplification of the high-frequency signal generated by the signal generation unit 10 based on the amount of gain adjustment calculated by the adjustment amount calculation unit 40.

The pair of switches 51, 52 are respectively disposed between the signal generating unit 10 and the variable amplifier 20, and between the high-frequency component 21 and the directional coupler 30. The pair of switches 51, 52 switch the path of the high-frequency signal from the signal generating unit 10 to the directional coupler 30 between a normal path and a bypass path. The normal transmission path is a path that passes through the variable amplifier 20 and the high-frequency component 21, and the bypass path is a path that bypasses the variable amplifier 20 and the high-frequency component 21.

When the bypass route is selected by the pair of switches 51, 52, the high frequency signal generated by the signal generating unit 10 passes substantially only through the directional coupler 30. In other words, the adjustment amount calculation unit 40 measures the characteristics of a measurement system that measures the high frequency signal near the output end 31. The high frequency output device 100 according to the first embodiment selects the bypass route by the pair of switches 51, 52, stores the measurement results of the adjustment amount calculation unit 40 at room temperature, and calculates the amount of gain adjustment in the variable amplifier 20 based on this as a reference.

In the high frequency output device 100 according to the first embodiment, even during use, a bypass path is temporarily selected by a pair of switches 51, 52 to measure the characteristics of a measurement system that measures high frequency signals near the output end 31. The difference in the measurement results between room temperature and during use is due to the influence of temperature changes in the measurement system. The measurement results of the normal path during use are measured with the influence of temperature changes in the measurement system superimposed. Therefore, in the high frequency output device 100 according to the first embodiment, the gain in the variable amplifier 20 is adjusted taking into account the influence of temperature changes in the measurement system that are superimposed. As a result, in the high frequency output device 100 according to the first embodiment, it is possible to eliminate the influence of temperature changes without performing calibration for temperature changes.

Figure 2 is a diagram showing the calibration of the high frequency output device according to the first embodiment. Also, Figure 3 is a diagram showing the use of the high frequency output device according to the first embodiment. Also, Figure 4 is a flow showing an overview of the high frequency output stabilization method according to the first embodiment.

As shown in FIG. 2, when calibrating the high frequency output device 100, a power meter 60 is connected to the output terminal 31 to measure the output at the output terminal 31. The output at the output terminal 31 measured by the power meter 60 during calibration is input automatically or manually to the adjustment amount calculation unit 40.

On the other hand, as shown in FIG. 3, when the high frequency output device 100 is in use, for example, an antenna 61 for propagating a high frequency signal through the air is connected to the output end 31. Note that when the high frequency output device 100 is in use, something other than the antenna 61 may be connected to the output end 31. For example, the output end 31 of the high frequency output device 100 may be connected to the input end of another device, with or without a cable.

The high frequency output stabilization method according to the first embodiment is performed in a state where a power meter 60 is connected to the output terminal 31 as shown in FIG. 2, and in a state where, for example, an antenna 61 is connected to the output terminal 31 as shown in FIG. 3. However, in the following description, the high frequency output stabilization method is performed using a high frequency output device 100, but the high frequency output stabilization method according to the first embodiment is not limited to the configuration of the high frequency output device 100. It can be performed with any general high frequency output device that has the function of stabilizing the output of the high frequency output device while measuring the high frequency signal near the output terminal.

As shown in FIG. 4, in the radio frequency output stabilization method according to the first embodiment, the radio frequency output device 100 is first calibrated with respect to frequency and output level (step S10). In this step S10, as shown in FIG. 2, the radio frequency output device 100 is calibrated with a power meter 60 connected to the output terminal 31 for measuring the output at the output terminal 31.

Next, in the high frequency output stabilization method according to the first embodiment, the characteristics of the measurement system that measures the high frequency signal near the output end 31 are measured with respect to the frequency and output level at room temperature (step S20). In this step S20, in the configuration of the high frequency output device 100, the high frequency signal output by the signal generating unit 10 is directly measured by the measurement system by selecting the pair of switches 51, 52 on the bypass path side. Note that this step S20 can be performed with a power meter 60 connected to the output end 31 that measures the output at the output end 31, as shown in FIG. 2.

Then, in the high frequency output stabilization method according to the first embodiment, the characteristics of a measurement system that measures high frequency signals near the output end 31 are measured with respect to the frequency and output level during use (step S30). During use, as shown in FIG. 3, an antenna 61 is connected to the output end 31 of the high frequency output device 100. In addition, in the configuration of the high frequency output device 100, a pair of switches 51, 52 are selected on the side of the path that passes through the variable amplifier 20 and the high frequency component 21.

Therefore, in the high-frequency output stabilization method according to the first embodiment, a pair of switches 51 and 52 is temporarily selected to the bypass path side. This temporary switching of the pair of switches 51 and 52 may be performed periodically, or may be performed automatically or manually by detecting a temperature change.

Then, in the radio frequency output stabilization method according to the first embodiment, the output of the radio frequency output device 100 is adjusted based on the difference in the measurement results of the characteristics of the measurement system at room temperature and during use (step 40). The difference in the measurement results at room temperature and during use is due to the influence of temperature changes in the measurement system. The measurement results of the normal path during use are measured with the influence of temperature changes in the measurement system superimposed. Therefore, in the radio frequency output stabilization method according to the first embodiment, the output of the radio frequency output device 100 is adjusted taking into account the influence of temperature changes in the measurement system that are superimposed. As a result, in the radio frequency output stabilization method according to the first embodiment, it is possible to eliminate the influence of temperature changes without performing calibration for temperature changes.

Second Embodiment
Fig. 5 is a diagram showing an outline of a high frequency output device according to the second embodiment. As shown in Fig. 5, the high frequency output device 200 includes a signal generating section 10, a variable amplifier 20, a directional coupler 30, an adjustment amount calculation section 40, and a pair of switches 51 and 52, as in the first embodiment. The high frequency output device 200 has the same configuration as the first embodiment except for the internal configuration of the adjustment amount calculation section 40, so that the same reference numerals are used for the common configurations and the description is omitted. For convenience of explanation, the figure shows a state in which a power meter 60 is connected to the output terminal 31, but as in the first embodiment, for example, an antenna 61 may be connected to the output terminal 31 during use.

As shown in FIG. 5, the adjustment amount calculation unit 40 includes a logarithmic amplifier 41 that logarithmically amplifies the high-frequency signal branched off from the directional coupler 30. The adjustment amount calculation unit 40 also includes an A/D (analog-digital) converter 42, a calculation processing unit 43, and a D/A (digital-analog) converter 44. The calculation processing unit 43 also includes a comparator 45 and a memory unit 46.

In the adjustment amount calculation unit 40, the logarithmic amplifier 41 logarithmically amplifies the high-frequency signal branched off from the directional coupler 30. Then, the A/D converter 42 converts the output of the logarithmic amplifier 41 into a digital signal. The comparator 45 of the calculation processing unit 43 compares the value input from the A/D converter 42 with the value stored in the memory unit 46 to calculate the gain adjustment amount in the variable amplifier 20. The D/A converter 44 converts the gain adjustment amount in the variable amplifier 20 calculated by the calculation processing unit 43 into an analog signal. The analog signal output by the D/A converter 44 is used as a gain control signal in the variable amplifier 20.

In the high frequency output device 200 according to the second embodiment, as in the first embodiment, the gain in the variable amplifier 20 is adjusted taking into account the effect of temperature changes in the measurement system that is measured in a superimposed manner. As a result, in the high frequency output device 200 according to the second embodiment, it is possible to eliminate the effect of temperature changes without performing calibration for temperature changes.

Figures 6 to 9 are flow charts showing an overview of the high frequency output stabilization method according to the second embodiment. The flow charts shown in Figures 6 to 9 are detailed explanations of steps S10 to S40 shown in Figure 4 in accordance with the configuration of the high frequency output device 200.

The steps shown in FIG. 6 show the details of the process of calibrating the high frequency output device 200 with respect to frequency and output level. As shown in FIG. 6, the high frequency output stabilization method according to the second embodiment records the measurement results of the output meter 60 and the adjustment amount calculation unit 40 with the output of the signal generation unit 10 near the maximum (step S11). Furthermore, the high frequency output stabilization method according to the second embodiment records the measurement results of the output meter 60 and the adjustment amount calculation unit 40 with the output of the signal generation unit 10 near the minimum (step S12). Note that steps S11 and S12 can be performed in any order.

The measurement results in the adjustment amount calculation unit 40 in steps S11 and S12 are values converted by the A/D converter 42. Therefore, by passing through the logarithmic amplifier 41, the values are logarithmically converted, and the values converted by the A/D converter 42 are values expressed in decibels. The measurement results in steps S11 and S12 may be stored in the memory unit 46 of the adjustment amount calculation unit 40, but may also be stored in the memory unit of a separate calibration device or on the operator's recording paper.

Next, in the high frequency output stabilization method according to the second embodiment, a slope and an intercept are calculated from the measurement results in the output meter 60 and the adjustment amount calculation unit 40 obtained in steps S11 and S12, and stored in the memory unit 46 of the adjustment amount calculation unit 40 (step S13). Here, the slope and the intercept are the ratio of the change in the measurement result in the adjustment amount calculation unit 40 to the change in the output meter 60, and the intercept on the axis of the value of the output meter 60, as shown in FIG. 10. As can be seen from their definitions, these slopes and intercepts represent the characteristics of the high frequency output device 200 with respect to the output level.

Then, in the high frequency output stabilization method according to the second embodiment, the processes from step S11 to step S13 are performed for each frequency to be used (step S14). As a result, the slope and intercept for each frequency are obtained, as shown in FIG. 10.

Next, the output of the signal generating unit 10 is set to a specified value (step 15).

Then, when the output level of the output meter 60 is high (for example, -10 dBm), the reading of the output meter 60 (this is set as PWRhigh), the reading of the A/D converter 42 (this is set as CODEhigh), and the input value of the D/A converter 44 (this is set as DAChigh) are obtained and stored in the memory unit 46 (step S16). Specifically, while incrementing or decrementing the input value of the D/A converter 44, the value when the output level of the output meter 60 is low is set as DAChigh. The reading of the output meter 60 at this time is set as PWRhigh, and the reading of the A/D converter 42 is set as CODEhigh.

Similarly, when the output level of the output meter 60 is low (e.g., -20 dBm), the reading of the output meter 60 (this is called PWRlow), the reading of the A/D converter 42 (this is called CODElow), and the input value of the D/A converter 44 (this is called DAClow) are obtained and stored in the memory unit 46 (step S17).

Then, steps S16 and S17 are performed for each frequency to be used (step S18). After that, for each frequency, the slope and intercept are calculated from PWRhigh, PWRlow, CODEhigh, and CODElow, and stored in the memory unit 46 (step S19).

Next, the high frequency output stabilization method according to the second embodiment measures the characteristics of a measurement system that measures high frequency signals near the output end 31 with respect to frequency and output level at room temperature. Each step shown in FIG. 7 shows the details of the process of measuring the characteristics of a measurement system that measures high frequency signals near the output end 31 with respect to frequency and output level at room temperature.

As shown in FIG. 7, in the high-frequency output stabilization method according to the second embodiment, first, a pair of switches 51, 52 are selected to the bypass path side (step S21). This allows the high-frequency signal output by the signal generating unit 10 to be directly measured by the measurement system. In other words, the reading of the A/D converter 42 measures the characteristics of the measurement system.

Therefore, in the high-frequency output stabilization method according to the second embodiment, the output of the signal generating unit 10 is set as a specified value, and the reading of the A/D converter 42 at this time (this is referred to as CAL_CODE) is stored in the memory unit 46 (step S22).

Then, step S22 is performed for each frequency that is planned to be used (step S23).

Next, the high frequency output stabilization method according to the second embodiment measures the characteristics of a measurement system that measures high frequency signals near the output end 31 with respect to the frequency and output level during use. Each step shown in FIG. 8 shows the details of the process of measuring the characteristics of a measurement system that measures high frequency signals near the output end 31 with respect to the frequency and output level at room temperature.

As shown in FIG. 8, the high frequency output stabilization method according to the second embodiment first selects the pair of switches 51, 52 to the bypass path side (step S31). As already described in the first embodiment, during use, the pair of switches 51, 52 are selected to the path side passing through the variable amplifier 20 and the high frequency component 21. Therefore, in step S31, the pair of switches 51, 52 are temporarily selected to the bypass path side. This switching may be performed, for example, when the temperature becomes high (for example, 50 degrees Celsius).

Then, the output of the signal generating unit 10 is set as a specified value, and the reading of the A/D converter 42 at this time (this is called CAL_CODE') is obtained (step S32).

Then, the pair of switches 51 and 52 are returned to the normal transmission path side (step S33).

Next, the radio frequency output stabilization method according to the second embodiment adjusts the output of the radio frequency output device 200 based on the difference in the measurement results of the characteristics of the measurement system at room temperature and during use. Each step shown in FIG. 9 adjusts the output of the radio frequency output device 200 based on the difference in the measurement results of the characteristics of the measurement system at room temperature and during use.

As shown in FIG. 9, the high frequency output stabilization method according to the second embodiment calculates CAL_CODEdiff=CAL_CODE-CAL_CODE' using the CAL_CODE stored in the memory unit 46 in step S22 and the CAL_CODE' obtained in step S32 (step S41).

Next, CAL_CODEdiff is added to the reading of the A/D converter 42 of the adjustment amount calculation unit 40 during use (for example, 50 degrees Celsius) (this is called CODE') (step S42). In other words, the high frequency output stabilization method according to the second embodiment uses the difference in the measurement results of the characteristics of the measurement system at room temperature and during use as a correction value to correct the measurement results of the output of the high frequency output device 200 during use.

Then, the output of the high frequency output device 200 is adjusted so that the measurement result of the output of the high frequency output device 200 during use, corrected as in step S42, falls within a predetermined range (step S43). Specifically, the comparator 45 compares the corrected CODE' with a predetermined range determined from the slope and intercept stored in the memory unit 46. If the corrected CODE' is outside the predetermined range, the gain in the variable amplifier 20 is adjusted by incrementing or decrementing the input to the D/A converter so that the corrected CODE' falls within the predetermined range. In this way, the high frequency output stabilization method according to the second embodiment makes it possible to eliminate the effects of temperature changes without performing calibration for temperature changes.

Although the present invention has been described above based on the embodiments, within the framework of the entire disclosure of the present invention (including the scope of the claims), and further based on the basic technical ideas thereof, modifications and adjustments of the embodiments or examples are possible. Furthermore, within the framework of the entire disclosure of the present invention, various combinations or selections (including at least partial non-selection) of various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) are possible. In other words, the present invention naturally includes the entire disclosure, including the scope of the claims, and modifications. In particular, with regard to the numerical ranges described in this document, any numerical value or subrange included within the range should be interpreted as being specifically described even if not otherwise specified. Furthermore, the disclosures of the above cited patent documents, etc. are incorporated into this document by reference.

REFERENCE SIGNS LIST 100, 200 High frequency output device 10 Signal generating section 20 Variable amplifier 21 High frequency component 30 Directional coupler 31 Output end 40 Adjustment amount calculation section 41 Logarithmic amplifier 42 A/D converter 43 Calculation processing section 44 D/A converter 45 Comparator 46 Memory section 51, 52 Switch 60 Output meter 61 Antenna

Claims (5)

A signal generating unit that generates a high frequency signal;
a variable amplifier that amplifies the high-frequency signal generated by the signal generating unit in such a way that the gain can be changed and inputs the signal to a high-frequency component;
a directional coupler that splits a high-frequency signal traveling from the high-frequency component to an output end between the high-frequency component and the output end;
a pair of switches disposed between the signal generating unit and the variable amplifier and between the high frequency component and the directional coupler, the pair of switches being configured to switch to a path that bypasses the variable amplifier and the high frequency component;
an adjustment amount calculation unit that corrects the measurement results of the frequency and output level of a high-frequency signal in a path that bypasses the variable amplifier and the high-frequency component during use based on a difference between measurement results at room temperature and during use of the frequency and output level of a high-frequency signal branched by the directional coupler in a path that bypasses the variable amplifier and the high-frequency component, and calculates an adjustment amount of a gain in the variable amplifier;
A high frequency output device comprising: The high frequency output device according to claim 1, characterized in that the adjustment amount calculation unit includes a logarithmic amplifier that logarithmically amplifies the high frequency signal branched off from the directional coupler. The high frequency output device according to claim 1 or 2, characterized in that the adjustment amount calculation unit includes an A/D converter, a calculation processing unit, and a D/A converter. A high-frequency output device according to any one of claims 1 to 3, characterized in that an antenna for propagating a high-frequency signal through the air is connected to the output terminal. The high frequency output device according to any one of claims 1 to 3, characterized in that a power meter for measuring the output at the output terminal is connected to the output terminal.

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