JP5258597B2 - High frequency amplifier circuit - Google Patents

Description

  The present invention relates to a high-frequency amplifier circuit that amplifies an input high-frequency signal by an amplifier element and outputs the amplified high-frequency signal, and more particularly to a high-frequency amplifier circuit capable of temperature compensation of the amplifier element.

  Conventionally, a high-frequency amplifier circuit using a transistor, FET, MMIC, or the like is generally used in a high-frequency circuit of a wireless communication device, and is often used particularly for a mobile phone or a mobile phone base station. In recent years, with the widespread use of mobile phones, the output of base stations, the number of lines, and the communication speed have been improved by adopting communication methods (W-CDMA, etc.), and the output of high-frequency amplifier circuits in base stations has been increased. .

  In general, even when a high-frequency amplifier circuit inputs a high-frequency signal of a rated level due to individual differences between devices and circuits, a difference in output level is observed for each individual. Therefore, a gain adjustment circuit that corrects individual variation and adjusts the gain to an allowable range is required. In addition, since the high frequency amplifier circuit is required to operate in a wide environmental temperature range (for example, −20 ° C. to 50 ° C.), even if a gain variation due to temperature change occurs in the amplifier element, the amplifier circuit has a predetermined gain. It is necessary to keep it within the range, and temperature compensation is required.

  FIG. 8 shows an example of a conventional high-frequency amplifier circuit 100. The high-frequency amplifier circuit 100 includes a volume 102 for adjusting individual variations and a temperature-sensitive resistor whose resistance value decreases as the temperature rises to compensate for a gain that decreases as the temperature rises. Connected to the side. However, there are individual variations in the gain temperature change characteristics of the amplifying element, and the allowable range may be exceeded depending on the combination with the temperature sensitive resistance. In this case, replacement work of the temperature sensitive resistance has occurred.

  As a method of avoiding such replacement, the temperature change and resistance change can be arbitrarily set, and the resistance change of the temperature sensitive resistance is detected by the A / D converter, and the resistance is reduced by the D / A converter. A variable closed loop control has been desired.

  Patent Document 1 discloses a technique for reducing bias fluctuation by measuring a drain current with an A / D converter and adjusting a gate voltage with a D / A converter based on the measured current value in a high-frequency amplifier circuit. It is disclosed.

Japanese Patent Laid-Open No. 10-290129

  As described above, when performing temperature correction with a temperature sensitive resistor, it is necessary to confirm the characteristics of the temperature sensitive resistor as an initial setting, adjust the volume to adjust for variations such as offset, and in some cases, replace the temperature sensitive resistor. there were. In order to solve this, a closed loop in which the resistance change of the temperature-sensitive resistor is detected by the A / D converter and the resistance is changed by the D / A converter so that the temperature change and the resistance change can be arbitrarily set. Incorporating control increases the cost of the high-frequency amplifier circuit.

  Further, in Patent Document 1, it is possible to reduce bias fluctuation by closed loop control using a computer, but gain adjustment in temperature fluctuation is not controlled, and it may not be able to cope with a deviation in output level of the amplifying element. is there.

  Therefore, even when the high-frequency amplifier circuit of the present invention is configured so that the amplifying elements are connected singly or in parallel, by providing a level adjusting means for correcting variation in characteristics between the amplifying elements due to temperature fluctuations, An object of the present invention is to provide a high-frequency amplifier circuit capable of adjusting the variation in accuracy of temperature compensation within a predetermined range.

The present invention provides a high-frequency amplifier circuit for amplifying and outputting the amplifying element the input high-frequency signal, a temperature detecting means for detecting the ambient temperature of the amplifying element, the level adjusting means for adjusting the level of the input high frequency signal And a storage means for storing a control value for the level adjustment means in association with the detected temperature detected by the temperature detection means , a control value corresponding to the detected temperature is obtained by referring to the storage means, and based on the control value and a control means for controlling said level adjusting means, said control means further comprises initial setting means for performing initial setting before controlling said level adjusting means, the initial setting means Is a control value for each of a plurality of different ambient temperatures, and is based on a control value that makes the output level of the amplifying element constant. The output level of the amplifying element and means for obtaining an approximate expression for associating the control value to be constant, based on the approximate expression, obtains a control value corresponding to the detected temperature, and means for storing in said memory means It is characterized by that.

The high frequency amplifier circuit according to the present invention desirably, the amplifying element comprises an element for a plurality of amplified connected in parallel.

Further, the present invention inputs a plurality of amplifying elements which are connected in parallel to the high-frequency signal, the radio frequency amplifier circuit for combining and outputting the output from the amplifying element, temperature detection for detecting the ambient temperature of the amplifier element and means, provided corresponding to said plurality of amplifying elements, and level adjusting means for adjusting the level of each high-frequency signal inputted, for each of the plurality of amplifying elements, detected by said temperature detecting means detecting A control unit that stores a control value for the level adjusting unit in association with a temperature, and a control value corresponding to the detected temperature is obtained for each of the plurality of amplifying elements with reference to the storage unit. and a control means for controlling said respective level adjusting means based on the value, the control means further first perform initial settings prior to controlling said respective level adjusting means The initial setting means is a control value for each of a plurality of different ambient temperatures, and based on a control value that makes the output level of the amplification element constant, the detected temperature and the amplification element Means for determining an approximate expression for associating a control value with a constant output level; and means for determining a control value corresponding to the detected temperature based on the approximate expression and storing the control value in the storage means. Each element is provided for each element . The present invention also provides a temperature detecting means for detecting an ambient temperature of the amplifier and a level adjusting means for adjusting the level of the inputted high frequency signal in a high frequency amplifier circuit for amplifying and outputting the inputted high frequency signal by an amplifier. And a storage means for storing a control value for the level adjustment means in association with the detected temperature detected by the temperature detection means, the control value for making the output level of the amplifier constant, and the storage means. And a control unit that obtains a control value corresponding to the detected temperature and controls the level adjusting unit based on the control value, and the amplifier includes a plurality of amplifying elements connected in parallel. One temperature detecting means, one level adjusting means, one storage means and one control means for the amplifying element group. It is characterized in that is.

  The high-frequency amplifier circuit according to the present invention can suppress the increase in cost, correct the variation in characteristics of the amplification element and the variation in accuracy of temperature compensation, and amplify by the level adjusting means even when the amplification element has an excessive input. There is an effect that the element can be protected.

1 is a circuit diagram showing a configuration of a high-frequency amplifier circuit according to a first embodiment of the present invention. It is a characteristic view which shows the gain characteristic in the 1st Embodiment of this invention. It is a flowchart figure which shows the flow of a control process of the high frequency amplifier circuit which concerns on 1st Embodiment. It is a flowchart figure which shows the flow of the process of the initial setting of the high frequency amplifier circuit which concerns on 1st Embodiment. It is a flowchart figure which shows the flow of a process of the real operation | movement of the high frequency amplifier circuit which concerns on 1st Embodiment. It is a circuit diagram which shows the structure of the high frequency amplifier circuit which concerns on 2nd Embodiment. It is a circuit diagram which shows the structure of the high frequency amplifier circuit which concerns on 3rd Embodiment. It is a circuit diagram which shows the structure of the high frequency amplifier circuit using the conventional temperature sensitive resistor.

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.
(First embodiment)

  FIG. 1 shows a configuration of a high-frequency amplifier circuit 1 according to the first embodiment. The high frequency amplifier circuit 1 is a circuit of a final stage amplifier of a base station, and a signal output from the high frequency amplifier circuit is supplied to an antenna device (not shown). The high-frequency amplifier circuit 1 is detected by an amplifying element 53 that amplifies a high-frequency signal, a voltage variable attenuator 36 connected to the previous stage of the amplifying element 53, a temperature IC 34 that detects the ambient temperature of the amplifying element 53, and a temperature IC 34. The CPU 12 outputs a control signal to the D / A converter 11 based on the detected temperature and the compensation value of the correction table 52, and amplifies the control signal from the D / A converter 11 and outputs it to the voltage variable attenuator 36. And an operational amplifier 35. The CPU 12 controls the output level of the amplifying element 53 by adjusting the input level to the amplifying element 53 using the voltage variable attenuator 36 with respect to the amplifying element 53 whose characteristics change due to temperature change.

  In the high-frequency amplifier circuit 1 according to the present embodiment, the temperature control function is shared by the CPU 12 that is also used for other purposes such as failure diagnosis for cost reduction. In order to eliminate the A / D converter, in this embodiment, a temperature IC 34 is used instead of the conventional temperature sensitive resistor, and a correction CPU 65 and a wattmeter 66 for creating a temperature compensation correction table 52 are used. ing.

  Furthermore, since the temperature IC 34 connected to the CPU 12 is a semiconductor temperature sensor having a serial communication port, it is more accurate than a temperature sensor such as a temperature sensitive resistor without being affected by the magnetic field and electric field in the vicinity of the amplification element 53. Temperature measurement is possible.

  In the present embodiment, the correction CPU 65 and the CPU 12 are connected by a serial line only when the correction table of the high-frequency amplifier circuit 1 is created, and the correction table 52 is created by connecting the wattmeter 66 to the high-frequency amplifier circuit 1. Thus, the characteristics of the amplifying element 53 can be grasped when the correction table is created.

  FIG. 2 shows gain characteristics of the amplifier 50 of the present embodiment, in which the horizontal axis represents the substrate temperature and the vertical axis represents the gain. The dotted line in the figure shows the change in gain before “Compensation for Individual Gain Variation / No Temperature Compensation” before the creation of the correction table, and the solid line in the figure shows the change in gain after “Compensation for Individual Gain Variation / With Temperature Compensation” Show. In the present embodiment, the individual variable gain at normal temperature (offset: A) is corrected by the voltage variable attenuator 36 in FIG. 1, and the inclination (inclination: B) with respect to the substrate temperature change due to temperature compensation is corrected to change from low temperature to high temperature. In the meantime, a constant gain is realized.

  FIG. 3 shows an outline of the control of the high-frequency amplifier circuit, and the initial setting in step S1 in the drawing indicates, for example, an initial setting process in the production line. Step S2 is a process for loading the temperature compensation data obtained by the initial setting, and step S3 shows the process of the temperature compensation actual operation after the power is turned on. Steps S1 and S3 are subroutines for executing a plurality of processes, and details thereof are shown in FIG. 4 (initial setting) and FIG. 5 (actual operation).

  In step S1 of FIG. 3, the amplifier is placed in a thermostatic chamber in which the ambient temperature can be freely changed to create temperature compensation data. These processes are executed by the CPU 12 and the correction CPU 65 of FIG.

  FIG. 4 shows details of the initial setting process flow. In step S10, the operator installs the high-frequency amplifier circuit 1 of FIG. In step S12, in order to perform individual gain variation (offset) compensation, the operator sets the constant temperature chamber to a normal temperature state (for example, 25 degrees), gives a rated input to the amplifier 50, and sets the output level at that time to the correction shown in FIG. The power is measured by the wattmeter 66 using the CPU 65 and transmitted to the CPU 12 of the high-frequency amplifier circuit 1 through the correction CPU 65. The CPU 12 adjusts the control value to the voltage variable attenuator 36 so that the rated gain of the amplifier 50 is obtained, and the CPU 12 stores the control value in the correction table 52. Thereafter, when the power of the amplifier 50 is turned on, the voltage variable attenuator 36 is controlled so that the amplifier 50 has a rated gain.

  Next, in step S14, the operator sets the inside of the thermostatic chamber to the lowest temperature (for example, -20 degrees) in the specifications of the amplifier 50, and sets the gain of the amplifier 50 in FIG. 1 to a specified value in the same manner as in step S12. Set. Further, the CPU 12 detects the control value of the voltage variable attenuator 36 and the ambient temperature of the amplifier 50 by the temperature IC 34 and stores them in the correction table 52.

  Next, in step S16, the operator sets the inside of the thermostatic chamber to the maximum temperature (for example, 50 degrees) in the specifications of the amplifier 50, and sets the gain of the amplifier 50 in FIG. 1 to a specified value in the same manner as in step S12. To do. Further, the CPU 12 detects the control value of the voltage variable attenuator 36 and the ambient temperature of the amplifier 50 by the temperature IC 34 and stores them in the correction table 52.

  Finally, in step S18, the CPU 12 calculates the slope of the control value of the voltage variable attenuator 36 from the result of the control value of the voltage variable attenuator 36 and the ambient temperature, which has a specified gain, from the measurement results of steps S12 to S16. Thus, the correction table 52 is created. In step S18 of FIG. 4, the temperature compensation data obtained in this way is incorporated as statistical data, and, for example, a polynomial approximation formula is obtained by applying the least square method to create a representative value. When the above process ends, the process proceeds to step S2 in FIG. In addition, when the temperature compensation data is stabilized in the production lot at the time of mass production, only the representative value of the completed temperature compensation data may be loaded in step S2. It is possible to grasp the characteristics of each production lot by statistically grasping the variation in the idle current set value during the initial setting.

FIG. 5 shows the flow of subroutine processing in the temperature compensation actual operation of the high-frequency amplifier circuit 1. In step S20, which is the temperature acquisition process of the actual operation (step S3 in FIG. 3), the ambient temperature is constantly measured by the temperature IC 34. Next, in step S22, the CPU 12 refers to the correction table 52 to obtain a control value at which the gain of the amplifier 50 becomes constant at each temperature, and outputs the control value to the D / A converter 11 in step S24. A control signal is output to the voltage variable attenuator 36 to control the input level of the amplifier 50 and return to the beginning. By repeating such processing, the temperature correction of the output level of the amplifier 50 becomes possible.
(Second Embodiment)

  FIG. 6 shows a configuration of the high-frequency amplifier circuit 2 in which two amplifier elements 53 are connected in parallel for high output. In the high-frequency amplifier circuit 2 according to the second embodiment, the ambient temperature is detected by one temperature IC 34 as an amplifier element group (third stage amplifier 50) in which the amplifier elements 53 are connected in parallel to form a group, and the CPU 12 has one Temperature compensation is performed by controlling the voltage variable attenuator 36 based on the correction table 52.

  In the high frequency amplifier circuit 2 of the present embodiment, the first stage amplifier 10 and the second stage amplifier 20 for driving the amplifier elements 53 connected in parallel are provided, and the voltage is variable at the input of the first stage amplifier 10 on the upstream side. By connecting the amplifier 36, it is assumed that the ambient temperature on the substrate is substantially equal, and the temperature compensation is performed including the first amplifier 10 and the second amplifier 20.

In the present embodiment, two amplifying elements 53 are connected in parallel. However, the present invention is not limited to this, and three or more in parallel may be connected. In this embodiment, the voltage attenuator is connected to the input of the first stage amplifier on the upstream side. However, the voltage attenuator can be provided at the input of the second stage amplifier or the third stage amplifier. It is not limited.
(Third embodiment)

  Next, a description will be given of a third embodiment in which a plurality of amplifying elements are subjected to temperature compensation using individual temperature ICs and correction tables. FIG. 7 shows that a third stage A amplifier and a third stage B amplifier are connected in parallel, the third stage A amplifier and the third stage B amplifier are connected to an amplifying element 53, a temperature IC 34, a voltage variable attenuator 36, The configuration of the high-frequency amplifier circuit 3 provided with the operational amplifier 35 and the corresponding correction table is shown.

  The input signal input to the input terminal IN is amplified by the first stage amplifier 10 and the second stage amplifier 20 and input to the third stage amplifier 50. The high frequency signal input to the third stage amplifier 50 is input to the third stage A amplifier and the third stage B amplifier, respectively. The CPU 12 measures the ambient temperature of each amplification element 53 with each temperature IC 34, and sets each voltage variable attenuator 36 with each D / A converter 11 and each operational amplifier 35 based on the correction value of each correction table 52. Control. Each voltage variable attenuator supplies the temperature-compensated input to each amplifying element 53, and an output signal having a uniform output level is synthesized and output from the output terminal OUT of the third stage amplifier 50.

  Such a high-frequency amplifier circuit 3 amplifies a high-frequency signal with a plurality of amplifying elements connected in parallel. In particular, when each amplification element is mounted on a separate substrate, the ambient temperature is not uniform, so that variations in gain and output level for each amplification element occur, and distortion in the output signal is likely to occur. In such a case, it is preferable to adjust the input level of the plurality of amplifying elements by using the voltage variable attenuator 36 provided for each amplifying element to keep the output level of each amplifying element uniform.

  In the case of a high-frequency amplifier circuit of several hundred watts realized by parallel connection, the performance degradation of the amplifier element becomes significant as the ambient temperature of the amplifier element approaches 50 degrees, for example. It is necessary to protect against overheating. In the present embodiment, the CPU 12 always detects the temperature with the temperature IC 34, and the gain can be controlled while keeping the output level of each amplifier uniform to prevent overheating.

  As described above, the high-frequency amplifier circuit according to the present embodiment realizes closed-loop control while suppressing an increase in cost, corrects variations in gain of the amplifying element and variations in accuracy of temperature compensation, and overloads the amplifying element. Even when there is an input, the amplification element can be protected by the level adjusting means. Further, in the high frequency amplifier circuit described in the present embodiment, it is built in a case and placed near the base station antenna or at a high place where it is exposed to direct sunlight. The highly accurate temperature compensation function shown is very suitable.

  The high-frequency amplifier according to the present invention particularly relates to a high-frequency amplifier circuit capable of temperature compensation of an amplifier element, and can be used for a high-frequency amplifier circuit that amplifies an input high-frequency signal by an amplifier element and outputs the amplified signal.

  1, 2, 3, 100 High frequency amplifier circuit, 10 1st stage amplifier, 11 D / A converter, 12 CPU, 20 2nd stage amplifier, 50 3rd stage amplifier, 51 3rd stage A amplifier, 35 operational amplifier, 34 temperature IC, 36 voltage variable attenuator, 53, 101 amplifying element, 61 3rd stage B amplifier, 52 compensation table, 65 CPU for correction, 66 wattmeter, 102 volume, 103 temperature sensitive resistor.

Claims (4)

In a high frequency amplification circuit that amplifies an input high frequency signal by an amplification element and outputs it,
Temperature detecting means for detecting the ambient temperature of the amplifying element,
Level adjusting means for adjusting the level of the input high-frequency signal;
Storage means for storing a control value for the level adjustment means in association with the detected temperature detected by the temperature detection means ;
Control means for referring to said storage means, obtains a control value corresponding to the detected temperature, controls the level adjusting means based on the control value,
Have
The control means further includes initial setting means for performing initial setting before controlling the level adjusting means, and the initial setting means includes:
A control value for each of a plurality of different ambient temperatures, wherein the detected temperature is associated with a control value for making the output level of the amplification element constant based on a control value for making the output level of the amplification element constant. Means for obtaining an approximate expression;
Based on the approximate expression, a control value corresponding to the detected temperature is obtained and stored in the storage means;
High-frequency amplifier circuit comprising: a. The high frequency amplifier circuit according to claim 1,
The amplifying element is a high frequency amplifier circuit, characterized in that it comprises an element for a plurality of amplified connected in parallel. In a high-frequency amplifier circuit that inputs a high-frequency signal to a plurality of amplifying elements connected in parallel and synthesizes and outputs the output from each amplifying element,
Temperature detecting means for detecting the ambient temperature of the amplifier element,
Provided corresponding to said plurality of amplifying elements, and level adjusting means for adjusting the level of each high-frequency signal inputted,
Storage means for storing a control value for the level adjustment means in association with the detected temperature detected by the temperature detection means for each of the plurality of amplification elements ;
Control means for referring to said storage means, obtains a control value corresponding to the detected temperature for each of the plurality of amplifying elements, for controlling the respective level adjusting means based on the control value,
Have
The control means further includes initial setting means for performing initial setting before controlling the level adjusting means, and the initial setting means includes:
A control value for each of a plurality of different ambient temperatures, wherein the detected temperature is associated with a control value for making the output level of the amplification element constant based on a control value for making the output level of the amplification element constant. Means for obtaining an approximate expression;
Based on the approximate expression, a control value corresponding to the detected temperature is obtained and stored in the storage means;
Each of the plurality of amplifying elements includes a high-frequency amplifier circuit. In the high frequency amplifier circuit for amplifying and outputting the amplified unit the input high frequency signal,
Temperature detecting means for detecting the ambient temperature of the amplifier circuit,
Level adjusting means for adjusting the level of the input high-frequency signal;
Storage means for storing a control value for the level adjusting means, which is associated with the detected temperature detected by the temperature detecting means, and which makes the output level of the amplifier constant ;
Referring to the storage means, obtains a control value corresponding to the detected temperature, the control means on the basis of the control value, for controlling said level adjusting means,
Have
The amplifier is an amplifying element group having a plurality of amplifying elements connected in parallel,
A high-frequency amplifier circuit comprising: one temperature detecting unit, one level adjusting unit, one storage unit, and one control unit for the amplification element group .

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