JPH07202581A - Power amplifier - Google Patents

Abstract

PURPOSE:To make the control circuit of the power amplifying part compact and monolithic and to compensate the linear amplifier characteristic for the change of the amplifying characteristic by controlling the bias of the power amplifying part so that the power level difference detected by a detecting means to zero. CONSTITUTION:The power level of the frequency component of the upper and lower band wave extracted by band pass filters 5 and 7 is detected by power level detection parts 9 and 11. A power level comparison part 13 outputs the power level difference of the output signal to a terminal T9 for the power level of the output signal to a terminal T7 to a terminal T11. A bias control part 15 outputs a bias control signal to the bias terminal T1 of the power amplifier part 1 based on the control function defined by the power level to be outputted to the terminal T11. The bias control signal controls the bias of the power amplifier part 1. The power level in the pass frequency range of the band-pass filter of the upper band wave and the power level in the pass frequency range of the band pass filter of the lower band are set to the absolute power level lower than the specified value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power amplification device for a radio transmitter used in a radio communication system adopting a linear modulation method.

[0002]

2. Description of the Related Art Conventionally, some wireless communication systems employ a linear modulation method. The power amplification unit of the wireless transmission device in the base station and mobile station of such a wireless communication system consumes most of the power consumption of the wireless device. For example, current analog cellular phones consume about 60% of power. For this reason, in a mobile station such as a portable device, it is important to increase the power efficiency of the power amplification device from the viewpoint of extending the call time, downsizing the battery, and reducing heat generation due to power consumption. As a means for improving power efficiency, for example, an analog F
In the M wireless communication system, a high efficiency power amplification section such as class C or class F is used.

On the other hand, in recent years, the shift from the conventional analog system to the digital system has been rapidly progressing in wireless communication. Used in a wireless communication system adopting such a digital system, a power amplification device of a base station and a mobile station wireless device is a digital modulation signal,
For example, in order to amplify a QPSK wave, it is essential to have a linear amplification characteristic.

Generally, the power amplification section for class A or class AB operation, which has a linear amplification characteristic, has a low power efficiency and cannot satisfy the above-mentioned requirement for high efficiency operation. In addition, since the power amplifier for class C or class F operation, which has high efficiency, operates in the non-linear region, the linear amplification characteristic is significantly deteriorated. There is a trade-off relationship between the linear amplification characteristic and the high-efficiency operation, and it is difficult to realize them at the same time. To realize these at the same time, it is necessary to provide the power amplification unit with some control means.

Therefore, a linear amplification characteristic compensating device called a linearizer has been proposed as a technique for realizing a linear amplification characteristic with high efficiency. Among this linearizer,
The drain voltage control linearizer is considered to be an effective method from the viewpoint of improving power efficiency and miniaturization. In this method, it is desirable to have a monolithic configuration including the power amplification unit and the control circuit in order to compensate for errors due to variations in temperature characteristics and amplification characteristics of the elements.

From this point of view, there has been proposed a drain voltage control linearizer in which a control circuit for linearization is constituted by an analog circuit and the control function is fixed only once (Japanese Patent Application No. 4-349524).

FIG. 15 shows a conventional drain voltage control linearizer. The configuration shown in FIG. 15 has only one control function for linearization for the purpose of reducing the size of the bias control unit 15 and configuring the power amplification unit 1 and the bias control unit 15 in a monolithic manner. The bias controller 15 can be fixed and can be realized by a simple analog circuit.
Therefore, when the linear amplification characteristic is compensated for variations in manufacturing of the plurality of power amplification sections and changes in the amplification characteristics of the power amplification section due to aging and temperature, there are the following drawbacks.

Since the amplification characteristics of the power amplification section when a modulation signal is input are different due to manufacturing variations, aging and temperature characteristics, the range of application of the control function for linearly compensating the amplification characteristics is exceeded and the linear amplification characteristics are If the input signal level is large, for example, 1
For an input level that gives a dB gain suppression point,
This is a drawback that the power level in the arbitrary frequency range of the upper sideband and the power level in the arbitrary frequency range of the lower sideband at the output of the power amplification unit are remarkably different and one intermodulation distortion level is significantly deteriorated.

In order to solve these drawbacks, as shown in FIG. 16, a linear amplification characteristic is obtained by adopting a configuration in which an input linear modulation signal and an output distortion signal are successively compared to correct a control function for linearization. An adaptive drain voltage control linearizer for compensation has also been proposed (Japanese Patent Laid-Open No. 3-17481).
No. 0). In the configuration shown in FIG. 16, the difference signal between the input signal and the output signal is used for the correction of the control function, and it is possible to cope with manufacturing variations of a plurality of power amplification units, changes over time and changes in the amplification characteristics of the power amplification units due to temperature characteristics. it can. This structure has the following drawbacks.

That is, since the configuration shown in FIG. 16 is a system for sequentially comparing the input signal and the output signal for responding to the change of the amplification characteristic and correcting the control function for linearization, the input signal and the output are It is necessary to accurately compensate for signal and control loop delays. In order to accurately compensate for this control loop delay, there is a drawback in that the control means becomes complicated and therefore the scale of the control circuit becomes large.

[0011]

As described above, the conventional drain voltage control linearizer for the purpose of miniaturization and monolithic output changes the amplification characteristic of the power amplification section, resulting in an output for the modulation signal. In some cases, the power level of the upper sideband in the arbitrary frequency range is different from the power level of the lower sideband in the arbitrary frequency range, and the intermodulation distortion level of one side may be significantly deteriorated.

Further, also in the case of the adaptive drain voltage control linearizer which sequentially corrects the control function for linearization in response to the change in the amplification characteristic of the power amplification section, the control means for accurately compensating the control loop delay. Was complicated and difficult to realize.

The present invention has been made in view of the above-mentioned problems, and a power amplifying device capable of miniaturizing a control circuit of a power amplifying unit and monolithically, and compensating a linear amplifying characteristic with respect to a change in the amplifying characteristic of the power amplifying unit. The purpose is to provide.

[0014]

In order to achieve the above object, the present invention is directed to an upper band of an output signal of a power amplifier for amplifying and outputting an input modulated signal in a power amplifier of a transmitter in a communication device. Detecting means for detecting a difference between respective power levels of a wave and a lower sideband in an arbitrary frequency range, and control for controlling a bias of the power amplifying portion so that the difference between the power levels detected by the detecting means becomes zero. The gist is to have means.

Preferably, the difference between the power level of the output signal of the power amplification section in the arbitrary frequency range of the upper sideband and the power level of the lower sideband in the arbitrary frequency range is detected,
The amplification characteristic is changed by controlling the bias of the amplification element of the power amplification unit according to the power level difference, and the relative power level and the lower sideband in the arbitrary frequency range of the upper sideband with respect to the power level of the transmission center frequency are changed. In a range where the relative power in an arbitrary frequency range is equal to or lower than a specific threshold value, the difference between the power level in an arbitrary frequency range of the upper sideband and the power level in an arbitrary frequency range of the lower sideband may be set to zero. That is, in terms of equalization, the control function for linearization is corrected by controlling the bias of the amplification element of the power amplification unit.

[0016]

According to the power amplifying device of the present invention, when the modulated signal is input to the power amplifying section which constitutes the transmitting section of the communication device,
This modulated signal is amplified and output. At this time, the difference between the power levels of the output signal of the power amplification unit in the arbitrary frequency range of the upper sideband and the lower sideband is detected by the detection means, and the detected power level difference is set to zero. By controlling the bias of the power amplification unit, the control function for linearization of the power amplification unit is corrected. That is, since the control function for linearization is uniquely fixed, the control circuit can be configured in a compact and monolithic manner, and by applying the above-mentioned solution, the linear amplification characteristic is compensated for the change in the amplification characteristic of the power amplification unit. it can.

Further, in the conventional method, when a modulated signal having a large input power level is input to the power amplification section, the power level in an arbitrary frequency range of the output upper sideband and the power level in an arbitrary frequency range of the lower sideband are changed. Although there is a disadvantage that unbalance occurs and one intermodulation distortion level is significantly deteriorated, by applying the above-mentioned solution, the power level in an arbitrary frequency range of the upper sideband of the output and the arbitrary level of the lower sideband are reduced. It is possible to suppress the intermodulation distortion level by compensating the imbalance of the power level in the frequency range of. in addition,
The imbalance between the power level in any frequency range of the output upper sideband and the power level in any frequency range of the lower sideband is noticeable when the input signal level is large. In the following, the above-mentioned means will not be necessary, and a simple conventional control for linearization is sufficient.

Further, in the conventional method of sequentially comparing the input signal and the output signal and correcting the control function for linearization to compensate for the change in the amplification characteristic of the power amplifier, the gain of the output signal with respect to the input signal is constant. It is necessary to match the timing of comparing both signals. Therefore, a complicated control means for compensating for the control loop delay has been essential. Since the present invention is a method for controlling the amplification characteristic of the power amplification section based only on the output frequency spectrum for a modulated signal whose power level changes with time, a complicated control means for compensating for the control loop delay of the conventional method is provided. It is unnecessary.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a first embodiment of a power amplification device according to the present invention.

As shown in FIG. 1, the modulation signal input from the input terminal T _{I is} input to the power amplification section 1. The output end of the power amplification section 1 is connected to the signal branch section 3, and the modulated signal amplified by the signal branch section 3 is branched into at least three, and one of them is output to the output terminal T _O. . Further, one of the modulation signals branched by the signal branching unit 3 is a terminal T ₃
To the bandpass filter 5, and the other one is output to the bandpass filter 7 via the terminal T ₅ . The modulated signal input to the band pass filter 5 passes through only a predetermined band, and is input to the power level comparison unit 13 via the power level detection unit 9 and the terminal T ₇ .

On the other hand, the modulated signal input to the band pass filter 7 passes through only a predetermined band different from that of the band pass filter 5, and is passed to the power level comparison unit 13 via the power level detection unit 11 and the terminal T _9. Is entered. The extracted signals input from the power level detecting unit 9 and the power level detecting unit 11 are compared by the power level comparing unit 13 and the terminal T ₁₁
Is input to the bias control unit 15 via the
It is used for bias control of.

The operation and action of this embodiment will be described in detail below. First, a modulation signal is input to the input terminal T _I of the power amplification unit 1, and the obtained output signal is output by the signal branching device 3.
Branch into at least three or more. The power amplification unit 1 may be, for example, a power amplification unit that is linearized by a linearizer. The signal branching unit 3 can be realized by, for example, a directional coupler, a power divider, a power splitter, or the like. The output signal to the output terminal T _O of the signal branching unit 3 is the transmission power of the radio equipment, is radiated into the air through an antenna, not shown.

On the other hand, the output signal to the terminal T ₃ and the output signal to the terminal T _{5 of} the signal branching unit 3 are input to a bandpass filter (denoted by BPF in the figure) 5 and a bandpass filter 7. As a result, the frequency components of the pass center frequencies of the band pass filters 5 and 7 of the respective output signals are extracted. Regarding the pass center frequencies of the band pass filters 5 and 7, for example, one is the frequency of the upper sideband of the transmission frequency and the other is the frequency of the lower sideband of the transmission frequency.

The power levels of the frequency components of the upper sideband and the lower sideband extracted by the band pass filters 5 and 7 are detected by the power level detectors 9 and 11, respectively. The power level detection units 9 and 11 can be easily configured by analog circuits by combining a diode detector and an integrator, for example.
A monolithic IC is also possible. The detected power levels are input to the terminals T ₇ and T ₉ of the power level comparison unit 13.

The difference in power level of the power level comparator 13 output signal to the terminal T ₉ to the power level of the output signal to the terminal T _7, or to the terminal T ₇ to the power level of the output signal to the terminal T ₉ The difference between the power levels of the output signals of the above is output to the terminal T ₁₁ . For example, when the power level input to the terminal T ₇ is −40 dBm and the power level input to the terminal T ₉ is −45 dBm, a power level difference of −5 dB is output to the terminal T ₁₁ .

The bias controller 15 outputs a bias control signal to the bias terminal T ₁ of the power amplifier 1 based on the control function defined by the power level output to the terminal T ₁₁ .
The bias control signal controls the bias of the power amplification unit 1,
The power level in the pass frequency range of the upper band wave band pass filter and the power level in the pass frequency range of the lower band wave band pass filter are set to the same absolute power level below a specific threshold value.

The procedure described above is repeated until the difference between the power level of the upper sideband and the power level of the lower sideband and the relative power level of the upper sideband and the relative power level of the lower sideband with respect to the transmission power level become equal to or less than the allowable value. It may be repeated. Since the control function of the bias control unit 15 is defined by the difference between the power level in the pass frequency range of the lower sideband bandpass filter and the power level in the pass frequency range of the upper sideband bandpass filter, in the used frequency band. From the input of the signal branching unit 3 to the terminals T ₇ and T ₉
The attenuation of the paths up to is the same. Alternatively, when the attenuation amount of the output signal to the terminal T ₃ and the attenuation amount of the output signal to the terminal T ₅ with respect to the input signal of the signal branching unit 3 are different, from the terminal T ₃ to the terminal T ₇ and from the terminal T ₅ You may adjust the attenuation amount in the path to the terminal T ₉ .

Further, the paths from the terminal T ₃ to the terminal T ₇ and from the terminal T ₅ to the terminal T ₉ are made to have the same amount of attenuation by using the same circuit element, and the terminal T for the input signal of the signal branching unit 3 is used. The attenuation amount of the output signal to ₃ and the attenuation amount of the output signal to the terminal T ₅ may be the same. Also, the control function is defined as the difference between the power level in the pass frequency range of the lower band wave and the power level in the pass frequency range of the band pass filter of the upper band wave. It may be defined by the difference in the power level in the pass frequency range of the upper band wave band pass filter with respect to the power level in the pass frequency range of.

FIG. 2 shows an example of the characteristic of the control function in the bias controller 15. The control characteristic will be described with reference to FIG. The horizontal axis of FIG. 2 is the difference between the power level in the pass frequency range of the lower sideband bandpass filter and the power level in the pass frequency range of the upper sideband bandpass filter. The vertical axis represents the control gate bias.

When the difference between the power level in the pass frequency range of the upper sideband bandpass filter and the power level in the passband range of the lower sideband bandpass filter is positive, the gate of the amplification element of the power amplifying device is detected. When the bias is large and the difference of the same power level is negative, the control function is described by the characteristic of monotonically increasing that the gate bias is small.

In an actual drain voltage control linearizer, the difference between the power level in the pass frequency range of the upper sideband bandpass filter and the power level in the pass frequency range of the lower sideband bandpass filter may be -10 dB or more. At this time, if the gate bias of the amplifying element (field effect transistor) is increased by about 0.2 V, the power level in the pass frequency range of the upper band wave bandpass filter with respect to the power level in the pass frequency range of the lower band wave band pass filter is increased. It was confirmed that the difference was about -2 dB.

When the difference between the power level in the pass frequency range of the lower sideband bandpass filter and the power level in the passband range of the upper sideband bandpass filter is -10 dB or more, the gate bias is set to 0.
It was confirmed that when the voltage was increased by about 4 V, the difference between the power level in the pass band range of the upper band wave and the power level in the pass frequency range of the band pass filter of the lower band wave was about +5 dB.

The control function may be a monotonically decreasing characteristic corresponding to the modulation method or the amplification characteristic of the power amplifier. Control functions for monotonic increase and monotonic decrease can be realized by a simple analog circuit with only one operational amplifier.
It is also possible. Further, when the amplification element of the power amplification device is a field effect transistor, the drain bias may be controlled, and when the amplification element is a bipolar transistor, the base bias or the collector bias may be controlled. Further, not only one bias but also the gate bias and the drain bias, or both the base bias and the collector bias may be controlled.

FIG. 3 is a block diagram showing a second embodiment according to the present invention. The operating principle will be described with reference to FIG. The output signal of the power amplification unit 1 is input to the signal branching unit 17 and branched into at least two signals. The output signal to the terminal T _O is the same as in the first embodiment described above. The output signal to the terminal T ₁₃ is branched into at least two signals by the signal branching unit 19.

In the case of the configuration shown in FIG. 3, the signal branching unit 17
Would allow the power to be shunted to the terminal T ₁₃ without compromising the power to the terminal T _O if, for example, a directional coupler were used. The signal branching unit 19, for example, when using a power splitter, the terminal T ₃ at the same attenuation amount from the terminal T ₁₃
And the power can be branched to the terminal T ₅ .

The terminals T ₃ and T of the signal branching unit 19
₅ and later, extraction of the frequency components of the frequency components and lower side bands of the upper sideband, detection of both power levels, comparison of both power levels, the operating principle of the bias control of the power amplifier to the first embodiment described above Same as the example. Further, the amount of attenuation from the terminal T ₁₃ to the terminal T ₃ and the amount of attenuation from the terminal T ₁₃ to the terminal T ₅ are the same as those in the first embodiment described above.

FIG. 4 is a block diagram showing a third embodiment according to the present invention. The operation principle will be described with reference to FIG.
The operation principle up to the signal branching unit 3 is the same as that of the first embodiment described above.

In the present embodiment, the signal addition unit 21 adds the frequency components of the upper sideband and the frequency components of the lower sideband extracted by the bandpass filter 5 and the bandpass filter 7, respectively. The output signal of the signal adder 21 is detected by the power level detector 9 to determine the difference between the power level in the pass frequency range of the upper band wave band pass filter and the power level in the pass frequency range of the upper band wave band pass filter, for example. To detect. Alternatively, the operation principle is the same even if the difference between the power level in the pass frequency range of the lower sideband bandpass filter and the power level in the pass frequency range of the lower sideband bandpass filter is detected.

The operation principle of the bias control of the power amplifier after the terminal T ₁₁ of the power level detector 9 is the same as that of the first embodiment. Furthermore, the amount of attenuation from the input of the signal branching unit 3 to the signal adding unit 21 is the same for both paths as in the first embodiment described above.

FIG. 5 is a block diagram showing a fourth embodiment according to the present invention. The operation principle will be described with reference to FIG.
The operation principle up to the signal branching unit 17 is the same as that of the second embodiment described above. In the present embodiment, the output signal to the terminal T ₁₃ is frequency-converted by the frequency converter 23 according to the frequency fc generated by the frequency oscillator 25. Frequency oscillator 25
May be used by sharing the local frequency oscillator of the wireless device, or a new frequency oscillator may be provided. After the frequency conversion, the signal branching unit 19 branches the signal into at least two or more signals. By inputting these signals to the bandpass filters 5 and 7, the frequency component of the pass center frequency is extracted. The band-pass filter or the low-pass filter has a function of extracting a frequency component in a desired band and also a function of removing high-order harmonics generated during frequency conversion. Bandpass filters 5 and 7
One of the pass center frequencies is the frequency of the difference between the frequency of the upper sideband and the frequency fc of the frequency oscillator 25, and the other is the frequency of the difference between the frequency of the lower sideband and the frequency fc of the frequency oscillator 25.

After the band pass filters 5 and 7, the power level of the frequency component of the upper sideband and the power level of the frequency component of the lower sideband are detected, the power levels of the two are compared, and the operation principle of the bias control of the power amplification device is detected. Is the same as the first embodiment described above. Further, the amount of attenuation from the terminal T ₃ to the terminal T ₇ and the amount of attenuation from the terminal T ₅ to the terminal T ₉ are the same as those in the first embodiment described above.

FIG. 6 is a block diagram showing a fifth embodiment according to the present invention. The operating principle will be described with reference to FIG. The operation principle up to the signal branching unit 3 is the same as that of the first embodiment described above. In this embodiment, the output signal to the terminal T ₃ of the signal branching unit 3 is frequency-converted by the frequency conversion unit 23 and the frequency oscillator 25, and the output signal to the terminal T ₅ is frequency conversion unit 2.
7 and frequency oscillator 29 for frequency conversion. The oscillation frequency f _c2 of the oscillation frequency f _c1 and frequency oscillator 29 of the frequency oscillator 25, for example may be a just different frequency difference between the frequencies of the frequency and the lower sideband of the upper sideband frequency and a lower side band of the upper sideband The frequency of the wave may also be used.

Oscillation frequency f of the frequency oscillators 25 and 29
_{When c1} and the oscillation frequency f _c2 are the frequency of the upper sideband and the frequency of the lower sideband, the frequency components of the upper sideband are generated by the frequency converters 23 and 27 without using the bandpass filters 5 and 7. And the frequency component of the lower sideband can be extracted.
In this case, a low-pass filter that can be realized with a simpler configuration than a band-pass filter can be used in order to remove high-order harmonics that occur due to frequency conversion.

After the band-pass filters 5 and 7, the frequency components of the upper sideband and the lower sideband are extracted, the power levels of both are detected, the power levels of both are compared, and the bias control of the power amplifier is performed. The principle is the same as that of the first embodiment described above. Further, as shown in FIG. 7, the frequency oscillator 25 may be one, and the operating principle is the same as that of the above-described fourth embodiment. Furthermore, from terminal T ₃ to terminal T
Attenuation of the terminal T ₉ from attenuation T ₅ to ₇ is the same as the first embodiment described above.

FIG. 8 is a block diagram showing a sixth embodiment according to the present invention. The operation principle will be described with reference to FIG. The operation principle up to the signal branching unit 17 is the same as that of the first embodiment of the present invention. In the present embodiment, the output signal to the terminal T ₁₃ of the signal branching unit 17 is frequency-converted by the frequency converter 23 and the frequency oscillator 25. The frequency oscillator 25 is
As shown in FIG. 9, it has a characteristic of generating different frequencies in time division. The frequency signal output from the frequency oscillator 25 is also output to the delay unit 35 described later.

Hereinafter, referring to FIG. 9, the frequency oscillator 25
The frequency generation characteristics of will be described. The horizontal axis of FIG. 9 is a time axis. At the timing T1, the frequency f1 is set to the timing T2.
Generates a frequency different from the frequency f2 at each timing, and generates a frequency fn at the timing Tn. For example, the frequency of the upper sideband and the frequency of the lower sideband may be generated in a time division manner.

The output signal to the terminal T ₁₃ of the signal branching unit 17 is frequency converted by the frequency converting unit 23 at the timing Ti with the frequency fi. A component of a desired frequency band is extracted by passing the frequency-converted signal through the bandpass filter 5. In the configuration shown in FIG. 8, even if a low pass filter is used instead of the band pass filter, the same operation principle is obtained.

The power level of the frequency component extracted by the band pass filter 5 is detected by the power level detecting section 9,
At this time, the changeover switch 31 is switched to the storage unit 33 side, and this power level detection signal is stored in the storage unit 33. This power level detection signal is stored in the storage unit 33 until the timing Tj at which the frequency fj to be compared with the frequency fi is generated.

At timing Tj, the changeover switch 3
1 is switched to the terminal T ₇ side of the power level comparison unit 13.
The power level detected at the timing Ti is read from the storage unit 33, input to the terminal T ₉ of the power level comparison unit 13, and compared with the power level detected at the timing Tj input to the terminal T ₂ of the power level comparison unit 13. To do.

As a result, the difference between the power level detected at the timing Ti and the power level detected at the timing Tj is output to the terminal T ₁₁ of the power level comparison unit 13. Alternatively, the operation principle is the same even if the difference between the power level detected at the timing Tj and the power level detected at the timing Ti is output.

A bias control signal is output to the terminal T ₁ of the power amplifier 1 based on the control function of the bias controller 15 defined by the difference between the power levels output to the terminal T ₁₁ of the power level comparator 13, and the power The bias of the amplification element of the amplification unit 1 is controlled.

The operation of the changeover switch 31 is performed by the synchronizing unit 3
Controlled by 7. The synchronizing unit 37 inputs the signal obtained by delaying the frequency signal of the frequency oscillator 25 by the delay unit 35 and the clock signal from the clock 39 to measure the operation timing of the changeover switch 31.

Further, as shown in FIG. 10 by the frequency oscillator 25, at the timing T1, the frequency f _{UB of the} upper sideband is
If it has the characteristic of continuously generating the frequency f _{LB of the} lower sideband at the timing T2, the power level of the frequency component of the upper sideband is detected at the timing T1, and the frequency of the lower sideband is detected at the timing T2. Since the power level of the component can be detected, the changeover switch 31 and the storage unit 33 are provided in
It can be configured with a simple analog hold circuit of about a unit scale, and can be made into a monolithic IC. In FIG. 10, the operating principle is the same with the characteristic that the frequency f _LB of the lower sideband is continuously generated at the timing T1 and the frequency f _{UB of the} upper sideband is continuously generated at the timing T2.

Further, as shown in FIG. 11, if the frequency switching width of the frequency oscillator has a characteristic of generating the frequency of the upper sideband and the frequency of the lower sideband which is a natural number multiple of the baud rate, as shown in FIG. , Distortion compensation is possible with a simple analog hold circuit with a scale of about one operational amplifier for all odd-order intermodulation distortions.
C conversion is also possible. In the configuration shown in FIG. 8, the pass center frequency of the band pass filter 5 and the detection characteristic of the power level detection unit 9 may have only one characteristic regardless of the frequency oscillated by the frequency oscillator 25. .

FIG. 12 is a block diagram showing a seventh embodiment according to the present invention. The operating principle will be described with reference to FIG. The operation principle up to the signal branching unit 17 is the same as that of the first embodiment of the present invention. In the configuration shown in FIG. 12, the frequency discriminating unit 41 is used as means for detecting the power level of the frequency of the upper sideband and the power level of the frequency of the lower sideband of the output signal to the terminal T ₁₃ of the signal branching unit 17. . As shown in FIG. 14, the frequency discriminating unit 41 has output characteristics such that the output is zero at the design center frequency fc, the output is negative in the frequency band of the lower sideband, and the output is positive in the frequency band of the upper sideband. There is. When the output signal from the terminal T ₁₃ of the signal branching unit 17 is input to the frequency discriminating unit 41, the power levels of all frequency components in the used frequency band are detected with respect to the frequency.

By integrating the output signal with respect to the frequency by the integrator 43, the difference between the power level of the frequency of the upper sideband and the power level of the frequency of the lower sideband can be detected. For example, when the power level of the frequency of the upper sideband is higher than the power level of the frequency of the lower sideband, the frequency discriminating unit 4
The integrated value of the output of 1 by the integrator 43 becomes positive. Alternatively, the operation principle is the same even if the difference between the power level of the frequency of the lower sideband and the power level of the frequency of the upper sideband is detected. Further, if the frequency range of the upper sideband and the frequency of the lower sideband are set to be a natural multiple of the baud rate with respect to the frequency range to be integrated and the transmission center frequency, it is possible to compensate for all odd-order intermodulation distortions. Become. Further, as shown in FIG. 13, even if the output signal to the terminal T ₁₃ of the frequency branching device 17 is frequency-converted by the frequency converter 23 and then input to the frequency discriminator 41, the operation principle is the same as that of the above-described seventh embodiment. Same as the embodiment.

As described above, according to each of the above-described embodiments, the linearization technique is performed by the change in the amplification characteristic of the power amplification device due to the element variation caused by the manufacture and the change in the amplification characteristic of the power amplification device due to temperature and aging. When the linearity of the amplification characteristics of the power amplifier device is deteriorated or the input power level is large, the power level in the arbitrary frequency range of the output upper sideband and the arbitrary frequency range of the lower sideband The compensation of the linear amplification characteristic can be realized by a simple analog circuit even when the power levels in the above are different, and the control circuit can be made monolithic.

Further, since it is possible to compensate the linear characteristic for the power amplifying device having the different amplifying characteristic by the unique control function for linearization, the control circuit and the power amplifying device can be configured by a monolithic IC.

Further, unlike the conventional method in which the input signal and the output signal are successively compared and the control function for linearization is corrected to cope with the change in the amplification characteristic of the power amplification device, the output in this embodiment is different. Since only the signal is used for control, complicated control means for accurately compensating for the control loop delay becomes unnecessary.

[0060]

As described above, the present invention has the effects that the control circuit of the power amplification unit can be made compact and monolithic, and that the linear amplification characteristic with respect to the change of the amplification characteristic of the power amplification unit can be compensated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment according to the present invention.

FIG. 2 is a diagram showing characteristics of a bias control function.

FIG. 3 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a fourth exemplary embodiment according to the present invention.

FIG. 6 is a block diagram showing a configuration of a fifth exemplary embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration in the case where one frequency oscillator according to a fifth embodiment of the present invention is used.

FIG. 8 is a block diagram showing a configuration of a sixth exemplary embodiment of the present invention.

FIG. 9 is a diagram showing an example of a change over time of an oscillation frequency of a frequency oscillator.

FIG. 10 is a diagram showing an example of a change over time of an oscillation frequency of a frequency oscillator.

FIG. 11 is a diagram showing an example of a change over time of an oscillation frequency of a frequency oscillator.

FIG. 12 is a block diagram showing a configuration of a seventh exemplary embodiment of the present invention.

FIG. 13 is a diagram showing a configuration example when a frequency converter is used in the seventh embodiment according to the present invention.

FIG. 14 is a diagram showing output characteristics of a frequency discriminating unit.

FIG. 15 is a diagram showing a conventional example of a linearizer.

FIG. 16 is a diagram showing a conventional example of an adaptive linearizer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 power amplification part 3,17 signal branching part 5,7 band pass filter 9,11 power level detection part 13 power level comparison part 15 bias control part 21 signal addition part 23,27 frequency conversion part 25,29 frequency oscillator 31 changeover switch 33 storage unit 35 delay unit 37 synchronization unit 39 clock 41 frequency discrimination unit 43 integrator T _I input terminal T _O output terminal T ₁ bias terminal

Front Page Continuation (72) Inventor Shuichi Sekine 1 Komukai Toshiba-cho, Kawasaki-shi, Kanagawa 1 Toshiba Corporation R & D Center

Claims (1)

[Claims] 1. A power amplification device for a transmission section in a communication device, wherein each power in an arbitrary frequency range of an upper sideband and a lower sideband of an output signal of the power amplification section which amplifies and outputs an input modulated signal. A power amplification apparatus comprising: a detection unit that detects a level difference; and a control unit that controls a bias of the power amplification unit so that the power level difference detected by the detection unit becomes zero.