JP2002325044A - Power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that an amplifier exhibiting a high efficiency constantly can not be provided because it is susceptible to temperature variation or aging when the magnitude of output power is detected by means of an analog detector and a control signal is generated. SOLUTION: Absolute values of a plurality of sets of I, Q baseband signal are compared individually by means of a plurality of comparators and the comparison results are determined in a majority processing section. A bias control section performs on/off control of the bias for each of a plurality of amplifiers connected in parallel in a common amplifier. An amplifier to be operated is then selected and operated with high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power amplifier, and more particularly to a high-frequency power amplifier suitable for a radio communication device for amplifying a plurality of carriers in common.

[0002]

2. Description of the Related Art As a conventional technology regarding a power amplifier,
For example, JP-A-11-308125 is mentioned. FIG. 4 is a circuit diagram of the above prior art. 201 is a transmitter input terminal, 202 is an amplifier, 203 is a frequency converter, 205 is a preamplifier, 206a and 206b are power amplifiers, 207
Is a directional coupler, 208 is a transmitter output terminal, 209 is a detector, 210 is a control circuit, 211 is a modem, 214 and 2
Reference numeral 15 denotes a switch.

[0003] In this conventional example, at least a wireless terminal device provided with a transmitter operating in a digital modulation system,
A first path having a predetermined gain, a second path having a lower gain than the first path, and a first path having a predetermined gain. Second
And a power supply circuit for supplying power to the power amplifier. When the output level of the transmitter required at the time of transmission is a level that requires the power amplifier, the first A control circuit that controls the switch to switch to the second path, controls the switch to switch to the second path when the level does not require the power amplifier, and stops power supply by the power circuit. Is provided.

According to such a configuration, a transmission signal modulated from an intermediate frequency band to a radio frequency band during transmission is output via a power amplifier having a signal path switching function. Here, when the output level of the transmitter required at the time of transmission is a level that requires a power amplifier, the signal is amplified to a predetermined level via the first path and output, and when the power amplifier is not required. In this case, the power is output via the second path and the power supply at that time is also stopped, so that the power consumption when the output level of the transmitter is low can be reduced without deteriorating the transmission performance.

[0005]

In the prior art, when detecting the output power level, a part of the output is taken out by a directional coupler connected to an output line, and the output level is converted into a DC voltage by a detector. I do. Since the detector is generally subjected to analog signal processing, it cannot follow changes in temperature or aging. Furthermore, since the switching of the amplifier is performed by the feedback from the output signal, the control time of the feedback is delayed, and it becomes difficult to faithfully amplify the transmission signal.

An object of the present invention is to provide a highly efficient power amplifier which stabilizes level detection and control signal generation relying on analog signal processing and faithfully amplifies a transmission signal.

[0007]

SUMMARY OF THE INVENTION A power amplifier according to the present invention comprises:
A quadrature modulator and a frequency converter that have a plurality of signal processing units that generate a baseband signal assigned to each frequency channel, and that convert the generated baseband signal into a quadrature modulation and a transmission frequency assigned to each channel.
A power combiner that combines transmission signals of the respective channels, and a common power amplifier that amplifies the power-combined transmission signal and that can switch the output power of the amplifier according to the number of transmission channels or the transmission power to improve power efficiency A plurality of comparators for comparing each baseband signal generated by each signal processing unit with a threshold value; a majority decision processing unit for determining a majority of a plurality of comparison results; and each amplifier of a common amplifier based on a result of the majority processing unit. In a transmitter of a frequency division digital type wireless communication system having a bias control unit for controlling ON / OFF of the bias of the baseband, the magnitude of the power input to the common amplifier is determined by the majority decision of the comparison result with respect to the threshold value of each baseband signal. The output power of the common amplifier can be switched.

In the power amplifier according to the present invention, the timing adjustment unit for adjusting and matching the delay time of the path from the quadrature modulator to the common amplifier and the delay time of the path for applying the bias signal from the comparator to the amplifier is provided. It is characterized by having. Further, the power amplifier of the present invention is characterized in that, in the above, a differential signal processing unit for superimposing a differential waveform on the bias control signal of the amplifier is provided.

In the above configuration, I and Q baseband signals output from a plurality of signal processors corresponding to respective carriers of the digital communication system are input to quadrature modulators, respectively, and the output signals of the respective quadrature modulators are The signals are input to a frequency converter for conversion into the corresponding carrier frequencies, and are combined into a multicarrier signal by a power combiner. The power-combined transmission signal is amplified to a desired transmission power by the common amplifier and transmitted from the transmission antenna to the aerial line.

In order to realize high efficiency, the common amplifier includes a plurality of amplifiers having the same or different output powers in parallel, and performs a switching operation according to the signal level to be handled.

In order to detect a signal level, a plurality of I and Q baseband signals, which are output signals of a plurality of signal processing units, are individually input to a plurality of comparators and absolute values are compared. The comparison result is determined by the majority processing unit. Based on the judgment result of the majority decision processing unit, the bias control unit controls ON / OFF of the bias of each of a plurality of parallel-connected amplifiers in the common amplifier, and selects an operating amplifier.

The processing performed by the comparator and the majority decision processing unit is as follows.
The correct level can be detected by using the mean square value of the signal input to the comparator. However, here, focusing on the simplicity of signal processing, the absolute value is compared with the comparator, and the signal is obtained by majority decision. The above problem is solved because it is possible to easily generate an amplifier switching control signal and to provide a highly efficient power amplifier that faithfully amplifies a transmission signal.

[0013]

FIG. 1 is a circuit block diagram of a power amplifier showing one embodiment of the present invention. The I and Q baseband signals output from the signal processing units 11, 12, and 13 of the digital communication system are orthogonal modulators 14, 15, 1
6, respectively. Quadrature modulators 14, 15, 16
Are input to frequency converters 17, 18, and 19, respectively, and converted into designated carrier frequencies, respectively.
The power combiner 20 combines the three carrier signals.

The power-combined signal is amplified to a desired transmission power by the common amplifier 24 and transmitted from the transmission antenna 23 to the aerial line. The common amplifier 24 has the same or different output power to realize high efficiency.
A plurality of units 1 and 22 are provided in parallel, and a switching operation is performed according to a signal level to be handled.

For detecting the signal level, the signal processing unit 1
The I, Q baseband signals of 1, 12, 13 are respectively compared with comparators 101, 102, 103, 104, 105, 10
Enter 6 The comparison result is determined by the majority decision processing unit 107. The judgment result of the majority processing unit 107 is transmitted to each amplifier 2 in the common amplifier 24 by the bias control unit 108.
ON / OFF control of biases 1 and 22 is performed to select an operating amplifier.

The comparators 101, 102, 103, 104,
The processing performed by the majority processing unit 107 and the processing performed by the majority processing unit 107 are essentially performed by the comparators 101, 102, 103, and 10.
The correct level can be detected by using the mean square value of the signals input to the comparators 4, 105, and 106. Here, the comparators 101, 102, and 10 are focused on the simplicity of signal processing.
By comparing the absolute values at 3, 104, 105, and 106 and taking a majority decision to determine the magnitude of the signal, it is possible to easily create an amplifier switching control signal and amplify the transmission signal faithfully. A highly efficient power amplifier can be provided.

FIG. 2 is a circuit block diagram of another embodiment of the present invention. In the present embodiment, the timing adjustment unit 10 is provided on the path of the majority decision processing unit 107 and the bias control unit 108 in FIG.
9 is provided.

The I and Q baseband signals output from the signal processing units 11, 12, and 13 are converted into quadrature modulators 14, 15, 1
6 to adjust the delay time of the path modulated by the common amplifier 6 and amplified by the common amplifier 24 and the timing of the bias signal given to each of the amplifiers 21 and 22 in the common amplifier 24. Also, by adjusting the response time of each of the amplifiers 21 and 22 to the bias signal, a time lag between the operation of the transmission signal and the operation of the amplifier is eliminated, and a highly efficient power amplifier that faithfully amplifies the transmission signal is provided. it can.

FIG. 3 is a circuit block diagram of still another embodiment of the present invention. This embodiment has a configuration in which a differential waveform superimposition processing unit 110 is provided on the path of the timing adjustment unit 109 and the bias control unit 108 in FIG.

Each of the amplifiers 2 and 22 in the common amplifier 24 is controlled by the junction capacitance of the transistors constituting the amplifiers 21 and 22.
Responses to the bias control signals 1 and 22 are integrated responses having a time constant. Therefore, in this embodiment, the response of each of the amplifiers 21 and 22 is made faster by superimposing on the bias control signal a differential characteristic having a characteristic opposite to the response of each of the amplifiers 21 and 22 to the bias control signal. Here, the differential waveform superimposition processing unit 110 includes a bias control unit 1
08 may be provided.

According to the present embodiment, it is possible to further eliminate a time lag between the operation of the transmission signal and the operation of the amplifier, and to provide a highly efficient power amplifier that faithfully amplifies the transmission signal.

[0022]

According to the present invention, switching control is performed by individually inputting the I and Q baseband signals to a plurality of comparators, comparing the absolute values, and judging the level of the signal level by the majority decision processing unit. Since a signal can be easily generated and the timing can be easily adjusted, a highly efficient power amplifier that faithfully amplifies a transmission signal can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a power amplifier according to one embodiment of the present invention.

FIG. 2 is a circuit block diagram of a power amplifier according to another embodiment of the present invention.

FIG. 3 is a circuit block diagram of a power amplifier according to another embodiment of the present invention.

FIG. 4 is a circuit block diagram of a conventional power amplifier.

[Explanation of symbols]

11: signal processing unit, 12: signal processing unit, 13: signal processing unit, 14: quadrature modulator, 15: quadrature modulator, 16: quadrature modulator, 17: frequency converter, 18: frequency converter, 1
9: frequency converter, 20: power combiner, 21: amplifier connected in parallel in a common amplifier, 22: amplifier connected in parallel in a common amplifier, 23: antenna, 24: common amplifier, 101: comparator, 102: comparator, 103: comparator, 104: comparator, 105: comparator, 106: comparator, 107: majority decision processing unit, 108: bias control unit,
109: timing adjustment unit; 110: differential waveform superimposition processing unit.

Claims (3)

[Claims] A quadrature modulator having a plurality of signal processing units for generating a baseband signal assigned to each frequency channel, orthogonally modulating the generated baseband signal and converting the generated baseband signal into a transmission frequency assigned to each channel, and a frequency converter And a power combiner for combining the transmission signals of the respective channels, and the output power of the amplifier can be switched according to the number of transmission channels or the transmission power for amplifying the power-combined transmission signal and improving power efficiency. A common power amplifier, a plurality of comparators for comparing each baseband signal generated in each signal processing unit with a threshold, a majority decision processing unit for majority decision of a plurality of comparison results, and a common amplifier based on the result of the majority decision processing unit Frequency division digital wireless communication system having a bias control unit for ON / OFF controlling the bias of each amplifier In Shin machine, power is characterized in that a switchable output power of the common amplifier performs size determination of power input to the common amplifier by majority of the comparison results for the threshold of each of the baseband signal amplifier. 2. The power amplifier according to claim 1, further comprising a timing adjustment unit that adjusts and matches a delay time of a path from the quadrature modulator to the common amplifier and a delay time of a path that supplies a bias signal from the comparator to the amplifier. A power amplifier, comprising: 3. The power amplifier according to claim 1, further comprising a differential signal processing unit for superimposing a differential waveform on a bias control signal of the amplifier.