JPH06232665A - Transmission output control method - Google Patents

Abstract

(57) [Abstract] [Purpose] To easily perform output control when the transmission wave of a wireless station such as a digital cellular telephone is a burst wave. A high-frequency signal amplified by a power amplifier 1 is partially extracted by a directional coupler 6, passes through a variable attenuator 3, and is square-law detected by a diode detector 2. The detected signal and the reference signal are compared by the error detection amplifier 4, and the error component is fed back to the variable gain amplifier 5 as a control voltage. Based on the reception level of the base station, the overall control unit 7 sends a control signal to the variable attenuator 3 to change its attenuation amount. As a result, the amount of feedback of the distortion compensation loop changes, so the gain of the variable gain amplifier changes, and the transmission output of desired power is output from the terminal 9. As the reference signal at this time, the envelope information of the burst wave having a gradual change in the rising and falling sections is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in high frequency band transmitters. In particular, the present invention relates to a transmission device that needs to switch the transmission output power of a mobile station according to the reception level of a base station such as digital cellular.

[0002]

2. Description of the Related Art Conventionally, in a power amplifier for FM waves, a variable attenuator is inserted in a feedback section where the output of the power amplifier is extracted by a directional coupler, and the transmission output power is changed by changing the attenuation amount. There is a transmission output control method that does. For example, U.S. Pat. No. 4,523,155. this is,
The reference signal is a DC signal corresponding to the signal level, considering only the case where the modulation signal is in the continuous mode.
At the time of no output, a means of disconnecting the circuit was used.

[0003]

In the conventional method, when the modulated signal is continuous, the purpose of output control can be achieved, but the transmission by the digital cellular mobile unit is in the burst mode, and when it does not output, there is a leak. You need to reduce the output. Further, there is a problem that an unnecessary spectrum is generated if a sudden rise is generated by a switch or the like when the output changes from the non-output to the normal output.

[0004]

SUMMARY OF THE INVENTION The present invention is characterized in that burst wave envelope information is used as a reference signal of an error detection amplifier in the burst mode.

[0005]

According to the present invention, the control signal is applied from the control unit to the variable attenuator of the feedback circuit of the linear transmitter according to the instruction from the base station, and the attenuation amount of the variable attenuator is changed stepwise. , The gain of the variable gain amplifier is changed. This controls the transmission output power from the mobile station to the base station.

Further, by using the envelope information of the burst wave as the reference signal of the error detection amplifier, the leak output when the burst wave is not output can be obtained without increasing the number of parts not only in the continuous mode but also in the burst mode. This can be reduced by the envelope signal, and the band-limited waveform at the burst rising edge can be traced accurately, and the generation of unnecessary spectrum can be prevented.

[0007]

1 is a block diagram of a linear transmitter according to an embodiment of the present invention.

This apparatus has a high frequency power amplifier 1, a detector 2 for detecting an envelope component from an output signal of the high frequency power amplifier, and a control signal from an overall control unit to change the attenuation stepwise (for example, 20 dB in 4 dB steps). Range) variable attenuator 3, error detection amplifier 4 for generating a difference component between the envelope signal obtained by the detector and the reference envelope signal obtained by digital operation processing in the baseband, and the difference component as a bias voltage. And a variable gain amplifier 5 that operates.

At the maximum transmission output, the output signal amplified by the power amplifier 1 is partially extracted by the directional coupler 6 and input to the variable attenuator 3. At this time, the variable attenuator 3 is applied with a control voltage by the overall control unit 7 and is controlled to have the maximum attenuation amount. The signal attenuated by the variable attenuator 3 to a level lower than the upper limit of the dynamic range of the detector 2 by several dB is square-law detected by the detector 2 and input to the inverting input of the error detection amplifier 4. On the other hand, from the digital envelope generator 8, the reference envelope information (envelope) ² generated by digital arithmetic processing in the baseband band is input to the non-inverting input of the error detection amplifier 4 as a constant input. The error detection amplifier 4 detects the error components of the two inputs, and the difference voltage is detected by the dual gate FET.
Is applied to the second gate of the variable gain amplifier 5.
The variable gain amplifier 5 sets a DC offset in the output of the error detection amplifier 4 so that it can be used at a level with sufficiently good linearity with respect to the change in the second gate voltage corresponding to the change in the transmission output power. deep. In the present embodiment, when the non-linear distortion of the high-frequency power amplifier 1 is only the amplitude distortion and the phase distortion is sufficiently small, the embodiment of FIG. 1 becomes an amplitude feedback loop, so that the effect of reducing the distortion is obtained. When the reception level of the base station with respect to the transmission output of the mobile station changes and the mobile station receives a control signal to suppress the transmission output of 4 dB, the overall mobile unit control unit controls the attenuation amount of the variable attenuator 3 to decrease by 4 dB. The voltage is applied to the variable attenuator 3, and the input power of the detector 2 increases by 4 dB. Due to this change, at the input of the error detection amplifier 4, the inverting input side becomes larger than the non-inverting input side, and the output voltage of the error detection amplifier 4 becomes a deeper negative voltage and is fed back to the variable gain amplifier 5. The gain of 5 is reduced by 4 dB, and as a result, the output power of the power amplifier 1 can be reduced by 4 dB. On the contrary, when the mobile station receives the control signal to increase the transmission output by 4 dB, the attenuation amount of the variable attenuator 3 increases by 4 dB and the input power of the detector 2 decreases by 4 dB. Due to this change, the inverting input side of the error detection amplifier 4 has a smaller input than the non-inverting input side, and its output voltage becomes a shallow negative voltage and is fed back to the variable gain amplifier 5, so that the gain of the variable gain amplifier 5 increases by 4 dB. As a result, the output power of the power amplifier 1 increases by 4 dB.

At this time, the output power of the variable attenuator 3 is kept constant. The output spectrum of the variable attenuator 3 becomes an input spectrum with respect to a change of the high frequency input signal such that the output power of the variable attenuator 3 becomes constant in the range from the maximum attenuation amount to the minimum attenuation amount (20 dB). On the other hand, it must not deteriorate. Further, the control error of the transmission output power is due to the monotonicity of the variable attenuator 3 and the error between the attenuation steps, but it is at a level where the practical accuracy can be easily obtained.

FIG. 2 shows a waveform of a conventional switch switching reference signal, and FIG. 3 shows a burst wave reference envelope signal used in the present invention. As shown in FIG. 2, when there is a sudden change in the waveform when the modulation signal is turned on and off, the signal that follows the change causes unnecessary distortion and the spectrum deteriorates. On the other hand, the present transmission output control device does not turn on / off the reference signal with a switch at the rise and fall of the burst, but switches with a gentle COS curve, I (t) and Q.
Since it is the control system using the burst wave reference envelope information and the quadrature modulation signal as shown in FIG. 3 generated by (t),
It is possible to obtain a stable output without the spectrum being greatly deteriorated by the abrupt change of the modulation signal.

[0012]

As described above, the burst wave transmission output control method of the present invention uses the envelope information of the burst wave as the reference signal, so that a gentle change occurs at the time of burst switching. It is possible to prevent a large deterioration and reduce the leak output when the burst wave is not output.

Further, the transmission output control in the burst mode can be performed without increasing the number of parts as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a waveform diagram of a switch switching reference signal.

FIG. 3 is a waveform diagram of burst wave reference envelope information.

[Explanation of symbols]

1 ... High-frequency power amplifier, 2 ... Detector, 3 ... Variable attenuator,
4 ... Error detection amplifier, 5 ... Variable gain amplifier, 6 ... Directional coupler, 7 ... Overall control unit, 8 ... Digital envelope generator, 9 ... High frequency signal input terminal, 10 ... High frequency signal output terminal, 11 ... Second Gate voltage terminal.

Claims (1)

[Claims] 1. A variable gain amplifier to which a quadrature-modulated signal is input, a high-frequency power amplifier for amplifying its output signal, and a detector for detecting a signal extracted by a directional coupler from the output of the high-frequency power amplifier. And an attenuator and a differential amplifier that controls the variable gain amplifier using a difference component between the envelope signal detected by the detection circuit and the reference envelope signal as a control signal, and the attenuator is controlled by the overall control unit. A variable output attenuator in which the amount of attenuation changes according to a signal, wherein the reference envelope signal is continuous mode and burst mode envelope information.