JPS61131918A - Transmission output control circuit - Google Patents

Abstract

PURPOSE:To attain stable output control by using a designation signal of a transmission output so as to control a voltage controlled attenuator and an amplifier thereby making a negative feedback quantity constant independently of the transmission output. CONSTITUTION:A control signal bringing the transmission output to the rated output is fed to voltage controllers 13, 14 via a controller 8. A control voltage being a level difference between the normal output and the minimum output is given from the controller 13 to the voltage controlled attenuator 12, a normal power supply voltage is given from the controller 14 to a power amplifier 3, an output subtracted by an attenuation is detected (6), compared and amplified (10) with an output of a reference voltage generator 7, and it is fed back negatively to a voltage controlled attenuator 21 as an error voltage. Thus, the transmission output at an output terminal 5 is kept constant. In minimizing the transmission output, a control signal designating the output to the minimum value is fed from the controller 8, and in bringing the attenuation of the attenuator 21 to the attenuation equal to that at the rated output, the transmission power is kept to the minimum value and the output of the detector 6 is made nearly equal for both the rated output and the minimum output.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an output control circuit for a transmitter used in a mobile radio device.

(Prior art) In the car telephone system, since the system is operated by Nissin, a mobile terminal station equipped with a mobile radio sets the transmission power of the mobile radio to an optimal value according to the size of the wireless zone of the system. It was necessary to set this and eliminate interference such as over-reach to other zones and cross-modulation caused by excessive input at the base station.

For this reason, there is a strong demand for a function that allows the transmission output of mobile radio equipment to be varied over multiple stages.

A typical example of such a conventional transmission output control circuit is shown in FIG. In FIG. 3, 1 is a transmission signal input terminal, 2 is a voltage controlled attenuator, 3 is a power amplifier, 4 is a directional coupler, 5 is a transmission signal output terminal, 6 is a wave detector, 7 is a reference voltage generator, 8
is a controller, and 9 is a control signal input terminal.

In FIG. 3, a transmission signal inputted from a transmission signal input terminal 1 is attenuated by a predetermined attenuation amount by a voltage control attenuator 2, and then power amplified by a power amplifier 3, and the transmission signal is output from a transmission signal output terminal 5. is output to. On the other hand,
A part of the output signal of the power amplifier 3 is extracted by a directional coupler 4 and converted into a DC voltage by a diode detector 6. Further, when a control signal specifying the transmission output is input to the controller 8 from the control signal input terminal 9, the reference voltage generator 7 outputs a reference voltage corresponding to the specified value of the transmission output. . This reference voltage and the diode detector 6
A DC voltage of 1% is applied to the comparator amplifier lO, and an error voltage is output from the comparator amplifier 1%lo. When this error voltage is input to the voltage regulator 11, the output voltage of the voltage controller 11 is negatively fed back as a control voltage of the voltage control attenuator 20, and the output of the power amplifier 3 is controlled to a specified value. . Here, the prescribed value of the output is set by changing the output voltage of the reference voltage generator in accordance with the control signal specifying the output.

(Problems to be Solved by the Invention) As described above, in the conventional transmitting output controller 8 that changes the transmitting output by changing the reference 'α pressure, the variable range of the transmitting output is small and ranges from a few dB variation. Well, there is no problem with i9,
Radio equipment that requires variable transmission output in multiple stages has the following drawbacks. In other words, in recent car telephone systems, the variable range of the transmission output is very large, reaching approximately 30 dB, so in order to satisfy such specifications with the conventional circuit system, the dynamic There is a need to widen the range. However, since a car battery is used as a power source for a mobile radio, the maximum detection output voltage is generally 10V even at the rated output. On the other hand, when the output is set to the lowest value, the voltage is very small, several hundred mV, and it is difficult to maintain the transmitting output stably at the specified value due to external noise, power supply voltage fluctuations, or temperature changes. I get into trouble. Also,
As the range of change in the output voltage of the detector 6 increases, the amount of feedback to the voltage controlled attenuator 2 also changes significantly.
The change in the 0 input level becomes large. However, since the power amplifier 3 is generally unable to handle large input level changes, increasing the variable range of the transmission output has the disadvantage that the operation of the negative feedback loop for output control tends to become unstable when the transmission output is lowered. Ta.

An object of the present invention is to control both the transmission output signal level to a detector that detects a part of one transmission output signal and the pressure at the epicenter other than the first stage amplification section of the power amplifier by a control signal specifying the transmission output. It is therefore an object of the present invention to provide a transmission output control circuit configured to eliminate the above-mentioned drawbacks and to be able to set the transmission output stably and over a wide range even with various changing specified values.

(Means for Solving the Problems) A transmission output control circuit according to the present invention includes a first voltage-controlled attenuator or first-stage amplifier, a '1 power amplifier, a directional coupler, and a second voltage-controlled attenuator. , a detector, a comparison amplifier,
It is configured to include first to third voltage controllers and a controller.

The first voltage-controlled attenuator or first-stage amplification section is the next one that provides a variable attenuation amount to the human-powered transmission signal.

The power amplifier is for amplifying the output of the 8gl voltage controlled attenuator or first stage amplifier.

The directional coupler is used to supply the RF output of the power amplifier to an external load as transmission power and to extract a portion of the power.

The second voltage controlled attenuator is for providing variable attenuation to a portion of the RF' output extracted by the directional coupler.

The detector is for converting the output of the second voltage controlled attenuator into a DC voltage.

The comparator amplifier compares the DC voltage obtained by the detector with a separately set reference voltage and outputs an error voltage.

The first voltage controller is for controlling the first voltage controlled attenuator or the first stage amplifier based on the error voltage output from the comparator amplifier.

The second voltage controller includes l'1. of the second voltage controlled attenuator.
This is for controlling the F output.

The third voltage controller is for controlling the gain of the power amplifier.

The controller controls the second and third voltage controllers to set the DC voltage obtained from the detector to a constant value regardless of the value of the transmission power.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 and FIG. 2 are block diagrams each showing the configuration of an embodiment of a transmission output control circuit according to the present invention. 1st
In the figure and FIG. 2, 1 is a transmission signal input terminal, 21
is the first voltage controlled attenuator, 3 is the power amplifier, and 31 is the power amplifier 7! 32 is an amplification stage section of power amplifier 3, 4 is a directional coupler, 5 is a transmission signal output terminal, 6 is a detector, 7 is a reference voltage generator, 8 is a controller, 9 is a control A signal input terminal, 10 is a comparison amplifier, 111 is a first voltage controller, 12 is a 1IX2 voltage controlled attenuator, 13 is a second controller, and 14 is a third voltage controller.

Here, to simplify the explanation, two stages will be described: a case where the transmission output is the rated output, for example, +35 dBm, and a case where the transmission output is the lowest output, for example, +5 dBm.

In Figure 1, the transmission output is the rated output (+35 dBm)
In this case, a control signal specifying the transmission output to the rated output (+35 dBm') is sent from the control signal input terminal 9 via the controller 8 to the pressure controller 13.1.
Added to 4. When the control signal is applied, the second voltage controller 13 changes the attenuation amount of the second voltage control attenuator 12 between the steady output (+35 dBm) and the minimum output (-) -5 dBm.
), i.e. (+35dBm) - (+5
A control voltage such that dBrn)=30 dB is applied to the second voltage controlled attenuator 12. The third voltage controller 14 provides a normal power supply voltage to the first stage amplifying section 31 of the power amplifier 3 . In this state, a part of the output of the power amplifier 3 taken out from the directional coupler 4 is transferred to the voltage controlled attenuator 1 of ta2.
2, the signal is attenuated by the above-mentioned attenuation -1, and converted into a DC voltage by a diode detector 6. This DC voltage and a reference voltage of a constant value outputted from the base 4 voltage generator 7 are applied to a comparator amplifier 10, and an error between the two is outputted as an error voltage. This error voltage is negatively fed back to the first voltage controlled attenuator 21 via the first voltage controller 111 as a control voltage. As a result, the attenuation amount of the first voltage-controlled attenuator 21 is set, and the output of the Deno amplifier 1 @ device 3, that is, the transmission output, is maintained at a steady value (+35 dBm).

Next, when lowering the transmission output to the minimum output value (+5 dBm), a control signal specifying the transmission output to the minimum output value (+5 dBm) is sent to the second and third 1-pressure controllers 13.14. ? Added from tllJ example-88. Therefore, the second one-voltage controller 13 applies a control voltage so that the amount of attenuation of the second voltage-controlled attenuator 12 becomes zero. The attenuation amount of the first voltage-controlled attenuator 21 is determined by the above rated output (+35
dBm), the third voltage controller 14 sets the DC voltage such that the transmission output becomes almost the minimum output (+5 dBm) to the power amplifier 3. It is given as the power supply voltage of the amplification stage section 32.

Therefore, the transmission output is “r (+35dBm)−(+
5dBm) -30dB to the lowest output value (+
5dBm). In this way, the output of the detector 6'
The voltage is the same when the transmission output is the rated output (+35 dBm) and the lowest output (+5 dBrn), and is a relatively large value, so even at the lowest output, there is no possibility of external noise, power supply voltage fluctuations, or It will not be affected by temperature changes.

Since the error output voltage of the comparison amplifier 10 does not change regardless of the value of the transmission output, the negative feedback error remains constant.

Therefore, the amount of attenuation of the first voltage controller 21 controlled via the first voltage controller 111 using this error output voltage, that is, the input level of the power amplifier 3 also changes depending on the value of the transmission output. There's nothing to do. Therefore, the power amplifier 3 can be operated under optimal operating conditions, and the power amplifier 3 will not become unstable due to a large change in the input level as in the conventional example. Therefore, stable transmission output control can be performed regardless of the value of the transmission output.

For ease of explanation, the case where the transmission output is at the rated output and the minimum output is explained here, but when changing the transmission output in multiple stages, the attenuation amount of the second voltage-controlled attenuator 12 and the The output voltage of the voltage controller 14 of No. 3 may be set using the method described above. The IEZ diagram is an embodiment showing a configuration in which the power supply voltage is controlled to change the output of the first stage amplifying section 31 of the power amplifier, and the other operations are the same as those described above.

(Effects of the Invention) As described above, the present invention includes a voltage control attenuator for varying the output detection amount of a power amplifier of a transmitter, and a negative feedback feedback of the input level of the first stage amplification section of the power amplifier or the power supply voltage. and a rounding amplification stage section controlled by a transmission output value, and controlling the voltage controlled attenuator and the amplification stage according to a designated signal of the transmission output so that the negative feedback 1 is constant regardless of the transmission output value. This has the effect that stable output control can be performed even if the transmission output changes.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing embodiments of a transmission output control circuit according to the present invention. FIG. 3 is a block diagram showing an example of a transmission output control circuit according to the prior art. 2.12... Voltage controlled attenuator 3...'1 power amplifier 31... First stage amplifier section 32
...Amplification stage section 4...Directional coupler 6...Detector 7...Reference voltage generator 8...Controller 1
o... Comparator 11... Voltage controller 111...
Voltage controller 1.5.9...terminal

Claims (1)

[Claims] a first voltage-controlled attenuator or first-stage amplification section for providing a variable attenuation amount to an input transmission signal; and a power amplifier for amplifying the output of the first voltage-controlled attenuator or first-stage amplification section. , a directional coupler for supplying the RF output of the power amplifier to an external load as transmission power and extracting a portion thereof; and a variable attenuation amount for the portion of the RF output extracted by the directional coupler. a second voltage-controlled attenuator for converting the output of the second voltage-controlled attenuator into a DC voltage, and a reference voltage set separately from the DC voltage obtained by the detector. a comparator amplifier for comparing and outputting an error voltage; and a first comparator for controlling the first voltage controlled attenuator or the first stage amplifier based on the error voltage output from the comparator amplifier. a voltage controller, a second voltage controller for controlling the RF output of the second voltage controlled attenuator, and a third voltage controller for controlling the gain of the power amplifier;
and a controller for controlling the second and third voltage controllers to set the DC voltage obtained from the detector to a constant value regardless of the value of the transmission power. A transmission output control circuit characterized by comprising: