JPH03224323A - Radiotelephony system - Google Patents

Abstract

PURPOSE:To eliminate the need for the power control of a booster circuit by controlling the fed back signal of a feedback circuit corresponding to the change of the output of a portable telephone set, and performing the control of the amplification degree of a power amplifier circuit. CONSTITUTION:A part of power distributed by a coupling circuit 9 is detected with a detection circuit 10, and is introduced to an input power comparator 11, and the level of detection output is decided. A signal in accordance with the level of a detection signal is introduced to a reference voltage generation circuit 12, and a reference voltage is supplied to the feedback circuit 13. The feedback circuit 13 performs control so that the output of the power amplifier circuit 14 can be stabilized with the amplification degree fitted in the power inputted to a high frequency input terminal 6 and the amplification degree can be kept constant. In such a manner, it is possible to search the change of the output with the portable telephone set 1 in the inside of the booster circuit 5, and to automatically set the amplification degree fitted in that.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an improvement in a radio telephone device equipped with a booster circuit for amplifying the output of a mobile telephone and guiding this amplified high frequency power to an antenna. For example, it is used as a car phone installed in a car.

[Prior Art] Conventional mobile phones have low output power, making it impossible to communicate with base stations and making it impossible to use wireless telephones. For this purpose, a configuration was adopted in which the output of the mobile phone was amplified by a booster circuit, and the amplified high-frequency output was sent out from the antenna.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional device, the output of the mobile phone is configured to be switched in multiple stages to suppress unnecessary power consumption. In other words, the radio waves emitted from the mobile phone are received by the base station, the base station measures the intensity of the radio waves radiated from the mobile phone, the results are fed back to the mobile phone, and the mobile phone outputs it using an internal microcomputer, etc. is configured to switch in multiple stages.

When connected to a booster circuit that has the function of stabilizing the amplification level of such a mobile phone, the amplification level of the booster circuit is switched in multiple stages according to the switching of the output of the mobile phone. Power control is required.

If this is not done, the above-mentioned function within the booster circuit will operate due to fluctuations in the booster input, and the multi-stage output of the booster circuit will not function properly.

Conventional configurations for this purpose require wiring for transmitting a signal indicating that the output of the mobile phone is switched, and wiring for exchanging power control signals between the mobile phone and the booster circuit.

However, this requires a plurality of wires between the mobile phone and the booster circuit, which causes an increase in the number of wires between the mobile phone and the booster circuit. Additionally, multiple wires are normally required for the wiring that carries the signal that indicates the switching of the mobile phone's output.
In order to use regular wiring, a multiplex communication circuit with multiple currents is required, which is expensive.

An object of the present invention is to provide a wireless telephone device in which such wiring is simplified and the wiring between the mobile phone and the booster circuit is connected by an inexpensive cord.

[Means for Solving the Problems] The present invention includes a booster circuit that includes a coupling circuit to which the output of a mobile phone is guided and which distributes the output, and a power amplifier circuit that amplifies a part of the output of the coupling circuit. , a detection circuit that converts another part of the output of the coupling circuit into a direct current; and a feedback circuit that feedback controls the amplification degree of the power amplifier circuit according to the output of the detection circuit.

Effect] In the above configuration, a feedback circuit is provided in the booster circuit for making the amplification degree of the booster circuit constant. This feedback circuit functions as a so-called automatic power control circuit that prevents the amplification degree of the booster circuit from changing due to temperature changes or the like. In the present invention, the signal fed back from the feedback circuit is controlled in accordance with changes in the output of the mobile phone, and the amplification degree of the power amplifier circuit is controlled, thereby eliminating the need for power control of the booster circuit. It is something to do.

For this purpose, a part of the output of the mobile phone is converted to DC by a detection circuit, and the DC voltage is applied to the feedback circuit described above so that the amplification degree of the power amplifier circuit changes according to the magnitude of this DC voltage. -ing

As a result, the darkness between the booster circuit and the mobile phone,
There only needs to be wiring to guide the high frequency output of the mobile phone, and there is no dedicated wiring to notify the booster circuit of changes in the mobile phone's output, or dedicated wiring to control the power of the booster circuit. This eliminates the need for a cord derived from a mobile phone, resulting in an inexpensive and simple configuration with a thin wire diameter.

[Effects of the Invention] In the present invention, in order to take advantage of the feature of a mobile phone that is light in weight when held in the hand, it is possible to simplify the configuration of a code derived from the mobile phone. That is, there is no need for multiple wires between the mobile phone and the booster circuit as in the conventional case.

For this reason, in the present invention, it is only necessary to set a lightweight wiring with a thin wire diameter and a simple structure between the mobile phone and the booster circuit. It is possible to improve feelings such as sensation.

[Example] Embodiments of the apparatus of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the device of the present invention,
FIG. 1 is a V block diagram showing the overall configuration.

1 is a mobile phone, and a microphone, a speaker, and a push button switch for input are attached to the front surface of the mobile phone. 2
is a telescopic antenna for mobile phones. A connector 3 can be connected to the mobile phone 1. A cord 4, which serves as wiring for guiding the high frequency output of the mobile phone, extends from the connector 3. One end of this cord 4 is connected to the high frequency output of the booster circuit 5. It is connected to input terminal 6. Further, a high frequency output terminal 7 of the booster circuit 5 is connected to an antenna 8. This antenna 8 constitutes a car phone antenna attached to the outside of the car.

In the above configuration, when the mobile phone 1 is used in a car, the connector 3 is connected to the mobile phone 1, and the high frequency output of the mobile phone 1 is guided to the booster circuit 5 via the cord 4. Radio frequency power is amplified and radio output is emitted from the antenna 8. As a result, when the distance between the base station of the car phone and the car phone becomes large, the transmitted radio waves are strengthened and the range of use of the car phone is expanded.

Next, the main parts of the present invention will be explained. The output of the mobile phone 1 inputted from the high frequency input terminal 6 is first guided to a coupling circuit 9, and a part of the power distributed by the coupling circuit 9 is detected by a detection circuit 10. The detected signal is then led to an input power comparison circuit 11, and this circuit 11 determines the level of the detected output. and,
A signal corresponding to the level of the detection signal is generated by the reference voltage generation circuit 12.
This circuit 12 generates a reference voltage according to the detected output. This reference voltage is then provided to the feedback circuit 13.

The feedback circuit 13 feeds back a part of the output of the power amplifier circuit 14 to keep the amplification degree of the power amplifier circuit 14 constant, that is, it constitutes an automatic power control circuit, and is a well-known circuit. It is something.

15 is a coupling circuit, the output of the power amplifier circuit 14 is distributed by the coupling circuit 15, a part of the power is guided to the detection circuit 16, and the output of the detection circuit 16 is further amplified by the DC amplifier circuit 17. The signal is further guided to a differential amplifier circuit 18. The X2 dynamic amplifier circuit 18 functions to compare the output of the DC amplifier circuit 17 and the reference voltage from the reference voltage generation circuit 12 and amplify the level difference. Further, the output of the differential amplifier circuit 18 is connected to a control terminal 14a that controls the amplification degree of the power amplifier circuit 14.

The output of the mobile phone 1 is switched in five stages, and there is a difference in output of 4 [decibels] between each stage. Such signals having different power levels are input to the high frequency input terminal 7-6, and a reference voltage corresponding to the signals is output from the reference voltage generation circuit 12.

The feedback circuit 13 performs control such that the output of the power amplifier circuit 14 has an amplification degree that is suitable for the power input to the above-mentioned high frequency input terminal 6 and that the amplification degree is constant. Specifically, the differential amplifier circuit 18 compares the reference voltage corresponding to the power input to the high frequency input terminal 6 and the signal level output from the DC amplifier circuit 17, and determines the level between the reference voltage and the signal level. The power amplifier circuit 14 is controlled so that the difference is constant. If the output of the DC amplifier circuit 17 is small, that is, the output of the power amplifier circuit 14 is small, a signal to increase the amplification degree of the power amplifier circuit 14 is sent from the differential amplifier circuit 18 to the control terminal +4a. Output. Conversely, when the DC voltage output from the DC amplifier circuit 17 is large, that is, the output of the power amplifier circuit 14 is large, a signal that attempts to lower the amplification degree of the power amplifier circuit 14 is transmitted to the differential amplifier circuit 18. The signal is output from the control terminal 14a to the control terminal 14a.

Furthermore, the level of power input to the high frequency input terminal 6 is
The reference voltage generated from the reference voltage generation circuit 12 is also switched to five levels in accordance with this switching. Therefore, the power amplifier circuit 14
A signal is input to the control terminal 14a of the mobile phone 1, which changes in accordance with the five-stage switching of the output of the mobile phone 1. Therefore, even if the signal flowing through the code 4 is only the transmission/reception signal of the mobile phone 1 and does not include a signal specifically indicating the switching of the output level of the mobile phone 1, the booster circuit 5 internally sends the signal to the mobile phone 1. to detect changes in the output,
You can automatically set the amplification degree that suits this.

As a result, the cord 4 can be configured with a single wire, and the weight of the cord 4 can be reduced by one. Therefore, it is possible to improve the feeling when holding the mobile phone 1 in the hand. In addition, when taking the mobile phone 1 out of the car, the connector 3 attached to the tip of the coat 4 is removed from the mobile phone 1, and the mobile phone 1 itself is taken out of the car and used.

FIG. 2 is a detailed diagram showing an example of the booster circuit 5 shown in FIG. 1, and the same numbers indicate the same parts. To explain it simply, combine times il! 8 consists of a circuit 9 for branching part of the high frequency power, and a detection circuit 10 consists of a diode, a capacitor, and a resistor. Further, the input power comparison circuit 11 includes a resistor and five comparators. Furthermore, the reference voltage generation circuit 12 is composed of an analog switch and a resistor that are turned on and off in response to the output of a comparator.
is composed of an operational amplifier 18, and a DC amplifier circuit 17
It also includes an operational amplifier 17 and a resistor.

Normally, when using the mobile phone 1 for telephone communication in a car, once the power for communication is switched by communication with the base station, the high frequency input is changed depending on the strength of the human voice. The level of power input to terminal 6, that is, the level of power output from mobile phone 1 does not change. That is, since the signal input to this high frequency input terminal 6 is a frequency-modulated audio signal, the power level itself is constant during that time. Further, while using the mobile phone 1 as a telephone, if the radio field intensity between the mobile phone 1 and the base station becomes weak due to changes in the position of the car, etc., the amplification degree of the mobile phone 1 may be changed even during transmission and reception as a telephone.

Next, the output characteristics of the booster circuit 5 shown in FIG. 1 will be explained based on FIG. 3.

The horizontal axis of FIG. 3 represents the high frequency input power input to the high frequency input terminal 6, and the vertical axis represents the high frequency output power output from the high frequency output terminal 7.

When the output of mobile phone 1 is switched in five stages,
That is, 2 in 5 steps starting from 11 dBm (decibel).
This shows that when the input power changes up to 7 dBm (decibels), the high-frequency output power changes in 5 steps accordingly.In other words, the output power obtained by accurately amplifying the input power by a certain amplification degree is the output power at the high-frequency output terminal. 7. At this time, even if the amplification degree of the power amplifier circuit 14 is about to fluctuate due to a temperature change or the like, a feedback signal is generated at the control terminal 14a that cancels out this fluctuation.
This feedback effect is controlled by a reference voltage that changes in response to switching of the output of the mobile phone 1. Therefore, even if the output of the mobile phone 1 fluctuates, the amplification degree of the booster circuit 5 itself is kept constant.

Therefore, since power control of the booster circuit 5 is not necessary,
The mobile phone 1 is connected between the mobile phone 1 and the booster circuit 5.
Only the cord 4 for guiding the high frequency output of the mobile phone 1i'll needs to exist, and the cord 4 derived from the mobile phone 1i'll can be made inexpensive and simple with a small wire diameter.

4 to 6 show a second embodiment of the device of the present invention,
FIG. 4 is a block diagram showing the overall configuration. The same reference numerals as in the first embodiment indicate the same members.

Reference numeral 19 denotes a DC amplifier circuit, which amplifies the output of the detection circuit 10. That is, the DC amplifier circuit 19 amplifies the signal converted into DC by the detection circuit 10. This DC voltage is applied to the differential amplifier circuit 20 of the feedback circuit 13.
guided by. The differential amplifier circuit 20 then compares the output voltage of the DC amplifier circuit 17 and the output voltage of the DC amplifier circuit 19, and functions to amplify the level difference.

When the DC voltage output from the DC amplifier circuit 17 is smaller than the DC voltage output from the DC amplifier circuit 19, that is, when the output of the power amplifier circuit 14 is small, the differential amplifier circuit 20 uses the power amplifier circuit 14. A signal for increasing the amplification degree of is output to the control terminal 14a. Conversely, when the DC voltage output from the DC amplifier circuit 17 is large, that is,
When the output of the power amplifier circuit 14 is large, a signal to lower the amplification degree of the power amplifier circuit 14 is sent to the control terminal 1.
Output to 4a.

FIG. 5 is a detailed diagram showing an example of the booster circuit 5 shown in FIG. 4, and the same reference numerals indicate the same parts. To explain briefly, the DC amplifier circuit 19 is composed of an operational amplifier 19 and a resistor, and the differential amplifier circuit 20 is composed of an operational amplifier 20.

Next, the output characteristics of the booster circuit 5 shown in FIG. 4 will be explained based on FIG. 6.

The horizontal axis of FIG. 6 represents the high frequency input power input to the high frequency input terminal 6, and the vertical axis represents the high frequency output power output from the high frequency output terminal 7.

When the output of the mobile phone 1 changes linearly, that is,
It is shown that when the input power input to the high frequency input terminal 6 changes linearly, the high frequency output power also changes linearly accordingly. That is, linear output power is generated from the high frequency output terminal 7 by amplifying the input power by a certain amplification degree accurately. At this time, even if the amplification degree of the power amplifier circuit 14 tends to fluctuate due to temperature changes or the like, a feedback signal is generated at the control terminal 14a to cancel out this fluctuation. Further, the voltage at the control terminal 14a of the power amplifier circuit 14 changes depending on the power input to the high frequency input terminal 6, that is, the power that changes according to the change in the output of the mobile phone 1. Therefore, even if the output of the mobile phone 1 fluctuates, the amplification degree of the booster circuit 5 itself is kept constant.

Therefore, similarly to the first embodiment, power control of the booster circuit 5 is not required.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the invention. 1st
2 is a detailed circuit diagram showing an example of a booster circuit, and FIG. 3 is an input/output characteristic diagram of the booster circuit. 4 to 6 show a second embodiment of the invention. Fourth
5 is a detailed circuit diagram showing an example of a booster circuit, and FIG. 6 is an input/output characteristic diagram of the booster circuit. In the diagram

Claims (1)

[Scope of Claims] 1) A radio telephone device comprising: a mobile phone whose output power changes; a booster circuit that amplifies the output of the mobile phone; and an antenna to which the high-frequency output of the booster circuit is guided; The circuit includes: a coupling circuit to which the output of the mobile phone is guided and which distributes this output; a power amplification circuit that amplifies a part of the output of the coupling circuit; and a power amplifier circuit that converts the other part of the output of the coupling circuit into DC. What is claimed is: 1. A radio telephone device comprising: a detection circuit for performing feedback control on the amplification degree of the power amplification circuit according to an output of the detection circuit.