JP2001053664A - Radio repeater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain optimum outputs for both CW waves and burst waves in the same circuit by providing an automatic gain control circuit with a peak hold circuit that almost holds the peak value of a signal inputted to the circuit. SOLUTION: An automatic gain control circuit is provided with a peak hold circuit which almost holds the peak value of a signal inputted to the circuit. Then, the automatic gain control circuit is further provided with an amplifier circuit 31 amplifying a signal inputted to the peak hold circuit, and the peak hold circuit consists of a diode 34 where a signal is transferred only in a forward direction, a charging and discharging circuit 32 charging and discharging a capacitor on the basis of an input signal and a high impedance buffer 35 whose output is connected to the circuit 31. By constructing such a configuration, it is possible to perform fast charging to the circuit 32 when inputting burst waves. Further, it is possible to realize a peak hold circuit with a simple circuit configuration because this device can be constructed just by adding a simple circuit to a conventional circuit configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio relay apparatus for relaying between a base station and a mobile terminal, and more particularly to an improvement of an automatic gain control circuit.

[0002]

2. Description of the Related Art At present, a service system of a radio base station converts digital and analog wired signals into a base band to be made wireless, and TDMA (Time-Division Multi-Acces).
s), FDMA (Frequency-Division Multi-Access),
And digitized by CDMA (Code-Division Multi-Access), and multiplexed wireless communication is performed using the number of channels corresponding to the station line.

[0003] The radio base station is set up through a thorough field test, an approach line design and a transmission propagation test. However, in mobile communication, there are areas other than service areas where services cannot be received. This area is referred to as “dead zone”. The wireless relay device is a device that enables communication between the above wireless base station and a mobile terminal located in a blind zone.

FIG. 6 is a diagram showing a schematic configuration of a radio relay apparatus. As shown in FIG. 6, the wireless relay apparatus has a first antenna 10 and a second antenna 20 to enable communication between a base station (not shown) and a mobile terminal. The dead zone is eliminated by enabling communication between the base station and the mobile terminal by transmitting and receiving between the first and second antennas 10 and 20 and the base station or the mobile terminal.

[0005] A specific operation of the wireless relay device will be described. First, the first antenna 10 to the second antenna 20
The signal flow to the device will be described. First antenna 10
Are input to the duplexer 11 and are amplified by the low noise amplifier (LNA) 12. Next, the attenuator (ATT)
12 is input to an automatic gain controller (AG) described later.
C) Based on the input from 30, if necessary, a predetermined amount of attenuation is applied so that the power amplifier (PA) 19 does not saturate. Then, the desired frequency 141 is mixed with the mixer 14 and amplified by the amplifier 15. Thereafter, the signal is converted into a signal of a desired frequency band by the bandpass filter 16, amplified by the amplifier 17, and mixed with the desired frequency 181 by the mixer 18. Finally, after being amplified by a predetermined amount in the PA 19, it is output (transmitted) from the second antenna 20 via the duplexer 21.

[0006] From the second antenna 20 to the first antenna 1
Since the flow of the signal to 0 is the same as the flow of the signal from the first antenna 10 to the second antenna 20, the description is omitted.

[0007] In this manner, communication between the base station and the mobile terminal in the blind zone is possible.

In the above configuration, in a normal radio relay apparatus, PA1 is controlled so that PA19 is not saturated.
9 is fed back to the ATT 13 to control the signal not to exceed a predetermined value to be input to the PA 19 to adjust the gain. This feedback circuit basically includes a detection circuit 40 and an AGC 30. FIG. 7 shows a schematic configuration of the AGC 30.

FIG. 7 is a diagram showing a schematic configuration of the entire feedback circuit, and FIG. 8 is a diagram showing a specific circuit example of the feedback circuit. The AGC shown in FIG.
Reference numeral 30 denotes an average power control type AGC because it controls the average of the power so that a predetermined signal or more is not input to the PA 19. The operation of the conventional feedback circuit will be described with reference to FIGS.

[0010] In FIGS. 7 and 8, first, the signal from the PA 19 is detected by a detection circuit 40. Detection circuit 40
Is usually composed of a combination of a resistor, a capacitor and a diode as shown in FIG. Next, the detected signal is amplified by an amplifier circuit 31, and its output is averaged by a charge / discharge circuit 32 including an RC circuit.
The averaged output is amplified by the AGC drive circuit 33 and output to the ATT 13.

As described above, the output of the PA 19 is adjusted to a desired size. However, the conventional A
The GC 30 has the following disadvantages. Referring to FIG.
Conventional problems will be described.

FIG. 9A shows a waveform from a point (A) to a point (C) in FIG. 7 in the case of a continuous wave (CW wave). As shown in FIG. 9A, in the case of a continuous wave (CW wave), since the input value basically does not fluctuate, a value proportional to the input / output value of the continuous wave is directly obtained as an average value.

FIG. 9B shows waveforms at points (A) to (C) in FIG. 7 when transmission and reception are performed by a burst wave such as TDMA as in the GSM system, for example. is there. Specifically, when a pulse is input via the amplifier circuit 31, the capacitor C1 of the charge / discharge circuit 32 is charged according to the time constant of the resistor R1. In addition,
In this case, the resistance value of the resistor R2 is set to a value that does not cause rapid discharge. Next, when there is no pulse input between pulses, the electric charge charged in the capacitor C1 is discharged via the resistor R2. In this way, an average of the power is taken.

At point (B) in FIGS. 9A and 9B, the average values of the CW wave and the burst wave are the same. At this time, since the average value of the output of the burst wave with respect to the time axis is taken as described above, in order to obtain the same average value as that of the CW wave, the input value of the burst wave, that is, the output of the PA 19 must be CW Must be bigger than the waves. For example, in the case of a burst wave, if the pulse width of the burst wave is t and the pulse period is 8t, the average value becomes 1/8 of the pulse height, so the average value of the burst wave and the CW wave is obtained. Requires the input of a pulse height eight times the CW wave. This means that CW
If the specified output power is adjusted with a wave, in the case of a burst wave,
This means that the output of the PA 19 exceeds the specified output power and the PA 19 is saturated as shown in FIG. 9B (point (C) in FIG. 9B). On the other hand, if the AGC 30 is set so that the PA 19 does not saturate when the burst wave is input, the output of the PA 19 is significantly reduced in the case of the CW wave as shown in FIGS. 9D and 9C. Would.

[0015]

As described above, the conventional average power control type AGC has a problem that an optimum output cannot be obtained for both the CW wave and the burst wave.

An object of the present invention is to provide a radio relay apparatus that can obtain an optimum output for both a CW wave and a burst wave with the same circuit.

[0017]

In order to solve the above-mentioned problems, a radio relay device according to the present invention is configured as follows.

(1) Automatic gain control for automatically adjusting the gain of an input signal to obtain an optimal output in a wireless relay apparatus that enables a base station and a mobile terminal to communicate with each other by relaying the base station and the mobile terminal. Circuit, wherein the automatic gain control circuit comprises:
A peak hold circuit for maintaining a peak value of a signal input to the automatic gain control circuit is provided.

By doing so, the same output is obtained because the peak value is maintained regardless of whether the wave is a continuous wave or a burst wave.

(2) In the above wireless relay device, the automatic gain control circuit further includes an amplifier circuit for amplifying a signal input to the peak hold circuit, and the peak hold circuit transfers a signal only in a forward direction. And a charge / discharge circuit for charging / discharging the capacitor based on an input signal, and a high impedance buffer having an output connected to the amplifier circuit.

With this configuration, it is possible to charge the charge / discharge circuit at a high speed when a burst wave is input. Further, since the present circuit can be configured only by adding a simple circuit to the conventional circuit configuration, a peak hold circuit can be realized with a simple circuit configuration.

(3) In the above-described wireless relay device, the peak hold circuit includes a comparison circuit for inputting a signal to one input terminal, a charge / discharge circuit for charging / discharging a capacitor based on an input signal, It is characterized by comprising a switching element which is arranged at a preceding stage of a charge / discharge circuit and turns on / off based on an output of the comparison circuit, and a high impedance buffer whose output is connected to another input terminal of the comparison circuit. .

With such a configuration, the charging / discharging circuit can be charged at a high speed when a burst wave is input, as described above. Further, since the present circuit can be configured only by adding a simple circuit to the conventional circuit configuration, a peak hold circuit can be realized with a simple circuit configuration.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) In this embodiment, since the basic configuration and functions of a wireless relay apparatus are the same as those in FIG. 7, illustration and description are omitted.

According to the present invention, in an automatic gain control (AGC) circuit applied to a radio repeater, the type of an input wave (CW wave, burst The gain is adjusted by taking the peak of the power value regardless of the type of wave. Hereinafter, the AGC circuit 30 of the present invention is referred to as a “peak hold type AGC circuit”.

FIG. 1 is a block diagram of a peak hold type AGC circuit 30 according to the first embodiment of the present invention. In FIG. 1, a peak hold type AGC circuit 30 of the present invention is shown.
Is a conventional average power control type AGC circuit,
4 and a high impedance buffer 35 are added.
The output of the high impedance buffer 35 is input to the amplifier circuit 31.

FIG. 2 is a diagram showing an example of a circuit configuration of the amplifier circuit 31 and the diode 34 according to the first embodiment of the present invention. In FIG. 2, (a) and (b) differ only in the position of the diode 34 and the resistor R1, and the other configurations are the same. 2A and 2B satisfies the function of the present invention. The resistance R3 is
It may be omitted.

FIG. 3 is a diagram showing a specific configuration example of the high impedance buffer 35 according to the first embodiment of the present invention. As the high impedance buffer 35,
As shown in FIG. 3A, it may be constituted by a MOS transistor, or as shown in FIG.
A P amplifier circuit may be used. As the high-impedance buffer 35, a current-consumption type such as an emitter follower is not preferable, and a buffer that does not allow an internal current to flow is preferable.

The operation of the peak hold type AGC circuit 30 according to the first embodiment of the present invention configured as described above will be described with reference to FIG.

The case of the CW wave is the same regardless of whether the average of the power is obtained or the peak value is obtained, so that the description is omitted. In the case of a burst wave, the output of the charge / discharge circuit 32 is not the average power value but becomes as follows. 1 and 2, first, since the output of the high impedance buffer 35 is input to the amplifier circuit 31, when a pulse is input to the amplifier circuit 31, the capacitor is connected via the diode 34 and the resistors R1 and R3. C1 is charged rapidly. Next, when there is no pulse signal (the period between pulses), the diode 3
4. The resistance R2 is set by the high impedance buffer 35.
Only through the capacitor C1 will be discharged slowly. The waveform at this time is shown at point (B) in FIG. In this case, the output at the point (B) is not the 1/8 of the pulse width as in the conventional case, but is substantially the same as the pulse width, so that even a burst wave can be treated in the same manner as a CW wave. It becomes possible. That is, optimal control can be performed regardless of the type of signal such as a CW wave or a burst wave.

As described above, according to the peak hold type AGC circuit 30 of the present embodiment, it is possible to operate stably with all the waveforms from the CW wave to the burst wave.

Incidentally, the charging / discharging circuit can set the optimum timing for various burst patterns by appropriately setting the values of the capacitor C1 and the resistors R1, R2 and R3.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of the embodiment. The difference from the first embodiment shown in FIG. 1 is that the input to the charge / discharge circuit 32 is controlled using a comparator 36 and a switching element 37 instead of the diode 34. In addition,
The output of the high impedance buffer 35 is
It is fed back to the comparator 36 instead of 1.

In the second embodiment, when the capacitor C1 is charged by the output of the comparator 36, the switching element 37 is closed and the capacitor C1 is closed.
When discharging 1, the switching element 37 is opened. Except for the above, the configuration is the same as that of the first embodiment.

(Modification) In the above description, the type of the mobile terminal or the like to which the present invention is applied is not mentioned. However, the present invention is applied to a band select type, a channel select type, a broadband type, and the like. Applicable.

Further, in the above-described embodiment, a specific example of a circuit configuration has been shown for each unit. However, the present invention is not limited to this, and any circuit configuration may be used as long as equivalent operations are possible.

Further, the high impedance buffer is M
It may be composed of an OS transistor or an OP amplifier.

[0038]

According to the present invention, it is possible to provide a radio relay apparatus having a peak hold type AGC circuit capable of operating stably with all waveforms from a CW wave to a burst wave.

[Brief description of the drawings]

FIG. 1 is a block diagram of a peak hold type AGC circuit 30 according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration example of an amplifier circuit 31 and a diode 34 according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a specific configuration example of a high impedance buffer 35 according to the first embodiment of the present invention.

FIG. 4 is a block diagram of a peak hold AGC circuit 30 according to a second embodiment of the present invention.

FIG. 5 shows a peak hold type AG according to an embodiment of the present invention.
FIG. 7 is a waveform chart of each part for explaining the operation of the C circuit.

FIG. 6 is a diagram showing a schematic configuration of a wireless relay device according to a conventional example.

FIG. 7 is a diagram showing a schematic configuration of a feedback circuit of the wireless relay device according to the conventional example.

FIG. 8 is a diagram showing a specific circuit example of a feedback circuit of the wireless relay device according to the conventional example.

FIG. 9 is a waveform chart of each part for explaining the problem of the conventional example.

[Explanation of symbols]

 31 ... amplifier circuit, 32 ... charge / discharge circuit, 33 ... AGC drive circuit, 34 ... diode, 35 ... high impedance buffer.

Claims (3)

[Claims] 1. An automatic gain control circuit for automatically adjusting a gain of an input signal to obtain an optimum output in a wireless relay apparatus for relaying between a base station and a mobile terminal and enabling mutual communication. A wireless relay apparatus comprising: a peak hold circuit that substantially maintains a peak value of a signal input to the automatic gain control circuit. 2. The wireless relay device according to claim 1, wherein the automatic gain control circuit further includes an amplifier circuit for amplifying a signal input to the peak hold circuit, and wherein the peak hold circuit receives a signal only in a forward direction. And a charge / discharge circuit for charging / discharging a capacitor based on an input signal, and a high impedance buffer having an output connected to the amplifier circuit. 3. The wireless relay device according to claim 1, wherein the peak hold circuit includes a comparison circuit for inputting a signal to one input terminal, and a charge / discharge circuit for charging / discharging a capacitor based on the input signal. A switching element disposed at a stage preceding the charging / discharging circuit to turn on / off based on an output of the comparing circuit; and a high impedance buffer having an output connected to another input terminal of the comparing circuit. Wireless relay device.