JPH09219625A - Radio communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication equipment which is capable of simultaneously and exactly suppressing the levels of a signal to be up-converted and transmitted in a transmission system and the signal that a received signal is down-converted in a reception system to each roughly constant level, by a simple constitution and at low cost. SOLUTION: This equipment has the frequency mixer 13 of a transmission system 6, the frequency mixer 19 of a reception system 7, a local oscillator 14, a variable gain amplifier 23 in which the local oscillation signals from the local oscillator 14 are supplied and the amplified outputs are supplied to the frequency mixers 19 and 13 of the transmission system 6 and the reception system 7 and a reception electric field intensity detector 8. Based on the detection output of the reception electric field intensity detector 8, the gain to the variable gain amplifier 23 is controlled to lower gain when reception electric field intensity is high and to raise gain when the intensity is low.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a wireless communication device.

[0002]

2. Description of the Related Art A conventional wireless communication device will be described below with reference to FIG. The transmission / reception antenna 1 is connected to the transmission system 6 and the reception system 7 through the transmission / reception switch 2.
The transmission system 6 and the reception system 7 are connected to a baseband processing circuit (conversion circuit) 3, and the baseband processing circuit 3 includes:
The microphone 4 and the speaker 5 are connected. The baseband processing circuit 3 includes an OQPSK (offset quadrature phase shift keying) modulator, a QPSK demodulator, when the wireless communication device is, for example, a cellular phone for CDMA (code division multiple access) digital cellular system in North America. C
It is composed of a DMA (code division multiple access) control circuit, a voice encoder, an audio interface, and the like.

First, the transmission system 6 will be described. The audio signal from the microphone 5 is processed by the baseband processing circuit 3
After being supplied to a voice encoder through the audio interface of the above to be converted into a digital voice signal, the digital voice signal is supplied to a CDMA control circuit, and after performing error correction coding, interleaving, scrambling, etc. of the digital voice signal, Supply to the OQPSK modulator. OQPSK
The phase difference is 9 from the modulated digital audio signal from the modulator.
Baseband signals I and Q of 0 degree are created, and the baseband signals I and Q are supplied to the quadrature modulator 11 and modulated to obtain quadrature modulated signals. This quadrature modulated signal is passed through a variable gain amplifier 12 to a frequency mixer (up converter).
13 and frequency-mixes it with the local oscillation signal from the local oscillator 14 common to the transmission system 6 and the reception system 7, and frequency-converts it into a high frequency signal. The high frequency signal from the frequency mixer 13 is passed through the band pass filter 15 and the power amplifier 16
Also, the signal is supplied to the transmission / reception antenna 1 through the transmission / reception switch 2 and transmitted.

Next, the receiving system 7 will be described. A high frequency signal received from the transmission / reception antenna 1 is supplied to a reception power amplifier 17 through a transmission / reception switch 2 and amplified, and then supplied to a frequency mixer (down converter) 19 through a bandpass filter 18 to provide a common local oscillator 14 The frequency is mixed with the local oscillation signal from and converted to a low frequency,
Obtain a quadrature modulated signal. The quadrature modulated signal is supplied to the quadrature demodulator 21 through the variable gain amplifier 20 and demodulated to obtain baseband signals I and Q having a phase difference of 90 degrees. The baseband signals I and Q are supplied to the QPSK demodulator of the baseband processing circuit 3 and demodulated to obtain a digital audio signal.
After being supplied to the A control circuit for descrambling, deinterleaving, error correction, etc., it is supplied to the audio encoder and converted into an analog audio signal, and the audio signal is supplied to the speaker 5 through the audio interface.

Baseband signals I and Q having a phase difference of 90 degrees from the quadrature demodulator 21 of the receiving system 7 are divided into √ (I ² + Q).
² ) The signal is supplied to the detector 8 to obtain a received electric field strength signal (RSSI signal). This detector 8 is composed of two square-law detectors, an adder for adding both detection outputs, and a square root detector.
It should be noted that the square root can be omitted and a level attenuator can be provided instead. The RSSI signal from the detector 8 is transmitted through the characteristic correctors 9 and 10 to the transmission system 6 and the reception system 7.
To the variable gain amplifier 20 for controlling the respective gains.

These characteristic correctors 9 and 10 are √ (I ² +
Q ² ) The output voltage of the detector 8 and the variable gain amplifiers 12, 2
In the circuit for correcting the characteristic between 0 and the gain, that is, the non-linear characteristic of the non-corrected gain in FIG. 5 to the linear characteristic of the non-corrected gain in FIG.
As shown in FIG. 6, it can be composed of a ROM table and an address converter. RSSI from input terminal Tin
The signal is supplied to the address converter A, the address signal from the address converter A is supplied to the ROM table M,
A linear gain control signal is available at the output terminal Tout. The gain control signal from the output terminal Tout is supplied to the variable gain amplifiers 12 and 20.

According to such a conventional radio communication device, when the received electric field strength is high (low), the level of the direct modulation signal is lowered (improved) by the variable gain amplifier 20 of the receiving system 7. The level of the quadrature modulated signal is lowered (improved) by the variable gain amplifier 12 of the transmission system 6, and the signal to be up-converted by the transmission system 6 and the received signal are down-converted by the reception system 7. At the same time, the signal levels are kept substantially constant (however, the substantially constant level of the transmission system 6 is higher than the substantially constant level of the reception system 7), so that the power source such as the battery of the wireless communication device is wasted. It is possible to reduce power consumption and avoid unnecessary interference of communication radio waves.

[0008]

In a conventional radio communication device, in order to suppress the levels of a signal to be up-converted in a transmission system and a signal to be down-converted in a reception system to be substantially constant at the same time. Since two variable gain amplifiers are required, the configuration of the wireless communication device is complicated and the cost is increased, and the gain characteristics of the two variable gain amplifiers are varied, so that accurate gain control is performed in the transmission system and the reception system. Was difficult. Further, since two characteristic correctors for correcting the characteristic between the received electric field strength by the received electric field strength detector and the gain of the variable gain amplifier are also required, the configuration of the wireless communication device becomes more complicated from this point, and The cost increases.

In view of the above points, the present invention has a simple structure and low cost, and at the same time, the levels of the signal to be up-converted in the transmission system and the signal to be down-converted in the reception system are substantially constant. It aims to propose a wireless communication device that can be accurately suppressed.

[0010]

According to a first aspect of the present invention, a frequency mixer for a transmission system, a frequency mixer for a reception system, a local oscillator, and a local oscillation signal from the local oscillator are supplied, and an amplified output thereof is provided. Has a variable gain amplifier supplied to the frequency mixers of the transmission system and the reception system, and a reception electric field strength detector, and based on the detection output of the reception electric field strength detector, when the reception electric field strength is large, the gain is adjusted. The wireless communication device is characterized in that the gain of the variable gain amplifier is controlled so that the gain is lowered and the gain is increased when the gain is small.

According to the present invention, the gain of the variable gain amplifier is controlled based on the detection output of the reception electric field strength detector so that the gain is decreased when the reception electric field strength is large and the gain is increased when the reception electric field strength is small. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Note that, in FIG. 1, portions corresponding to those in FIG. 4 are denoted by the same reference numerals. The transmission / reception antenna 1 is connected to the transmission system 6 and the reception system 7 through the transmission / reception switch 2. The transmission system 6 and the reception system 7 are connected to a baseband processing circuit (conversion circuit) 3, and the baseband processing circuit 3 is connected to a microphone 4 and a speaker 5. The baseband processing circuit 3 is, for example, a North American CDMA (code division multiple access) radio communication device.
If it is a mobile phone for digital cellular system,
QPSK (Offset Quadrature Phase Shift Keying) modulator, Q
It is composed of a PSK demodulator, a CDMA (code division multiple access) control circuit, a voice encoder, an audio interface and the like.

First, the transmission system 6 will be described. The audio signal from the microphone 5 is processed by the baseband processing circuit 3
After being supplied to a voice encoder through the audio interface of the above to be converted into a digital voice signal, the digital voice signal is supplied to a CDMA control circuit, and after performing error correction coding, interleaving, scrambling, etc. of the digital voice signal, Supply to the OQPSK modulator. OQPSK
The phase difference is 9 from the modulated digital audio signal from the modulator.
Baseband signals I and Q of 0 degree are created, and the baseband signals I and Q are supplied to the quadrature modulator 11 and modulated to obtain quadrature modulated signals. This quadrature-modulated signal is supplied to the frequency mixer (up converter) 13 as it is, frequency-mixed with the local oscillation signal from the power splitter 24, and frequency-converted into a high-frequency signal. This frequency mixer 1
The high frequency signal from 3 is supplied to the transmission / reception antenna 1 through the band pass filter 15, the power amplifier 16 and the transmission / reception switch 2 to be transmitted.

Next, the receiving system 7 will be described. The high frequency signal received from the transmission / reception antenna 1 is supplied to the reception power amplifier 17 through the transmission / reception switch 2 to be amplified, and then supplied to the frequency mixer (down converter) 19 through the band pass filter 18 to be supplied from the power splitter 24. Frequency mixing with local oscillation signal and converting to low frequency,
Obtain a quadrature modulated signal. The quadrature modulated signal is directly supplied to the quadrature demodulator 21 and demodulated to obtain baseband signals I and Q having a phase difference of 90 degrees. The baseband signals I and Q are supplied to the QP of the baseband processing circuit 3.
It is supplied to the SK demodulator and demodulated to obtain a digital audio signal,
This digital audio signal is supplied to the CDMA control circuit,
After performing descrambling, deinterleaving, error correction, etc., it is supplied to a voice encoder and converted into an analog voice signal, and the voice signal is supplied to a speaker 5 through an audio interface.

The frequency mixer 13 of the transmission system 6 and the reception system 7
A common local oscillator 14 is provided for the frequency mixer 19 and the local oscillation signal is passed through a variable gain amplifier 28.
The local oscillation signal from the gain amplifier 23 is supplied to the power splitter 24 so that the frequency mixer 13 of the transmission system 6 is supplied with a larger power than the frequency mixer 19 of the reception system 7. The signal is divided by a predetermined power division ratio and supplied to the frequency mixers 13 and 19 of the transmission system 6 and the reception system 7, respectively.

The baseband signals I and Q having a phase difference of 90 degrees from the quadrature demodulator 21 of the receiving system 7 are √ (I ² + Q
² ) The signal is supplied to the detector 8 to obtain a received electric field strength signal (RSSI signal). This detector 8 is composed of two square-law detectors, an adder for adding both detection outputs, and a square root detector.
It should be noted that the square root can be omitted and a level attenuator can be provided instead. The RSSI signal from the detector 8 is supplied to the variable gain amplifier 23 through the characteristic corrector 22 to control its gain.

The characteristic corrector 23 is √ (I ² + Q ² )
The characteristic between the output voltage of the detector 8 and the gain of the variable gain amplifier 23, that is, the non-linear characteristic of the uncorrected gain in FIG. 5 is changed to the linear gain characteristic when corrected in FIG. The conversion circuit can be constituted by, for example, a ROM table and an address converter as shown in FIG. The RSSI signal from the input terminal Tin is supplied to the address converter A, the address signal from the address converter A is supplied to the ROM table M, and the gain control signal is obtained at the output terminal Tout. The gain control signal from the output terminal Tout is supplied to the variable gain amplifier 23.

According to this radio communication device, when the received electric field strength is high (low), the variable gain amplifier 20 of the receiving system 7 lowers (improves) the level of the direct modulation converted signal.
At the same time, the level of the quadrature-modulated signal is lowered (improved) by the variable gain amplifier 12 of the transmission system 6, and the signal to be up-converted by the transmission system 6 and the received signal are received by the reception system 7. The level of the down-converted signal is approximately constant at the same time (however,
(The level of the transmission system 6 is substantially higher than that of the reception system 7) to reduce unnecessary power consumption of the power source such as the battery of the wireless communication device, and unnecessary communication radio waves. Interference can be avoided.

The frequency mixer 1 for the local oscillation signal supplied to the frequency mixers 13 and 19 of the transmission system 6 and the reception system 7.
The leakage power to each output side of 3 and 19 is as shown in FIG.
It is known that the power of a signal to be up-converted and transmitted by the transmission system 6 increases as the power of the signal increases. Therefore, in the conventional wireless communication device of FIG. 4, the level of the local oscillation signal from the local oscillator 14 is high and is constant, so that the frequency mixer 13 of the transmission system 6 and the reception system 7 as shown in FIG. Leakage power of the local oscillation signals supplied to the frequency mixers 13 and 19 to the respective output sides of the frequency mixers 13 and 19 is high and constant.

However, in the case of the wireless communication device of the above-described embodiment, the frequency mixers 13 and 1 of the transmission system 6 and the reception system 7 are used.
Since the level of the local oscillation signal supplied to 9 can be varied and the level can be reduced, the transmission system 6 and the reception system 7
Frequency mixer 1 supplied to the frequency mixers 13 and 19 of
As can be seen from FIG. 3, the leakage power to the output side of each of 3 and 19 can be reduced.

Next, another embodiment of the present invention will be described with reference to FIG. 2. In FIG. 2, parts corresponding to those in FIG. To do. In the embodiment of FIG. 2, when the received high frequency signal received by the transmitting / receiving antenna 1 includes a level control signal (power control signal), the gain of the variable gain amplifier 23 is also controlled by this level control signal. This is the case when it is controlled. Down-converted signals from the frequency mixer 19 of the reception system 7, that is, baseband signals I and Q
The level control signal (power control signal) included in
The level control signal is separated (extracted) by the level control signal separating (extracting) circuit provided in the baseband processing circuit 3, and the obtained level control signal and the received electric field strength signal from the √ (I ² + Q ² ) detector 8 ( The information synthesizer 25 synthesizes the RSS signal) with a predetermined synthesis ratio and supplies the synthesized signal to the characteristic corrector 22. Other configurations and operations are similar to those of the embodiment shown in FIG.

When a local oscillation signal having a different frequency is supplied to the frequency mixer 13 of the transmission system 6 and the frequency mixer 19 of the reception system 7, the power splitter 24 and the frequency mixer are used in FIG. 1 or 2. A cascade circuit composed of a frequency mixer and a band pass filter at the next stage may be newly inserted between the frequency mixer 13 and 19 and a local oscillator for supplying a local oscillation signal to the frequency mixer may be newly provided. .

In the above embodiment, the case where the wireless communication device is a mobile phone for CDMA (code division multiple access) digital cellular system in North America has been described, but a mobile phone of another system, a car phone, a wireless phone, etc. The present invention can be applied to the wireless telephones, wireless communication devices other than telephones, such as transceivers.

[0024]

According to the first aspect of the present invention, a frequency mixer for a transmission system, a frequency mixer for a reception system, a local oscillator, and a local oscillation signal from the local oscillator are supplied, and an amplified output thereof is transmitted. A variable gain amplifier supplied to the frequency mixer of the system and the receiving system, and a reception electric field strength detector, based on the detection output of the reception electric field strength detector, when the reception electric field strength is large, lower the gain, When it is small, increase the gain,
Since the gain of the variable gain amplifier is controlled, the level of the signal to be up-converted in the transmission system and the level of the signal down-converted from the reception signal in the transmission system can be omitted at the same time with a simple configuration and low cost. (EN) A wireless communication device that can be accurately suppressed to a constant level and that can reduce leakage power of a local oscillation signal from a local oscillator to each output side of a transmission system frequency mixer and a reception system frequency mixer. Obtainable.

According to the second aspect of the present invention, in the radio communication device according to the first aspect of the present invention, a local oscillation signal having a larger power is supplied to the frequency mixer of the transmission system than to the frequency mixer of the reception system. As described above, the local oscillating signal from the gain amplifier is divided by a predetermined power division ratio, and the power splitters supplied to the frequency mixers of the receiving system and the transmitting system are respectively provided with the variable gain amplifier, the receiving system and the transmitting system. In addition to the effect of the first invention, since it is provided between the frequency mixer and
Even with only one variable gain amplifier, it is possible to obtain a radio communication device capable of supplying a local oscillation signal having a larger power to the frequency mixer of the transmission system than the frequency mixer of the reception system. .

According to the third aspect of the present invention, in the wireless communication device of the first aspect of the present invention, the gain of the variable gain amplifier is controlled also based on the level control signal included in the high frequency reception signal. Therefore, in addition to the effect of the second aspect of the present invention, the level conversion signal included in the reception high frequency signal of the transmission signal transmitted from the wireless communication base station or the other terminal wireless communication device also causes up conversion in the transmission system. Thus, it is possible to obtain a wireless communication device capable of controlling the level of the signal to be transmitted and the level of the signal obtained by down-converting the received signal in the receiving system.

According to the fourth aspect of the present invention, in the radio communication device of the first aspect of the present invention, the characteristic between the detection output from the reception electric field strength detector and the gain of the variable gain amplifier is linearly corrected. Since the characteristic corrector is inserted between the reception electric field strength detector and the variable gain amplifier, in addition to the effect of the first aspect of the present invention, the detection output from the reception electric field strength detector,
It is possible to obtain a wireless communication device that can linearly correct the characteristics between the gain and the variable gain amplifier.

According to the fifth aspect of the present invention, in the radio communication device according to the second aspect of the present invention, the characteristic between the detection output from the reception electric field strength detector and the gain of the variable gain amplifier is linearly corrected. Since the characteristic corrector is inserted between the reception electric field strength detector and the variable gain amplifier, in addition to the effect of the second aspect of the present invention, the detection output from the reception electric field strength detector,
It is possible to obtain a wireless communication device capable of linearly correcting the characteristic between the gain and the variable gain amplifier.

According to the sixth aspect of the present invention, in the radio communication device according to the third aspect of the present invention, the characteristic between the detection output from the reception electric field strength detector and the gain of the variable gain amplifier is linearly corrected. Since the characteristic corrector is inserted between the reception electric field strength detector and the variable gain amplifier, in addition to the effect of the third aspect of the present invention, the detection output from the reception electric field strength detector,
It is possible to obtain a wireless communication device capable of linearly correcting the characteristic between the gain and the variable gain amplifier.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a characteristic of leakage power of a local oscillation signal.

FIG. 4 is a block diagram showing a conventional example.

FIG. 5 is a characteristic diagram showing a gain characteristic of a variable gain amplifier.

FIG. 6 is a block diagram showing a specific example of a characteristic corrector.

[Explanation of symbols]

1 transmitting / receiving antenna, 2 transmitting / receiving switch, 3 baseband processing circuit, 4 microphone, 5 speaker, 6
Transmission system, 7 reception system, 8 √ (I ² + Q ² ) detector,
13 frequency mixer, 14 local oscillator, 15 bandpass filter, 16 amplifier, 17 amplifier, 18 bandpass filter, 19 frequency mixer, 21 quadrature modulator, 22 characteristic corrector, 23 variable gain amplifier, 24
Power splitter.

Claims (6)

[Claims] 1. A frequency mixer for a transmission system, a frequency mixer for a reception system, a local oscillator, and a local oscillation signal from the local oscillator are supplied, and an amplified output thereof is a frequency mixture for the transmission system and the reception system. A variable gain amplifier supplied to the receiver, and a reception electric field strength detector, based on the detection output of the reception electric field strength detector, lower the gain when the reception electric field strength is large, A radio communication device, characterized in that the gain of the variable gain amplifier is controlled so as to increase. 2. The wireless communication device according to claim 1, wherein a local oscillation signal having a larger power is supplied to the frequency mixer of the transmission system than to the frequency mixer of the reception system, A power splitter that divides the local oscillation signal from the gain amplifier with a predetermined power division ratio and supplies the frequency splitters to the frequency mixers of the reception system and the transmission system, respectively, of the variable gain amplifier and the reception system and the transmission system. A radio communication device provided between the frequency mixer and the frequency mixer. 3. The radio communication device according to claim 1, wherein the gain of the variable gain amplifier is controlled also based on a level control signal included in a high frequency reception signal of the reception system. And wireless communication equipment. 4. The radio communication device according to claim 1, further comprising a characteristic corrector that linearly corrects a characteristic between a detection output from the reception electric field strength detector and a gain of the variable gain amplifier, A wireless communication device, wherein the wireless communication device is inserted between the reception electric field intensity detector and the variable gain amplifier. 5. The radio communication device according to claim 2, further comprising a characteristic corrector that linearly corrects a characteristic between a detection output from the reception electric field strength detector and a gain of the variable gain amplifier, A wireless communication device, wherein the wireless communication device is inserted between the reception electric field intensity detector and the variable gain amplifier. 6. The radio communication device according to claim 3, further comprising a characteristic corrector that linearly corrects a characteristic between a detection output from the reception electric field strength detector and a gain of the variable gain amplifier, A wireless communication device, wherein the wireless communication device is inserted between the reception electric field intensity detector and the variable gain amplifier.