JPH07212297A - Radio telephone equipment - Google Patents

Abstract

PURPOSE:To make possible the control of a reception input level without increasing the number of components by decreasing the base bias of low noise amplification and operating a switch so as to decrease the gain when it is judged that the level is stronger than a certain value. CONSTITUTION:This equipment is composed of a variable gain amplifier 1, radio frequency filter 2, first mixer 3, intermediate frequency filter 4, local oscillation filter 5, level detection part 6, attenuation selection and decision part 7 inside a control part, and selective attenuation changeover switch 8. A signal received from an antenna and a DC signal, whose frequency is converted, corresponding to the level detected by the RSSI level detection part 6 is transmitted to the control part. An RSSI output is correlated with the received signal level and when it is judged by the attenuation selection and decision part 7 that the reception input level is stronger than a certain value, the reception level is reduced by decreasing the base bias of the low noise amplifier 1 and operating the switch 8 so as to decrease the gain of the low noise amplifier 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiotelephone device, and more particularly to a reduction in gain at a strong reception input level and a reduction in power consumption.

[0002]

2. Description of the Related Art In a portable communication device such as a cordless telephone or a mobile telephone, there is a problem that the transmission or reception level is too strong, such as when the transmission side and the reception side are close to each other. In the case of digital communication, if the reception level is too strong on the receiving side, saturation distortion occurs in the receiving circuit, intersymbol interference increases, and bit error rate increases.

In order to prevent this, in the conventional device, an attenuator circuit for attenuating the transmission level or the reception level is provided on the transmission side or the reception side, and this is selected according to the signal level.

For example, FIG. 16 shows a block diagram of a front end portion of a receiver circuit of a linear modulation digital radio telephone. The function will be described with reference to FIG.

Radio frequency (RF:
The Radio Frequency signal is amplified by a low noise amplifier (LNA) 81, is attenuated by a radio frequency attenuator (RF-ATT) 86 when the reception level is high, and is unnecessary by a radio frequency (RF) filter 82 outside the band. After the frequency component is removed, the first mixer (1st Mix)
At 83, it is mixed with the primary local signal supplied from the synthesizer section and converted into a primary intermediate frequency (1st IF) signal. The primary intermediate frequency signal is the primary intermediate frequency filter 8
At 4, the signal in the selected band is removed and output to the intermediate frequency section.

In this circuit, a radio frequency attenuator 86 is provided at the output of the low noise amplifier 81, and when the reception level is strong, the attenuator 86 attenuates the radio frequency attenuator 86 to prevent saturation in the first mixer 83. However, in this method, even when the signal level is low and the radio frequency attenuator 86 is turned off, there is an insertion loss at the insertion part of the radio frequency attenuator 86, which becomes a factor that deteriorates the noise figure of the entire receiver. Further, the existence of the radio frequency attenuator 86 causes a problem that the number of parts increases, which causes an increase in cost, a decrease in reliability, an increase in circuit space / weight, and an increase in power consumption.

In order to solve this, as shown in FIG. 17, there is also a method of controlling the gain by lowering the level of the primary local signal supplied from the synthesizer, but the output saturation level of the first mixer 83 is This causes a phenomenon in which the dynamic range is lowered and the output level is saturated even though the output level is lowered.

FIG. 18 is a block diagram of a transmission circuit of a digital radio telephone in the linear modulation system. In the transmission circuit of the digital linear modulation type radio device, the output amplifier 93 is a linear (class A) amplifier and is made of GaAs because of the necessity of linear operation.
A circuit using FET is used. FIG. 19 shows the output of each block of the transmission circuit when the transmission output reduction control for lowering the transmission output level from the rated value by −N dB is performed.

Paying attention to the current consumption at this time, the transmission output reduction control is performed so that the transmission output level is -Nd higher than the rated value.
Even when B is lowered, each circuit element operates with the same current consumption as in the case of full power output not subjected to transmission output reduction control. In particular, the current consumption in the output amplifier 93 that consumes the most power does not change. Therefore, in a wireless telephone such as a mobile telephone that operates using a battery as a power source, there is a problem that current consumption becomes large and battery life becomes short.

FIG. 20 shows TDMA-TDD (Time D
ivision MultipleAccess-Ti
FIG. 1 is a block diagram of a cordless telephone device based on a me Division Duplex (time division multiple access-time division two-way communication) system. Also in this circuit, an attenuator 123 is provided on the transmission side for controlling the transmission power. See also T
The transmitting circuit 121 includes an antenna for the DMA-TDD system.
And a transmission / reception switching circuit 1 for switching to the reception circuit 120
08 is provided.

In a cordless telephone device or the like, especially in a portable device or a child device, an increase in the number of parts causes an increase in cost, a decrease in reliability, an increase in power consumption, an increase in weight and the like, which is not preferable.

[0012]

As described above, in a conventional wireless telephone such as a cordless telephone or a mobile telephone, in order to prevent an increase in inter-symbol interference due to saturation distortion when the reception level is too strong, the transmission side or The reception level has been suppressed by providing means such as providing an attenuator circuit on the reception side. Providing such a circuit, which is not necessary at the normal reception level, results in an increase in the number of parts, resulting in an increase in cost, a decrease in reliability, an increase in weight, and the like. In this case, the current consumption does not decrease, and it is often unfavorable as a portable communication device.

According to the present invention, such a problem is solved, the level can be controlled without increasing the number of parts, and the power consumption can be correspondingly reduced when the transmission level is lowered on the transmitting side. The purpose.

[0014]

According to a first aspect of the present invention, in a digital radio telephone apparatus using a linear modulation method, which comprises a low noise amplifier using a transistor in a front end portion of a receiving circuit, a receiving input level is set. Is provided and a switch for varying the base bias of the low noise amplifier is provided, and when the means for detecting the reception input level determines that the reception input level is stronger than a certain value, the base bias of the low noise amplifier is lowered. The switch is operated so that the gain of the low noise amplifier is lowered, and the reception level is reduced.

In the second invention of this patent, the FE is used in the transmission circuit.
In a digital radiotelephone device using a linear modulation system having a high frequency output amplifier using T, means for switching the gate bias voltage of the FET of the high frequency output amplifier in accordance with the transmission output signal level is provided, and at the time of low transmission output Reduce current consumption.

In the third invention of this patent, the TDMA-TD is provided with an antenna, a transmission circuit, a reception circuit, and a transmission / reception switch for connecting the antenna and the transmission circuit or the reception circuit.
In the radio telephone apparatus using the D method, a means for detecting the reception input level is provided, and when the means for detecting the reception input level determines that the reception input level is higher than a certain value, the transmission / reception switcher is transmitting. The transmission level is reduced by operating so as to connect the antenna and the receiving circuit.

[0017]

In the first and third aspects of the invention, the reception level or the transmission level can be reduced without providing an attenuator circuit and without making a great change to the conventional circuit, so that the number of parts can be reduced. The cost can be reduced, the reliability can be increased, the circuit space and the weight can be reduced, and the portability can be improved.

Further, according to the second aspect of the present invention, the current consumption at the time of low transmission output can be reduced, and in the case of the portable device, the life of the battery as the power source can be extended.

[0019]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a receiving front end circuit of a radio telephone according to an embodiment of the first invention. In the figure, 1 is a variable gain amplifier, 2 is a radio frequency filter, and 3 is a first
Mixer 4, intermediate frequency filter, 5 local oscillation frequency filter, 6 RSSI (Re
receive Signal Strength Ind
Icate) level detection unit, 7 is an attenuation selection determination unit in the control unit, and 8 is an attenuation selection changeover switch.

FIG. 2 is an operation flowchart of the circuit shown in the block diagram of FIG. The signal received from the antenna is frequency-converted, and a DC signal corresponding to the level detected by the RSSI level detector 6 is sent to the controller.
The RSSI output has a correlation with the received signal level, and the attenuation selection determination unit 7 in the control unit determines whether or not to lower the gain based on this DC signal. Then, the attenuation selection changeover switch 8 controls the gain of the variable gain amplifier 1.

FIG. 3 is a circuit diagram of one embodiment of the variable gain amplifier 1 used in the embodiment shown in FIG.

This circuit is a typical grounded-emitter current feedback type bias circuit. In the figure, 9 and 10 are input / output DC
Coupling capacitor for cutting, 11 and 12 are base bias resistors, 13 is an emitter resistor, 14 is a damping inductor, 15 and 16 are bypass capacitors, 17 is a base bias variable resistor, 18 is a variable resistor short-circuit switch, and 19 is an amplifying transistor. Where A is the base input and B
Shows the collector output.

In this circuit, the variable resistance short circuit switch 18
The base bias variable resistor 17 is short-circuited or released to control the gain. Variable resistance short-circuit switch 1
8 is turned on, the base bias variable resistor 17 is short-circuited, and the power supply voltage Vcc is directly applied to the base bias resistor 11. When the RSSI level detection unit 6 detects that the received signal level is high, and the radio frequency attenuation control signal from the attenuation selection determination unit 7 turns off the variable resistance short-circuit switch 18, the base is placed between the power supply voltage Vcc and the base bias resistor 11. When the bias variable resistor 17 is inserted, the division ratio of the resistors 11, 12 and 17 for applying the base bias voltage is changed, the base bias voltage is lowered, and the potential of the base input is lowered, so that the potential of the collector output is also lowered. , The collector current also decreases and the gain decreases.

FIG. 4 shows a circuit diagram of another embodiment of the variable gain amplifier 1 of the present invention.

This circuit uses a switching operation of a transistor to control the gain. In the figure, 20 and 22 are switching transistors, and 21 and 23 are base input resistors. At the normal reception signal level, the radio frequency attenuation control signal (“H”) from the attenuation selection determination unit 7 is input to the switching transistor 22 through the base input resistor 23, and when the switching transistor 22 is turned on, the switching transistor 22 is turned on. 20 is also turned on, and the base bias variable resistor 17 is short-circuited.

When the received signal level becomes strong, the radio frequency attenuation control signal becomes 0V ("L") voltage, the switching transistors 20 and 22 are turned off, and the power supply voltage Vcc is generated.
A base bias variable resistor 17 is inserted between the base bias resistor 11 and the base bias resistor 11. As a result, the gain decreases as in the example of FIG.

FIG. 5 is a graph showing the input / output characteristics of the variable gain amplifier 1 in the examples shown in FIGS. From this, it is understood that when the base bias variable resistor 17 is inserted by the switch operation and the gain is lowered, the amplifier does not saturate up to a wider range of the input signal level and the linearity is maintained.

FIG. 6 shows still another embodiment of the variable gain amplifier 1 of the present invention.

In this example, depending on the received signal level, 2
By outputting the types of base bias control signals C and D from the attenuation selection determination unit 7, the gain of the variable gain amplifier 1 can be changed in multiple stages, and the gain control can be widely performed.

FIG. 7 is a block diagram of a transmitting circuit of a wireless telephone which represents an embodiment of the second invention. In FIG. 7, 41 is an attenuator, 42 is an up-converter mixer, 43 is an output amplifier, 44 is a bandpass filter, 45 is an antenna, 4
6 is a switching circuit.

Before describing this circuit, the output amplifier 43
The operation of the amplifier using the gallium arsenide FET used in FIG.

FIG. 8 shows the relationship between the gate bias voltage Vg and the amplifier gain of the output amplifier 43 using the gallium arsenide FET. As can be seen from the figure, even if the gate bias voltage is changed from Vg1 to Vg2, the gain of the amplifier at the small signal level does not change so much. On the other hand, the relationship between the gate bias voltage Vg and the drain current of the output amplifier 3 is as shown in FIG. 9, which is greatly changed by changing the gate bias voltage from Vg1 to Vg2. In order to stably operate the gallium arsenide FET with respect to the normal input and to obtain the maximum transmission output, the voltage of Vg1 is required as the gate bias voltage, and thus the drain current Id1 is also required. However, when the transmission output control is performed, the output of the wireless device is reduced to -Ndb, so the gate bias voltage is Vg2 if the gain of the amplifier is obtained.
Then, the drain current can be reduced to Id2.

By utilizing the characteristics of the amplifier using such a gallium arsenide FET, a transmitter circuit of a radio device is constructed as shown in FIG.

When the attenuator 41 is turned on to control the transmission output, the control signal is used to switch the gate bias voltage Vg of the output amplifier 43 by the switching circuit 46 from Vg1 to Vg2. As a result, the transmission output becomes -NdB, and the drain current of the output amplifier 43 decreases from Id1 to Id2. Therefore, the output amplifier 4
It is possible to reduce the power consumption without changing the gain of No. 3.

FIG. 10 shows a modification of the second embodiment of the present invention, in which the output amplifier 3 is a MIC (Microwaveave).
The integrated circuit structure is integrated, and an attenuator circuit and a gate bias voltage switching circuit are integrated inside. A specific circuit of the output amplifier MIC43 is shown in FIG.

By constructing the dedicated MIC in this way, the structure of the transmission circuit can be made smaller and simpler.

FIG. 12 is a circuit diagram showing a third embodiment of the present invention. This is a circuit of a cordless telephone based on the TDMA-TDD system.

The basic operation of this circuit will be described. On the transmitting side, the audio signal input from the microphone 51 is
It is converted into digital data by the voice encoder 52, temporally compressed by the burst data generator 53, and then converted into burst data with additional bits added before and after. The digital modulator 54 generates a phase modulation wave (intermediate frequency signal) from the burst data. Further, this phase modulated wave signal is mixed with the local oscillation signal output from the frequency synthesizer 56 by the up converter mixer 55T, converted into a transmission frequency signal, amplified by the transmission power amplifier 57 to a predetermined power, and transmitted / received by the transmission / reception switch 58. It is supplied to the antenna 59 through and is radiated as a burst-shaped phase modulation wave.

On the other hand, on the receiving side, the burst-like phase modulated wave is received by the antenna 59, amplified by the low noise amplifier 60 via the transmission / reception switch 58, and input to the down converter mixer 55R. Down converter mixer 55R
Then, this signal is mixed with the local oscillation signal output from the frequency synthesizer 56 to obtain an intermediate frequency signal. The output of the mixer 55R is amplified to a required level by an intermediate frequency amplifier 61 with an RSSI output, demodulated for phase modulation by a digital demodulator 62, frame-synchronized and bit-synchronized, and then reproduced as digital data. It This digital data is subjected to error detection and the like by the burst data combiner 63, and the compressed data on the time axis is returned to its original form, and is returned to the analog voice signal by the voice decoder 64, and is output from the speaker 65. Is output.

On the other hand, when the control data is not the voice data, it is directly input from the control microcomputer 66 to the burst data generator 53 on the transmitting side. On the receiving side, the burst data combiner 63 directly transfers the burst data combiner 63 to the control microcomputer 66.

The control microcomputer 66 and the control circuit 67 control the entire apparatus and each block.
The input keys and the display unit 68 are for the user to input and output information other than voice. Further, the power supply circuit 69 supplies necessary power to each block.

Now, consider the transmission / reception switch 58.
Since this circuit realizes bidirectional communication in a time division manner, it has a switching function of connecting the antenna 59 to the transmission circuit 71 or the reception circuit 70 by the control voltage from the control circuit 67. The circuit is composed of semiconductor switches for fast switching.

FIG. 13 shows an embodiment of the circuit of the transmission / reception switch 58.

In the transmission / reception switch 58, if the antenna 59 is now connected to the transmission circuit 71,
The connection with the receiving circuit 70 is blocked, and the receiving circuit 70
Connection to the transmission circuit 71 is blocked. However, since the transmission / reception frequency is an extremely high frequency of quasi-microwave, a slight signal leakage exists even in the blocking state.

By making good use of this leakage and connecting the antenna 59 in the transmitting state to the receiving circuit 70 side to block the connection with the transmitting circuit 71, the transmission output can be reduced without providing an attenuator circuit. It can be performed.

FIG. 14 shows the switching state of the transmission / reception switch 58, where (a) is the transmitting state and (b) is the receiving state. The attenuation amount shown in the figure is a value that is usually obtained when a semiconductor switch is used in the quasi-microwave band.

FIG. 15 shows a case (a) in which the equalizer circuit of the transmitter is in the transmitting state and in the switching state of FIG. 14 (a), and FIG.
The case of the switching state of (b) is shown as (b). RSS
RSSI output 72 from intermediate frequency amplifier 61 with I output
When it is determined by the control unit 67 that the partner station is far away, the controller 67 determines that the partner station is too close to the switching state of FIG. 14A so that the equalization circuit of FIG. Is (b)
The switching state of FIG. 14B is selected so that the equalization circuit of FIG. As a result, when the switching state of FIG. 14B is selected, it is equivalent to inserting an attenuator of about 24 dB on the transmission side, and the attenuator circuit is removed even if the attenuator circuit is not provided in the transmission circuit. Equivalent functions can be realized with a slight modification in the conventional circuit.

[0049]

As described above, according to the first invention of the present patent, in the digital radio telephone apparatus using the linear modulation system having the low noise amplifier using the transistor in the front end portion of the receiving circuit, the reception is performed. When the means for detecting the input level and the switch for varying the base bias of the low noise amplifier are provided and the means for detecting the reception input level determines that the reception input level is stronger than a certain value, the base bias of the low noise amplifier is provided. And the switch is operated so that the gain of the low noise amplifier is lowered by reducing the signal level to reduce the reception level.

In the second invention of this patent, the FE is used in the transmission circuit.
In a digital radiotelephone device using a linear modulation system having a high frequency output amplifier using T, means for switching the gate bias voltage of the FET of the high frequency output amplifier in accordance with the transmission output signal level is provided, and at the time of low transmission output Reduce current consumption.

In the third invention of this patent, the TDMA-TD is provided with an antenna, a transmitting circuit, a receiving circuit, and a transmission / reception switcher connecting the antenna and the transmitting circuit or the receiving circuit.
In the radio telephone apparatus using the D method, a means for detecting the reception input level is provided, and when the means for detecting the reception input level determines that the reception input level is higher than a certain value, the transmission / reception switcher is transmitting. The transmission level is reduced by operating so as to connect the antenna and the receiving circuit.

As a result, in the first and third inventions, the reception level or the transmission level can be reduced without providing an attenuator circuit and without significantly modifying the conventional circuit. By omitting the attenuator circuit, the number of parts is reduced and the cost is reduced.
The reliability can be increased, the circuit space and the weight can be reduced, and the portability can be improved.

Further, in the second aspect of the invention, the current consumption at the time of low transmission output can be reduced, and in the case of the portable device, the life of the battery as the power source can be extended.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a reception front end circuit of a wireless telephone according to the first invention.

2 is an operation flowchart of the circuit of the embodiment of FIG.

3 is a circuit diagram of an embodiment of a variable gain amplifier used in the reception front end circuit of FIG.

4 is a circuit diagram of another embodiment of a variable gain amplifier used in the reception front end circuit of FIG.

5 is an input / output characteristic of the variable gain amplifier shown in FIGS. 3 and 4. FIG.

6 is a circuit diagram of still another embodiment of a variable gain amplifier used in the reception front end circuit of FIG.

FIG. 7 is a block diagram of an embodiment of a transmission circuit of a wireless telephone according to the second invention.

8 is a gallium arsenide FET used in the embodiment of FIG.
Gain characteristics of the amplifier.

9 is a gallium arsenide FET used in the embodiment of FIG.
Amplifier drain current characteristics.

FIG. 10 is a block diagram of another embodiment of the transmission circuit of the wireless telephone according to the second invention.

11 is an output amplification MIC used in the embodiment of FIG.
FIG.

FIG. 12 is a block diagram of an embodiment of a wireless telephone according to the third invention.

13 is a circuit diagram of an embodiment of a transmission / reception switch used in the embodiment of FIG.

FIG. 14 is a diagram showing a switching state of the transmission / reception switch of FIG.

FIG. 15 is an equalizer circuit of the transmitter in the switching state shown in FIG.

FIG. 16 is a block diagram of a conventional example of a reception front-end circuit of a wireless telephone.

FIG. 17 is a block diagram of another conventional example of the reception front-end circuit of the wireless telephone.

FIG. 18 is a block diagram of a conventional example of a transmission circuit of a wireless telephone.

19 is an output characteristic of each block of the transmission circuit shown in FIG.

FIG. 20 is a block diagram of a conventional example of a cordless telephone based on the TDMA-TDD system.

[Explanation of symbols]

1 Variable Gain Amplifier 2, 82 Radio Frequency Filter 3, 83 First Mixer 4, 84 Intermediate Frequency Filter 5, 85 Local Oscillation Frequency Filter 6 RSSI Level Detection Section 7 Attenuation Selection Judgment Section 8 Attenuation Selection Changeover Switch 9, 10, 24 DC cut coupling capacitor 11, 12 Base bias resistance 13 Emitter resistance 14 Damping inductor 15, 16 Bypass capacitor 17 Base bias variable resistance 18 Variable resistance short-circuit switch 19, 31 Amplification transistor 20, 22, 25, 26 Switching transistor 21, 23 base input resistance 27 to 30, 74, 75 resistance 41, 91, 123 attenuator 42, 55T, 92, 105T up converter mixer 43, 93 output amplifier 44, 94 band pass filter 45, 59, 95, 109 antenna 46 switching circuit 51, 101 microphone 52, 102 voice encoder 53, 103 burst data generator 54, 104 digital modulator 55R, 105R down-converter mixer 56, 106 frequency synthesizer 57, 107 transmission power amplifier 58, 108 transmission / reception switching Receiver 60,110 reception amplifier 61,111 intermediate frequency amplifier with RSSI output 62,112 digital demodulator 63,113 burst data combiner 64,114 voice decoder 65,115 speaker 66,116 control microcomputer 67,117 control circuit 68, 118 Input keys and display unit 69, 119 Power supply circuit 70, 120 Reception circuit 71, 121 Transmission circuit 72-1, 122-1 RSSI output signal 72-2, 122-2 Control signal 73 Diode 9 equalizer attenuator 81 low noise amplifier 86 RF attenuator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Honjo 1-chome, 3-1, Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Factory, a stock company (72) Inventor Toru Mizumoto 3-chome, Asahigaoka, Hino-shi, Tokyo 1 Toshiba Corporation Hino factory inside

Claims (3)

[Claims] 1. A digital radiotelephone device using a linear modulation system, which comprises a low noise amplifier in a front-end part of a receiving circuit, means for detecting a reception input level, and a switch for varying a bias of the low noise amplifier. When the means for detecting the reception input level determines that the reception input level is stronger than a certain value, the bias of the low noise amplifier is changed to turn on the switch so that the gain of the low noise amplifier is lowered. A wireless telephone device characterized by being operated. 2. A digital radiotelephone device using a linear modulation system having a high-frequency output amplifier, characterized in that means is provided for switching the bias voltage of the high-frequency output amplifier in accordance with the transmission output signal level. Telephone device. 3. An antenna, a transmitting circuit, a receiving circuit,
In a radiotelephone device using the TDMA-TDD system, which comprises means for detecting a reception input level and a transmission / reception switcher for connecting the antenna and the transmission circuit or the reception circuit, the means for detecting the reception input level is a reception unit. A radiotelephone device, characterized in that when the input level is judged to be stronger than a certain value, a connection control means for connecting the antenna and the receiving circuit is provided even when the transmission / reception switch is transmitting.