JPH1028066A - Mobile radio equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately suppress the influence of interference waves even in the case of using in an environment with many interference waves by performing the changeover control of a switch corresponding to the signal strength of reception signals. SOLUTION: This equipment is provided with a switch 5 for selection whether or not to operate an attenuator 6 and the switch 3 for switching both the input side and output side of a low noise amplifier 4 so as to selectively form the bypass route of the low noise amplifier 4. Then, corresponding to the signal strength, the attenuator 6 present in the preceding stage of the low noise amplifier 4 is operated or the low noise amplifier 4 is bypassed and changeover 15 performed so as to directly connect a shared device 2 and the next stage. Thus, the attenuation amount of the reception signals is switched in many stages. Thus, in the case that the level of signal waves is high and the level of the interference waves is also high, the level of the interference waves to be inputted to a reception mixer 8 is appropriately lowered corresponding to the level and the influence of the interference waves is appropriately suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio used in an environment where an interfering wave is present, and more particularly, to reducing the influence of the interfering wave.

[0002]

2. Description of the Related Art Mobile radios are often used in an environment where a large number of interfering waves are present, and mixing of the interfering waves causes a decrease in reception quality. Therefore, when the reception level is high and the level of the interfering wave is also high, the gain of the high frequency stage is adjusted to attenuate the input signal level and lower the level of the interfering wave.

A conventional mobile radio having such a function is:
As shown in FIG. 7, an antenna 1 for transmitting and receiving a radio signal
And a duplexer 2 for sharing the antenna 1 for transmission and reception;
A low noise amplifier 4 for amplifying a received signal;
, An attenuator 6 for attenuating the received signal level, a switch 5 for selecting whether or not to operate the attenuator 6, and a receiving bandpass filter 7 for limiting the band of the amplified received signal And a reception mixer 8 for converting a reception signal passed through the reception band-pass filter 7 into a signal of an intermediate frequency, a first local oscillator 11 for outputting a local oscillation signal to the mixer 8, and removing unnecessary components from an output of the mixer 8 Receiving intermediate frequency filter 9, an intermediate frequency variable gain amplifier 10 for adjusting the gain of the converted intermediate frequency signal, and a quadrature demodulator 12 for performing quadrature detection using a local oscillation signal oscillated by a second local oscillator 15. And low-pass filters 13 and 14 for removing unnecessary components of the demodulated I and Q outputs, a signal strength detector 16 for detecting the strength of the converted baseband signal, and a detected signal strength. Adjust the gain between frequency variable gain amplifier 10, and a signal strength determiner 17 for controlling the ON / OFF switch 5.

[0004] A received signal transmitted from a radio base station passes through an antenna 1 and a duplexer 2, is amplified by a low noise amplifier 4, and then passes through a reception bandpass filter 7.
The signal is converted into a reception intermediate frequency by the reception mixer 8. Then, after passing through the reception intermediate frequency filter 9, the gain is adjusted by the intermediate frequency variable gain amplifier 10, and I,
It is converted to a Q demodulated signal. After passing the I and Q signals through low-pass filters 13 and 14 for I and Q demodulation output, the signal strength detector 16 detects the signal strength. The detection result of the signal strength is input to the signal strength determiner 17,
When it determines that the signal strength exceeds a certain threshold level, it operates the attenuator 6 in the preceding stage of the low noise amplifier 4 to switch the attenuation of the received signal.

[0005]

However, in this conventional configuration, the amount of attenuation of the received signal can be switched only in two stages, and it is difficult to secure a large amount of attenuation. Therefore, when the level of the signal wave is large and the level of the interfering wave is large (when there is a strong interfering wave that generates an intermediate frequency (IM) component), the level of the interfering wave input to the reception mixer 8 is reduced. And the signal-to-interference ratio (C / IM ratio) is extremely deteriorated in the reception mixer.

The present invention solves such a conventional problem. Even when the present invention is used in an environment where there are many interfering waves,
An object of the present invention is to provide a mobile wireless device capable of appropriately suppressing the influence of an interfering wave by finely adjusting the amount of attenuation of a received signal according to the signal strength.

[0007]

Therefore, in the mobile radio of the present invention, a first switch for selecting / non-selecting the operation of the attenuator located in front of the low noise amplifier, and a path for bypassing the low noise amplifier. And a second switch for selecting / non-selecting is provided, and the determiner is configured to perform switching control of the first switch and the second switch according to the signal strength of the received signal.

[0008] Therefore, by operating the attenuator in the previous stage of the low noise amplifier or by switching the duplexer to be directly connected to the next stage by bypassing the low noise amplifier in accordance with the signal strength, Switching of the amount of attenuation of the received signal can be performed in multiple stages. Therefore, when the level of the signal wave is large and the level of the interference wave is also large, the level of the interference wave input to the reception mixer can be appropriately reduced according to the level, and the influence of the interference wave can be suppressed appropriately. it can.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a low-noise amplifier for amplifying a received signal, an attenuator located in front of the low-noise amplifier, and detecting the signal strength of the received signal. A first switch for selecting / non-selecting the operation of the attenuator in a mobile wireless device including a detector and a determiner for determining a detected signal strength and performing switching control of an amount of attenuation of a received signal; A second switch for selecting / non-selecting a path bypassing the low-noise amplifier, wherein the determiner performs switching control of the first switch and the second switch according to the signal strength of the received signal. In addition to switching the amount of attenuation of the received signal depending on whether or not to operate the attenuator located in front of the low noise amplifier, the low noise amplifier is bypassed, and the duplexer and the next stage are switched. Direct connection with By selecting the route that can be performed switching of attenuation.

According to a second aspect of the present invention, when the detected signal strength is larger than the threshold level A, the decision unit selects the operation of the attenuator by the first switch, and determines the detected signal strength. Is larger than the threshold level B, a path for bypassing the low-noise amplifier is selected by the second switch, so that the attenuation can be switched to at least three or more stages.

According to a third aspect of the present invention, the relationship between the threshold level A and the threshold level B is defined as A <B
When the signal strength of the received signal increases, first, the operation of the attenuator is selected by the first switch, and when the signal strength of the received signal further increases, the low noise amplifier is set by the second switch. A path to bypass is selected.

According to a fourth aspect of the present invention, the relationship between the threshold level A and the threshold level B is expressed as A ≧ B
When the signal strength of the received signal increases, first, a path that bypasses the low noise amplifier is selected by the second switch, and when the signal strength of the received signal further increases, the path is attenuated by the first switch. Vessel operation is selected.

According to a fifth aspect of the present invention, the second switch is formed by a switch having a two-circuit configuration for switching both the input side and the output side of the low noise amplifier. When the path bypassing the amplifier is selected, the low noise amplifier is electrically disconnected from the receiving circuit.

According to a sixth aspect of the present invention, when the second switch is formed by a single-pole switch, and when the second switch selects a path bypassing the low-noise amplifier, the low-noise amplifier operates in conjunction therewith. A switch for turning off the power supply is provided. Passage loss can be reduced as compared with a case where a switch having a two-circuit configuration is used as the second switch.

According to a seventh aspect of the present invention, in the second switch having a two-circuit configuration, an attenuator is provided between the input side switch and the output side switch of the low noise amplifier, and the low noise amplifier is bypassed. It is possible to increase the amount of attenuation when a path to be selected is selected.

According to an eighth aspect of the present invention, in the second switch, a plurality of selectable attenuators are provided between the input side switch and the output side switch of the low noise amplifier, and the decision unit comprises:
The configuration is such that the selection of a plurality of attenuators is controlled in accordance with the signal strength of the received signal, and the amount of attenuation of the received signal can be switched in more stages.

According to a ninth aspect of the present invention, a plurality of attenuators whose operation is selected by the first switch are provided, and the determiner controls the selection of the plurality of attenuators according to the signal strength of the received signal. With such a configuration, the amount of attenuation of the received signal can be switched in more stages.

According to a tenth aspect of the present invention, when the signal strength of the received signal tends to increase, the determinator determines that the received signal has a larger signal strength than when the signal strength of the received signal tends to decrease. It is configured to switch the amount of attenuation, so that the judgment level in the judgment unit can have a hysteresis characteristic, and even when the signal strength fluctuates near the threshold level, the amount of attenuation is frequently switched. The occurrence can be prevented.

[0019] According to an eleventh aspect of the present invention, when the signal strength of the received signal tends to increase, the determiner uses the first switch when the detected signal strength exceeds the threshold level A1. When the operation of the attenuator is selected and the signal strength of the received signal is decreasing, the operation of the attenuator is performed by the first switch when the signal strength falls below the threshold level A2 (A2 <A1). When the signal strength of the received signal is increasing and the detected signal strength exceeds the threshold level B1, a path for bypassing the low-noise amplifier by the second switch is selected. When the signal strength of the received signal is decreasing, the signal strength becomes the threshold level B2 (B2 <B
1) When the value falls below, the path for bypassing the low-noise amplifier is deselected by the second switch, and the determination is made by setting the relationship of A2 <A1, B2 <B1. The level can have a hysteresis characteristic.

According to a twelfth aspect of the present invention, the relationship between the threshold level A1 and the threshold level B1 is
A1 <B1 is set, and the selection / non-selection of the operation of the attenuator by the first switch is performed when the signal strength of the received signal is low, and the second operation is performed when the signal strength of the received signal is high. Selection / non-selection of the path bypassing the low-noise amplifier is performed by the switch.

According to a thirteenth aspect of the present invention, the relationship between the threshold level A1 and the threshold level B1 is
A1 ≧ B1 is set, and when the signal strength of the received signal is low, selection / non-selection of the path for bypassing the low-noise amplifier by the second switch is performed, and when the signal strength of the received signal is high. , The selection / non-selection of the operation of the attenuator by the first switch is performed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) As shown in FIG. 1, a mobile radio device according to a first embodiment includes an antenna 1, a duplexer 2, a low-noise amplifier 4 for amplifying a received signal, and a low-noise amplifier. An attenuator 6 located before the noise amplifier 4, a switch 5 for selecting whether or not to operate the attenuator 6, and a low noise amplifier 4 for selectively forming a bypass path of the low noise amplifier 4;
A switch 3 for switching both the input side and the output side of the
A reception bandpass filter 7, a reception mixer 8 for converting a reception signal into an intermediate frequency signal, a first local oscillator 11 for outputting a local oscillation signal to the mixer 8, and a reception intermediate for removing unnecessary components from the output of the mixer 8 A frequency filter 9, an intermediate frequency variable gain amplifier 10, a second local oscillator 15, a quadrature demodulator 12 for performing quadrature detection using the same,
Low-pass filters 13 and 14 for removing unnecessary components of the Q output, a signal strength detector 16 for detecting the strength of the converted baseband signal, and a gain of the intermediate frequency variable gain amplifier 10 based on the detected signal strength. And a signal strength determiner 17 for controlling ON / OFF of the switch 5 and the switch 3.

After the received signal transmitted from the radio base station has passed through the antenna 1 and the duplexer 2, if the switch 3 has selected a path passing through the low-noise amplifier 4, the received signal is amplified by the low-noise amplifier 4. The amplified reception signal passes through a reception band-pass filter 7 and is converted by a reception mixer 8 into a reception intermediate frequency. Then, after passing through the reception intermediate frequency filter 9, the gain is adjusted by the intermediate frequency variable gain amplifier 10 and converted into I and Q demodulated signals by the quadrature demodulator 12. After the I and Q signals have passed through low-pass filters 13 and 14 for I and Q demodulation outputs, their signal strengths are measured by a signal strength detector.
The signal detected by the signal strength detector 16 is input to the signal strength determiner 17.

When the signal level exceeds the threshold level A, the signal strength determiner 17 activates the attenuator 6 in the stage preceding the low noise amplifier 4. When a stronger signal wave is input from the antenna 1 and the signal level exceeds the threshold level B, the signal strength determiner 17 switches the low noise amplifier 4 to the switch 3.
Is operated to further increase the amount of attenuation of the received signal and lower the level of the signal wave input to the reception mixer 8.

By thus lowering the level of the signal wave, the level of the interfering wave input to the reception mixer is similarly reduced. Therefore, by setting in this way, when the level of the signal wave is large and the level of the interference wave is also large,
Without increasing the output intercept point of the reception mixer, the IM component generated in the reception mixer can be reduced, and the signal-to-interference ratio can be reduced.

As described above, the mobile radio of the first embodiment switches the amount of attenuation so that the gain of the high-frequency stage of the received signal becomes 3
Can be changed in stages.

The threshold level A and the threshold level B can be arbitrarily set in consideration of the amount of attenuation of the attenuator 6, the gain of the low noise amplifier 4, and the required reception IM characteristics. In addition, the relationship is not only A ≦ B, but A ≧ B, that is, when the reception level rises, the bypass by the switch 3 is executed first, and when the reception level further rises, the switch 3 May select a path via the low-noise amplifier 4 and the switch 5 is switched to operate the attenuator 6.

(Second Embodiment) As shown in FIG. 2, the receiver of the second embodiment has a single-pole switch 19 for selectively forming a bypass path of the low-noise amplifier 4 and an interlocked switch. And a switch 18 for turning on / off the power supply of the low noise amplifier 4. Other configurations are the same as those of the first embodiment (FIG. 1).

In this receiver, when the switch 19 is turned on to select a path for bypassing the low noise amplifier 4, the switch 18 simultaneously turns off the power supply of the low noise amplifier 4.
As a result, the input / output impedance of the low-noise amplifier 4 becomes high, so that the switch 19 for selecting a path for bypassing the low-noise amplifier 4 is turned ON / OFF with a single pole.
Can be a switch. This has an advantage that the passage loss is smaller than that of the switch 3 having a two-circuit configuration for switching both the input side and the output side of the low noise amplifier 4 shown in the first embodiment. This is NF (noise fact)
er) In addition to the above advantages, the gain of the low noise amplifier 4 may be slightly reduced, so that the current consumption can be reduced.

(Third Embodiment) The receiver according to the third embodiment includes an attenuator 26 in a path of a switch 20 that bypasses the low noise amplifier 4, as shown in FIG.
Other configurations are the same as those of the first embodiment (FIG. 1).

The attenuator 26 is composed of three resistors in a π-type, and an appropriate amount of attenuation can be obtained by appropriately setting the resistance value of each resistor. The attenuator 26 may have a configuration other than this configuration (for example, a T-type attenuator).

As described above, by inserting the attenuator in the path for bypassing the low-noise amplifier 4, when a stronger signal wave and an interfering wave are input, the attenuation can be further increased.

(Fourth Embodiment) In a receiver according to a fourth embodiment, as shown in FIG. 4, a plurality of attenuators 24 and 25 are arranged in front of a low noise amplifier 4 to switch between them. Switch 23
And a plurality of attenuators 26, in a path of a switch 22 that bypasses the low-noise amplifier 4.
27 are arranged so that they can be selected. Other configurations are the same as those of the first embodiment (FIG. 1).

Changeover switches 23 for selecting the attenuators 24 and 25,
The changeover switches for selecting the attenuators 26 and 27 have the same number of switching terminals as the number of attenuators, and select an appropriate attenuator according to the received signal strength.

At this time, each of the attenuators 24 and 25 selected by the changeover switch 23 has the threshold levels A1 and A
2, ‥, An (n is the number of attenuators),
Respectively correspond to the threshold levels B1, B2, ‥, Bn (n is the number of attenuators), and A1 <A2 <‥ <An and B1 <B2 <‥ <Bn And each of the attenuators 24 and 25 has a relationship of An <B1.
And the attenuators 26, 27 are set, the threshold levels A1, A
The attenuators corresponding to 2, ‥, An, B1, B2, ‥, and Bn are sequentially selected, and the attenuation can be switched in multiple stages.

In this case, the attenuators 24 and 25 and the attenuators 26 and 27 can be set so that A1 ≧ Bn.

By providing a plurality of attenuators in this way, the amount of attenuation of the received signal can be switched in more stages, and more fine switching control of the amount of attenuation is possible.

(Fifth Embodiment) In a receiver according to a fifth embodiment, as shown in FIG. 5, the signal strength judgment circuit 21 controls the ON / OFF operation of the switch 5 and the switch 3 in the direction of the state change. And a hysteresis circuit 27 that differs depending on the condition. Other configurations are the same as those of the first embodiment (FIG. 1).

Since the signal strength determiner 21 has a hysteresis characteristic, switch switching does not occur frequently even if the signal strength fluctuates near the threshold level.

FIG. 6 shows an example in which the signal strength judgment unit 21 has a hysteresis characteristic in the judgment. The horizontal axis indicates the input level of the signal, and the input level increases as going to the right. The vertical axis indicates the amount of attenuation, and the lower the amount, the greater the amount of attenuation.

When the received signal level changes from a low level to a high level, when the signal strength exceeds -92.5 dBm at the antenna end, the switch 5
Is turned on in the first stage. This switching increases the amount of attenuation to 5 dB. Next, when the signal strength exceeds -81 dBm at the antenna end, a second-stage switching for bypassing the low-noise amplifier 4 is performed. By this switching, the attenuation increases to 17 dB.

On the other hand, when the signal changes from a larger signal to a smaller signal, the signal strength determiner 21 switches the first stage when the signal strength becomes −96.5 dBm or less at the antenna end. The second stage switching is performed when the signal strength is -8.
It is performed when it becomes 4 dBm or less.

By setting as above, in the first stage, 4d between -96.5 dBm and -92.5 dBm is set.
B, 3 between -84 dBm and -81 dBm in the second stage
It can have dB of hysteresis.

By doing so, the signal strength becomes close to the threshold level (from -96.5 dBm to -92.5 dBm in the first stage, from -84 dBm to -8 in the second stage).
Even if it fluctuates by 1 dBm), gain switching does not occur frequently, and good reception characteristics can be maintained.

[0046]

As is apparent from the above description, the mobile radio of the present invention prevents deterioration of the signal-to-interference ratio by switching the attenuation of the received signal in multiple stages according to the signal strength. The effect of the interference wave can be suppressed.

Further, by performing the switching of the attenuation with a hysteresis characteristic, it is possible to avoid the frequent switching of the attenuation even when the signal strength fluctuates near the threshold level. Therefore, there is an effect that control of signal strength detection does not require high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a mobile wireless device according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing a configuration of a mobile wireless device according to a second embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a mobile wireless device according to a third embodiment of the present invention;

FIG. 4 is a block diagram showing a configuration of a mobile wireless device according to a fourth embodiment of the present invention;

FIG. 5 is a block diagram illustrating a configuration of a mobile wireless device according to a fifth embodiment of the present invention;

FIG. 6 is a diagram showing a hysteresis characteristic of a signal strength determiner of a mobile wireless device according to a fifth embodiment;

FIG. 7 is a block diagram illustrating a configuration of a conventional mobile wireless device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Antenna 2 Duplexer 3, 20, 22 Switch for selecting bypass path of low noise amplifier 4 Low noise amplifier 5, 23 Switch 6, 24, 25, 26, 27 Attenuator 7 Receive bandpass filter 8 Receive mixer 9 Receive intermediate frequency Filter 10 Intermediate frequency variable gain amplifier 11 First local oscillator 12 Quadrature demodulator 13, 14 Low-pass filter 15 Second local oscillator 16 Signal strength detector 17, 21 Signal strength determiner 18 Power ON / OFF switch for low noise amplifier 19 Single-pole switch for bypass path selection of low-noise amplifier 28 Hysteresis circuit

Claims (13)

[Claims] A low-noise amplifier for amplifying a received signal, an attenuator positioned upstream of the low-noise amplifier, a detector for detecting the signal strength of the received signal, and determining the detected signal strength. A mobile wireless device comprising a determiner for performing switching control of a received signal attenuation amount, wherein a first switch for selecting / non-selecting an operation of the attenuator and a path for bypassing the low noise amplifier are selected / non-selected. And a second switch that performs the first switch and the second switch according to the signal strength of the received signal.
A mobile radio device for controlling the switching of the switches. 2. The method according to claim 1, wherein when the detected signal strength is greater than a threshold level A, the determiner selects the operation of the attenuator by the first switch, and the detected signal strength becomes a threshold. 2. The mobile radio according to claim 1, wherein when the level is higher than a hold level B, a path that bypasses the low noise amplifier is selected by the second switch. 3. The mobile wireless device according to claim 2, wherein the relationship between the threshold level A and the threshold level B is A <B. 4. The mobile wireless device according to claim 2, wherein the relationship between the threshold level A and the threshold level B is A ≧ B. 5. The mobile wireless device according to claim 1, wherein the second switch is a switch having a two-circuit configuration for switching both an input side and an output side of the low noise amplifier. 6. The second switch is a single-pole switch, and when the second switch selects a path that bypasses the low-noise amplifier, powers off the low-noise amplifier in conjunction with the selection. The mobile radio device according to claim 1, further comprising a switch for setting the mobile radio device. 7. The mobile radio according to claim 5, wherein the second switch includes an attenuator between an input side switch and an output side switch of the low noise amplifier. 8. The low-noise amplifier includes a plurality of attenuators that can be selected between input-side and output-side switches of the low-noise amplifier, wherein the determiner is responsive to a signal strength of a received signal. The mobile radio according to claim 7, wherein selection of the plurality of attenuators is controlled. 9. An attenuator whose operation is selected by the first switch, wherein the determiner controls the selection of the plurality of attenuators according to the signal strength of a received signal. The mobile wireless device according to claim 1. 10. The receiving device according to claim 1, wherein the determining unit switches the attenuation of the received signal when the signal strength of the received signal is increasing, when the signal strength of the received signal is increasing. The mobile wireless device according to claim 1, wherein: 11. The attenuator according to claim 1, wherein, when the signal strength of the received signal is increasing, when the detected signal strength exceeds a threshold level A1, the first switch switches the attenuator. When the operation is selected and the signal strength of the received signal is decreasing, the operation of the attenuator is performed by the first switch when the signal strength falls below a threshold level A2 (A2 <A1). When the signal strength of the received signal is increasing, the detected signal strength is set to a threshold level B.
When the signal strength exceeds 1, a path bypassing the low-noise amplifier is selected by the second switch, and when the signal strength of the received signal tends to decrease, the signal strength becomes the threshold level B2 (B2 <B1). )
The mobile radio according to claim 10, wherein a path bypassing the low noise amplifier is not selected by the second switch. 12. The mobile radio device according to claim 11, wherein the relationship between the threshold level A1 and the threshold level B1 is A1 <B1. 13. The mobile radio device according to claim 11, wherein the relationship between the threshold level A1 and the threshold level B1 is A1 ≧ B1.