JP2001086172A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a receiver adopting the CDMA system or the like to have the best reception sensitivity and adjacent channel selectivity at all times under every radio wave environment independently of presence of an adjacent channel disturbing wave. SOLUTION: The receiver receives and demodulates a received wave including a desired wave and a disturbing wave of adjacent channels, and is provided with a 1st variable gain amplifier, a processing circuit that applies prescribed signal processing to an output signal from the 1st variable gain amplifier, a filter that suppresses the disturbing wave component from the output signal of the processing circuit to extract a desired wave component, a 2nd variable gain amplifier that amplifies an output signal of the filter, a 1st detector that detects an output signal level of the 2nd variable gain amplifier, a 2nd detector that the detects a level of an input signal-output signal of the processing circuit, and a gain control section 16 that dynamically controls a share of the gain to the 1st and 2nd variable gain amplifies so that signal level at the post-stage of the 2nd variable gain amplifier on the basis of the result of detection of the 1st detector is constant and the output of the processing circuit is not saturated on the basis of the result of detection of the 2nd detector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a receiver having both high adjacent channel selectivity and sensitivity. The receiver according to the present invention is particularly effective when applied to a CDMA receiver using a code division multiple access system (hereinafter abbreviated as CDMA) that performs automatic gain control (hereinafter abbreviated as AGC).

[0002]

2. Description of the Related Art FIG. 10 shows a schematic configuration of a conventional CDMA receiver. In FIG. 10, an RF signal (radio frequency signal) received by an antenna 31 is input to a radio reception unit 32. The wireless receiving unit 32 is connected to the wireless unit 321 and A
It comprises a GC unit 322. The radio unit 321 receives the R
After low-noise amplification of the F signal to suppress components other than the desired frequency band components, the frequency is converted to an IF signal in an IF (intermediate frequency) band, and then the band other than the desired frequency band is further suppressed by a band-pass filter (BPF). , And a circuit for amplifying and outputting with a variable gain amplifier. AGC section 322 performs quadrature demodulation of the IF signal with a quadrature demodulator to obtain an I channel and a Q signal.
It is a circuit that demodulates to the baseband signal of the channel,
The radio unit 3 controls the signal amplitude in the baseband unit to be constant.
Automatic gain control (AG) of the variable gain amplifier
C) Yes.

[0003] The baseband signal demodulated by the receiving section 32 is then sent to a RAKE receiving section 33. RAK
The E receiving unit 33 has a despread demodulator, and the RAKE receiving unit 33 despreads the input baseband signal with a predetermined spreading code, and performs RAKE reception. The signal after the RAKE reception is demodulated by the demodulation unit 34.

Here, the radio waves received by the antenna 31 include not only a desired wave carrying data to be received but also a radio wave of a channel adjacent to the frequency band of the desired wave (hereinafter, adjacent channel interference wave). Is included.
In a CDMA receiver, even if suppression is performed by a band-pass filter (BPF) or the like provided in a wireless reception unit, it is still allowable that the level of an adjacent channel interference wave is higher than the level of a desired wave. . This is C
In a DMA receiver, there is a (de) spread gain,
This is because a desired signal can be demodulated even when the signal-to-noise ratio falls below 1. Further, by synthesizing (maximum ratio synthesizing) the signals despread by each finger, a delayed wave can be synthesized, and the signal-to-noise ratio can be further improved.

The AGC operation of the conventional CDMA receiver will be described below with reference to FIG. FIG. 11 shows a conventional CDMA.
FIG. 3 is a configuration diagram of a wireless reception unit 32 of the receiver. The received wave amplified by the low noise amplifier 1 is transmitted to a bandpass filter 2.
In this case, unnecessary radio waves outside the reception band are reduced.
Is mixed with the local oscillation signal generated by the local oscillator 4 and converted into an IF signal (intermediate frequency signal). This IF signal is subjected to bandpass filter 5 to reduce interference wave components such as adjacent channels.

[0006] The IF signal from which the interference wave component has been reduced is then amplified in a variable gain amplifier 6 and then output to a quadrature demodulator 7.
Is input to In the quadrature demodulator 7, the IF signal is mixed with the signal from the second local oscillator 8, and
It is converted into a baseband signal for each of the Q channels. In this case, the frequency band of the desired wave in the baseband signal is frequency-shifted to near DC, and the bandwidth is halved.

[0007] In the baseband signal of the I channel, out-of-band components including adjacent channel interference waves are suppressed in the low-pass filter 9. The baseband signal whose adjacent channel interference wave is reduced by the low-pass filter 9 is supplied to the amplifier 1.
After being amplified to an appropriate level at 0 ′, it is input to the A / D converter 11. The baseband signal is converted into a digital signal in the A / D converter 11 and input to the amplitude detector 15. On the other hand, the baseband signal of the Q channel is also a low-pass filter 12 and an amplifier 1 like the I channel.
3 ′, converted into a digital signal through the A / D converter 14,
Input to the amplitude detector 15.

The amplitude detector 15 synthesizes the baseband signals of the I channel and the Q channel, and if the IQ amplitude is larger than the set value, the gain controller 16 'reduces the gain of the variable gain amplifier 6 of the radio unit. A control signal (gain increase / decrease signal) is generated, and a control signal is generated so as to increase the gain if the IQ amplitude is smaller than the set value. The gain control section 16 ′ changes a control signal (gain control signal) supplied to the variable gain amplifier 6 based on the control signal from the amplitude detection section 15. By this operation, the A / D converters 11 and 14
, The amplitude of the baseband signal input is kept constant. Here, the amplitude may be a maximum value, an average value, or an effective value of the amplitude.

Next, FIGS. 12 and 13 show a level diagram configuration in the CDMA receiver. Here, the horizontal axis is C
Each circuit arranged along a signal path through which a received signal flows in the DMA receiver is shown, and the vertical axis represents the output signal level of each circuit. In the figure, a solid line S connecting black symbols represents a signal level of a desired wave, and a dotted line N connecting black symbols represents a signal level of an adjacent channel interference wave. In addition, the symbol ■ indicates the output saturation level of each circuit. Normally, when an input signal having a level exceeding the output saturation level is input to each circuit, the output signal has distortion.

In the following description, for simplicity,
Although only the circuit on the I channel side is given as the circuit in the base band, the same applies to the Q channel.

Now, the RAKE receiving section 33 at the subsequent stage of the radio receiving section 32 performs AGC control so that the output of the baseband amplifier 10 ', that is, the level at the input section of the A / D converter 11 is -20 dBm. Is assumed to have been applied.

First, as shown in FIG.
Reception level of the desired wave at (for example, -100 dBm)
Approx. 1 from the reception level of the interference wave (for example, -85 dBm)
AGC control in the case of 5 dB lower will be described.

Both the desired wave and the interference wave received by the antenna 31 are input to the bandpass filter 5 via the low noise amplifier 1, the filter 2, and the mixer 3. Here, the disturbing wave is greatly attenuated (about 30 dB) by the band-pass filter 5 whose pass band is set to the desired wave (however, the level is still higher than the 20 dB desired wave). The interference wave and the desired wave attenuated by the band-pass filter 5 are further input to the IF variable gain amplifier 6, and are input to the baseband amplifiers 10 ′ and 13 ′ via the quadrature demodulator 7 and the low-pass filters 9 and 12. You.

The AGC control is performed in the baseband 10 ', 1
This is realized by controlling the gain of the IF variable gain amplifier 6 based on the output level 3 ′. That is, FIG.
2, the slope of the graph between the bandpass filter 5 and the IF variable gain amplifier 6 fluctuates, and the baseband amplifier 10 ′,
The level at 13 'is controlled to be -20 dBm (in this case, the level of the desired wave is -20 dBm).
m).

Next, as shown in FIG.
Reception level of the desired wave at (for example, -100 dBm)
50 from the reception level of the interference wave (for example, -50 dBm)
AGC control in the case of a low dB will be described.

The desired wave and the interference wave received by the antenna 31 are both input to the band-pass filter 5 via the low noise amplifier 1, the filter 2, and the mixer 3. Here, the disturbing wave is greatly attenuated (about 30 dB) by the bandpass filter 5 whose pass band is set to the desired wave. The interfering wave and the desired wave attenuated by the band-pass filter 5 are further input to an IF variable gain amplifier 6, and output to a quadrature demodulator 7,
The signals are input to baseband amplifiers 10 ′ and 13 ′ via low-pass filters 9 and 12.

The AGC control is performed in the baseband 10 ', 1
This is realized by controlling the gain of the IF variable gain amplifier 6 based on the output level 3 ′. That is, FIG.
3, the slope of the graph between the bandpass filter 5 and the IF variable gain amplifier 6 fluctuates, and the baseband amplifier 10 ′,
The level at 13 'is controlled to be -20 dBm (in this case, it can be considered that the level of the interference wave is controlled to be -20 dBm).

[0018]

Here, the following can be seen by further observing FIGS. 12 and 13 showing the level diagram.

1. When the input level of the interfering wave is close to the input level of the desired wave (or lower than the level of the desired wave) as shown in FIG. 12, the level of the output signal of the baseband amplifiers 10 'and 13' becomes the level of the desired wave. Is higher, AG
The C control also strongly depends on the output level of the desired wave. Then, a signal of a high level that does not reach the saturation point is input to the quadrature demodulator 7, and it can be seen that ideal gain distribution is realized.

2. On the other hand, when the reception level of the interference wave is higher than the level of the desired wave as shown in FIG. 13, the level of the output signal of the baseband amplifiers 10 'and 13' is higher than that of the interference wave, and the AGC control is performed. It is strongly dependent on the output level of the jammer. Then, in the quadrature demodulator 7, the saturation point has been reached, and the desired wave and the interfering wave are both distorted.

As described above, in the conventional AGC control, the quadrature demodulator 7 sets the saturation point in the quadrature demodulator 7 according to the relationship between the levels of the output signals of the baseband amplifiers 10 'and 13' (the level ratio between the desired wave and the interference wave). May be reached.

Here, in order to avoid the saturation, it is conceivable to set the gain of the baseband amplifiers 10 'and 13' to be high. However, in the preceding stage in which the thermal noise due to the characteristics of the circuit elements is small, the gain is further increased. Although amplification can be performed, amplification is always performed at a high gain in the subsequent stage. Depending on the level ratio between the desired signal and the interfering signal in the input signal, an ideal gain distribution is not obtained, and thermal noise and the like are not obtained. Will be increased.

Further, the IF variable gain amplifier 6 and the baseband gain amplifier 1 are simply associated with the level of the input signal.
The gains of 0 ′ and 13 ′ are respectively stored, and the IF variable gain amplifier 6 and the baseband gain amplifiers 10 ′ and 13 ′ are stored in accordance with the input levels according to the stored gains.
May be changed, but even if the input level is the same, the level of the signal input to the quadrature demodulator 7 changes depending on the ratio between the level of the desired wave and the level of the interfering wave (bandpass). The amount of attenuation in the filter 5 differs between the desired wave and the interfering wave), the saturation point may be reached in the quadrature demodulator 7, or the gain distribution may not be ideal. Similarly, the output levels of the baseband amplifiers 10 'and 13' cannot be made constant due to the difference in attenuation between the desired wave and the interference wave in the low-pass filters 9 and 12, and the problem is solved. Absent.

[0024] The present invention has been made in view of the above-mentioned problems, and always performs amplification with an optimum gain distribution irrespective of the level of an interfering wave and a desired wave included in a received signal, thereby obtaining a signal pair. The main purpose is to obtain a signal with a good noise ratio. It is another object of the present invention to prevent an operating point of a mixer or the like constituting a quadrature demodulator from reaching a saturation region.

[0025]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a receiver according to the present invention receives and demodulates a reception wave including a desired wave of a target channel and an interference wave of an adjacent channel. A first variable gain amplifier for amplifying a received signal, a processing circuit for performing predetermined signal processing on a signal output from the first variable gain amplifier, and a signal output from the processing circuit A filter for suppressing a disturbing wave component to extract a desired wave component, a second variable gain amplifier for amplifying a signal output from the filter, and a level for a signal output from the second variable gain amplifier. A first detector for detecting, and a second detector for detecting a level of a signal input to or output from the processing circuit.
And the signal level at the subsequent stage of the second variable gain amplifier is made constant based on the detection result of the first detector, and the output of the processing circuit is saturated based on the detection result of the second detector. And a gain controller for dynamically controlling the gain distribution to the first and second variable amplifiers. In the above-described receiver, when the reception electric field level of the reception wave increases, the gain of the first variable gain amplifier is reduced, and the reception signal is distorted by preventing the saturation reduction in the processing circuit at the subsequent stage. Prevent that.
If the received electric field level of the received wave is small, the gain of the first variable gain amplifier is increased to prevent an increase in noise figure due to a decrease in the overall gain from the antenna to the processing circuit. In addition to this, the gain distribution of the first and second variable gain amplifiers is dynamically performed in accordance with the ratio between the desired wave and the interfering wave included in the received wave. Specifically, in the receiver according to the present invention, when the level of the interfering wave included in the received wave is higher than the desired wave level, the gain of the first variable gain amplifier is reduced to thereby reduce the processing circuit. , The saturation level of the filter is reduced, and the attenuation characteristic of the filter sufficiently contributes to the elimination of adjacent channel interference waves. In this case, the gain of the second variable gain amplifier is increased to obtain a constant output. To do. On the other hand, when the interference wave level is lower than the desired wave level or when there is no interference wave, the input level of the processing circuit is increased by increasing the gain of the first variable gain amplifier, and the noise of the entire receiver is increased. The index is reduced to improve the receiving sensitivity, and in this case, the gain of the second variable gain amplifier is reduced to obtain a constant output. By such dynamic allocation of gain, it is possible to always obtain the best adjacent channel selectivity and reception sensitivity under all radio wave conditions.

The gain control section detects an input signal to the processing circuit by the second detector, and sets the input signal to the processing circuit to a predetermined level which does not exceed a signal level that saturates the processing circuit. By keeping it at the input signal level, or
By detecting the output signal of the processing circuit with the second detector and maintaining the level of the output signal of the processing circuit at a predetermined output signal level not exceeding the saturation output level of the processing circuit, the processing circuit It can be configured not to be saturated.

The second detector may be arranged such that the level of an input signal to the processing circuit does not exceed an “excessive” level at which the processing circuit is saturated or a level at which the output of the processing circuit is saturated. It is configured to output a detection signal indicating whether the level is “appropriate” near that level, or the level of the output signal to the processing circuit is “excessive” level exceeding the saturation output level of the processing circuit, or The gain control section is configured to output a detection signal indicating whether the level is “appropriate” or less than the saturation output level, and the gain control section is configured to output the detection signal indicating “excess” from the second detector. It can be configured such that the gain of the first variable gain amplifier is decreased and the gain of the second variable gain amplifier is increased.

The receiver is a code division multiple access type CD.
An MA receiver, wherein the first variable gain amplifier amplifies a received signal in an intermediate frequency band, and the processing circuit includes a base circuit for converting an intermediate frequency band signal output from the first variable gain amplifier into a base signal. It can be configured to be a demodulator for demodulating a signal in a band. The demodulator is a quadrature demodulator for demodulating the I channel and the Q channel. The filter and the second variable gain amplifier are provided for the I channel and the Q channel, respectively. Can combine the baseband signals of the I channel and the Q channel and detect the level of the combined signal.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a wireless receiving unit of a receiver as one embodiment of the present invention. In this embodiment, the present invention is applied to a CDMA receiver.
The overall configuration of the CDMA receiver is the same as that shown in FIG. 1 is a low-noise amplifier for amplifying a received high-frequency signal. 2 is a filter for suppressing unnecessary interference waves outside the receiving band such as an image frequency, and 3 is a mixer (frequency converter) for mixing the received signal and the local oscillation signal generated by the local oscillator 4 and converting the signal into an IF signal of an intermediate frequency. It is. Reference numeral 5 denotes a bandpass filter, which suppresses unnecessary frequency components such as adjacent channels. Reference numeral 6 denotes a variable gain amplifier. The IF signal amplified by the variable gain amplifier 6 is input to a quadrature demodulator 7.

The quadrature demodulator 7 mixes the IF signal and the signal generated by the second local oscillator 8 and converts them into baseband signals for the respective I and Q channels. This quadrature demodulator 7 has a saturation output level of −20 dBm. If a signal having a level exceeding this level is output, the output signal waveform will be distorted.

The l-channel baseband signal is then subjected to a low-pass filter 9 to reduce unnecessary high frequency band components (adjacent channel interference wave components). Thereafter, the signal is amplified by the variable gain amplifier 10 to a level required for the input of the A / D converter 11. Subsequently, the I-channel base band signal is converted into a digital signal in the A / D converter 11 and input to the amplitude detector 15. Similarly, the baseband signal Q is applied to the low-pass filter 1.
2. The signal is input to the amplitude detector 15 via the variable gain amplifier 13 and the A / D converter 14, and is input to a RAKE combining unit (not shown) at a subsequent stage.

Variable gain amplifiers 10 and 1 in baseband section
In both cases, the gain is changed by the same gain control signal supplied from the gain control unit 16. In the amplitude detector 15, when the amplitude of the signal obtained by synthesizing the baseband signals of the I channel and the Q channel is larger than the set value of the predetermined width, the gain of the signal path (variable gain amplifier 6)
, And a gain “decrease” signal is output to the gain control unit 16 so as to reduce the combined amplitude of the baseband signal. A gain “increase” signal is output to the gain control unit 16 to increase the gain. If the combined signal is within the range of the set value, a gain “maintenance” signal is output.

Reference numeral 17 denotes a level detector for detecting the output level of the variable gain amplifier 6 in the IF stage. FIG. 4 shows a detailed configuration of the level detector 17. An output signal (detector input) from the variable gain amplifier 6 is input to a detector 31, and a detection signal level demodulated by the detector 31 is compared with a reference level generated by a reference level generator 33 by a comparator 32. Is done. The comparator 32 outputs a level detection signal indicating “excess” when the detected signal level exceeds the reference level and a level detection signal indicating “appropriate” when the detected signal level is equal to or lower than the reference level, to the gain control unit 16. You.

The gain controller 16 increases or decreases the gain control signal for controlling the gains of the variable gain amplifiers 6, 10, and 13 according to the gain increase / decrease signal from the amplitude detector 1. However, if
When the level detector 17 of the stage detects that a signal of an output level or higher at which the quadrature modulator 7 is saturated is output from the variable gain amplifier 6 (that is, input to the quadrature demodulator 7), the IF Lower the gain of the stage variable gain amplifier 6,
The variable gain amplifiers 10 and 13 corresponding to the base band portion
The gain control unit 16 adjusts the gain control signal so as to increase the gain.

FIG. 2 shows a schematic configuration of the gain control section 16. As shown in the figure, a control unit 21 to which a gain increase / decrease signal from the amplitude detection unit 15 and a level detection signal from the level detection unit 17 are input, and a gain control signal supplied to the variable gain amplifier 6 at the IF stage are D / D A to convert to analog signal D
/ A converter 22 and baseband stage variable gain amplifier 1
A D / A converter 23, which converts the gain control signals supplied to 0 and 13 into analog signals by D / A conversion, and a D / A converter 2
And a register 24 for storing the current values of 2 and 23.

In the gain control section 16, the control section 201
Sets the gain control voltage set values for the variable gain amplifiers of the IF stage and the baseband stage held in the register 24 based on the gain increase / decrease signal from the amplitude detector 15 and the detection signal from the level detector 17. Change, D / A
Output to converters 22 and 23. D / A converter 22
Generates a gain control voltage for the variable gain amplifier 6 in the IF stage, and the D / A converter 23 generates a gain control voltage for the variable gain amplifiers 10 and 13 in the verse band stage.

FIG. 3 shows a control unit 21 in the gain control unit 16.
The detailed configuration of is shown. As shown in the figure, a D / A control value converter 211 for obtaining and outputting a D / A converter control value from a table of FIG. 5 described later based on a value of a combination of a gain increase / decrease signal and a level detection signal, and an IF stage A reading unit 214 for reading the D / A setting value for the baseband stage from the register 24, a reading unit 217 for reading the D / A setting value for the baseband stage from the register 24, and a D / A converter control value and reading unit for the IF stage. An adder 212 for adding the D / A setting value of the IF stage read at 214; and a D / A converter control value of the baseband stage and the D / A setting value of the baseband stage read by the reading unit 217. Adder 213 for adding, adder 2
12 is subjected to overflow processing, and D / D
An overflow processing unit 215 that supplies the A converter 22;
An overflow processing unit 216 and the like are provided for performing an overflow process on the output signal of the adder 213 and supplying it to the D / A converter 23 in the baseband stage.

FIG. 5 shows a table used in the D / A control value converter 211, which expresses the operation of the controller in the gain controller. The set value (gain control voltage) of the D / A converter is increased (+) in accordance with the gain increase / decrease signal from the amplitude detector 15 and the level detection signal from the level detector 17.
1, D + A converter control values (change values) for instructing whether to decrease (such as 1, +2), decrease (such as -1, -2), or maintain (set as 0).

More specifically, as shown in FIG. 5, the gain increase / decrease signal from the amplitude detector 15 is “increase” or “decrease”.
There are three values of “maintenance”, and the level detection signal from the level detection unit 17 has two values of “proper” and “excess”.
The change of the D / A output value corresponding to these two inputs is shown in the table of FIG.

When the gain increase / decrease signal is “increase”, and when the level detection signal is “appropriate”, the set values of the D / A converters 22 and 23 for generating both IF / baseband gain control voltages are set to “1”. "To increase. If the level detection signal is “excessive”, the set value of the D / A converter 22 in the IF stage is reduced by “1”,
The set value of the D / A converter 23 in the base band stage is increased by “2”.

When the gain increase / decrease signal is “decrease”, if the level detection signal is “proper”, the set values of the D / A converters 22 and 23 of the IF stage and the baseband stage are both reduced by “1”, and “ If “excessive”, the set value of the D / A converter 22 in the IF stage is reduced by “2”, and the D / A converter 2 in the base band stage is reduced.
The set value of 3 is not changed.

When the gain increase / decrease signal is "maintained" and the level detection signal is "appropriate", the set values of the D / A converters 22 and 23 in both the IF stage and the base band stage do not change. Is “excessive”, D / A of IF stage
The set value of the converter 22 is reduced by “1”, and the set value of the D / A converter 23 in the baseband stage is increased by “1”. If the set value is the upper or lower limit of each register, no further addition or subtraction is performed.

The operation of this embodiment will now be described with reference to FIGS.
This will be described with reference to each level diagram configuration shown in FIG. FIG. 6 shows an example (1) of a level diagram by the variable gain control when the interference wave is at a level of +50 dB with respect to the desired wave. The desired wave level is shown by a solid line S, and adjacent channel interference waves are shown by dotted lines N1 and N2. The saturation level of each circuit is indicated by a square (四). This CDMA receiver has a digital demodulation capability such that a bit error rate corresponding to a sensitivity point is obtained when the signal-to-interference ratio at the output side of the variable gain amplifiers 10 and 13 in the baseband stage is -15 dB. Shall have. The attenuation of the adjacent channel interference wave in each filter is 20 dB by the band-pass filter 5 in the IF stage,
15 dB with baseband stage low-pass filters 9 and 12
It is. The AGC loop controls the gain so that the input level to the amplitude detector 15 becomes -20 dB.

Now, the desired signal is input to the receiver at -100 dB.
m and an interference wave of -50 dBm are input. When the AGC is normally performed by the conventional method, the level becomes as indicated by a dotted line N2, and the level of the interference wave on the output side of the quadrature demodulator 7 exceeds the output saturation level of the quadrature demodulator 7.

On the other hand, in the present invention, when the level at the input section of the quadrature modulator 7 is higher than a value (set value) that saturates the output side, the level is detected by the level detection section 17 and gain control is performed. An “excess” level detection signal is sent to the unit 16. The transmission of the "excessive" level detection signal is continued until the input level of the quadrature modulator 7 falls below the set value. As a result, the gain controller 16 sets D
/ A converter control value, whereby the gain of the variable gain amplifier 6 in the IF stage is reduced to 20 dB, and the variable gain amplifiers 10 and 1 in the base band stage are used instead.
Increase the gain of 3 to 20 dB. As a result, the level diagram becomes like the dotted line N1, and the saturation phenomenon at the output of the quadrature modulator 7 is eliminated. As shown in FIG. 9, the overall noise figure of the receiver (ie, the total noise figure of the antenna) at this time is 6.6 dB.

FIG. 7 shows that the interference wave is +40 dB with respect to the desired wave.
7 shows an example (2) of a level diagram by the above variable gain control when the level is at the level (1). The desired wave is indicated by a solid line S,
The adjacent channel interference wave is indicated by a dotted line N, and the saturation level of each circuit is indicated by a square (■). Since the level of the interference wave is low, there is a margin before the output level of the quadrature demodulator 7 is saturated as compared with the case of FIG. 6 described above, and more gain is distributed to the variable gain amplifier 6 in the IF stage. Can be. At this time, the noise figure (same as above) of the entire receiver is, as shown in FIG.
0 dB.

FIG. 8 shows an example (3) of the level diagram of the CDMA receiver according to the present invention when no interfering wave exists. The desired wave level is represented by a solid line S, and the saturation level of each circuit is represented by a square (■). At this time, the gain can be distributed to the variable gain amplifier 6 in the IF stage to the maximum. The noise figure (same as above) for the entire receiver is 4.8 dB.

In carrying out the present invention, various modifications are possible. For example, in the above-described embodiment, the first variable gain amplifier 6 is arranged after the mixer 3, but the present invention is not limited to this, and the variable gain amplifier 6 may be arranged before the mixer 3. . In this case, according to the output signal of the filter 5 disposed after the mixer 3 or the level of the output signal of the second variable gain amplifiers 10 and 13,
First variable gain amplifier 6 and second variable gain amplifier 1
The gain of 0,13 is dynamically changed.

Further, in the above-described embodiment, the output signal level of the variable gain amplifier 6 is directly detected by the level detecting section 17 arranged at the subsequent stage of the variable gain amplifier 6, but the present invention is not limited to this. Instead, for example, the input signal level of the variable gain amplifier 6 is detected, and the variable gain amplifier 6 is detected from the input signal level and the gain value of the variable gain amplifier 6.
May be obtained by calculating the output signal level. This is the same for the variable gain amplifiers 10 and 13 in the second stage.

[0050]

As described above, according to the present invention,
Since the gain distribution is dynamically optimized irrespective of the level of the interference wave and the desired wave included in the received signal, it is possible to obtain a receiver having a high selectivity and always having the best receiver noise figure, that is, the reception sensitivity. . This provides a receiver that is highly resistant to deterioration of the radio wave environment for the user, and allows the operator to perform more code multiplexing on the same frequency.

[Brief description of the drawings]

FIG. 1 is a diagram showing a detailed configuration of a wireless receiving unit of a receiver as one embodiment according to the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of a gain control unit in the receiver according to the embodiment.

FIG. 3 is a diagram illustrating a detailed configuration of a control unit in a gain control unit in the receiver according to the embodiment.

FIG. 4 is a diagram illustrating a detailed configuration of a level detection unit in the receiver according to the embodiment.

FIG. 5 is a diagram illustrating a control table used by a control unit in a gain control unit in the receiver according to the embodiment.

FIG. 6 shows an example of a level diagram in a receiver according to an embodiment (1) [When an interference wave is particularly larger than a desired wave (+50);
(dB)].

FIG. 7 is a diagram illustrating an example (2) of a level diagram in the receiver according to the embodiment (when the interference wave level is slightly higher than the desired wave level (+40 dB));

FIG. 8 shows an example of a level diagram in the receiver according to the embodiment (3) [in the case where there is only a desired wave level without any interference wave]
FIG.

FIG. 9 is a diagram illustrating a noise figure of the receiver according to the embodiment.

FIG. 10 is a diagram illustrating an overall configuration of a CDMA receiver.

FIG. 11 is a diagram illustrating a conventional configuration of a wireless reception unit of a CDMA receiver.

FIG. 12 is a diagram showing an example (1) of a level diagram in a conventional receiver (when the gain of the amplifier in the baseband stage is small).

FIG. 13 is a diagram illustrating an example (1) of a level diagram in a conventional receiver (when the gain of an amplifier in a baseband stage is large).

FIG. 14 is a diagram illustrating a noise figure of a conventional receiver.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Low noise amplifier 2 Band pass filter 3 Mixer 4 Local oscillator 5 Band pass filter 6 Variable gain amplifier of IF stage 7 Quadrature demodulator 8 Second local oscillator 9 Low pass filter 10, 13 Variable gain amplifier of base band stage 11, 14 A / D converter 15 Amplitude detection unit 16 Gain control unit 17 Level detection unit 21 Control unit 22, 23 D / A converter 24 Register 31 Antenna 32 Wireless reception unit 33 RAKE reception unit 34 Demodulation unit 211 D / A control value conversion unit 212, 213 Adder 214, 215 D / A set value reading unit 215, 216 Overflow processing unit

Claims (10)

[Claims] 1. A receiver for receiving and demodulating a received wave including a desired wave of a target channel and an interfering wave of an adjacent channel, wherein the first variable gain amplifier amplifies a received signal, and the first variable gain amplifier. A processing circuit for performing predetermined signal processing on the signal output from the filter, a filter for suppressing a disturbing wave component from the signal output from the processing circuit and extracting a desired wave component, and a signal output from the filter A second variable gain amplifier that amplifies the signal; a first detector that detects a level of a signal output from the second variable gain amplifier; and a level of a signal input to or output from the processing circuit. A constant level based on the detection result of the first detector, and a signal level at a subsequent stage of the second variable gain amplifier, and an upper level based on the detection result of the second detector. A receiver comprising: a gain control unit that dynamically controls a gain distribution to the first and second variable amplifiers so that an output of the processing circuit is not saturated. 2. The gain control section detects an input signal to the processing circuit by the second detector, and causes the input signal to the processing circuit to exceed a signal level that saturates the processing circuit. 2. The receiver according to claim 1, wherein the processing circuit is not saturated by maintaining the input signal level at a predetermined level. 3. The receiver according to claim 2, wherein said gain control section sets said predetermined input signal level to a value near an input signal level that saturates said processing circuit. 4. The gain control section detects an output signal of the processing circuit with the second detector, and sets a level of the output signal of the processing circuit to a predetermined level which does not exceed a saturation output level of the processing circuit. 2. The receiver according to claim 1, wherein the processing circuit is not saturated by maintaining the output signal level. 5. The receiver according to claim 4, wherein said gain control section sets said predetermined output signal level to a value near said saturated output signal level. 6. The second detector according to claim 1, wherein the level of the input signal to the processing circuit does not exceed an "excessive" level at which the processing circuit is saturated or a level at which the output of the processing circuit is saturated. And outputting a detection signal indicating an “appropriate” level near the level, wherein the gain control section outputs the detection signal indicating “excess” from the second detector when the second detector outputs a detection signal indicating “excess”. 4. The receiver according to claim 2, wherein the gain distribution is configured so that the gain of the first variable gain amplifier is decreased and the gain of the second variable gain amplifier is increased. 7. The second detector determines whether the level of an output signal to the processing circuit is an “excess” level exceeding a saturation output level of the processing circuit or an “appropriate” level below the saturation output level. The gain control unit is configured to output a detection signal indicating “excessive” from the second detector, and to decrease the gain of the first variable gain amplifier when the detection signal indicating “excessive” is output from the second detector. 6. The receiver according to claim 4, wherein the receiver is configured to increase the gain of the variable gain amplifier. 8. The receiver is a code division multiple access type CD.
An MA receiver, wherein the first variable gain amplifier amplifies a received signal in an intermediate frequency band, and the processing circuit converts an intermediate frequency band signal output from the first variable gain amplifier into an amplified signal. The receiver according to any one of claims 1 to 7, wherein the receiver is configured to be a demodulator that demodulates a signal in a baseband. 9. The demodulator is a quadrature demodulator for demodulating an I channel and a Q channel.
Are provided for each of the I channel and the Q channel, and the detector of the hugging device 2 combines the baseband signals of the I channel and the Q channel and detects the level of the combined signal. Item 9. The receiver according to Item 8. 10. A CDMA receiver, comprising: a first variable gain amplifier for amplifying a received signal; and a mixing unit provided at a subsequent stage of the first variable gain amplifier for mixing the amplified signal with another signal. Means, a filter provided after the mixing means, a second variable gain amplifier provided after the filter, an input signal or an output signal to the first variable gain amplifier, A gain controller that dynamically changes the gains of the first and second variable gain amplifiers according to the output signal or the level of the output signal of the second variable gain amplifier. A CDMA receiver, characterized in that: