JP2002359575A - Direct conversion receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flexibly adapt to the diversified modes of circuit system and channel control and to avoid self mixing inexpensively with high likelihood ratio in a direct conversion receiver that performs the homodyne detection of reception waves, and performs processing at the baseband region of the reception waves, without going through an intermediate frequency filter in a transmission system reception end. SOLUTION: The direct conversion receiver has a detection means 11 for performing the homodyne detection of reception waves by a local oscillation signal and outputting a baseband signal. In addition, a local oscillation preceding injection means 12, having a transfer function being conjugate with the transfer function of a path reaching a reception wave input end, where reception waves enter from the local oscillation input end of the detection means 11, is connected to the local oscillation input end and the reception wave input end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct conversion receiver capable of performing homodyne detection of a received wave at a receiving end of a transmission system and processing the received wave in a baseband region without passing through an intermediate frequency filter. .

[0002]

2. Description of the Related Art In recent years, in mobile communication systems, CDMA
By applying a multiple access system such as a system, various services corresponding to multimedia and WEB are being provided. Various functions are added to the terminal device and the base station device of such a mobile communication system under the competition between manufacturers and communication companies, and further miniaturization is pursued along with cost reduction. .

[0003] Therefore, in these devices, a receiving section for receiving a received wave arriving via a radio transmission path is advantageous in that the above-described factors which hinder the cost reduction and miniaturization can be eliminated. The homodyne detection method is being actively applied.・ LSI integration is possible. -Since a received wave can be directly converted into a baseband signal without passing through a high frequency filter, the scale of hardware and power consumption can be reduced.

[0004] In principle, image disturbance which causes deterioration of transmission quality does not occur. FIG. 7 is a diagram illustrating a configuration example of a terminal device in which a homodyne detection method is applied to a receiving unit. In the figure, the antenna 7
One feeding end is connected to an antenna terminal of an antenna duplexer (DUP) 72, and a reception output of the antenna duplexer 72 is connected to one input / output port of a control unit 74 via a reception unit 73. The analog port of the control unit 74 has a microphone 7
5 and a speaker 76, and the other input / output port of the control unit 74 is connected to a transmission input of the antenna duplexer 72 via a transmission unit 77.

[0005] The receiving section 73 includes the following elements. A band filter 81 and a high-frequency amplifier 82 cascaded to the reception output of the antenna duplexer 72; mixers 83a and 83b having one input connected to the output of the high-frequency amplifier 82; a low-frequency filter cascaded to the output of the mixer 83a. A low-pass filter 84b, a capacitor 85b and an amplifier 86b cascaded to the output of the mixer 83b; a control in accordance with an analog port connected to the output of each of the amplifiers 86a and 86b. An interface unit 87 having a digital port connected to the first input / output port of the unit 74; a local oscillator 88 having one output directly connected to a local input of the mixer 83a; and the other output of the local oscillator 88 and the mixer 83b. Phase shifter (π / 2) placed between the stage and the local oscillation input 8
9 In the receiving section 83 having such a configuration (hereinafter, referred to as a “direct conversion receiver”), the received wave arriving at the antenna 71 is transmitted to the antenna duplexer 72 and the bandpass filter 8.
1 and mixers 83a, 83 via the high-frequency amplifier 82.
is given in parallel with b.

On the other hand, the local oscillator 88 generates a local signal having the same frequency as the carrier frequency of the above-mentioned received wave (hereinafter, referred to as a "first local signal"). Mixers 83a, 83
b shows the first local oscillation signal and the second local oscillation signal obtained by shifting the phase of the first local oscillation signal by 90 degrees by the phase shifter 89. Each given.

Further, the mixers 83a and 83b respectively take the product of the above-mentioned received wave and the first local signal and the product of the received wave and the second local signal in parallel, and By cooperating with the filters 84a and 84b, the components distributed in the occupied band of the received wave are converted into two baseband signals I and Q orthogonal to each other. Capacitor 85
a and 85b suppress the DC components included in these baseband signals I and Q. The interface unit 87 outputs the baseband signals i and q with the DC components suppressed in this manner.
Is transferred to the control unit 74 as a signal of a predetermined format.

The control unit 74 takes in the baseband signals i and q delivered in this way based on channel control and man-machine interface procedures, and performs predetermined processing (not only internal processing but also speaker 76 and transmission unit 77). And a process of delivering these baseband signals i and q to
Is applied. The receiving unit 73 to which such a homodyne detection method is applied has a frequency and an occupied bandwidth of a reception wave that are suitable values (for example, in a WCDMA mobile communication system, the reception frequency is occupied by 2).
The occupied bandwidth is 5 MHz in the GHz band. ), The above-described baseband signal can be obtained without using a high frequency filter (intermediate frequency filter).

The capacitors 85a and 85b can be replaced with, for example, a high-pass filter having the above-described characteristic of blocking DC components. The processing performed by the transmission unit 27 is the opposite of the processing performed by the reception unit 73 under the control of the control unit 74 as described above, and is not related to the present invention. Is omitted.

[0010]

By the way, in such a conventional example, a part of the local oscillation signal supplied to the mixer 83a (83b) has the following path as shown by a curve with an arrow in FIG. Is again input to the mixer 83a (83b). Mixer 83a (83b) → high-frequency amplifier 82 (output end thereof) → mixer 83a (83b) Mixer 83a (83b) → high-frequency amplifier 82 → band filter 81 and antenna duplexer 72 → antenna 71 →
Some reflector → antenna 71 → antenna duplexer 72 →
Bandpass filter 81 → high frequency amplifier 82 → mixer 83a
(83b) Hereinafter, the local signal input to the mixer 83a (83b) in this manner is simply referred to as a “reflected wave”.

That is, since such a reflected wave is subjected to homodyne detection together with the received wave, the mixer 83a (83
In (b), "self-mixing" occurs in which the DC component (FIG. 9 (b)) is superimposed unnecessarily on the baseband signal (FIG. 9 (a)) obtained at the output end of the low-pass filter 84a (84b). Transmission quality could be degraded. It should be noted that such self-mixing can be suppressed or avoided when the degree of coupling and isolation of the local signal between the local input and the input terminal of the mixer 84a (84b) is sufficiently high.

[0012] However, elements and circuit systems that achieve such coupling and isolation are actually realized without being restricted by technical restrictions and restrictions on cost, mountability, and the like. Was difficult.
Therefore, in the conventional example, in order to prevent the dynamic range of the A / D conversion of the baseband signals i and q performed in the interface unit 87 from being narrowed by the above-described DC component, the capacitor 85a that blocks these DC components is used. , 85b are located between the stages of low pass filters 84a, 84b and amplifiers 86a, 86b.

However, these capacitors 85a, 85
In general, the capacitance of b must be set to a value large enough that the components of the baseband signal described above are not unnecessarily suppressed. Further, the time constant between a section from the output end of the low-pass filter 84a to the output end of the amplifier 86a and a section from the output end of the low-pass filter 84b to the output end of the amplifier 86b is such that the larger these capacitances are, To increase.

Further, immediately after the DC component superimposed on the baseband signal changes in a stepwise manner as shown in FIG. 10A, the amplifier 86 as shown in FIG.
The larger the time constant is, the longer the above-mentioned time constant is, the longer the time is transmitted to the output terminals a and 86b, so that deterioration of the transmission quality is not sufficiently avoided. SUMMARY OF THE INVENTION An object of the present invention is to provide a direct conversion receiver that can flexibly adapt to various forms of circuit systems and channel control, and that can avoid self-mixing at low cost and with high accuracy.

[0015]

FIG. 1 is a block diagram showing the principle of a direct conversion receiver according to the present invention. According to the first aspect of the present invention, the detection means 11 performs homodyne detection of the received wave using the local oscillation signal, and outputs a baseband signal. The local emission preceding injection means 12 has a transfer function conjugate to a transfer function of a path from the local emission input end of the detection means 11 to the reception wave input end to which the above-mentioned reception wave is input. Further, the local oscillation preceding injection means 12 returns the local oscillation signal used for the homodyne detection described above by the detection means 11 to the input terminal (or the previous stage) of the detection means 11.

That is, the level of the local oscillation signal that causes self-mixing in the process of homodyne detection due to leakage to the input terminal of the detection means 11 depends on the transfer function of the local advance injection means 12 due to the characteristic of the detection means 11. As long as it is set as a transfer function that is accurately adapted, it is highly accurately suppressed.
Therefore, a decrease in sensitivity, performance, and transmission quality due to self-mixing is reduced.

According to the second aspect of the present invention, the detecting means 11
Performs homodyne detection of a received wave using a local oscillation signal, and outputs a baseband signal. The local precedence injection means 12A includes:
An input terminal (or a preceding stage) of the detection unit 11 to which the above-described received wave is input from the local oscillation signal input terminal of the detection unit 11 is
A local oscillation signal used for homodyne detection is returned. The control unit 13 sets the transfer function of the local precedence injection unit 12A to a value that minimizes the DC component superimposed on the baseband signal output by the detection unit 11.

That is, since the transfer function of the local precedence injection means 12A is automatically set by the control means 13, the reduction of sensitivity, performance and transmission quality due to self-mixing is achieved with high accuracy and stability. . According to the third aspect of the present invention, the detection means 11 performs homodyne detection of the received wave using the local oscillation signal, and outputs a baseband signal. The sub-local oscillation means 21 generates a local oscillation signal having the same frequency as that of the local oscillation signal. Local injection device 22
Detects the local oscillation signal generated in this manner by the detection means 11.
To the input end of (or the previous stage). The control means 23
The transfer function of the local precedence injection unit 22 is set to a value that minimizes the DC component superimposed on the baseband signal output by the detection unit 11.

That is, even if the deviation of the characteristic of the detecting means 11 is large or the characteristic can be changed in accordance with environmental conditions (including fluctuation of the power supply voltage), aging and other factors, the self-mixing is not performed. It is reduced or suppressed with high accuracy. Therefore, sensitivity, performance, and transmission quality are stably maintained at a high level. According to the fourth aspect of the present invention, the control means 13 and 23 determine when a predetermined event is identified under the channel control of the radio channel provided for transmission of the received wave, and when the predetermined event is identified under the channel control. The transfer function of the local preceding injection means 12A, 22 is updated only during and / or during the predetermined period.

That is, the local preceding injection means 12A, 22
The level and phase of the local oscillation signal to be injected into the input terminal (or the preceding stage) of the detection means 11 are set, or the time and period to be updated are appropriately determined based on a procedure such as channel control. . Therefore, the zone configuration,
Flexible adaptation to channel arrangement and other configurations becomes possible, and transmission quality and performance are stably maintained at a high level.

According to the fifth aspect of the present invention, the local injection means 12, 12A is provided with the local injection means 12, 12A.
Keep the latest transfer function of A and apply that latest transfer function at startup. That is, the local injection preceding injection means 12, 1
The level and phase of the local signal injected into the input terminal (or the previous stage) of the detection means 11 by 2A are set at the time of starting or when the time when these levels and phases are to be updated is set again. In comparison, it quickly converges to a suitable value.

Therefore, responsiveness is improved and good transmission quality is stably maintained. According to the third aspect of the present invention, the sub-local oscillation means 21 changes the frequency of the local oscillation signal used for homodyne detection and changes the frequency of the local oscillation signal to the same frequency as that of the local oscillation signal. Generate the frequency of That is, when the frequency of the received wave to be homodyne-detected by the detection means 11 is changed,
The frequency of the local oscillation signal generated by the sub-oscillation means 21 is updated to a value that matches the frequency of the local oscillation signal used for homodyne detection.

Therefore, even when channel switching is performed, self-mixing can be stably reduced or suppressed. In the invention related to the third aspect of the invention, the sub-local oscillation means 21 is obtained by the frequency synthesizer 24 that generates a local oscillation signal used for homodyne detection, and is applied to the generation of the local oscillation signal. A local signal is generated by performing frequency synthesis based on the ratio or a synthesis ratio uniquely determined with respect to the synthesis ratio.

That is, the local oscillation signal used for reducing or suppressing the self-mixing and the local oscillation signal used for the homodyne detection are generated by sharing the hardware for providing the above-described combination ratio. Therefore, the size and power consumption of the hardware can be reduced as compared with a case where hardware for individually generating these local signals is mounted.

According to a first aspect of the present invention relating to any one of claims 2 to 4, the control means 13, 2
Reference numeral 3 updates the transfer function of the local precedence injection units 12A and 22 based on adaptive control that minimizes the DC component superimposed on the baseband signal output by the detection unit 11. That is, the level and the phase of the local oscillation signal to be input to the input terminal (or the previous stage) of the detection means 11 are identified under the above-described channel control or the like as long as the above-described adaptive control is possible. It is updated repeatedly at the desired frequency regardless of the event or period.

Therefore, a rapid change in the characteristic of the detecting means 11 which may occur due to environmental conditions or the like is flexibly and promptly followed, and the transmission quality and performance are stably maintained at a high level. According to a second invention related to the invention described in any one of claims 2 to 4, the control means 13, 2
Reference numeral 3 designates an offset component generated according to the characteristic inherent to the detection unit 11 among the DC components superimposed on the baseband signal output by the detection unit 11. Further, the control means 13 and 23 adjust the local preceding injection means 12A and 22A to a value that minimizes the difference between the DC component and the offset component.
Set the transfer function of

That is, the local preceding injection means 12A, 22
The level and phase of the local signal to be injected into the input terminal of the detection means 11 and the preceding stage are maintained at appropriate values even if the above-mentioned offset is large. Therefore, as long as the dynamic range in the baseband region is sufficiently wide, responsiveness is improved, and transmission quality and performance are stably maintained at a high level.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a diagram showing a first embodiment of the present invention. In the drawing, the main difference from the conventional example shown in FIG. 7 is that a receiving unit 31 having a configuration different from that of the receiving unit 73 in the following points is provided. The amplifiers 32a and 32b are provided between the high-frequency amplifier 82 and the mixers 83a and 83b, respectively.

A phase shifter (Φ) 33 a and an attenuator (ATT) 34 a in which the local oscillation inputs of the mixer 83 a are cascaded.
To the input of the mixer 83a. A local input of the mixer 83b is connected to an input of the mixer 83b via a cascade-connected phase shifter (Φ) 33b and attenuator (ATT) 34b. Hereinafter, the operation of the first embodiment of the present invention will be described.

The phase shift amount of the phase shifter 33a is equivalent to the phase shift amount of an equivalent circuit (hereinafter referred to as "internal feedback path a") in a section from the local oscillation input to the input terminal of the mixer 83a inside the mixer 83a. Is adjusted or set in advance to a value that satisfies one of the following conditions (a) and (b). (a) Absolute values are equal and signs are opposite.

(B) The difference is an odd multiple of 180 degrees. Further, the phase shift amount of the phase shifter 33b is equal to the phase shift amount of an equivalent circuit (hereinafter, referred to as “internal feedback path b”) in a section from the local input to the input terminal of the mixer 83b inside the mixer 83b. On the other hand, the value is adjusted or set in advance to a value that satisfies one of the conditions (a) and (b) described above.

Further, the attenuation of the attenuators 34a and 34b is adjusted or set in advance to a value equal to the attenuation of the internal feedback paths a and b, respectively. Each of the phase shifters 33a and 33b has an input impedance that is significantly larger than the output impedance of the local oscillator 88 and the phase shifter 89. Therefore, the mixer 83
The local signal input to the local input of the mixer 83a and leaked to the input terminal of the mixer 83a via the internal feedback path a described above is:
The mixer 8 is connected via a phase shifter 33a and an attenuator 34a.
It is almost canceled by the local signal that is fed back in parallel to the input terminal 3a.

Further, the signal is supplied to the local oscillation input of the mixer 83b, and is supplied to the mixer 83b via the internal feedback path b.
Is almost canceled by the local signal that is fed back in parallel to the input terminal of the mixer 83b via the phase shifter 33b and the attenuator 34b. That is, in the mixers 83a and 83b, the local oscillation signal which has been subjected to self-mixing in
As long as the phase shift amounts of a and 33b and the attenuation amounts of the attenuators 34a and 34b are accurately set or adjusted to values suitable for the characteristics of the internal feedback paths a and b described above, the suppression is performed with high accuracy. .

Therefore, according to the present embodiment, reductions in sensitivity, performance and transmission quality due to such self-mixing are reduced. FIG. 3 is a diagram showing second, fourth, and fifth embodiments of the present invention. The main differences between the present embodiment and the first embodiment described above are as follows.

Variable phase shifters (Φ) 41a, 41b are provided in place of the phase shifters 33a, 33b. A variable attenuator (AT) instead of the attenuators 34a and 34b
T) 42a, 42b are provided. 2 individually connected to the outputs of the mixers 83a and 83b
A feedback controller 43 having two analog input ports and having two outputs respectively connected to the control inputs of the variable phase shifters 41a and 41b and the variable attenuators 42a and 42b is provided.

FIG. 4 is an operation flowchart of the second embodiment of the present invention. Hereinafter, the operation of the second embodiment of the present invention will be described with reference to FIGS. 3, 4, and 7. The feature of this embodiment lies in the following processing procedure performed by the feedback control unit 43. The feedback control unit 43 is given or measured as a value suitable for the deviation of the characteristics of the above-described internal feedback paths a and b formed inside the mixers 83a and 83b, and outputs the values to the outputs of the mixers 83a and 83b. A value indicating a DC component that is constantly superimposed on the obtained baseband signal (hereinafter, referred to as
Simply referred to as the “offset value”, and here, for simplicity,
Assume given as voltage. ) Is given in advance.

In the following, description relating to the common operation of each unit corresponding to each of the mixers 83a and 83b will be described with a suffix "x" applicable to any of these mixers 83a and 83b. And “b”. Further, at the time of starting, the feedback control unit 43 performs the following series of processes corresponding to the mixers 83a and 83b in parallel.

(1) Each unit corresponding to the mixer 83x waits for a time required for starting a steady operation (FIG. 4 (1)). (2) The attenuation of the variable attenuator 42x is set to the minimum value (FIG. 4 (2)). (3) The phase shift amount of the variable phase shifter 41x is set to a predetermined range (for example,
It ranges from 0 degrees to 360 degrees. ), The difference between the DC component superimposed on the baseband signal obtained at the output of the mixer 83x and the offset value is monitored while updating at a prescribed frequency and accuracy (FIG. 4 (3)).

(4) It is determined whether or not the difference is minimized (FIG. 4 (4)). (5) If the result of the determination is false, the variable attenuator 4
The 2x attenuation is updated to a large value over a specified value (FIG. 4 (5)), and the above processes (3) to (4) are repeated. (6) If the result of the above determination is true, the variable phase shifter 41 updated based on the procedures of the above processes (3) to (5)
x latest phase shift amount (hereinafter referred to as “appropriate phase shift amount”)
And the latest attenuation amount of the variable attenuator 42x (hereinafter referred to as “appropriate attenuation amount”) (FIG. 4 (6)).

(7) These proper phase shift amounts and proper attenuation amounts are set in the variable phase shifter 41x and the variable attenuator 42x, respectively (FIG. 7 (7)). That is, the phase shift amount of the variable phase shifter 41x and the attenuation amount of the variable attenuator 42x are automatically set under the processing performed by the feedback control unit 43 based on the above-described procedure. Accordingly, the desired transmission quality and performance can be more accurate than those of the first embodiment, in which these phase shift amounts and attenuation amounts must be set appropriately based on actual measurements or specifications or other values. Highly and stably achieved.

In the present embodiment, the variable phase shifter 41x
And the amount of attenuation of the variable attenuator 42x are set based on the procedure of the above-described processing performed by the feedback control unit 43 only during startup. However, the present invention is not limited to such a configuration. For example, as shown by a dotted line in FIG. 4, the feedback control unit 43 cooperates with the control unit 74 that initiatively performs channel control via the interface unit 87. Thus, when an event such as channel switching, mode update, occurrence of a predetermined call, or any other change relating to the wireless transmission path is to be performed, the processing described above (FIG. 4 (1) to FIG.
(7)) may be appropriately performed.

In the present embodiment, the variable phase shifter 41x
The condition for determining the phase shift amount of the variable attenuator and the attenuation amount of the variable attenuator 42x is defined in relation to the above-described offset value. However, such a condition is satisfied without applying the above-described offset value, for example, “variable phase shifter 4
The absolute value of the DC component superimposed on the baseband signal obtained at the output of the mixer 83x (or the preceding value of the DC component, while updating the phase shift amount of 1x at a predetermined frequency and accuracy in a predetermined range). The absolute value of the difference is below an upper limit given in advance)
Mixer 8 according to environmental conditions (including fluctuations in power supply voltage)
Performance may be improved along with flexible follow-up of variations in 3a, 83b and other characteristics.

Further, in the present embodiment, a local oscillation signal applied to the local oscillation input of the mixer 83x is injected into the input end of the mixer 83x via the variable phase shifter 41x and the variable attenuator 42x. Mixing is eased and avoided. However, the present invention is not limited to such a configuration. For example, as shown in FIG. 5, as hardware different from the local oscillator 88, a local oscillator having a frequency equal to the nominal value of the frequency of the local oscillation signal may be used. Emission signal (hereinafter,
It is called "sub-station-originated signal." ) Is provided, and the sub-local signal may be provided to the input terminal of the variable attenuator 41x instead of the local signal described above.

FIG. 6 is a diagram showing a third embodiment of the present invention. The main difference between the present embodiment and the embodiment shown in FIG. 5 is that a frequency synthesizer 60 composed of the following elements is provided instead of the local oscillator 88 and the frequency synthesizer 51. A voltage controlled oscillator 61 whose output is connected to the local input of the mixer 83a and the input of the phase shifter 89. A voltage controlled oscillator 62 whose one output is connected to the input of the variable phase shifter 33a. A phase shifter (π / 2) 63 whose output is connected to the other output of the variable phase shifter 33b and whose output is connected to the control input of these voltage controlled oscillators 61 and 62 Combination ratio setting section 64 having an output A reference oscillator 65 that supplies a reference signal of a predetermined frequency to the combination ratio setting section 63. Hereinafter, the operation of the third embodiment of the present invention will be described.

The voltage controlled oscillators 61 and 62 are mounted, for example, in a region close to each other on a common circuit board or a chip and in close thermal coupling, and at the same time with the same voltage-frequency conversion with a predetermined accuracy. Has characteristics. On the other hand, the combining ratio setting unit 63
Calculates the frequency synthesis ratio based on the frequency of the reference signal steadily given by the reference oscillator 64, and outputs a common control voltage indicating the frequency synthesis ratio to the voltage controlled oscillator 61,
Give in parallel to 62.

That is, the voltage controlled oscillators 61 and 62
In accordance with such a control voltage, the frequency is the same with the precision described above, and the local oscillation signal and the sub-local oscillation signal to be respectively supplied to the mixers 83a and 83b are generated in parallel. As described above, according to the present embodiment, the oscillation frequency of the voltage-controlled oscillator 61 that generates the local oscillation signal and the oscillation frequency of the voltage-controlled oscillator 62 that generates the sub-local oscillation signal are the same as those of the voltage-controlled oscillators 61 and 62. Are set under the initiative of a single combination ratio setting unit 63 that gives a common control voltage to

Therefore, as compared with the embodiment shown in FIG. 5, simplification of the hardware configuration and reduction of power consumption are achieved, and quick response to events such as channel switching is achieved with high accuracy. Hereinafter, a fourth embodiment of the present invention will be described. The main difference between the present embodiment and the second embodiment described above is that a feedback control unit 43A is provided instead of the feedback control unit 43.

Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. The feature of this embodiment lies in a procedure of a process in which the feedback control unit 43A updates the appropriate phase shift amount of the variable phase shifter 41x and the appropriate attenuation amount of the variable attenuator 42x. The feedback control unit 43A repeats the following processing at a predetermined frequency, not only at the time of startup, unless otherwise restricted under the channel control mainly performed by the control unit 74.

(1) A DC component superimposed on the baseband signal output by the mixer 83x is obtained. (2) The variable phase shifter 41 is preceded by the value of the DC component.
x and the variable attenuator 42x, respectively, according to the proper phase shift amount and the proper attenuation amount, based on an adaptive algorithm for minimizing the value of the DC component, the proper phase shift amount and the proper attenuation amount. To update.

Under the adaptive control performed based on such an adaptive algorithm, the appropriate phase shift amount and the appropriate attenuation amount are almost constantly maintained at the appropriate values at the frequency described above. Therefore, it is highly likely that the appropriate phase shift amount and the appropriate attenuation amount are set or the time and period to be updated are regulated under procedures such as channel control, zone configuration, channel arrangement and other conditions. Compared with the above-described second and third embodiments, transmission quality and performance are stably maintained at a high level, and flexible adaptation to deviations in element characteristics, changes in environmental conditions and aging can be achieved.

In this embodiment, the adaptive algorithm to be actually applied is not specifically shown. However, for such adaptive algorithms, for example,
It can be realized by applying various known techniques such as LMS method, learning identification method (NLMS method),
Moreover, since it is not a feature of the present invention, its description is omitted here.

Hereinafter, a fifth embodiment of the present invention will be described. The main difference between the present embodiment and the above-described fourth embodiment is that the feedback control unit 4
3A in that an appropriate value storage unit 44 exclusively accessed by 3A and having a nonvolatile storage area is provided. Hereinafter, the operation of the fifth embodiment of the present invention will be described with reference to FIG.

The feature of this embodiment lies in the following processing procedure performed by the feedback control unit 43A. The feedback control unit 43A stores the proper phase shift amount and the proper attenuation amount in the variable phase shifter 41x and the variable attenuator 42x each time the new proper phase shift amount and the proper attenuation amount are set. The data is stored in the corresponding storage area of the unit 44. In addition, the feedback control unit 43A starts (when the above-described event occurs or at a predetermined time).
The variable phase shifter 41x refers to the latest proper phase shift amount and proper attenuation amount previously stored in the proper value storage unit 44, and uses these proper phase shift amount and proper attenuation amount as initial values. And the variable attenuator 42x.

The proper phase shift amount and proper attenuation amount set in this way quickly converge to suitable values as compared with the case where the above-described setting is performed again at the time of starting or the like. Therefore, as compared with the above-described second to fourth embodiments, the responsiveness is improved, and good transmission quality is stably maintained.
Note that the present embodiment is configured by adding a proper value storage unit 44 to the fourth embodiment described above.

However, the present invention is not limited to such a configuration. For example, as shown by dotted lines in FIGS. 5 and 6, the appropriate value storage section 44 is provided in the second and third embodiments described above. It may be configured by being added. In the above-described second to fifth embodiments, an error caused by an offset value unique to a circuit is determined when the proper phase shift amount and the proper attenuation amount are determined.

However, the present invention is not limited to such a configuration. For example, when an error caused by such an offset value is small enough to be ignored, a process related to compression of the error is omitted. Thus, the processing amount may be reduced and the responsiveness may be improved. In addition, the present invention is not limited to the above-described embodiment, and various embodiments can be realized within the scope of the present invention, and some or all of the constituent devices are improved. May be done.

Hereinafter, the configuration of the present invention disclosed in each of the above-described embodiments is arranged hierarchically and multilaterally, and is listed as an appendix. (Supplementary Note 1) A detection unit 11 that performs homodyne detection of a received wave using a local oscillation signal and outputs a baseband signal,
The local injection leading means 12 having a transfer function conjugate to a transfer function of a path from the local input terminal of the detection means 11 to the received wave input terminal to which the received wave is input, the local injection input means A direct conversion receiver connected to the reception wave input terminal.

(Supplementary Note 2) Detection means 11 for homodyne detection of a received wave using a local oscillation signal and outputting a baseband signal, a local oscillation signal input terminal of the detection means 11 and an input to which the reception wave is input Local injection preceding injection means 1 for connecting the end
2A and control means 13 for setting the transfer function of the local precedence injection means 12A to a value that minimizes the DC component superimposed on the baseband signal output by the detection means 11. And a direct conversion receiver.

(Supplementary Note 3) Detection means 11 for homodyne detection of the received wave using a local oscillation signal and outputting a baseband signal, and sub-local oscillation for generating a local oscillation signal having the same frequency as the frequency of the local oscillation signal Means 21, a local precedence injection means 22 for injecting a local oscillation signal input from the sub-local oscillation means 21 into an input terminal or a preceding stage of the detection means 11, and a baseband signal output by the detection means 11. A direct conversion receiver comprising: a control unit that sets a transfer function of the local injection unit to a value that minimizes a superposed DC component.

(Supplementary note 4) In the direct conversion receiver according to supplementary note 3, the sub-local oscillation means 21
Wherein a frequency of a local oscillation signal having the same frequency as that of the local oscillation signal is generated in response to a change in the frequency of the local oscillation signal provided for the homodyne detection.

(Supplementary Note 5) In the direct conversion receiver according to Supplementary Note 3 or 4, the sub-local oscillation means 21 is obtained by a frequency synthesizer 24 that generates a local oscillation signal used for the homodyne detection. A direct conversion receiver that generates a local oscillation signal by performing frequency synthesis based on a synthesis ratio applied to generation of a local oscillation signal, or a synthesis ratio uniquely determined for the synthesis ratio.

(Supplementary Note 6) In the direct conversion receiver according to any one of Supplementary Notes 2 to 5, the control means 13 and 23 may control the radio channel provided for transmission of the received wave under channel control. Updating the transfer function of the local precedence injection means 12A, 22 only when and / or when a predetermined event is identified and / or during a predetermined period identified under the channel control. Direct conversion receiver characterized by the following.

(Supplementary Note 7) In the direct conversion receiver according to any one of Supplementary Notes 2 to 6, the control units 13 and 23 may include a direct current superimposed on a baseband signal output by the detection unit 11. A direct conversion receiver for updating a transfer function of the local injection means 12A, 22 based on adaptive control for minimizing a component.

(Supplementary note 8) In the direct conversion receiver according to any one of Supplementary notes 1 to 7, the local precedence injection means 12 and 12A may include the latest transmission of the local precedence injection means 12 and 12A. A direct conversion receiver characterized by holding the function and applying its latest transfer function at startup.

(Supplementary Note 9) In the direct conversion receiver according to any one of Supplementary Notes 2 to 7, the control units 13 and 23 may include a direct current superimposed on the baseband signal output by the detection unit 11. Among them, an offset generated according to the characteristic characteristic of the detection means 11 is given, and the local preceding injection means 12A,
22. A direct conversion receiver, wherein 22 transfer functions are set.

[0066]

As described above, according to the first aspect, the reduction in sensitivity, performance and transmission quality due to self-mixing is reduced. According to the second and third aspects of the present invention, sensitivity, performance and transmission quality caused by self-mixing can be reduced with high accuracy and stably. According to the fourth aspect of the invention, it is possible to flexibly adapt to the zone configuration, the channel arrangement, and other configurations, and the transmission quality and the performance are stably maintained at a high level.

According to the fifth aspect of the present invention, the responsiveness is enhanced, and good transmission quality is stably maintained. According to the third aspect of the invention, self-mixing can be stably reduced or suppressed even when channel switching is performed. In the invention related to the third aspect, the scale of hardware and the power consumption can be reduced.

According to the first aspect of the present invention, it is possible to flexibly follow a sudden or fluctuating characteristic that may occur due to environmental conditions and the like.
The transmission is performed promptly, and the transmission quality and performance are stably maintained at a high level. According to the second invention related to the invention described in any one of claims 2 to 4, as long as the dynamic range in the baseband region is sufficiently wide, the responsiveness is enhanced, and the transmission quality and the performance are stabilized. Will be kept high.

Therefore, in the transmission system to which these inventions are applied, the advantage of the homodyne detection system can be effectively utilized in a desired frequency band without deteriorating the performance, and the service quality and reliability can be improved. In addition, the running cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a principle block diagram of a direct conversion receiver according to the present invention.

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

FIG. 3 is a diagram showing second, fourth, and fifth embodiments of the present invention.

FIG. 4 is an operation flowchart of a second embodiment of the present invention.

FIG. 5 is a diagram showing another configuration of the second embodiment of the present invention.

FIG. 6 is a diagram showing a third embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration example of a terminal device to which a homodyne detection method is applied.

FIG. 8 is a diagram (1) illustrating a problem of the conventional example.

FIG. 9 is a diagram (2) for explaining a problem of the conventional example.

FIG. 10 is a diagram (3) for explaining a problem of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Detection means 12, 12A, 22 Local precedence injection means 13, 23 Control means 21 Sub local oscillation means 24, 51, 60 Frequency synthesizer 31, 73 Receiving parts 32a, 32b, 86a, 86b Amplifiers 33a, 33b Phase shifter ( Φ) 34a, 34b Attenuator (ATT) 41a, 41b Variable phase shifter (Φ) 42a, 42b Variable attenuator (ATT) 43, 43A, 74 Control unit 44 Proper value storage unit 61, 62 Voltage controlled oscillator 63, 89 Phase shifter (π / 2) 64 Combination ratio setting unit 65 Reference oscillator 71 Antenna 72 Antenna duplexer (DUP) 75 Microphone 76 Speaker 77 Transmitter 81 Bandpass filter 82 High frequency amplifier 83a, 83b Mixer 84a, 84b Low-pass filter 85a, 85b Capacitor 87 Interface unit 88 Local oscillator

Claims (5)

[Claims] 1. A receiving wave input terminal for detecting a received wave by homodyne detection using a local oscillation signal and outputting a baseband signal, wherein the receiving wave is input from a local oscillation input terminal of the detection device. A direct conversion receiver, characterized in that local injection preceding injection means having a transfer function conjugate to a transfer function of a path leading to the path is connected to the local input terminal and the received wave input terminal. 2. A detecting means for performing homodyne detection of a received wave using a local oscillation signal and outputting a baseband signal, and connecting a local oscillation signal input terminal of the detection means to an input terminal to which the received wave is input. Local injection preceding means, and control means for setting the transfer function of the local injection preceding means to a value that minimizes the DC component superimposed on the baseband signal output by the detection means. Direct conversion receiver characterized by the following. 3. A detecting means for detecting a received wave by homodyne detection using a local oscillation signal and outputting a baseband signal; a sub-local oscillation means for generating a local oscillation signal having the same frequency as the frequency of the local oscillation signal; A local precedence injection means for injecting a local oscillation signal input from the sub-local oscillation means into an input end or a preceding stage of the detection means, and a DC component superimposed on a baseband signal output by the detection means is minimized. Control means for setting a transfer function of the local injection means to a predetermined value. 4. The direct conversion receiver according to claim 2, wherein the control unit identifies a predetermined event under channel control of a radio channel provided for transmission of the received wave. A direct conversion receiver characterized in that the transfer function of the local injection device is updated only during and / or during a predetermined period identified under the channel control. 5. The direct-conversion receiver according to claim 1, wherein the local-precision preceding injection means holds the latest transfer function of the local-preceding preceding injection means, and starts up. Direct conversion receiver characterized by sometimes applying its latest transfer function.