JP2005311775A - Receiving machine - Google Patents

Abstract

[PROBLEMS] A conventional receiver using an IRM detects the IF signal level from the IRM and controls the input level to the IRM, but the IRM output has already suppressed the mixed wave of the image signal and the LO wave. Therefore, the intensity of the image signal is not considered.
In addition, the method of directly detecting the RF signal input to the IRM requires the level detector to operate in the high frequency RF band, which increases the cost.
An IRM having first and second frequency converters for mixing a received signal and a local oscillation signal, and a synthesizer for combining outputs of the two frequency converters; A first level detecting means for inputting an output signal of any one of the second frequency converters and outputting a signal corresponding to the intensity of the input signal; and the image rejection by the output from the first level detecting means. Signal level control means for controlling the signal level of the received signal input to the mixer.
[Selection] Figure 1

Description

  The present invention relates to a receiver using an image rejection mixer (IRM).

The image rejection mixer (IRM) suppresses the mixed wave of the image signal and LO (local oscillator oscillation signal) by combining the outputs of the two mixers with a phase difference, and mixes the desired wave and the LO wave. In an ordinary heterodyne receiver, the image signal removal filter provided in the preceding stage of the mixer can be deleted (for example, Non-Patent Document 1).
A receiver using a conventional image rejection mixer (IRM) uses a level detector to measure the intensity of the IF (intermediate frequency) signal output from the IRM in order to avoid saturation of the IRM when a high level signal is received. The output of the variable gain amplifier in front of the IRM is controlled using this output (for example, Patent Document 1). Another method for avoiding IRM saturation is to directly detect the RF signal intensity input to the IRM using a level detector in the RF (received signal frequency) band, and use the output to detect the IRM upstream. A method of reducing the gain of the variable gain amplifier is also conceivable.

By Behzad Razavi, translated by Tadahiro Kuroda “RF Microelectronics” Maruzen Co., Ltd., March 25, 2002, P151-160 Special Table 2001-513275 No. 4

  The receiver using the conventional IRM shown in Patent Document 1 detects the level of the IF signal output from the IRM and obtains the strength of the signal input to the IRM. However, since the mixed signal of the image signal and the LO wave is already suppressed in the IRM output, there is a problem in that the intensity of the image signal at the IRM input is not considered when the IRM output is used for level detection.

  In addition, when directly detecting an RF signal input to the IRM, the level detector must be operated in an RF band having a high frequency, which increases the cost.

  The present invention has been made to solve the above problems, and an object thereof is to accurately detect the intensity of a signal input to an IRM using an IF band level detector.

The receiver according to the present invention combines at least first and second frequency converters for mixing the received signal and the local oscillation signal, and the outputs of the two frequency converters to mix the image signal and the LO wave. An image rejection mixer (IRM) having a synthesizer that suppresses the wave and outputs a mixed wave of the desired wave and the LO wave;
First level detection means for inputting an output signal of one of the first and second frequency converters and outputting a signal corresponding to the intensity of the input signal;
Signal level control means for controlling the signal level of the received signal input to the image rejection mixer by the output from the first level detection means.

  The receiver according to the present invention can accurately detect the level of the signal input to the IRM using a level detector that detects the intensity of the IF (intermediate frequency) signal, so that the cost does not increase. Play.

Embodiment 1 FIG.
A receiver according to Embodiment 1 of the present invention will be described with reference to the drawings. 1 is a diagram showing a configuration of a receiver according to Embodiment 1 of the present invention. In addition, in each figure, the same code | symbol shows the same or equivalent part.

In FIG. 1, 1 is a variable gain amplifier (RF-AGC) in the RF (received signal frequency) band as signal level control means, 2 is a first in-phase distributor, and 3 and 4 are frequency converters. The second unit mixer, 5 is the second in-phase distributor, 6 and 7 are the first and second 90-degree phase shifters that cause a 90-degree phase shift delay, 8 is the in-phase synthesizer, and 9 is 2 Image Rejection Mixer (IRM) with ~ 8 as the component, 10 is the IF band passband filter (IF-BPF), 11 is the IF (intermediate frequency) band variable gain amplifier (IF-AGC), and 12 is the first A first level detector 13 monitors the output signal level of the unit mixer 3, and a second level detector 13 monitors the output signal level of the IF-AGC 11.
In the first embodiment, the second 90-degree phase shifter 7 and the in-phase synthesizer 8 constitute a synthesizer.

  Next, the operation of the power detector according to the first embodiment will be described with reference to the drawings.

  A reception (RF) signal from the antenna terminal is amplified by RF-AGC 1 and input to IRM 9. The RF signal is firstly distributed in phase by the in-phase distributor 2 and input to the first and second unit mixers 3 and 4. On the other hand, the LO wave supplied from the outside is in-phase distributed by the second in-phase distributor 5 and then one is directly supplied to the first unit mixer 3 and the other is passed through the first 90-degree phase shifter 6. A 90-degree phase delay is generated and supplied to the second unit mixer 4, and the first and second unit mixers 3 and 4 respectively mix the desired wave of the RF band with the LO wave and the image signal. An IF band signal that is a mixed wave of LO waves is output.

  At this time, the desired wave and the LO wave mixed wave have a +90 degree phase difference between the output of the first unit mixer 3 and the output of the second unit mixer 4. On the other hand, the mixed wave of the image signal and the LO wave has a phase difference of −90 degrees between the output of the first unit mixer 3 and the output of the second unit mixer 4.

  The output of the second unit mixer 4 undergoes a phase change of −90 degrees when passing through the second phase shifter 7. As a result, the desired wave and the LO wave are in phase with each other at the output of the first unit mixer 3 and the output of the second phase shifter 7. On the other hand, the mixed wave of the image signal and the LO wave has a phase difference of −180 degrees between the output of the first unit mixer 3 and the output of the second phase shifter 7 and is in reverse phase.

  When these signals are in-phase combined by the in-phase synthesizer 8, the mixed wave of the image signal and the LO wave is suppressed, and only the mixed wave of the desired wave and the LO wave is output. Since the output of IRM9 includes unnecessary waves near the desired wave, they are removed by IF-BPF 10 and then amplified by IF-AGC 11 and output to the AD converter.

  In order to avoid saturation of IRM9 when a high level RF signal is input, the output of the first unit mixer 3 constituting the IRM9 is input to the first level detector 12, and RF- Controls the gain of AGC1. Further, the gain of the IF-AGC 11 is controlled by using the output of the IF-AGC 11 by monitoring the output signal level of the IF-AGC 11 with the second level detector 13 so that the input level to the AD converter becomes appropriate.

  In order to avoid the saturation of IRM, the receiver shown in Patent Document 1 monitors the output signal of IRM9 and controls the level of the RF signal input to IRM9. However, since the mixed wave of the image signal and the LO wave has already been suppressed at the output of the IRM9, when the image signal is at a high level, the input level cannot be detected accurately, and saturation cannot be avoided. On the other hand, in the present embodiment, the output of the first unit mixer 3 before the mixed wave of the image signal and the LO wave is suppressed is input to the level detector 12, and the level of the RF signal input to the IRM 9 is controlled. Therefore, the saturation of the IRM 9 can be avoided regardless of the intensity of the image signal. Further, since the frequency of the signal input to the level detector 12 is in the IF band, it is not necessary to use an expensive RF band level detector with a complicated configuration, and the manufacturing cost can be reduced.

  In this embodiment, the intensity of the input signal of the IRM9 is controlled using the RF variable gain amplifier ((RF-AGC) 1). Instead, the amplifier in the preceding stage of the IRM9 is passed as the path of the received signal. A configuration in which a variable attenuator is used in place of the variable gain amplifier 1 and a method of lowering the gain by shutting off the power supply of the amplifier are possible, and similar effects are obtained.

  In the present embodiment, the gain of the variable gain amplifier ((RF-AGC) 1 in front of the IRM 9 is directly controlled by using the output of the level detector 12, but the present invention is not limited to this, and the level detection is performed. The output of the detector 12 may be taken into a microcomputer to generate a control signal, which may be used to control the gain of the amplifier in front of the IRM 9. The relationship between the input power and output signal of the level detector 12 and the variable gain amplifier By measuring the relationship between the control signal 1 and the gain in advance and storing it in a table or function on the microcomputer, high-accuracy gain control is possible.

  In the present embodiment, the input of the second level detector 13 is an analog signal that is the output of the IF-AGC 11. However, the present invention is not limited to this, and the analog signal that is the output of the IF-AGC 11 is used. The gain of IF-AGC 11 may be controlled by converting the signal into a digital signal with an AD converter and detecting the level with a digital unit.

  In the present embodiment, the output of the first unit mixer 3 is input to the first level detector 12. However, the present invention is not limited to this, and the output of the second unit mixer 4 The output of the second phase shifter 7 may be input to the first level detector 12, which has the same effect.

  FIG. 2 is a diagram illustrating a configuration of a receiver according to another example of the present embodiment. In the drawings, the same reference numerals indicate the same or corresponding parts.

  In FIG. 2, 14 is a polyphase filter.

  The polyphase filter 14 in this embodiment has a function of synthesizing the outputs of the first and second unit mixers 3 and 4 with a phase difference of 90 degrees. In the first embodiment shown in FIG. This is a circuit having a function in which the phase shifter 7 and the in-phase synthesizer 8 are combined.

  Also in this embodiment, the phase relationship between the desired wave and the LO wave mixed wave and the image signal and the LO wave mixed wave in the IRM 9 is the same, and the former is output and the latter is suppressed in the output of the polyphase filter 14. Is done. Therefore, by inputting the output of the first unit mixer 3 in which the mixed wave of the image signal and the LO wave is not suppressed to the first level detector 12, the signal level input to the IRM 9 can be accurately detected. By controlling the gain of the RF-AGC 1 provided in the preceding stage of the IRM 9 using the output, there is an effect that the saturation of the IRM 9 can be avoided. Further, since the frequency of the signal input to the level detector 12 is in the IF band, it is not necessary to use an expensive RF band level detector with a complicated configuration, and the manufacturing cost can be reduced.

Embodiment 2. FIG.
In the first embodiment described above, in order to avoid saturation of IRM9 due to the RF signal including the image signal, the input terminal of the level detector 12 is connected to the output terminal of one unit mixer constituting the IRM9. The level of the input signal is accurately detected. Next, a branch is provided at the output of the other unit mixer that constitutes the IRM9, and an impedance element of an appropriate value is connected to the branch to each unit mixer. In this embodiment, the impedance seen from the load side and the impedance seen from the signal source side from the two input terminals of the output side synthesizer are made equal to avoid the deterioration of the image suppression ratio of the IRM9.

  FIG. 3 is a block diagram of such an embodiment. In the figure, 15 is an impedance element. The same components as those in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, as in the first embodiment, the output of the first unit mixer 3 constituting the IRM 9 is input to the first level detection circuit 12. Then, an impedance element 15 having an appropriate impedance value is connected in parallel to a connection portion between the second unit mixer 4 and the polyphase filter 14 constituting the IRM 9.

  In general, in order to secure 40 dB of the suppression amount (image suppression ratio) of the mixed wave of the image signal and LO wave in IRM9, it is necessary that the amplitude error during synthesis is 0.1 dB or less and the phase error is 1 degree or less. Since the load impedance or signal source impedance of the first unit mixer 3 and the polyphase filter 14 constituting the IRM 9 changes due to the connection of the first level detector 12, it is natural that the output signal amplitude and Phase, pass characteristics, etc. change. However, the amount of change must be within a range where a desired image suppression ratio can be secured, and is a very small value.

  Therefore, as shown in the present embodiment, an impedance element having an appropriate impedance value on the output side of the second unit mixer 4 on the side opposite to the first unit mixer 3 to which the first level detector 12 is connected. 15 are connected in parallel so that the impedance when the load side is viewed from the first and second unit mixers 3 and 4 and the impedance when the signal source side is viewed from the two input terminals of the polyphase filter 14 are made equal. In this way, the two unit mixers 3 and 4 and the polyphase filter 14 cause the same characteristic change and suppress the deterioration of the image suppression ratio as much as possible, and the same as in the above-described embodiments. The signal level input to the IRM 9 can be accurately detected. By using the detected output to control the gain of the RF-AGC 1 provided in the previous stage of the IRM 9, saturation of the IRM 9 can be avoided. Further, since the frequency of the signal input to the level detector 12 is in the IF band, it is not necessary to use an expensive RF band level detector with a complicated configuration, and the manufacturing cost can be reduced.

  Further, in the present embodiment, an appropriate impedance element 15 is connected in parallel to the output side of the second unit mixer 4, but the present invention is not limited to this, and the same is true even if impedance elements are connected in series. effective.

Embodiment 3 FIG.
In the first and second embodiments described above, in order to avoid the saturation of IRM9 due to the RF signal including the image signal, the input terminal of the level detector 12 is connected to the output terminal of one unit mixer constituting the IRM9. The level of the signal input to IRM9 is accurately detected. Next, the outputs of the two unit mixers that make up IRM9 are input to level detector 12 to avoid saturation of IRM9. The form is shown.

  FIG. 4 is a block diagram of such an embodiment. Constituent elements that are the same as those in the previous drawings are given the same numbers, and descriptions thereof are omitted.

  In the present embodiment, the outputs of both the first and second unit mixers 3 and 4 constituting the IRM 9 are input to the first level detection circuit 12, whereby the first and second units inside the IRM 9 are input. The signal level input to the IRM9 is accurately adjusted while equalizing the change in the load impedance of the unit mixers 3 and 4 and the change in the signal source impedance at the two input terminals of the polyphase filter 14 while suppressing deterioration of the image suppression ratio. It detects and avoids saturation of IRM9.

  By using a level detector having two equal input circuits as the first level detector 12, the load impedance of the first and second unit mixers 3 and 4 and the two signal source impedances of the polyphase filter 14 are obtained. Are equal to each other, and the deterioration of the image suppression ratio due to the connection of the first level detector 12 can be suppressed.

  As a matter of course, the signal level input to the IRM 9 can be accurately detected and the gain of the RF-AGC 1 provided in the previous stage of the IRM 9 can be controlled by using the output as in the embodiment described so far. , IRM9 saturation can be avoided. Further, since the frequency of the signal input to the level detector 12 is in the IF band, it is not necessary to use an expensive RF band level detector with a complicated configuration, and the manufacturing cost can be reduced.

  The first level detector 12 may simply output an output signal corresponding to the mean square of the two signals. In principle, the levels of the signals output from the first and second unit mixers 3 and 4 should be the same.

  However, the level of the output signal of one unit mixer may be higher than that of the other due to, for example, the distribution error of the first in-phase distributor 2. In order to cope with such a case, the first level detector 12 may output an output signal corresponding to the level of the larger one of the signals input to the two input terminals. If this is used to control the gain of the RF-AGC 1 in front of the IRM 9, saturation of the IRM 9 can be avoided without fail.

Embodiment 4 FIG.
In the above embodiment, the input terminal of the level detector 12 is connected to the output terminal of one unit mixer constituting the IRM9, and the gain of the RF-AGC1 in the previous stage of the IRM9 is controlled using the output signal. Next, an embodiment in which the gain of the IF-AGC 11 subsequent to the IRM 9 is simultaneously controlled using the output signal of the level detector 12 will be described.

  FIG. 5 is a block diagram of such an embodiment. Constituent elements that are the same as those in the previous drawings are given the same numbers, and descriptions thereof are omitted.

  In the present embodiment, the output signal of the first level detector 12 is used to control the gains of both the RF-AGC1 before the IRM9 and the IF-AGC11 after the IRM9.

  When there is no strong adjacent signal in the signal input to IRM9, the signal level output from IRM9 is estimated based on the input signal level of IRM9, and the gain of IF-AGC11 is changed to perform AD conversion. It is also possible to adjust the level input to the device.

  As a result, the second level detector 13 can be deleted.

Embodiment 5 FIG.
In the above embodiment, in order to avoid saturation of IRM9 by the RF signal including the image signal, the intensity of the output signal of the unit mixer constituting the IRM9 is monitored to control the gain of the RF band variable gain amplifier. Next, an embodiment in which IRM9 bias current is controlled to avoid saturation of IRM9 will be described.

  FIG. 6 is a block diagram of such an embodiment. In the figure, 16 is a bias control circuit for controlling the bias of the first and second unit mixers 3 and 4 constituting the IRM 9, and 17 is an RF band amplifier (RF-AMP) having a predetermined gain. It is assumed that the saturation characteristics of the second unit mixers 3 and 4 can be changed by a bias current. The same components as those in FIG. 1 to FIG.

  Also in the present embodiment, as in the first embodiment, the output of the first unit mixer 3 constituting the IRM 9 is input to the first level detection circuit 12. Then, the output signal is input to the bias control circuit 16 to control the bias currents of the first and second unit mixers 3 and 4 constituting the IRM 9. If the saturation power is increased when the bias current is increased, the saturation of the IRM9 can be avoided even when an RF signal including a strong image signal is input.

  Further, when the first in-phase distributor 2 constituting the IRM 9 is configured by an active circuit, saturation of the IRM 9 can be avoided by simultaneously controlling the bias current.

  In the present embodiment, when a high level RF signal is input, the bias current is controlled to avoid saturation of the IRM9. However, the present invention is not limited to this, and the bias of the RF band amplifier 17 in the previous stage is not limited to this. The current may also be controlled to avoid saturation of both. In addition, when RF signals with low levels are received by actively using bias current control, the bias currents of the RF band amplifier 17 and IRM9 are set low so that the level of the received RF signal is large. As the bias current increases, the power consumption of the entire receiver can be reduced.

  In the present embodiment, as in the third embodiment, in order to suppress a decrease in the image removal ratio due to the connection of the level detector 12 to the output of one unit mixer 3, the two unit mixers 3 and 4 A configuration in which the output is input to the level detector 12 can be considered. In this case, since the level of the signal output from the two unit mixers 3 and 4 can be obtained independently, it is also possible to independently control the bias currents of the two unit mixers 3 and 4 constituting the IRM9. . The configuration of the receiver according to such an embodiment is shown in FIG. In FIG. 7, the level detector 12 inputs the outputs of the two unit mixers 3 and 4 separately, and obtains the signal level independently. The bias control circuit 16 determines the first level according to the level of the signal from the level detector 12. The bias current of the second unit mixers 3 and 4 is optimally controlled. With this configuration, the bias currents of the two unit mixers 3 and 4 are optimally controlled, avoiding saturation when the input signal level is high, and reducing power consumption to a minimum when the input signal level is low be able to.

Embodiment 6 FIG.
In the above embodiment, a Hartley type IRM is used as the IRM 9. Next, a configuration using a Weber type IRM will be described.

  FIG. 8 is a configuration diagram of an embodiment of a receiver according to the present invention using a Weber type IRM24. In the figure, 18 and 19 are the first and second low-pass filters (LPF), 20 is the third in-phase distributor, 21 is the third 90-degree phase shifter, and 22 and 23 are the third, The fourth unit mixer 24 is a Weber type IRM, and the same components as those in FIGS. 1 to 7 are denoted by the same reference numerals and description thereof is omitted.

  The Weber type IRM 24 used in the present embodiment filters the outputs of the first and second unit mixers 3 and 4 with the first and second LPFs 18 and 19, and then the third and second downstream units. This is a configuration in which frequency conversion is performed again by the four unit mixers 22 and 23. The LO waves of the third and fourth unit mixers 22 and 23 in the subsequent stage are distributed in-phase with the LO wave (LO2) supplied from the outside by the third in-phase distributor 20, and then one is directly and the other is the third. The phase shifter 21 is applied to the third and fourth unit mixers 22 and 23 in the subsequent stage with a phase difference of 90 degrees. At the output, the mixed wave of the desired wave and LO wave is in phase, and the mixed wave of the image signal and LO wave is in reverse phase. Only the mixed wave is output.

  Also in the present embodiment, since the output of the first unit mixer 3 constituting the IRM 24 is input to the level detector 12, the intensity of the RF signal including the image signal input to the IRM 24 can be accurately obtained. Since the gain of the RF band variable gain amplifier 1 in the previous stage is controlled by the output of the level detector 12, saturation of the IRM 24 can be avoided.

  In the present embodiment, the output of the first unit mixer 3 constituting the IRM 24 is input to the level detector 12, but the present invention is not limited to this, and the output of the second unit mixer 4 is level detected. It may be input to the device 12. The output of the third unit mixer 22 or the fourth unit mixer 23 may be input to the level detector 12.

Further, as shown in FIG. 9, the output of the first level detector 12 is used to control the bias current of the first, second, third and fourth unit mixers 3, 4, 22, and 23 constituting the IRM 24. Thus, the saturation characteristics of each unit mixer can be improved, and saturation of the IRM24 when a strong level signal is received can be avoided.
In this configuration, the level detector 12 inputs the output of the first unit mixer 3 to detect the signal level, and the bias control circuit 14 uses the first, second, third, and fourth unit mixers 3, The bias current of 4, 22, and 23 is controlled.

Embodiment 7 FIG.
In the above embodiment, the output of the first or second unit mixer constituting the Weber type IRM is input to the level detector. Next, the output of the third or fourth unit mixer in the subsequent stage is input. Is input to the level detector 12. FIG.

  FIG. 10 is a block diagram of an embodiment of a receiver according to the present invention. The same components as those in FIGS. 1 to 9 are denoted by the same reference numerals and description thereof is omitted.

  In the present invention, as shown in FIG. 10, the output signal of the third unit mixer 22 following the first unit mixer 3 is input to the level detector 12. Since the mixed wave of the image signal and the LO wave is suppressed after the output of the in-phase synthesizer 8, the level of the signal input to the IRM 24 including the image signal can also be detected by this configuration.

  FIG. 11 shows another example of the present embodiment, in which 25 is a first AD converter and 26 is a second AD converter. In this configuration, the outputs of the first and second unit mixers 3 and 4 are filtered by the first and second LPFs 18 and 19, and then AD converted by the first and second AD converters 25 and 26. Frequency conversion is performed on the digital signal by the third and fourth unit mixers 22 and 23 in the subsequent stage on the digital circuit. Thereby, it is possible to suppress errors at the time of frequency conversion of the third and fourth unit mixers 22 and 23 in the subsequent stage. Also, since the first level detector 12 can be configured on a digital circuit, the detection accuracy can be easily increased.

  Also in the present embodiment, for example, when the first level detector 12 is connected to the output of the first unit mixer 3, an appropriate impedance element is connected to the output of the second unit mixer 4, so that the IRM 24 It is possible to suppress degradation of the image suppression ratio. Similarly, for example, by inputting the outputs of both the first unit mixer 3 and the second unit mixer 4 to the first level detector 12, it is possible to suppress the deterioration of the image suppression ratio of the IRM 24.

  Since the present invention accurately detects the intensity of the signal input to the IRM using the IF band level detector, the IRM saturation can be avoided with an inexpensive configuration, and the front of the digital television receiver (DTV) can be avoided. When applied to a receiver using an IRM such as an end, the cost of these devices can be reduced.

1 is a diagram showing a configuration of a receiver according to Embodiment 1 of the present invention. FIG. 7 is a diagram showing a configuration of another example of the receiver according to the first embodiment of the present invention. FIG. 6 is a diagram showing a configuration of a receiver according to Embodiment 2 of the present invention. FIG. 6 is a diagram showing a configuration of a receiver according to Embodiment 3 of the present invention. FIG. 10 is a diagram showing a configuration of a receiver according to Embodiment 4 of the present invention. FIG. 10 is a diagram showing a configuration of a receiver according to Embodiment 5 of the present invention. FIG. 11 is a diagram showing a configuration of another example of a receiver according to embodiment 5 of the present invention. FIG. 11 is a diagram showing a configuration of a receiver according to Embodiment 6 of the present invention. FIG. 11 is a diagram showing a configuration of another example of a receiver according to the sixth embodiment of the present invention. FIG. 11 is a diagram showing a configuration of a receiver according to Embodiment 7 of the present invention. FIG. 11 is a diagram showing a configuration of another example of a receiver according to embodiment 7 of the present invention.

Explanation of symbols

  1 RF band variable gain amplifier (RF-AGC) 2 1st in-phase distributor 3 1st unit mixer 4 2nd unit mixer 5 2nd in-phase distributor 6 1st 90 degree shift Phaser, 7 Second 90 degree phase shifter, 8 In-phase synthesizer, 9 Image rejection mixer (IRM), 10 IF band passband filter (IF-BPF), 11 IF band variable gain amplifier (IF- AGC), 12 first level detector, 13 second level detector, 14 polyphase filter, 15 impedance element, 16 bias control circuit, 17 RF band amplifier (RF-AMP), 18 first low frequency band Pass filter (LPF), 19 second low pass filter (LPF), 20 third in-phase distributor, 21 third 90 degree phase shifter, 22 third unit mixer, 23 fourth unit mixer, 24 Weber type IRM, 25 1st AD converter, 26 2nd AD converter.

Claims (13)

At least first and second frequency converters for mixing the received signal and the local oscillation signal, and the outputs of the two frequency converters are combined, the mixed wave of the image signal and the LO wave is suppressed, and the desired wave An image rejection mixer having a synthesis means for outputting a mixed wave of LO waves;
First level detection means for inputting an output signal of one of the first and second frequency converters constituting the image rejection mixer and outputting a signal corresponding to the intensity of the input signal;
A receiver comprising: signal level control means for controlling a signal level of a reception signal input to the image rejection mixer by an output from the first level detection means.   2. The receiver according to claim 1, wherein the signal level control means is a variable gain amplifier that controls a gain of a reception signal input to the image rejection mixer by an output from the first level detection means. . The synthesizing means includes a 90-degree phase shifter that generates a 90-degree phase shift difference between the other outputs of the first and second frequency converters;
The receiver according to claim 1 or 2, comprising an in-phase synthesizer that synthesizes the output of the 90-degree phase shifter and one of the outputs of the first and second frequency converters. .   3. The receiver according to claim 1, wherein the synthesizing unit is constituted by a polyphase filter.   The receiver according to claim 1, wherein an impedance element is connected to a connection portion between the other output terminal of the frequency converter and an input terminal of the combining means.   5. The first level detection means receives the output signals of both the first and second frequency converters constituting the image rejection mixer. Receiving machine.   7. The reception according to claim 2, wherein the first level detection means is configured to control a gain of an intermediate frequency variable gain amplifier that amplifies the output of the image rejection mixer. Machine.   Second level detection means for inputting an output signal of an intermediate frequency variable gain amplifier for amplifying the output of the image rejection mixer and controlling the gain of the intermediate frequency variable gain amplifier according to the intensity of the output signal is provided. The receiver according to any one of claims 2 to 6. At least first and second frequency converters for mixing the received signal and the local oscillation signal, and the outputs of the two frequency converters are combined, the mixed wave of the image signal and the LO wave is suppressed, and the desired wave An image rejection mixer having a synthesizer that outputs a mixed wave of LO waves;
Level detection means for inputting an output signal of one of the first and second frequency converters constituting the image rejection mixer and outputting a signal corresponding to the intensity of the input signal;
A bias control circuit that controls the bias currents of the first and second frequency converters by the output from the level detection means and adjusts the saturation characteristics of the first and second frequency converters; A receiver comprising:   The bias control circuit also controls a bias current of a variable gain amplifier that amplifies a reception signal input to the image rejection mixer. When a low level RF signal is received from the level detection means, the bias control circuit 2 10. The receiver according to claim 9, wherein the bias current of one frequency converter is set low and the bias current is increased as the level of the received RF signal increases.   The receiver according to any one of claims 1 to 10, wherein a Hartley-type image rejection mixer is used as the image rejection mixer. As the image rejection mixer,
First and second previous frequency converters;
The third and fourth frequency converters in the subsequent stage, which respectively input the outputs of the first and second previous frequency converters;
A Weber-type image rejection mixer having synthesis means for synthesizing outputs of the third and fourth frequency converters, suppressing a mixed wave of the image signal and the LO wave, and outputting a mixed wave of the desired wave and the LO wave. The receiver according to claim 1, wherein the receiver is used.   The first level detecting means is configured to input an output signal of any one of the third and fourth frequency converters in the subsequent stage and output a signal corresponding to the intensity of the input signal. The receiver according to claim 12.

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