JP2004289713A - Frequency convertor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a miniaturization, energy saving and cost reduction in a frequency converter for conducting frequency conversion in two ways of both transmission and reception. <P>SOLUTION: The frequency converter is provided with a RF (radio frequency) diplexer 53 and an IF diplexer 54 when it is used for FDD (frequency division duplex) system communications. The RF diplexer 53 transmits radio side transmitting waves only from a mixer 52 to a radio side output unit 42 while it transmits radio side receiving waves only from the radio side input unit 43 to the mixer 52. The IF diplexer 54 transmits cabled side transmitting waves only from a cabled side input unit 41 to a mixer 52 while it transmits cabled side receiving waves only from the mixer 52 to the cabled side output unit 44, and the mixer is shared by transmission (up-convert) and reception (down-convert). When the device is used for TDD (time division duplex) system communications, the diplexer is replaced by a switch and the transmission path is switched over between transmission and reception. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a frequency conversion device that performs mutual conversion between a wireless high frequency and a wired intermediate frequency used in wireless communication, and relates to a frequency conversion device having a simple configuration while preventing interference between transmitted and received signals.
[0002]
[Prior art]
In recent years, with the rapid spread of the Internet, there is a strong need for a wireless communication system that can realize a high-speed communication environment without laying coaxial cables or optical fibers.
As such a wireless communication system, a bidirectional wireless communication system for performing high-speed wireless communication between a base station (master station) and a subscriber station (slave station) using a high frequency of microwaves or millimeter waves of 10 GHz or more. Is being developed. In this two-way wireless communication system, a modem for modulating and demodulating a communication signal and a wireless device having a frequency converter are used.
The conventional frequency converter includes a down converter that converts a high frequency received from a communication partner into an intermediate frequency (usually about several hundred MHz to 3 GHz) for input to a modem, and a down converter that transmits the high frequency received from the modem to the communication partner. Two frequency converters (frequency converters) are provided, including an up-converter that converts the frequency of the intermediate frequency into a high frequency for wireless transmission. The configuration of such a wireless device is disclosed, for example, in Patent Document 1 and Patent Document 2.
Here, the wireless devices disclosed in Patent Literature 1 and Patent Literature 2 are used for time division duplex (TDD) wireless communication, but the basic configuration is the same even in frequency division duplex (FDD). It is.
[0003]
FIG. 4 is a block diagram illustrating a schematic configuration of a conventional wireless device 2.
A transmission signal (hereinafter, referred to as a transmission IF signal) which is an intermediate frequency output from a modulator (modulator) of the modem 3 is frequency-converted to a high frequency by an up-converter A1, and then transmitted through a band-pass filter 15 to a transmission antenna 16 Transmitted (radiated) as radio waves.
The upconverter A1 includes an oscillator 11 that outputs a reference oscillation signal, a transmission mixer 12 that performs frequency conversion (conversion to a high frequency) of the transmission IF signal from the modem 3 using the oscillation signal from the oscillator 11, and a transmission mixer 12. A band-pass filter 13 which receives an output signal of the mixer 12 and passes only a radio frequency band (that is, cuts off other frequency bands); a transmission amplifier 14 which amplifies an output signal of the band-pass filter 13; Is provided. The signal (high frequency) amplified by the transmission amplifier 14 is radiated by the transmission antenna 16 as a radio wave.
On the other hand, a high frequency (hereinafter, referred to as a reception RF signal) transmitted from a communication partner and received by the reception antenna 26 is input to the down-converter A2 via a predetermined band-pass filter 25, and is transmitted to the down-converter A2. After being frequency-converted to a frequency, it is input to the demodulator 32 of the modem 3 (output as viewed from the down-converter A2).
The down-converter A2 includes a receiving amplifier 24 for amplifying a signal received by the receiving antenna 26, a receiving mixer 22 for receiving an output signal of the receiving amplifier 24, and a modem 3 for receiving an output signal of the receiving mixer 22 and receiving the output signal. A band-pass filter 23 that passes only the intermediate frequency band used (that is, blocks other frequency bands). A signal (intermediate frequency) subjected to frequency discrimination by the band-pass filter 23 is input to a demodulator 32 (demodulator) of the modem 3.
Here, the two oscillators 11 and 21 may be combined into one, and the output may be shared by the up-converter A1 and the down-converter A2 by dividing the output by a divider. In this case, the oscillators are individually provided. About twice as much output power (+ α: divider loss) as required is required.
Further, the two antennas 16 and 26 are made into one, and the connection destination is branched by a circulator or a switch as shown in Patent Documents 1 and 2 and connected to the up converter A1 and the down converter A2, respectively. It may be configured as follows.
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-12889 [Patent Document 2]
JP-A-11-262504
[Problems to be solved by the invention]
However, the conventional frequency converter in a wireless device requires a mixer (frequency mixer) for each of the two systems of an up-converter for transmission and a down-converter for reception. There is a problem that it is contrary to cost reduction.
Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a frequency conversion device that performs frequency conversion in both transmission and reception directions by using a mixer (frequency mixer) for transmission (up-conversion). An object of the present invention is to provide a frequency conversion device that can be reduced in size, power consumption, and cost by sharing the frequency converter for reception and down-conversion.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a radio frequency receiving radio wave, which is inputted from a radio input unit, is converted into a wired receiving wave, which is an intermediate frequency, and is output to a wired output unit. A frequency conversion device that converts a wired transmission wave, which is an intermediate frequency input from a side input unit, into a radio transmission wave, which is a high frequency, and outputs the radio transmission wave to a radio output unit.
One frequency mixing unit that performs both frequency conversion from the wireless-side received wave to the wired-side received wave and from the wired-side transmitted wave to the wireless-side transmitted wave;
The wireless-side input unit is provided between the wireless-side output unit and the frequency mixing unit, and transmits the wireless-side reception wave only from the wireless-side input unit to the frequency mixing unit and transmits the wireless-side transmission wave. A wireless connection circuit for transmitting only from the frequency mixing means to the wireless output unit;
The wired-side input section, the wired-side output section, and the frequency-mixing section are provided between the wired-side input section, the wired-side output section, and the frequency-mixing section. And a wired connection circuit for transmitting only from the wired input unit to the frequency mixing means.
Thereby, the radio reception wave wraps around to the radio side output unit and becomes noise of the radio transmission wave wirelessly transmitted to the communication partner, and the wire side transmission wave wraps around to the wire side output unit. Thus, one of the frequency mixing means (that is, the mixer and the reference oscillator) can be shared in both transmission and reception directions while preventing the reception wave from becoming noise on the wired side.
[0007]
For example, when a communication method performed by using the frequency conversion device is a frequency division duplex (FDD) method, the wireless connection circuit connects the wireless reception circuit between the wireless input unit and the frequency mixing unit. A first band-pass filter that allows a wave to pass therethrough and cuts off the radio-side transmission wave; and allows the radio-side transmission wave to pass between the radio-side output unit and the frequency mixing means, and filters the radio-side reception wave. A first diplexer with a second bandpass filter for blocking,
A third band-pass filter configured to pass the wire-side transmission wave and block the wire-side reception wave between the wire-side input unit and the frequency mixing unit; A second diplexer including a fourth band-pass filter that passes the wire-side reception wave and blocks the wire-side transmission wave between the unit and the frequency mixing unit can be considered.
[0008]
Further, when the method of communication performed using the frequency conversion apparatus is a time division duplex (TDD) method, the wireless connection circuit determines a connection destination with the frequency mixing means in the communication of the time division duplex method. A first switch for switching to either the wireless-side input unit or the wireless-side output unit according to a signal transmission direction;
The wired-side connection circuit includes a second switch that switches a connection destination with the frequency mixing unit to either the wired-side input unit or the wired-side output unit according to a signal transmission direction in the time division duplex system. Things are conceivable.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments and examples of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. The following embodiments and examples are mere examples embodying the present invention, and do not limit the technical scope of the present invention.
Here, FIG. 1 is a block diagram showing a schematic configuration of a wireless device provided with the frequency conversion device X according to the embodiment of the present invention, and FIG. 2 is an SN of a reception signal in the frequency conversion device according to the embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a ratio, FIG. 3 is a block diagram illustrating a schematic configuration of a wireless device including a frequency conversion device X1 according to an embodiment of the present invention, and FIG. 4 is a schematic configuration of a wireless device including a conventional frequency conversion device. It is a block diagram showing.
[0010]
Hereinafter, a frequency converter X (hereinafter, referred to as a converter X) according to an embodiment of the present invention will be described with reference to the block diagram of FIG.
The wireless device 1 provided with the converter X is used for wireless communication of the frequency division duplex (FDD) system, and transmits and receives radio waves to the modem 3, which modulates and demodulates transmission / reception data, the converter X, and a transmission partner. ), A receiving antenna 26 for receiving a radio wave from a transmission partner, and predetermined band-pass filters 15 and 16.
A transmission signal (hereinafter, referred to as a transmission IF signal, which is an example of the wire-side transmission wave) which is an intermediate frequency output from a modulator (modulator) of the modem 3 is input from a wire-side input unit 41 to a converter X, and After being frequency-converted to a high frequency by X, the signal is output from the wireless output unit 42 and transmitted (emitted) as a radio wave from the transmitting antenna 16 via the band-pass filter 15. The transmission signal after the frequency conversion (up-conversion) is hereinafter referred to as a transmission RF signal (an example of the radio-side transmission wave).
A high-frequency signal transmitted from a communication partner and received by the reception antenna 26 (hereinafter, referred to as a reception RF signal, which is an example of the radio-side reception wave) is transmitted through a predetermined band-pass filter 25 to the radio-side input unit 43. Is input to the converter X, is converted to an intermediate frequency by the converter X, is output from the wired output unit 44, and is input to the demodulator 32 of the modem 3. The received signal after the frequency conversion (down conversion) is hereinafter referred to as a reception IF signal (an example of the reception wave on the wired side).
[0011]
The converter X includes one mixer 52 for performing both frequency conversion from the reception RF signal to the reception IF signal and from the transmission IF signal to the transmission RF signal, and a reference oscillator 51 for outputting a reference oscillation signal to the mixer 52. A diplexer 53 (hereinafter, referred to as an RF diplexer, an example of the wireless-side connection circuit) provided between the wireless-side input unit 43, the wireless-side output unit 42, and the mixer 52; A diplexer 54 (hereinafter, referred to as an IF diplexer, which is an example of the wired-side connection circuit) provided between the mixer 41 and the wired-side output unit 44 and the mixer 52; a transmission amplifier 14 that amplifies the transmitted RF signal; A reception amplifier 24 for amplifying the reception RF signal. Here, the mixer 52 and the reference oscillator 51 are an example of the frequency mixing means.
Further, the RF diplexer 53 (an example of the first diplexer) allows the reception RF signal to pass (the frequency band of the reception RF signal) between the wireless-side input unit 43 and the mixer 52, and the transmission RF signal A first band-pass filter 53b for blocking a frequency band), and a first band-pass filter 53b for blocking the transmission RF signal and blocking (the frequency region of) the reception RF signal between the wireless output unit 42 and the mixer 52. And two band-pass filters 53a.
This prevents the received RF signal received by the receiving antenna 26 from sneaking into the wireless output unit 42 and becoming noise in the transmitted RF signal wirelessly transmitted to the communication partner.
Similarly, the IF diplexer 54 (an example of the second diplexer) allows the transmission IF signal (the frequency band thereof) to pass between the wired-side input unit 41 and the mixer 52 and the reception IF signal (of the same). A third band-pass filter 54a for blocking the frequency band of the received IF signal and a frequency band of the transmission IF signal between the wired output unit 44 and the periphery of the mixer 52. And a fourth band-pass filter 54b for blocking the band.
This prevents the transmission IF signal output from the modulator of the modem 3 from sneaking into the demodulator of the modem 3 and becoming noise in the reception IF signal received by the modem 3.
[0012]
FIG. 2 shows a case (b) in which the IF diplexer 54 is provided (for the converter X) and a case in which the IF diplexer 54 is directly connected (the wired input unit 41, the wired output unit 44, and the mixer 52 are directly connected). 5A schematically shows the signal level (the level of the transmission signal and the reception signal) of the signal input to the demodulator of the modem 3 and the noise level (the level of the noise floor) in FIG. The horizontal axis represents frequency.
As shown in FIG. 2A, when the IF diplexer 54 is not provided, the transmission signal (the transmission IF signal) is transmitted to the reception signal due to the influence of the transmission signal (the transmission IF signal) wrapping around the demodulator side (wire side output unit) of the modem 3. The signal is superimposed, the noise floor of the reception signal (the reception IF signal) increases, and the SNR (SNR) of the reception signal deteriorates. As a result, communication quality deteriorates.
On the other hand, as shown in FIG. 2B, when the IF diplexer 54 is provided (the present invention), the signal is isolated by the IF diplexer 54, and the SN ratio inherent in the received signal can be maintained. .
The same applies to the presence or absence of the RF diplexer 53. By providing the RF diplexer 53, the S / N ratio of the received signal (transmitted signal as viewed from the wireless device 1) at the communication partner is maintained without deteriorating. can do.
Also, since only one mixer and one reference oscillator occupy much of the space, power consumption, and cost of the device (the output power of the reference oscillator only needs to be one mixer), even if the diplexers 53 and 54 are provided, the conventional It is possible to reduce the size, power consumption, and cost of the device.
[0013]
【Example】
Although the converter X (frequency conversion device) is used for wireless communication of the FDD system, a frequency converter X1 (hereinafter, referred to as a converter X1) according to an embodiment used for wireless communication of the time division duplex (TDD) system. ) Is also conceivable.
FIG. 3 is a block diagram illustrating a schematic configuration of a wireless device 1 ′ including the converter X1.
The wireless device 1 'is obtained by replacing the converter X in the wireless device 1 with a converter X1.
Further, the converter X1 replaces the RF diplexer 53 and the IF diplexer 54 in the converter X with first and second switches 53 'and 54', respectively (hereinafter, referred to as RF switches 53 'and IF switches 54'). Further, a signal detecting means 61 for detecting the generation (power level) of the transmission IF signal is provided between the IF switch 54 'and the wired side input section 41, and the detection result of the signal detecting means 61 A switching circuit 62 for switching the two switches 53 'and 54' based on the switching circuit 62 is provided.
Here, when the signal detection means 61 detects the generation of the transmission IF signal, the switching circuit 62 switches both switches 53 ′ and 54 ′ on the transmission side (the wireless output unit 42 and the wired input unit 41). Side), and in other cases, switch to the receiving side (the side of the wireless side input unit 43 and the wired side output unit 44).
Thereby, according to the signal transmission direction (transmission from the wireless device 1 ′ to the communication partner / transmission from the communication partner to the wireless device 1 ′) in the communication of the TDD system, the connection destination of the mixer 52 (wire-side input unit) 41 and the connection to the wire-side output unit 44 and the connection to the wire-side output unit 43) are switched, so that the reception signal and the transmission signal are isolated. As a result, the transmission IF signal can be prevented from sneaking into the demodulator side (wired output part) of the modem 3 and the reception RF signal can be prevented from sneaking into the wireless output part 42, and the SN of the reception signal and the transmission signal can be prevented. The ratio can be maintained.
Here, if a signal delay circuit for delaying signal transmission for a predetermined time is provided between the signal detection means 61 and the IF switch 54 ', the completion of switching of the IF switch 54' is delayed from the arrival of the transmission IF signal. Can be reliably prevented.
The connection of the switches 53 ′ and 54 ′ may be switched by a control signal from an external device, such as by being controlled by the modem 3 that controls the transmission timing.
Further, the two antennas 16 and 26 are made into one, and the connection destination is branched by a circulator or a switch as shown in Patent Literatures 1 and 2, and the radio output unit 42 and the radio input unit 43 are separated. You may comprise so that it may connect with each. According to this embodiment as well, only one mixer and one reference oscillator occupy much of the space, power consumption and cost of the device (the output power of the reference oscillator is also one mixer). Even if 54 'or the like is provided, it is possible to reduce the size, power consumption, and cost of the device as compared with the related art.
[0014]
【The invention's effect】
As described above, according to the present invention, in a frequency conversion device that performs frequency conversion in both directions of transmission and reception, a connection circuit such as a diplexer or a switch is provided so that a mixer (frequency mixer) can be used for transmission (up-conversion). By sharing the signal for reception (down-conversion), it is possible to reduce the size, power consumption, and cost of the device while maintaining the SN ratio of the transmission and reception signals.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of a wireless device including a frequency conversion device X according to an embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating an SN ratio of a received signal in the frequency conversion device according to the embodiment of the present invention.
FIG. 3 is a block diagram illustrating a schematic configuration of a wireless device including the frequency conversion device X1 according to the embodiment of the present invention.
FIG. 4 is a block diagram illustrating a schematic configuration of a wireless device including a conventional frequency conversion device.
[Explanation of symbols]
1, 1 '... wireless device (the present invention)
2. Conventional wireless device 3. Modem 11, 21, 51. Reference oscillators 12, 22, 51. Mixer 14. Transmit amplifier 16. Transmit antenna 24. Receive amplifier 26. Receive antenna 53. RF diplexer (wireless side connection circuit, The first diplexer)
53 'RF switch (wireless connection circuit, first switch)
54.. IF diplexer (wired side connection circuit, second diplexer)
54 'IF switch (wired side connection circuit, second switch)

Claims (3)

The radio-frequency reception wave, which is a high frequency input from the radio-side input unit, is frequency-converted into a radio-wave reception wave, which is an intermediate frequency, and output to the radio-side output unit. In a frequency converter that converts the frequency of a wire-side transmission wave into a radio-frequency transmission wave that is a high frequency and outputs the converted signal to a radio-side output unit,
One frequency mixing unit that performs both frequency conversion from the wireless-side received wave to the wired-side received wave and from the wired-side transmitted wave to the wireless-side transmitted wave;
The wireless-side input unit is provided between the wireless-side output unit and the frequency mixing unit, and transmits the wireless-side reception wave only from the wireless-side input unit to the frequency mixing unit and transmits the wireless-side transmission wave. A wireless connection circuit for transmitting only from the frequency mixing means to the wireless output unit;
The wired-side input section, the wired-side output section, and the frequency-mixing section are provided between the wired-side input section, the wired-side output section, and the frequency-mixing section. And a wired connection circuit for transmitting only from the wired input unit to the frequency mixing means. The method of communication performed using the frequency conversion device is a frequency division duplexing method,
A first band-pass filter that allows the wireless-side reception wave to pass and blocks the wireless-side transmission wave between the wireless-side input unit and the frequency mixing unit; A first diplexer having a second bandpass filter that passes the radio-side transmission wave and blocks the radio-side reception wave between the unit and the frequency mixing unit;
A third band-pass filter configured to pass the wire-side transmission wave and block the wire-side reception wave between the wire-side input unit and the frequency mixing unit; 2. The frequency according to claim 1, further comprising a second diplexer including a fourth bandpass filter that passes the wire-side reception wave and blocks the wire-side transmission wave between the unit and the frequency mixing unit. Conversion device. The method of communication using the frequency converter is a time division duplex method,
A first switch configured to switch a connection destination with the frequency mixing unit to one of the wireless input unit and the wireless output unit according to a signal transmission direction in the time division duplex communication; Consisting of
The wired-side connection circuit includes a second switch that switches a connection destination with the frequency mixing unit to either the wired-side input unit or the wired-side output unit according to a signal transmission direction in the time division duplex system. The frequency conversion device according to claim 1.

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