Branching filter and wireless communication receiver

Abstract

To provide a radio communication receiver capable of simultaneously receiving two RF signals of two frequency bands in multiband / multimode communication.SOLUTION: A radio communication receiver includes a branching filter 4 for branching a reception wave into a first 1RF signal and a second 2RF signal of different frequency bands, a second 1BDC91 for generating the second 1RF signal by frequency-converting the first 1IF signal, and a second 2BDC92 for generating the second 2RF signal by frequency-converting the second 2IF signal. The multiplexer 4 includes the isolators 41 to which the reception wave is input, the MGT42 that demultiplexes the reception wave that has passed through the isolators 41 into the first incident wave and the second incident wave having equal amplitudes, the first 1RF that generates the first 1BPF45 signal by filtering the first incident wave with the first frequency band as the pass band, and the second 2RF that generates the second 2BPF46 signal by filtering the second incident wave with the second frequency band as the pass band.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wireless communication receiving device used in a wireless communication system using a microwave band or a millimeter wave band. [Background technology]

[0002] In recent years, there has been a rapid increase in demand for low-earth orbit satellites, such as communication satellites and observation satellites. Low-earth orbit satellites are closer to earth stations, resulting in less propagation loss during communications and allowing for smaller sizes. A "satellite constellation configuration" has been put into practical use, in which multiple low-earth orbit satellites are placed in roughly the same orbital plane and operate in cooperation to enable large-capacity communications with earth stations.

[0003] In satellite constellations, "multi-band multi-mode communications" are used, which divide the frequency band and combine multiple modulation methods to make effective use of the specified frequency band. Multi-band multi-mode communications are not limited to satellite communications, but are also widespread in terrestrial communications (especially mobile communications with limited communication areas). When used for communications between low-earth orbit satellites and earth stations, multi-band multi-mode communications require communications between multiple satellites and between multiple satellites and multiple earth stations on a periodic, short-duration basis. For this reason, multi-band multi-mode communications are assigned a relatively wide frequency band to transmit a given amount of data, and quasi-millimeter wave or millimeter wave bands are often used.

[0004] Conventional receivers used in multiband / multimode communications divide the received signal received by the antenna into predetermined RF bandwidths. To achieve this, the receiver has a filter bank, which consists of multiple bandpass filters arranged in parallel, each with a different passband frequency. RF switches (single-pole, multi-throw) are connected to the input and output terminals of the filter bank. By controlling the RF switches, the filter bank outputs an RF signal that has passed through the predetermined passband (RF band). The output RF signal undergoes superheterodyne frequency conversion using a predetermined local oscillator and mixer, converting it into an intermediate frequency IF signal. The IF signal is then transmitted to the receiver, which includes a demodulator in the downstream stage.

[0005] The part that supports multiband is the RF front end. The RF front end includes a low-noise amplifier that performs low-noise amplification of the received wave, a filter bank, a mixer that is a frequency conversion circuit, a local oscillator, an IF filter, an IF amplifier, etc. Multimode refers to multiple modulation methods. The part that supports multimode is the demodulation section that is connected after the IF signal generated by frequency conversion.

[0006] Patent Document 1 discloses a receiving device that uses a filter bank to discriminate and select a predetermined frequency band from a received wave. Patent Document 2 discloses a wireless communication device used for spectrum sensing. This wireless communication device uses a filter bank to discriminate and select a predetermined band from a received wave, and detects the IF signal spectrum generated by superheterodyne frequency conversion. The wireless communication device can arbitrarily set the number of bandpass filters, and uses a switch matrix to select the bandpass filters to be used in the filter bank. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-189670 [Patent Document 2] Japanese Patent Application Publication No. 2015-095842 Summary of the Invention [Problem to be solved by the invention]

[0008] In Patent Document 1, one of two frequency bands is selected from the received signal, and the RF signal of the selected frequency band is frequency-converted to output an IF signal. Therefore, the receiving device of Patent Document 1 cannot meet the requirements of multi-band / multi-mode communication, which simultaneously frequency-converts two RF signals of different frequency bands and simultaneously outputs two IF signals. Patent Document 2 aims to receive and detect RF signals in space where the frequency and amplitude of the RF signal change over time. The wireless communication device of Patent Document 2 has too many unnecessary functions when used for multi-band / multi-mode communication. In other words, even though the wireless communication device of Patent Document 2 can simultaneously receive two RF signals by switching between switch matrices, the device is large and cost-intensive due to the need for switch matrix control signal generation and switch drivers, making it impractical.

[0009] The present invention solves these problems, and its main objective is to provide a wireless communication receiving device that can simultaneously receive two types of RF signals in two frequency bands during multi-band / multi-mode communication, frequency-convert the RF signals, and simultaneously output two types of IF signals. [Means for solving the problem]

[0010] The duplexer of the present invention is a duplexer that separates a received wave into a first RF signal and a second RF signal of different frequency bands, and is characterized by comprising: a waveguide magic-tee that separates the received wave into a first incident wave and a second incident wave of equal amplitude; a first filter that generates the first RF signal by filtering the first incident wave using a predetermined first frequency band as a pass band; and a second filter that generates the second RF signal by filtering the second incident wave using a second frequency band different from the first frequency band as a pass band. [Effects of the Invention]

[0011] According to the present invention as described above, during multi-band / multi-mode communication, it is possible to simultaneously receive two types of RF signals in two frequency bands, frequency-convert the RF signals, and simultaneously output two types of IF signals. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a circuit diagram of a wireless communication receiving device. [Figure 2] An explanatory diagram of a splitter. [Figure 3] FIG. 3 is a diagram illustrating the relationship between the passbands of a first BPF and a second BPF. [Figure 4] FIG. 1 is a circuit diagram of a wireless communication receiving device. [Figure 5] FIG. 1 is a circuit diagram of a wireless communication receiving device. [Figure 6] FIG. 1 is a circuit diagram of a wireless communication receiving device. [Figure 7] FIG. 1 is a circuit diagram of a wireless communication receiving device. [Figure 8] FIG. 1 is a circuit diagram of a wireless communication receiving device. [Figure 9] FIG. 1 is a circuit diagram of a wireless communication receiving device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary. Note that the numerical values ​​of frequency bands, frequencies, bandwidths, etc. used in the following description are merely examples and are not limited to the numerical values ​​in the specification.

[0014] (First embodiment) 1 is a circuit diagram of a wireless communication receiving device of the first embodiment. The wireless communication device is a receiving device for a wireless communication system using a wideband radio frequency. The wireless communication device includes a low noise amplifier (hereinafter referred to as "LNA") 2, a branching filter 4 using a waveguide magic-tee (hereinafter referred to as "MGT") 42, a first frequency conversion unit (hereinafter referred to as "first BDC") 91, and a second frequency conversion unit (hereinafter referred to as "second BDC") 92.

[0015] The wireless communication device generates and outputs two types of IF signals from two types of received waves (RF signals) belonging to a predetermined frequency band received by an antenna (not shown) using a first BDC 91 and a second BDC 92. The received waves in this embodiment have a frequency in the quasi-millimeter wave band of 20 GHz to 26 GHz, for example, but are not limited to this and may be in the millimeter wave band. The wireless communication device has an input terminal 1 to which the received waves are input.

[0016] The LNA 2 amplifies the received wave (RF signal) input from the input terminal 1 with a predetermined gain. The received wave (RF signal) amplified by the LNA 2 is transmitted to the demultiplexer 4. The demultiplexer 4 includes an isolator 41, an MGT 42 in which a reflectionless terminator 43 is provided in the branching waveguide of an E-plane T-branch circuit, a first band-pass filter (hereinafter referred to as "first BPF") 45, and a second band-pass filter (hereinafter referred to as "second BPF") 46. The first BPF 45 and the second BPF 46 are, for example, waveguide-type band-pass filters and have different passbands. The passband of the first BPF 45 is, for example, 20 GHz to 22 GHz. The passband of the second BPF 46 is, for example, 24 GHz to 26 GHz. The demultiplexer 4 simultaneously splits the received wave (RF signal) into RF signals of different frequency bands and outputs them. In this embodiment, the demultiplexer 4 splits the received wave (RF signal) into two signals: an RF signal (first RF signal) in the band of 20 GHz to 22 GHz, and an RF signal (second RF signal) in the band of 24 GHz to 26 GHz.

[0017] The first BDC 91 includes a first mixer 9, a first local oscillator 10, a first IF bandpass filter 11, and a first IF amplifier 12. The first local oscillator 10 outputs, for example, a 19 GHz AC signal. The first BDC 91 converts the first RF signal in the 20 GHz to 22 GHz band output from the first BPF 45 into a first IF signal in the 1 GHz to 3 GHz band. The first IF signal generated in this manner is output from an output terminal 13.

[0018] The second BDC 92 includes a second mixer 16, a second local oscillator 17, a second IF bandpass filter 18, and a second IF amplifier 19. The second local oscillator 17 outputs, for example, a 23 GHz AC signal. The second BDC 92 converts the second RF signal in the 24 GHz to 26 GHz band output from the second BPF 46 into a second IF signal in the 1 GHz to 3 GHz band. The second IF signal generated in this manner is output from an output terminal 20.

[0019] FIG. 2 is an explanatory diagram of the duplexer 4. The MGT 42 is a hybrid power divider (power combiner) configured by combining a rectangular waveguide of an H-plane T-branch circuit and a rectangular waveguide of an E-plane T-branch circuit. The fundamental mode in which the MGT 42 operates is the fundamental mode of the rectangular waveguide, TE 10 The MGT 42 has a first port P1 provided in the branching waveguide of the H-plane T-junction, a second port P2 provided at one end of the main waveguide of the H-plane T-junction, a third port P3 provided at the other end of the main waveguide of the H-plane T-junction, and a fourth port P4 provided in the branching waveguide of the E-plane T-junction.

[0020] An isolator 41 is connected to the first port P1. The isolator 41 is, for example, a waveguide isolator. An input terminal 3 is provided at the input end of the isolator 41. A received wave (RF signal) amplified by the LNA 2 is input to the isolator 41 via the input terminal 3. The received wave (RF signal) input from the input terminal 3 is input to the first port P1 of the MGT 42, with a forward loss caused by the isolator 41. The received wave (RF signal) is split into an RF incident wave 51 and an RF incident wave 54 of equal amplitude within the H-plane T-branch circuit. The RF incident wave 51, which is one of the split received waves, is output from the second port P2. The RF incident wave 54, which is the other of the split received waves, is output from the third port P3.

[0021] The RF incident wave 51 output from the second port P2 is input to the first BPF 45. The first BPF 45 filters the RF incident wave 51 according to the pass band (band-1). The RF incident wave 51 is filtered by the first BPF 45 to become a first RF signal 52, which is a transmitted wave. The RF incident wave 54 output from the third port P3 is input to the second BPF 46. The second BPF 46 filters the RF incident wave 54 according to the pass band (band-2). The RF incident wave 54 is filtered by the second BPF 46 to become a second RF signal 55, which is a transmitted wave.

[0022] An RF incident wave 51 outside the passband of the first BPF 45 is reflected by the first BPF 45 and becomes an RF reflected wave 53. The RF reflected wave 53 is equally divided into an RF reflected wave 53E and an RF reflected wave 53H. The RF reflected wave 53E is transmitted to the fourth port P4. The RF reflected wave 53H is transmitted to the first port P1.

[0023] The fourth port P4 is provided with a non-reflection terminator 43 made up of a radio wave absorber 44 inside the waveguide. The RF reflected wave 53E transmitted to the fourth port P4 is terminated by the non-reflection terminator 43 and disappears. The RF reflected wave 53H is a backward transmission wave of the isolator 41 connected to the first port P1. Therefore, the RF reflected wave 53H is absorbed and attenuated by the isolator 41, and is reduced to a negligible level as a transmission signal.

[0024] An RF incident wave 54 outside the passband of the second BPF 46 is reflected by the second BPF 46 and becomes an RF reflected wave 56. The RF reflected wave 56 is equally divided into an RF reflected wave 56E and an RF reflected wave 56H. The RF reflected wave 56E is transmitted to the fourth port P4. The RF reflected wave 56H is transmitted to the first port P1. Like the RF reflected wave 53E, the RF reflected wave 56E is terminated by the non-reflection terminator 43 and disappears. Like the RF reflected wave 53H, the RF reflected wave 56H is absorbed and attenuated by the isolator 41 and reduced to a level that can be ignored as a transmission signal.

[0025] In this way, the demultiplexer 4 demultiplexes the input received wave (RF signal) into two (first RF signal 52 and second RF signal 55) while maintaining practical performance using the isolator 41, MGT 42, first BPF 45, and second BPF 46. When the isolator 41, MGT 42, first BPF 45, and second BPF 46 are all formed of waveguides, the demultiplexer 4 can also be configured as an integrated structure.

[0026] FIG. 3 is an explanatory diagram of the relationship between the passbands of the first BPF 45 and the second BPF 46. A guard band is provided between the passband (band-1) of the first BPF 45 and the passband (band-2) of the second BPF 46. The setting amount of the guard band is determined by the out-of-band attenuation of each of the first BPF 45 and the second BPF 46. That is, the out-of-band attenuation of the first BPF 45 is determined so as to ensure the band-1 interference suppression amount specified for the receiving device at the lower limit frequency of the passband (band-2) of the second BPF 46. The out-of-band attenuation of the second BPF 46 is determined so as to ensure the band-2 interference suppression amount specified for the receiving device at the upper limit frequency of the passband (band-1) of the first BPF 45. The interference suppression amount is usually set to about 30 dB. The insertion loss of the entire demultiplexer 4 is the sum of the insertion loss within the passband of the first BPF 45 or the second BPF 46, the insertion loss due to the isolator 41, and the distribution loss due to the MGT 42. The distribution loss due to the MGT 42 is defined to include the insertion loss of the MGT 42, and is approximately 3 dB in this embodiment.

[0027] Returning to the explanation of FIG. 1 , the first RF signal 52 that has passed through the first BPF 45 is output from the first output terminal 8 of the branching filter 4 and input to the first BDC 91. The first BDC 91 is a frequency conversion section that uses a superheterodyne single conversion method. The first RF signal 52 is mixed by the first mixer 9 with the local signal Lo-1, which is an AC signal input from the first local oscillator 10. This generates a mixed wave that includes unwanted waves. The first IF bandpass filter 11 discriminates the first IF signal IF-1 of a predetermined frequency from the mixed wave. The first IF amplifier 12 amplifies the first IF signal IF-1 and outputs it from the output terminal 13.

[0028] The second RF signal 55 that has passed through the second BPF 46 is output from the second output terminal 15 of the demultiplexer 4 and input to the second BDC 92. The second BDC 92 is a frequency conversion unit that uses the superheterodyne single conversion method, similar to the first BDC 91. The second RF signal 55 is processed by the second BDC 92 in the same way as the first RF signal 52, and is output from the output terminal 20 as the second IF signal IF-2.

[0029] The wireless communication receiving device configured as described above can demultiplex a received wave including RF signals of multiple frequency bands received by an antenna into each frequency band, and generate an IF signal for each demultiplexed RF signal. In the above example, a received wave including a frequency band of 20 GHz to 22 GHz and a frequency band of 24 GHz to 26 GHz is demultiplexed, and two IF signals in a frequency band of 1 GHz to 3 GHz are generated.

[0030] Therefore, during multi-band / multi-mode communication, the wireless communication receiving device separates a received wave containing RF signals of two frequency bands into two RF signals of different frequency bands, and can receive each independently and simultaneously. Each RF signal is converted to a predetermined IF signal by frequency conversion. The IF signal can also be demodulated to generate a baseband signal, for example.

[0031] (Second embodiment) FIG. 4 is a circuit diagram of a wireless communication receiving device of the second embodiment. Like the first embodiment, the wireless communication device of the second embodiment is a receiving device for a wireless communication system using a wideband radio frequency. The first and second embodiments differ in the conversion method used by the frequency converter. Specifically, the first and second BDCs 91 and 92 of the first embodiment employ a superheterodyne single-conversion method, whereas the first frequency converter (hereinafter referred to as "first BDC") 97 and the second frequency converter (hereinafter referred to as "second BDC") 98 of the second embodiment employ a superheterodyne double-conversion method. Since the other components (LNA 2 and duplexer 4) are the same, their descriptions will be omitted, and only the differences will be described.

[0032] The first BDC 97 includes a first frequency conversion mixer 971, a first frequency conversion band-pass filter 972, a first frequency conversion amplifier 973, a first frequency conversion output terminal 974, a second frequency conversion mixer 975, a second frequency conversion local oscillator 976, a second frequency conversion band-pass filter 977, and an output terminal 978. The second BDC 98 includes a first frequency conversion mixer 981, a first frequency conversion band-pass filter 982, a first frequency conversion amplifier 983, a first frequency conversion output terminal 984, a second frequency conversion mixer 985, a second frequency conversion local oscillator 986, a second frequency conversion band-pass filter 987, and an output terminal 988.

[0033] The first frequency conversion mixer 971 of the first BDC 97 and the first frequency conversion mixer 981 of the second BDC 98 are supplied with an AC signal from a common first local oscillator 989. The AC signal output from the first local oscillator 989 is distributed by a power divider 979 to the first frequency conversion mixer 971 and the first frequency conversion mixer 981.

[0034] In the second embodiment, the demultiplexer 4 receives a received wave (RF signal) of 37 GHz to 43 GHz and outputs a first RF signal 52 of 37 GHz to 39 GHz and a second RF signal 55 of 41 GHz to 43 GHz. The first local oscillator 989 outputs a first local signal Lo, which is an AC signal of 29 GHz. The local oscillator 976 for secondary frequency conversion of the first BDC 97 outputs a second local signal Lo-1, which is an AC signal of 7 GHz. The local oscillator 986 for secondary frequency conversion of the second BDC 98 outputs a second local signal Lo-2, which is an AC signal of 11 GHz.

[0035] The first RF signal 52 output from the first output terminal 8 of the demultiplexer 4 is input to the first frequency conversion mixer 971 of the first BDC 97. The first frequency conversion mixer 971 mixes the first RF signal 52 with the first local signal Lo input from the first local oscillator 989 to generate a first mixed wave including undesired waves. The first frequency conversion bandpass filter 972 filters the first mixed wave to discriminate a first filtered signal of a predetermined frequency band. Here, the frequency band of the first filtered signal is, for example, 8 GHz to 10 GHz.

[0036] The first filtered signal is amplified by a first frequency conversion amplifier 973 at a predetermined gain and input from a first frequency conversion output terminal 974 to a second frequency conversion mixer 975. The second frequency conversion mixer 975 mixes the first filtered signal input from the first frequency conversion output terminal 974 with a second local signal Lo-1 input from a second frequency conversion local oscillator 976 to generate a second mixed wave including undesired waves. The second frequency conversion bandpass filter 977 filters the second mixed wave and discriminates a first IF signal IF-1 of a predetermined frequency band. Here, the frequency band of the first IF signal IF-1 is, for example, 1 GHz to 3 GHz. The first IF signal IF-1 is output from an output terminal 978.

[0037] The second RF signal 55 output from the second output terminal 15 of the demultiplexer 4 is input to a first frequency conversion mixer 981 of the second BDC 98. Each component of the second BDC 98 operates in the same manner as the corresponding component of the first BDC 97, and therefore detailed description thereof will be omitted. The second BDC 98 ultimately outputs a second IF signal IF-2 of a predetermined frequency band from an output terminal 988. The frequency band of the second IF signal IF-2 is, for example, 1 GHz to 3 GHz.

[0038] The wireless communication receiving device configured as described above can demultiplex a received wave including RF signals of multiple frequency bands received by an antenna into each frequency band, and generate an IF signal for each demultiplexed RF signal. In the above example, a received wave including a frequency band of 37 GHz to 39 GHz and a frequency band of 41 GHz to 43 GHz is demultiplexed, and two IF signals in a frequency band of 1 GHz to 3 GHz are generated.

[0039] Therefore, during multi-band / multi-mode communication, the wireless communication receiving device separates a received wave containing RF signals of two frequency bands into two RF signals of different frequency bands, and can receive each independently and simultaneously. Each RF signal is converted to a predetermined IF signal by frequency conversion. The IF signal can also be demodulated to generate a baseband signal, for example.

[0040] (Third embodiment) FIG. 5 is a circuit diagram of a wireless communication receiving device of the third embodiment. Like the first embodiment, the wireless communication device of the third embodiment is also a receiving device for a wireless communication system using a wideband radio frequency. The third embodiment differs from the first and second embodiments in that it ultimately demodulates an RF signal into an analog baseband signal and outputs the signal. For this reason, the wireless communication receiving device of the third embodiment has a configuration for demodulating an IF signal into an analog baseband signal, which is connected to the downstream of the wireless communication receiving device of the first or second embodiment. FIG. 5 shows an example in which a configuration for demodulating an IF signal into an analog baseband signal is connected to the downstream of the wireless communication receiving device of the first embodiment (see FIG. 1).

[0041] 5, the configurations of the LNA 2, the demultiplexer 4, the first BDC 91, and the second BDC 92 are the same as those of the wireless communication receiving device of the first embodiment. However, the frequencies of the first local signal Lo-1 output by the first local oscillator 10 of the first BDC 91 and the second local signal Lo-2 output by the second local oscillator 17 of the second BDC 92 are different. Here, an example will be described in which the frequency of the first IF signal IF-1 generated by the first BDC 91 is fixed to a bandwidth of 500 MHz.

[0042] The first BDC 91 divides the bandwidth of the input first RF signal 52 into 500 MHz increments, and varies the frequency of the first local signal Lo-1 output by the first local oscillator 10 in steps that match the 500 MHz bandwidth according to the frequency band of the first IF signal IF-1 to be generated. In other words, the frequency of the first local signal Lo-1 varies in 500 MHz intervals.

[0043] To give a specific example, the frequency band of the first RF signal 52 is assumed to be 22 GHz to 23 GHz. The first RF signal 52 is divided into a 500 MHz bandwidth and subjected to frequency conversion processing. In the frequency conversion processing, first, the frequency of the first RF signal 52 is 22.0 GHz to 22.5 GHz (500 MHz bandwidth), while the frequency of the local signal Lo-1 is set to 19.0 GHz. As a result, a first IF signal IF-1 of 3.0 GHz to 3.5 GHz (500 MHz bandwidth) is obtained. In the next step, the frequency of the first RF signal 52 is 22.5 GHz to 23.0 GHz (500 MHz bandwidth), while the frequency of the local signal Lo-1 is set to 19.5 GHz, thereby obtaining a first IF signal IF-1 of 3.0 GHz to 3.5 GHz (500 MHz bandwidth).

[0044] That is, the demultiplexer 4 divides the frequency band (22 GHz to 26 GHz) of the received wave (RF signal) into two and outputs a first RF signal 52 with a frequency band of 22 GHz to 23 GHz and a second RF signal 55 with a frequency band of 25 GHz to 26 GHz. The first BDC 91 divides the first RF signal 52 into 500 MHz bandwidths and performs frequency conversion on each of the divided first RF signals 52 by varying the frequency of the local signal Lo-1 in 500 MHz steps, thereby generating a first IF signal IF-1 with a frequency band of 3.0 GHz to 3.5 GHz (bandwidth of 500 MHz).

[0045] The second BDC 92 operates in the same manner as the first BDC 91, and generates a second IF signal IF-2 having a frequency band of 3.0 GHz to 3.5 GHz (bandwidth of 500 MHz) from the second RF signal 55. The local signal Lo-2 of the second BDC 92 has a frequency band of 22 GHz to 22.5 GHz and is variable in 500 MHz intervals.

[0046] In this way, the RF signals (first RF signal 52 and second RF signal 55) are divided into predetermined bandwidths (500 MHz width), and the frequency of the local signal is varied in 500 MHz steps for the RF signals of each divided bandwidth to generate a mixed wave. This mixed wave is filtered to generate an IF signal with a frequency band of 3.0 GHz to 3.5 GHz.

[0047] The IF signals for each bandwidth (first IF signal IF-1, second IF signal IF-2) generated in this way are demodulated into baseband signals. To this end, a first baseband conversion unit (hereinafter referred to as "first BBC") 100 is provided after the first BDC 91, and a second baseband conversion unit (hereinafter referred to as "second BBC") 101 is provided after the second BDC 92. The first BBC 100 and the first BBC 101 have the same configuration.

[0048] The first BBC 100 includes an I-component mixer 60, an I-component variable-bandwidth LPF (Low-pass Filter) 61, and an I-component variable-gain amplifier 62 to generate an I-component baseband signal. A local signal LoIF-1, which is an AC signal, is input to the I-component mixer 60 from a local oscillator 67. The I-component mixer 60 mixes the first IF signal IF-1 and the local signal LoIF-1 to generate a mixed wave containing the I-component baseband signal. Here, the frequency of the first IF signal IF-1 and the frequency of the local signal LoIF-1 are the same. The mixed wave has its high-frequency components filtered out by the I-component variable-bandwidth LPF 61 and is then amplified by the I-component variable-gain amplifier 62, thereby extracting an I-component baseband signal of a predetermined amplitude. The I-component baseband signal is output from an output terminal 68.

[0049] The first BBC 100 includes a Q component mixer 63, a Q component variable band LPF 65, and a Q component variable gain amplifier 66 to generate a Q component baseband signal. A local signal LoIF-1 is input from a local oscillator 67, with its phase shifted by 90° by a 90° phase shifter 64. The Q component mixer 63 mixes the first IF signal IF-1 with the phase-shifted local signal LoIF-1 to generate a mixed wave including a Q component baseband signal. The mixed wave has its high-frequency components filtered by the Q component variable band LPF 65 and is then amplified by the Q component variable gain amplifier 66, thereby extracting a Q component baseband signal of a predetermined amplitude. The Q component baseband signal is output from an output terminal 69.

[0050] The second BBC 101 has the same configuration as the first BBC 100 and performs the same operation. The second BBC 101 performs the same processing on the second IF signal IF-2 output from the output terminal 20 as the first BBC 100 performed on the first IF signal IF-1, thereby generating an I-component baseband signal and a Q-component baseband signal. Here, the second IF signal IF-2 of the second BBC 101 and the local signal LoIF-2, which is an AC signal output from the local oscillator 77, have the same frequency. The I-component baseband signal is output from the output terminal 78. The Q-component baseband signal is output from the output terminal 79.

[0051] In this way, the baseband signal is preserved even when the RF signal (IF signal) is frequency converted. Therefore, for high-frequency RF signals, it is practical to first convert them to a lower frequency using a frequency converter and then convert them to baseband. This method is called the direct conversion method.

[0052] The baseband signals output from output terminals 68 and 69 are analog signals. To convert the baseband signals into digital signals, the baseband signals must be AD converted by sampling. The same applies to the baseband signals output from output terminals 78 and 79.

[0053] While the configuration in which the first BBC100 and the first BBC101 are added to the wireless communication receiving device of the first embodiment has been described above, similar processing is possible with a configuration in which the first BBC100 and the first BBC101 are added to the wireless communication receiving device of the second embodiment. In this case, the first local signal Lo output from the first local oscillator 989, the second local signal Lo-1 output from the second frequency conversion local oscillator 976, and the second local signal Lo-1 output from the second frequency conversion local oscillator 986 are varied in steps matching the bandwidth according to the frequency band of the IF signal to be generated. The wireless communication receiving device of the third embodiment has the same effects as the first and second embodiments, and is capable of generating a baseband signal by demodulating the IF signal converted from the RF signal.

[0054] (Fourth embodiment) 6 and 7 are circuit diagrams of a wireless communication receiving device of the fourth embodiment. Like the first and second embodiments, the wireless communication device of the fourth embodiment is a receiving device for a wireless communication system using a wideband radio frequency. The first and second embodiments differ from the fourth embodiment in that the fourth embodiment simultaneously receives and frequency-converts a first RF signal 52 and a second RF signal 55 obtained by dividing an RF signal into two, and then outputs the respective IF signals alternately in a time-division manner.

[0055] Fig. 6 is a circuit diagram of a wireless communication receiving device according to a modified example of the first embodiment. This wireless communication receiving device has a configuration in which a single-pole double-throw switch (hereinafter referred to as "SPDT") 21 that operates in the IF signal band is provided between the output terminal 13 of the first BDC 91 and the output terminal 20 of the second BDC 92 in Fig. 1. The SPDT 21 has a branch terminal 13A to which the output terminal 13 of the first BDC 91 is connected, a branch terminal 20A to which the output terminal 20 of the second BDC 92 is connected, and a common terminal 22.

[0056] An IF receiving unit (not shown) including a demodulator is connected downstream of the common terminal 22. The SPDT 21 is driven and controlled in synchronization with the IF receiving unit, and the branch terminal connected to the common terminal 22 is switched between branch terminal 13A and branch terminal 20A. By switching between branch terminal 13A and branch terminal 20A, the demultiplexed first RF signal 52 and second RF signal 55 are alternately transmitted to the downstream in a time-division manner. This enables time-division reception of the first RF signal 52 and the second RF signal 55.

[0057] Fig. 7 is a circuit diagram of a wireless communication receiving device according to a modification of the second embodiment. This wireless communication receiving device has a configuration in which an SPDT 21 that operates in the IF signal band is provided between the output terminal 978 of the first BDC 97 and the output terminal 988 of the second BDC 98 in Fig. 4. The SPDT 21 operates in the same manner as in Fig. 6. This enables time-division reception of the first RF signal 52 and the second RF signal 55.

[0058] As described above, by adding the SPDT 21 to the wireless communication receiving device of the first and second embodiments, during multiband / multimode communication, a received wave containing RF signals of two frequency bands can be demultiplexed into RF signals of two frequency bands, and each can be received independently and simultaneously. The two IF signals obtained by frequency conversion of the two RF signals are output in a time-division manner.

[0059] (Fifth embodiment) 8 and 9 are circuit diagrams of a wireless communication receiving device of the fifth embodiment. Like the first to fourth embodiments, the wireless communication device of the fifth embodiment is a receiving device for a wireless communication system using a wideband radio frequency. The fifth embodiment differs from the first to fourth embodiments in that the received wave (RF signal) is divided into three or four parts for each predetermined frequency band. For this reason, the wireless communication receiving device of the fifth embodiment is configured to include a plurality of the branching filters 4 described in the first embodiment.

[0060] Fig. 8 shows a wireless communication receiving device in which a received wave (RF signal) is divided into three parts with different predetermined frequency bands. Fig. 8 shows a configuration in which a second branching filter 104 is connected to the second output terminal 15 of the branching filter 4 in Fig. 1, and a third BDC 93 and a fourth BDC 94 are connected in a stage subsequent to the second branching filter 104. The first BDC 91, the third BDC 93, and the fourth BDC 94 are all frequency conversion sections of the superheterodyne single conversion system.

[0061] The demultiplexer 4 outputs a first RF signal 52 and a second RF signal 55. The first RF signal 52 is input to the first BDC 91 as in the first embodiment, and is frequency-converted by the first BDC 91 to a first IF signal IF-1. The second RF signal 55 is input to the second demultiplexer 104, and is demultiplexed by the second demultiplexer 104 into a third RF signal and a fourth RF signal. The third RF signal is input to the third BDC 93, and is frequency-converted by the third BDC 93 to a third IF signal. The fourth RF signal is input to the fourth BDC 94, and is frequency-converted by the fourth BDC 94 to a fourth IF signal.

[0062] The third BDC 93 and fourth BDC 94 have the same configuration as the first BDC 91, differing only in the frequency of the AC signal output from the local oscillator. Here, the first local oscillator 10 of the first BDC 91 outputs a local signal Lo-1, which is an AC signal of 19 GHz. The third local oscillator 117 of the third BDC 93 outputs a local signal Lo-3, which is an AC signal of 23 GHz. The fourth local oscillator 127 of the fourth BDC 94 outputs a local signal Lo-4, which is an AC signal of 25 GHz. The first BDC 91 outputs a first IF signal IF-1 of 1 GHz to 4 GHz. The third BDC 93 outputs a third IF signal of 1 GHz to 2 GHz. The fourth BDC 94 outputs a fourth IF signal of 1 GHz to 2 GHz.

[0063] Fig. 9 shows a wireless communication receiving device in which a received wave (RF signal) is divided into four parts with different predetermined frequency bands. Fig. 9 shows a configuration in which a third demultiplexer 204 is connected to the first output terminal 8 of the first-stage demultiplexer 4 in Fig. 8, and a fifth BDC 95 and a sixth BDC 96 are connected in a stage subsequent to the third demultiplexer 204. The third BDC 93, fourth BDC 94, fifth BDC 95, and sixth BDC 96 are all frequency conversion sections of the superheterodyne single conversion system.

[0064] The demultiplexer 4 outputs a first RF signal 52 and a second RF signal 55. As described in FIG. 8 , the second RF signal 55 is demultiplexed by the second demultiplexer 104 into a third RF signal and a fourth RF signal, and then frequency-converted by the third BDC 93 and the fourth BDC 94 into a third IF signal and a fourth IF signal. The first RF signal 52 is input to the third demultiplexer 204 and demultiplexed by the third demultiplexer 204 into a fifth RF signal and a sixth RF signal. The fifth RF signal is input to the fifth BDC 95 and frequency-converted by the fifth BDC 95 into a fifth IF signal. The sixth RF signal is input to the sixth BDC 96 and frequency-converted by the sixth BDC 96 into a sixth IF signal.

[0065] The fifth BDC 95 and sixth BDC 96 have the same configuration as the third BDC 93 and fourth BDC 94, differing only in the frequency of the AC signal output from the local oscillator. The third BDC 93 and fourth BDC 94 have local signals Lo-3 and Lo-4 that are the same as those in FIG. 8, and the frequency bands of the IF signals are also the same. The fifth local oscillator 210 of the fifth BDC 95 outputs a local signal Lo-5 that is a 19 GHz AC signal. The sixth local oscillator 217 of the sixth BDC 96 outputs a local signal Lo-6 that is a 21 GHz AC signal. The fifth BDC 95 outputs a fifth IF signal of 1 GHz to 2 GHz. The sixth BDC 96 outputs a sixth IF signal of 1 GHz to 2 GHz.

[0066] The wireless communication receiving device configured as described above can demultiplex a received wave including RF signals of multiple frequency bands received by an antenna into each frequency band, and generate an IF signal for each demultiplexed RF signal. In the above example, a received wave including a frequency band of 20 GHz to 23 GHz and a frequency band of 24 GHz to 27 GHz is demultiplexed into three in Fig. 8 and into four in Fig. 9. In Fig. 8, three IF signals are generated in the frequency bands of 1 GHz to 2 GHz, 1 GHz to 2 GHz, and 1 GHz to 4 GHz. In Fig. 9, a total of four IF signals are generated in the frequency band of 1 GHz to 2 GHz.

[0067] For this reason, during multiband / multimode communication, the wireless communication receiving device can separate received waves containing RF signals of multiple frequency bands into multiple frequency bands and receive each of the multiple frequency bands independently and simultaneously. Each RF signal is converted into a predetermined IF signal by frequency conversion. The IF signal can also be demodulated to generate a baseband signal. For example, the baseband signal can be generated by providing the baseband conversion units described in FIG. 5 after the third to sixth BDCs 93 to 96. In this case, as described in FIG. 5, the third to sixth BDCs 93 to 96 mix the RF signal and the local signal at predetermined bandwidths (for example, 500 MHz) when generating the mixed wave to generate the IF signal.

[0068] 8 and 9 illustrate an example in which frequency conversion units (third to sixth BDCs 93 to 96) employ a superheterodyne single-conversion system, but the third to sixth BDCs 93 to 96 may be configured using a superheterodyne double-conversion system as described in FIG. 4. In this case, a baseband signal can also be generated by providing the baseband conversion units described in FIG. 5. In this case, the third to sixth BDCs 93 to 96 generate an IF signal by mixing an RF signal and a local signal at predetermined bandwidths (for example, at 500 MHz) when generating a mixed wave, as described in FIG. 5.

Claims

1. A duplexer that demultiplexes a received wave into a first RF signal and a second RF signal of different frequency bands, a waveguide magic tee that splits the received wave into a first incident wave and a second incident wave of equal amplitude; a first filter that generates the first RF signal by filtering the first incident wave using a predetermined first frequency band as a passband; a second filter that generates the second RF signal by filtering the second incident wave using a second frequency band that is different from the first frequency band as a pass band. Duplexer.

2. further comprising an isolator to which the received wave is input, At least one of the isolator, the first filter, and the second filter is configured by a waveguide, and the isolator, the waveguide magic tee, the first filter, and the second filter are configured as an integrated structure.

2. The duplexer according to claim 1.

3. 10. A radio communication receiving device comprising the duplexer according to claim 1.

Images