Diplexer and Wireless Communication Receiving Device

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 receiver used in a wireless communication system using a microwave band or a millimeter wave band.

Background Art

[0002] In recent years, the demand for artificial satellites such as communication satellites and observation satellites using low-earth orbit has been rapidly increasing. An artificial satellite orbiting in a low-earth orbit has less propagation loss during communication and can be miniaturized because it is close to the earth station. A "satellite constellation configuration" for performing high-capacity communication with an earth station by arranging a plurality of artificial satellites on substantially the same orbital plane in a low-earth orbit and operating them in cooperation has been put into practical use.

[0003] In the satellite constellation configuration, "multi-band multi-mode communication" that divides a frequency band and combines a plurality of modulation methods is used for effective use of a prescribed frequency band. Multi-band multi-mode communication is not limited to satellite communication and is widespread in terrestrial communication (especially mobile communication with a specified communication area). When multi-band multi-mode communication is used for communication between a low-earth orbit artificial satellite and an earth station, communication between a plurality of artificial satellites and periodic short-time communication between a plurality of artificial satellites and a plurality of earth stations are required. Therefore, in order to transmit a predetermined amount of data, a relatively wide frequency band is allocated to multi-band multi-mode communication, and the quasi-millimeter wave band or the millimeter wave band is often used.

[0004] Conventional multiband / multimode receiving devices divide the received wave from the antenna into predetermined RF bandwidths. To achieve this, the receiving device has a filter bank consisting of multiple band-pass filters arranged in parallel, each with a different frequency band as its passband. 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 is then converted into an intermediate frequency IF signal through superheterodyne frequency conversion using a predetermined local oscillator and mixer. The IF signal is then transmitted to the receiving section, which includes a demodulator.

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

[0006] Patent Document 1 discloses a receiving device that discriminates and selects a received wave to a predetermined frequency band using a filter bank. Patent Document 2 discloses a wireless communication device used for spectral sensing. This wireless communication device discriminates and selects a predetermined band using a filter bank from a received wave and detects the IF signal spectrum generated by a superheterodyne frequency conversion. The wireless communication device allows for arbitrary setting of the number of band-pass filters and selects the band-pass filters to be used in the filter bank using a switch matrix. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2001-189670 [Patent Document 2] Japanese Patent Publication No. 2015-095842 [Overview of the project] [Problems that the invention aims to solve]

[0008] Patent Document 1 describes a device that selects and receives one of two frequency bands from a received wave, and then frequency-converts the RF signal in the selected frequency band to output an IF signal. For this reason, the receiving device in Patent Document 1 cannot meet the requirements of multiband multimode communication, which requires simultaneous frequency conversion of two RF signals with different frequency bands and simultaneous output of two IF signals. Patent Document 2 aims to receive and detect RF signals in a space where the frequency and amplitude of the RF signal change on the time axis. The wireless communication device in Patent Document 2 has too many unnecessary functions when used for multiband multimode communication. That is, even though the wireless communication device in Patent Document 2 can simultaneously receive two types of RF signals by switching a switch matrix, the device becomes large and cumbersome due to the control signal generation of the switch matrix and the switch driver, making it impractical from a cost perspective.

[0009] The present invention aims to solve these problems by providing a wireless communication receiving device that can simultaneously receive two types of RF signals in two frequency bands during multiband multimode communication, and simultaneously output two types of IF signals by frequency-converting the RF signals. [Means for solving the problem]

[0010] The demultiplexer of the present invention is a demultiplexer that demultiplexes 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 demultiplexes 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 with a predetermined first frequency band as the passband; and a second filter that generates the second RF signal by filtering the second incident wave with a second frequency band different from the first frequency band as the passband. [Effects of the Invention]

[0011] According to the present invention as described above, in multiband multimode communication, it is possible to simultaneously receive two types of RF signals in two frequency bands, and to simultaneously output two types of IF signals by frequency-converting these RF signals. [Brief explanation of the drawing]

[0012] [Figure 1] Circuit diagram of a wireless communication receiver. [Figure 2] Diagram explaining a signal splitter. [Figure 3] A diagram illustrating the relationship between the passbands of the first and second bandpass filters. [Figure 4] Circuit diagram of a wireless communication receiver. [Figure 5] Circuit diagram of a wireless communication receiver. [Figure 6] Circuit diagram of a wireless communication receiver. [Figure 7] Circuit diagram of a wireless communication receiver. [Figure 8] Circuit diagram of a wireless communication receiver. [Figure 9] Circuit diagram of a wireless communication receiver. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described in detail below with reference to the drawings. The following description and drawings have been omitted and simplified as appropriate, and in each drawing, the same elements are denoted by the same reference numerals, and redundant explanations have been omitted where necessary. The numerical values ​​such as frequency band, frequency, and bandwidth used in the following description are examples only and are not limited to the numerical values ​​in the specification.

[0014] (First Embodiment) FIG. 1 is a circuit diagram of a wireless communication receiver according to the first embodiment. The wireless communication device is a receiver of a wireless communication system using a broadband radio frequency. The wireless communication device includes a low-noise amplifier (hereinafter referred to as "LNA") 2, a splitter 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 by the first BDC 91 and the second BDC 92 from two types of received waves (RF signals) belonging to a predetermined frequency band received by an antenna (not shown). The received wave in this embodiment is, for example, a frequency in the quasi-millimeter wave band of 20 GHz to 26 GHz, but is not limited thereto and may be in the millimeter wave band. The wireless communication device includes an input terminal 1 to which the received wave is 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 splitter 4. The splitter 4 includes an isolator 41, an MGT 42 in which a non-reflective terminator 43 is provided in a branch 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 pass bands from each other. The first BPF 45 has a pass band of, for example, 20 GHz to 22 GHz. The second BPF 46 has a pass band of, for example, 24 GHz to 26 GHz. The splitter 4 simultaneously divides the received wave (RF signal) into RF signals in a plurality of different frequency bands and outputs them. In this embodiment, the splitter 4 divides the received wave (RF signal) into two, 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 band-pass filter 11, and a first IF amplifier 12. The first local oscillator 10 outputs an AC signal of, for example, 19 GHz. The first BDC 91 converts a 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 way is output from the output terminal 13.

[0018] The second BDC 92 includes a second mixer 16, a second local oscillator 17, a second IF band-pass filter 18, and a second IF amplifier 19. The second local oscillator 17 outputs an AC signal of, for example, 23 GHz. The second BDC 92 converts a 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 way is output from the output terminal 20.

[0019] FIG. 2 is an explanatory diagram of the demultiplexer 4. MGT42 is a hybrid power divider (power combiner) formed by combining a rectangular waveguide of an H-plane T-branch circuit and a rectangular waveguide of an E-plane T-branch circuit. The basic mode in which MGT42 operates is the TE 10 mode, which is the basic mode of the rectangular waveguide. MGT42 has a first port P1 provided in the branch waveguide of the H-plane T-branch, a second port P2 provided at one end of the main waveguide of the H-plane T-branch, a third port P3 provided at the other end of the main waveguide of the H-plane T-branch, and a fourth port P4 provided in the branch waveguide of the E-plane T-branch.

[0020] An isolator 41 is connected to the first port P1. The isolator 41 is, for example, a waveguide type isolator. An input terminal 3 is provided at the input end of the isolator 41. The received wave (RF signal) amplified by the LNA2 is input to the isolator 41 via input terminal 3. The received wave (RF signal) input from input terminal 3 is input to the first port P1 of the MGT42, accompanied by the forward loss of the isolator 41. The received wave (RF signal) is split into an RF incident wave 51 and an RF incident wave 54 with equal amplitude within the H-plane T-branch circuit. One of the split received waves, the RF incident wave 51, is output from the second port P2. The other split received wave, the RF incident wave 54, is output from the third port P3.

[0021] The RF incident wave 51 output from the second port P2 is input to the first bandpass filter 45. The first bandpass filter 45 filters the RF incident wave 51 according to the passband (band-1). By being filtered by the first bandpass filter 45, the RF incident wave 51 becomes the transmitted wave, the first RF signal 52. The RF incident wave 54 output from the third port P3 is input to the second bandpass filter 46. The second bandpass filter 46 filters the RF incident wave 54 according to the passband (band-2). By being filtered by the second bandpass filter 46, the RF incident wave 54 becomes the transmitted wave, the second RF signal 55.

[0022] The 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 RF reflected wave 53E and 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 equipped with a reflectionless terminator 43 consisting of a radio wave absorber 44 inside the waveguide. The RF reflected wave 53E transmitted to the fourth port P4 is terminated and annihilated by the reflectionless terminator 43. The RF reflected wave 53H is the reverse 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 level that can be ignored as a transmission signal.

[0024] The RF incident wave 54 outside the passband of the second BPF 46 is reflected by the second BPF 46 and becomes the RF reflected wave 56. The RF reflected wave 56 is equally divided into RF reflected wave 56E and 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. The RF reflected wave 56E, like the RF reflected wave 53E, is terminated and annihilated by the non-reflectional terminator 43. The RF reflected wave 56H, like the RF reflected wave 53H, is absorbed and attenuated by the isolator 41 and reduced to a level that is negligible as a transmitted signal.

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

[0026] Figure 3 is an explanatory diagram illustrating the relationship between the passbands of the first BPF45 and the second BPF46. A guard band is provided between the passband of the first BPF45 (band-1) and the passband of the second BPF46 (band-2). The amount of the guard band is determined by the out-of-band attenuation of the first BPF45 and the second BPF46, respectively. Specifically, the out-of-band attenuation of the first BPF45 is determined so that the band-1 interference suppression amount specified for the receiving device is secured at the lower frequency limit of the passband (band-2) of the second BPF46. The out-of-band attenuation of the second BPF46 is determined so that the band-2 interference suppression amount specified for the receiving device is secured at the upper frequency limit of the passband (band-1) of the first BPF45. Typically, the interference suppression amount is set to about 30 dB. Furthermore, the total insertion loss of the 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 in this embodiment it is approximately 3 dB.

[0027] Returning to the explanation of Figure 1, the first RF signal 52 that has passed through the first BPF 45 is output from the first output terminal 8 of the demultiplexer 4 and input to the first BDC 91. The first BDC 91 is a superheterodyne single-conversion frequency converter. The first RF signal 52 is mixed with the local signal Lo-1, which is an AC signal input from the first local oscillator 10, by the first mixer 9. This generates a mixed wave containing 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, having 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, like the first BDC 91, is a superheterodyne single-conversion frequency converter. The second RF signal 55 is processed by the second BDC 92 in the same way as the first RF signal 52 and output as the second IF signal IF-2 from the output terminal 20.

[0029] A wireless communication receiver with the above configuration can split a received wave containing RF signals of multiple frequency bands received by the antenna into separate frequency bands and generate an IF signal for each of the split RF signals. In the example above, a received wave containing frequency bands of 20GHz to 22GHz and 24GHz to 26GHz is split, and two IF signals in the 1GHz to 3GHz frequency band are generated.

[0030] Therefore, in multiband multimode communication, the wireless communication receiver can split the received wave, which includes RF signals from two frequency bands, into two separate RF signals and receive each independently and simultaneously. Each RF signal is converted into a predetermined IF signal by frequency conversion. The IF signal can, for example, be demodulated to become a baseband signal.

[0031] (Second Embodiment) Figure 4 is a circuit diagram of the wireless communication receiver of the second embodiment. Similar to the first embodiment, the wireless communication receiver of the second embodiment is also a receiver for a wireless communication system using broadband radio frequencies. The first and second embodiments differ in the conversion method used by the frequency conversion unit. Specifically, the first and second BDCs 91 and 92 of the first embodiment employ a superheterodyne single conversion method, while the first frequency conversion unit (hereinafter referred to as "first BDC") 97 and the second frequency conversion unit (hereinafter referred to as "second BDC") 98 of the second embodiment employ a superheterodyne double conversion method. Other components (LNA2 and demultiplexer 4) are the same, so their explanation will be omitted, and the differences will be explained.

[0032] The first BDC97 comprises a first-order frequency converter mixer 971, a first-order frequency converter band-pass filter 972, a first-order frequency converter amplifier 973, a first-order frequency converter output terminal 974, a second-order frequency converter mixer 975, a second-order frequency converter local oscillator 976, a second-order frequency converter band-pass filter 977, and an output terminal 978. The second BDC98 comprises a first-order frequency converter mixer 981, a first-order frequency converter band-pass filter 982, a first-order frequency converter amplifier 983, a first-order frequency converter output terminal 984, a second-order frequency converter mixer 985, a second-order frequency converter local oscillator 986, a second-order frequency converter band-pass filter 987, and an output terminal 988.

[0033] The first frequency conversion mixer 971 of the first BDC97 and the first frequency conversion mixer 981 of the second BDC98 are supplied with AC signals from a common first local oscillator 989. The AC signals output from the first local oscillator 989 are distributed to the first frequency conversion mixers 971 and 981 by the power distributor 979.

[0034] In the second embodiment, the demultiplexer 4 receives a received wave (RF signal) in the range of 37 GHz to 43 GHz and outputs a first RF signal 52 in the range of 37 GHz to 39 GHz and a second RF signal 55 in the range 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 second frequency conversion local oscillator 976 of the first BDC 97 outputs a second local signal Lo-1, which is an AC signal of 7 GHz. The second frequency conversion local oscillator 986 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 containing unwanted waves. The first frequency conversion band-pass filter 972 filters the first mixed wave to discriminate a first filtered signal in 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 with a predetermined gain by the first-order frequency conversion amplifier 973 and input to the second-order frequency conversion mixer 975 from the first-order frequency conversion output terminal 974. The second-order frequency conversion mixer 975 mixes the first filtered signal input from the first-order frequency conversion output terminal 974 with the second local signal Lo-1 input from the second-order frequency conversion local oscillator 976 to generate a second mixed wave containing unwanted waves. The second-order frequency conversion band-pass filter 977 filters the second mixed wave to discriminate the first IF signal IF-1 in 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 the output terminal 978.

[0037] The second RF signal 55 output from the second output terminal 15 of the demultiplexer 4 is input to the first-order frequency converter mixer 981 of the second BDC 98. Detailed explanations of each component of the second BDC 98 are omitted because they operate similarly to the corresponding components of the first BDC 97. The second BDC 98 ultimately outputs a second IF signal IF-2 with a predetermined frequency bandwidth from its output terminal 988. The frequency bandwidth of the second IF signal IF-2 is, for example, 1 GHz to 3 GHz.

[0038] A wireless communication receiver with the above configuration can split a received wave containing RF signals of multiple frequency bands received by the antenna into separate frequency bands and generate an IF signal for each of the split RF signals. In the example above, a received wave containing frequency bands of 37GHz to 39GHz and 41GHz to 43GHz is split, and two IF signals in the 1GHz to 3GHz frequency band are generated.

[0039] Therefore, in multiband multimode communication, the wireless communication receiver can split the received wave, which includes RF signals from two frequency bands, into two separate RF signals and receive each independently and simultaneously. Each RF signal is converted into a predetermined IF signal by frequency conversion. The IF signal can, for example, be demodulated to become a baseband signal.

[0040] (Third embodiment) Figure 5 is a circuit diagram of the wireless communication receiver of the third embodiment. Similar to the first embodiment, the wireless communication receiver of the third embodiment is a receiver 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 the RF signal into an analog baseband signal and outputs it. For this reason, the wireless communication receiver of the third embodiment has a configuration for demodulating the IF signal into an analog baseband signal after the wireless communication receiver of the first and second embodiments. Figure 5 shows an example of connecting the configuration for demodulating the IF signal into an analog baseband signal after the wireless communication receiver of the first embodiment (see Figure 1).

[0041] In Figure 5, the configurations of the LNA2, demultiplexer 4, first BDC91, and second BDC92 are the same as those of the wireless communication receiver in the first embodiment. However, the frequencies of the first local signal Lo-1 output by the first local oscillator 10 of the first BDC91 and the second local signal Lo-2 output by the second local oscillator 17 of the second BDC92 are different. Here, we will explain using the case where the frequency of the first IF signal IF-1 generated by the first BDC91 is fixed to a bandwidth of 500 MHz as an example.

[0042] The first BDC91 divides the bandwidth of the input first RF signal 52 into 500MHz segments and varies the frequency of the first local signal Lo-1 output by the first local oscillator 10 in steps that match the 500MHz bandwidth according to the frequency bandwidth of the generated first IF signal IF-1. In other words, the frequency of the first local signal Lo-1 is varied in 500MHz intervals.

[0043] Let's take a concrete example. The frequency bandwidth of the first RF signal 52 is set to 22GHz to 23GHz. The first RF signal 52 is divided into 500MHz bandwidth segments and subjected to frequency conversion processing. In the frequency conversion processing, first, while the frequency of the first RF signal 52 is 22.0GHz to 22.5GHz (bandwidth 500MHz), the frequency of the local signal Lo-1 is set to 19.0GHz. This yields the first IF signal IF-1 with a frequency of 3.0GHz to 3.5GHz (bandwidth 500MHz). In the next step, while the frequency of the first RF signal 52 is 22.5GHz to 23.0GHz (bandwidth 500MHz), the frequency of the local signal Lo-1 is set to 19.5GHz, yielding the first IF signal IF-1 with a frequency of 3.0GHz to 3.5GHz (bandwidth 500MHz).

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

[0045] The second BDC92 operates similarly to the first BDC91, generating a second IF signal IF-2 from the second RF signal 55 with a frequency bandwidth of 3.0 GHz to 3.5 GHz (bandwidth of 500 MHz). The local signal Lo-2 of the second BDC92 has a frequency bandwidth of 22 GHz to 22.5 GHz and is variable in 500 MHz increments.

[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 a mixed wave is generated by varying the frequency of the local signal in 500 MHz steps for each divided bandwidth RF signal. By filtering this mixed wave, an IF signal with a frequency bandwidth of 3.0 GHz to 3.5 GHz is generated.

[0047] The IF signals for each bandwidth generated in this way (first IF signal IF-1, second IF signal IF-2) are demodulated into baseband signals. For this purpose, a first baseband converter (hereinafter referred to as "first BBC") 100 is provided after the first BDC 91, and a second baseband converter (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 BBC100 includes an I-component mixer 60, a low-pass filter (LPF) 61 for the I-component, and a variable-gain amplifier 62 for the I-component to generate an I-component baseband signal. The I-component mixer 60 receives a local signal LoIF-1, which is an AC signal, 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 frequencies of the first IF signal IF-1 and the local signal LoIF-1 are the same. The mixed wave is filtered of high-frequency components by the variable-gain LPF 61 for the I-component and then amplified by the variable-gain amplifier 62 to extract an I-component baseband signal of a predetermined amplitude. The I-component baseband signal is output from the output terminal 68.

[0049] The first BBC100 includes a Q component mixer 63, a Q component bandwidth variable LPF 65, and a Q component gain variable amplifier 66 to generate a Q component baseband signal. The Q component mixer 63 receives a local signal LoIF-1 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 containing the Q component baseband signal. The mixed wave is filtered of high-frequency components by the Q component bandwidth variable LPF 65 and then amplified by the Q component gain variable amplifier 66 to extract a Q component baseband signal of a predetermined amplitude. The Q component baseband signal is output from the output terminal 69.

[0050] The second BBC101 has the same configuration and operates similarly to the first BBC100. The second BBC101 generates the I component baseband signal and the Q component baseband signal by performing the same processing on the second IF signal IF-2 output from output terminal 20 as the first BBC100 performed on the first IF signal IF-1. Here, the frequency of the second IF signal IF-2 of the second BBC101 and the local signal LoIF-2, which is an AC signal output from local oscillator 77, are the same. The I component baseband signal is output from output terminal 78. The Q component baseband signal is output from output terminal 79.

[0051] Thus, even when an RF signal (IF signal) is frequency-converted, the baseband signal is preserved. Therefore, for high-frequency RF signals, it is practical to first convert them to a lower frequency using a frequency converter, and then perform baseband conversion. 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 to digital signals, it is necessary to perform AD conversion by sampling the baseband signals. The same applies to the baseband signals output from output terminals 78 and 79.

[0053] The above describes a configuration in which the first BBC100 and the first BBC101 are added to the wireless communication receiver of the first embodiment. However, the same processing is possible even if the first BBC100 and the first BBC101 are added to the wireless communication receiver 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 that match the bandwidth according to the frequency band of the generated IF signal. The wireless communication receiver 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) Figures 6 and 7 are circuit diagrams of the wireless communication receiver of the fourth embodiment. Similar to the first and second embodiments, the wireless communication receiver of the fourth embodiment is also a receiver for a wireless communication system using a wideband radio frequency. The fourth embodiment differs from the first and second embodiments in that it simultaneously receives the first RF signal 52 and the second RF signal 55, which are obtained by splitting the RF signal into two, performs frequency conversion, and then alternately outputs their respective IF signals in a time-division multiplexing manner.

[0055] Figure 6 is a circuit diagram of a modified wireless communication receiver according to the first embodiment. This wireless communication receiver 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 BDC91 and the output terminal 20 of the second BDC92 in Figure 1. The SPDT 21 has a branch terminal 13A to which the output terminal 13 of the first BDC91 is connected, a branch terminal 20A to which the output terminal 20 of the second BDC92 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. The switching operation between branch terminal 13A and branch terminal 20A causes the delimited first RF signal 52 and second RF signal 55 to be transmitted alternately to the downstream stage in time division. This enables time division reception of the first RF signal 52 and the second RF signal 55.

[0057] Figure 7 is a circuit diagram of a modified wireless communication receiver according to the second embodiment. This wireless communication receiver has an SPDT21 that operates in the IF signal band, provided between the output terminal 978 of the first BDC97 and the output terminal 988 of the second BDC98 in Figure 4. The SPDT21 operates in the same manner as in Figure 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 SPDT21 to the wireless communication receiver of the first and second embodiments, in multiband multimode communication, the received wave containing RF signals of two frequency bands can be split into two RF signals of two frequency bands and received independently and simultaneously. The two IF signals obtained by frequency conversion from the two RF signals are output in time division.

[0059] (Fifth embodiment) Figures 8 and 9 are circuit diagrams of the wireless communication receiver of the fifth embodiment. Similar to the first to fourth embodiments, the wireless communication receiver of the fifth embodiment is a receiver for a wireless communication system using a wideband radio frequency. The fifth embodiment differs from the first to fourth embodiments in that it divides the received wave (RF signal) into three or four predetermined frequency bands. For this purpose, the wireless communication receiver of the fifth embodiment is configured to have multiple demultiplexers 4 as described in the first embodiment.

[0060] Figure 8 shows a wireless communication receiving device when the received wave (RF signal) is divided into three predetermined different frequency bands. In Figure 8, the second demultiplexer 104 is connected to the second output terminal 15 of the demultiplexer 4 in Figure 1, and the third BDC 93 and fourth BDC 94 are connected downstream of the second demultiplexer 104. The first BDC 91, third BDC 93, and fourth BDC 94 are all superheterodyne single-conversion frequency converters.

[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 to a first IF signal IF-1 by the first BDC 91. The second RF signal 55 is input to the second demultiplexer 104, and is demultiplexed to a third RF signal and a fourth RF signal by the second demultiplexer 104. The third RF signal is input to the third BDC 93, and is frequency-converted to a third IF signal by the third BDC 93. The fourth RF signal is input to the fourth BDC 94, and is frequency-converted to a fourth IF signal by the fourth BDC 94.

[0062] The third BDC93 and fourth BDC94 have the same configuration as the first BDC91, differing only in the frequency of the AC signal output from the local oscillator. Here, the first local oscillator 10 of the first BDC91 outputs local signal Lo-1, which is an AC signal of 19 GHz. The third local oscillator 117 of the third BDC93 outputs local signal Lo-3, which is an AC signal of 23 GHz. The fourth local oscillator 127 of the fourth BDC94 outputs local signal Lo-4, which is an AC signal of 25 GHz. The first BDC91 outputs the first IF signal IF-1, which is between 1 GHz and 4 GHz. The third BDC93 outputs the third IF signal, which is between 1 GHz and 2 GHz. The fourth BDC94 outputs the fourth IF signal, which is between 1 GHz and 2 GHz.

[0063] Figure 9 shows a wireless communication receiver when the received wave (RF signal) is divided into four predetermined different frequency bands. In Figure 9, the third demultiplexer 204 is connected to the first output terminal 8 of the first stage demultiplexer 4 in Figure 8, and the fifth BDC 95 and sixth BDC 96 are connected after the third demultiplexer 204. The third BDC 93, fourth BDC 94, fifth BDC 95, and sixth BDC 96 are all superheterodyne single-conversion frequency converters.

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

[0065] The 5th BDC95 and 6th BDC96 have the same configuration as the 3rd BDC93 and 4th BDC94, differing only in the frequency of the AC signal output from the local oscillator. The local signals Lo-3 and Lo-4 of the 3rd BDC93 and 4th BDC94 are the same as in Figure 8, and the frequency bandwidth of the IF signal is also the same. The 5th local oscillator 210 of the 5th BDC95 outputs local signal Lo-5, which is an AC signal of 19 GHz. The 6th local oscillator 217 of the 6th BDC96 outputs local signal Lo-6, which is an AC signal of 21 GHz. The 5th BDC95 outputs the 5th IF signal in the range of 1 GHz to 2 GHz. The 6th BDC96 outputs the 6th IF signal in the range of 1 GHz to 2 GHz.

[0066] A wireless communication receiver with the configuration described above can split a received wave containing RF signals of multiple frequency bands received by the antenna into separate frequency bands and generate an IF signal for each of the split RF signals. In the example above, a received wave containing frequency bands of 20GHz to 23GHz and 24GHz to 27GHz is split into three in Figure 8 and into four in Figure 9. In Figure 8, three IF signals are generated for the frequency bands of 1GHz to 2GHz, 1GHz to 2GHz, and 1GHz to 4GHz. In Figure 9, a total of four IF signals are generated for the frequency band of 1GHz to 2GHz.

[0067] To this end, the wireless communication receiver can, in multiband and multimode communication, split the received wave, which includes RF signals from multiple frequency bands, into multiple frequency bands and receive each independently and simultaneously. Each RF signal is converted into a predetermined IF signal by frequency conversion. The IF signal can also be demodulated to a baseband signal, for example. For example, by providing a baseband conversion unit, as explained in Figure 5, after the 3rd to 6th BDCs 93 to 96, a baseband signal can be generated. In this case, as explained in Figure 5, the 3rd to 6th BDCs 93 to 96 mix the RF signal and the local signal at predetermined bandwidth intervals (for example, every 500 MHz) when generating the mixed wave to generate the IF signal.

[0068] Furthermore, while Figures 8 and 9 illustrate an example using a superheterodyne single-conversion frequency conversion unit (3rd to 6th BDC93 to 96), the configuration of the 3rd to 6th BDC93 to 96 may also be a superheterodyne double-conversion unit as described in Figure 4. In this case as well, a baseband signal can be generated by providing a baseband conversion unit as described in Figure 5. In this case, as described in Figure 5, the 3rd to 6th BDC93 to 96 mix the RF signal and the local signal at predetermined bandwidth intervals (for example, every 500 MHz) when generating a mixed wave to generate an IF signal.

Claims

1. A demultiplexer that splits 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 the passband, The invention is characterized by comprising 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 passband, Duplexer.

2. The system further includes an isolator to which the received wave is input, The isolator, the first filter, and the second filter are configured as a waveguide, and the isolator, the waveguide magic tee, the first filter, and the second filter are configured as an integrated structure. The splitter according to claim 1.

3. A wireless communication receiving device characterized by comprising the demultiplexer described in claim 1.

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