JP2012049790A - Transmitter and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter and a receiver having a frequency conversion function that can achieve both cost and footprint reduction by circuit simplification and phase noise reduction.SOLUTION: The transmitter performs frequency conversion by upconverting an intermediate frequency signal IF into n grades (where n is a natural number greater than or equal to two) with n mixers and transmits an output frequency signal RF. The transmitter includes a local oscillator generating a local oscillation signal based on a reference oscillation signal. The transmitter divides the local oscillation signal into n parts, supplies them to the n mixers, and sequentially mixes the local oscillation signal into the intermediate frequency signal IF in n-grades to obtain the output frequency signal RF.

Description

  The present invention relates to a high-frequency device having a frequency conversion function, and mainly relates to a transmission device and a reception device used for satellite communication, satellite broadcasting, and the like.

Conventionally, various methods for up-converting an intermediate frequency signal to a transmission frequency signal have been proposed, and the following three methods are known as typical ones.
The first method is a single conversion method, and the configuration is shown in FIG. The intermediate frequency signal IF (1.5 GHz to 2 GHz) and the local oscillation signal Lo (29 GHz) are mixed by a mixer to obtain an output frequency signal RF (30.5 GHz to 31 GHz). However, in this method, spurious signals such as unnecessary image signals and local oscillation signals that are output by the difference between the local oscillation signal and IF (27.5 GHz to 28 GHz) and the output frequency signal RF are close in frequency. Therefore, in order to remove these unnecessary signals, for example, a waveguide filter type BPF having a very high blocking property must be used, which makes it difficult to design and increases the cost. There is.

  The second method is a double conversion method, and the configuration is shown in FIG. Two local oscillation signals are mixed with the intermediate frequency signal IF by two mixer sections, respectively, to obtain an output frequency signal RF. Specifically, for example, a signal (7.25 GHz) from the first stage local oscillator is mixed by the first mixer with respect to the intermediate frequency signal IF (1.5 GHz to 2 GHz), and then the second stage. An output frequency signal RF (30.5 GHz to 31 GHz) is obtained by mixing the signal from the local oscillator (21.75 GHz) by the second mixer. According to the second method, the image signal and the local oscillation signal are separated from the RF signal, and unnecessary signals can be removed by a general BPF, so that the disadvantage of the first method is solved. However, since this system requires two local oscillator circuits, there is a problem that the circuit scale increases, the mounting area increases, and the cost increases.

The third method is, for example, the method shown in Patent Document 1, and the configuration is shown in FIG. Although this third method is a double conversion method, a desired output frequency signal RF is obtained by mixing each output in turn using one local oscillation circuit and one multiplier. Specifically, for example, the signal (7.25 GHz) from the local oscillator is mixed by the first mixer with respect to the intermediate frequency signal IF (1.5 GHz to 2 GHz), and then the signal from the local oscillator is further multiplied. The output frequency signal RF (30.5 GHz to 31 GHz) is obtained by mixing the signal (21.75 GHz) multiplied by, for example, 3 with a second mixer using the second mixer. According to the third method, since only one local oscillator is required as compared with the second method, the circuit scale is reduced and the increase in cost can be suppressed.
Japanese Patent Laid-Open No. 11-17564

According to the method described in Patent Document 1, since only one local oscillator is required compared to the second method shown in FIG. 5, the circuit scale can be reduced. In this method, a multiplier is used. Therefore, for example, when the local oscillation signal is multiplied by 3, the phase noise of the local oscillation signal is also tripled. As a result, the C / N (Carrier) of the output frequency signal RF is increased.
to Noise Ratio) is a problem.

  The present invention has been made in view of the above problems, and provides a transmission apparatus and a reception apparatus having a frequency conversion function that achieves both cost reduction and mounting area reduction and phase noise reduction due to circuit simplification. It is intended.

  Claim 1 of the present invention is a transmission apparatus that up-converts an input intermediate frequency signal into n stages with n (n is a natural number of 2 or more) mixers, converts the frequency into an output frequency signal, and transmits the signal. A local oscillator for generating an oscillation signal is provided, the local oscillation signal is distributed into n parts, supplied to the n mixers, and the local oscillation signal is sequentially mixed in n stages with respect to the input intermediate frequency signal. Thus, the transmission apparatus is characterized in that the output frequency signal is obtained.

  Claim 2 of the present invention is a transmission device that upconverts an input intermediate frequency signal into two stages by two mixers, converts the frequency into an output frequency signal, and transmits the output signal. A local oscillator for generating a local oscillation signal is provided. The local oscillation signal is divided into two, supplied to the two mixers, and the local oscillation signal is sequentially mixed in two stages with respect to the input intermediate frequency signal to obtain the output frequency signal. A transmission device characterized by the above.

  According to a third aspect of the present invention, in addition to the first or second aspect, the frequency of the local oscillation signal is a frequency difference between an output frequency signal and an input intermediate frequency signal corresponding to the output frequency signal. It is a transmitter characterized by setting so as to be a frequency divided by.

  According to a fourth aspect of the present invention, there is provided a receiving apparatus for down-converting an input frequency signal into n stages with n (n is a natural number of 2 or more) mixers and converting the frequency into an output intermediate frequency signal, A local oscillator that generates the signal, distributes the local oscillation signal to n, supplies the local oscillation signal to the n mixers, and sequentially mixes the local oscillation signal into n stages with respect to the input frequency signal. A receiving apparatus is characterized in that a frequency signal is obtained.

  According to a fifth aspect of the present invention, there is provided a receiving apparatus for down-converting an input frequency signal into two stages by two mixers and converting the frequency into an output intermediate frequency signal, comprising a local oscillator for generating a local oscillation signal. The local oscillation signal is divided into two and supplied to the two mixers, and the local oscillation signal is sequentially mixed in two stages with respect to the input frequency signal to obtain the output intermediate frequency signal. It is the receiver characterized by these.

  According to a sixth aspect of the present invention, in addition to the fourth or fifth aspect, the frequency of the local oscillation signal is a frequency difference between an input frequency signal and an output output intermediate frequency signal corresponding to the same input frequency signal. It is a transmitter characterized in that it is set to have a frequency divided by the number.

According to the transmitting apparatus of the present invention, the local oscillation signal is divided into n and supplied to n mixers, and the local oscillation signal is sequentially mixed in n stages with respect to the input intermediate frequency signal to obtain an output frequency signal. Therefore, since only one local oscillator is required, the circuit scale can be reduced, and since a multiplier is not employed as in the prior art, the phase noise of the local oscillation signal does not increase, and C / An output frequency signal can be obtained without deteriorating N.
In particular, in the double conversion system in which the local oscillation signal is divided into two and supplied to two mixers, and the local oscillation signal is sequentially mixed in two stages with respect to the input intermediate frequency signal to obtain an output frequency signal. The circuit scale can be minimized.
In any case, since the frequency of the local oscillation signal is different from the frequency of the output frequency signal, unnecessary signals can be easily separated by a BPF (band pass filter).
The frequency of the local oscillation signal is set so that the frequency difference between the output frequency signal and the input intermediate frequency signal corresponding to the output frequency signal is divided by the number of mixers, thereby obtaining a desired output frequency signal. Thus, frequency conversion is possible.

According to the receiving apparatus of the present invention, the local oscillation signal is divided into n and supplied to the n mixers, and the local oscillation signal is sequentially mixed in n stages with respect to the input frequency signal to obtain an output intermediate frequency signal. Therefore, since only one local oscillator is required, the circuit scale can be reduced, and since a multiplier is not employed as in the prior art, the phase noise of the local oscillation signal does not increase, and C An output intermediate frequency signal can be obtained without deteriorating / N.
In particular, in the double conversion method in which the local oscillation signal is divided into two and supplied to two mixers, and the local oscillation signal is sequentially mixed in two stages with respect to the input frequency signal to obtain an output intermediate frequency signal. The circuit scale can be minimized.
In either case, since the frequency of the local oscillation signal is different from the frequency of the input frequency signal, unnecessary signals can be easily separated by a BPF (band pass filter).
The frequency of the local oscillation signal is set so that the frequency difference between the input frequency signal and the output intermediate frequency signal corresponding to the input frequency signal is divided by the number of mixers, thereby obtaining a desired intermediate frequency signal. Thus, frequency conversion is possible.

It is a block diagram showing the structure of the transmitter by this invention. It is a block diagram showing the structure of the receiver by this invention. It is a block diagram showing the other structure of the transmitter by this invention. It is a block diagram showing the transmission apparatus by the conventional single conversion system. It is the block diagram showing the transmission apparatus by the double conversion system using two conventional local oscillators. It is the block diagram showing the transmitter by the double conversion system which employ | adopted the multiplier using one conventional local oscillator.

  A transmission device according to the present invention is a transmission device that up-converts an input intermediate frequency signal into n stages by n mixers, converts the frequency to an output frequency signal, and transmits the output frequency signal, and includes a local oscillator that generates a local oscillation signal. The local oscillation signal is divided into n and supplied to the n mixers, and the local oscillation signal is sequentially mixed in n stages with respect to the input intermediate frequency signal to obtain an output frequency signal. It is a feature. Hereinafter, the case where n = 2 will be described in detail as an example.

  A first embodiment of the present invention will be described with reference to FIG. First, a local oscillator 12 that generates a local oscillation signal has a configuration in which a local oscillation signal (14.5 GHz) is obtained by a phase-locked oscillator (PLO) using a 10 MHz reference oscillator (crystal oscillator) 11 as a reference signal source. Yes. The local oscillation signal (14.5 GHz) obtained in this way is divided into two by a distributor 13 such as a Wilkinson divider, and one is supplied to the first mixer 20 via an amplifier 14 and a BPF 15, and the other is an amplifier. 16 and the BPF 17 are supplied to the second mixer 24.

  The input intermediate frequency signal IFin (1.5 GHz to 2 GHz) input to the input terminal is amplified by the amplifier 18, the unnecessary signal is removed by the BPF 19, and input to the first mixer 20. In the first mixer 20, the local oscillation signal Lo (14.5 GHz) is mixed with IFin (1.5 GHz to 2 GHz), and a signal of 16 GHz to 16.5 GHz is generated. At this time, unnecessary spurious signals such as an image signal (local oscillation signal Lo-IFin = 13 GHz to 13.5 GHz) and a local oscillation signal Lo (14.5 GHz) are generated and pass to the subsequent stage, but are reduced to some extent by the BPF 21. (Since the necessary 16 GHz to 16.5 GHz signal and the unnecessary spurious signal are close in frequency, some unnecessary signals pass through the BPF 21). After the signal passing through the BPF 21 is amplified by the amplifier 22, unnecessary signals are removed by the BPF 23 and input to the second mixer 24.

  Subsequently, in the second mixer 24, the local oscillation signal Lo (14.5 GHz) is mixed again with the signal of IFin + 14.5 GHz (16 GHz-16.5 GHz), and IFin + 14.5 GHz + 14.5 GHz (30.5 GHz-31 GHz) is obtained. Is output. The image signal (IFin + local oscillation signal Lo−local oscillation signal Lo = 1.5 GHz to 2 GHz) and local oscillation signal Lo (14.5 GHz) pass to the subsequent stage, but are removed by the BPF 25. The BPF 25 has a characteristic of passing around 30.5 GHz to 31 GHz. However, the frequency of the BPF 25 is different from that of various unnecessary spurious signals generated in the mixing process of the first mixer 20 and the second mixer 24. Therefore, the removal is easy and reliable. Thereafter, the output frequency signal RFout is output from the output terminal through the amplifier 26 and the LPF 27 that cuts off the harmonics.

  As described above, the local oscillation signal (14.5 GHz) from the local oscillator 12 is divided into two by the distributor 13 and mixed in two stages by the first mixer 20 and the second mixer 24. Upconversion by a double conversion method can be realized with one local oscillator without using a multiplier, and an output frequency signal RFout can be obtained without deteriorating C / N.

In the present invention, when the frequency in the local oscillator 12 is determined, the frequency is set such that the difference between RFout and IFin is divided by two.
Although the RFout frequency has been described as a microwave Ka band of 30.5 GHz to 31 GHz, the present invention is not limited to this frequency, and can also be applied to transmission devices of different frequency bands such as Ku and C bands. is there.

  In the first embodiment, the up-conversion in the transmission apparatus has been described. However, the same principle can be applied to the down-conversion in the reception apparatus, and this is shown in FIG. The difference between this circuit and the circuit that obtains the output frequency signal RFout from the input intermediate frequency signal IFin in FIG. 1 is that the present circuit is a receiving device and performs down-conversion to obtain the output intermediate frequency signal IFout from the input frequency signal RFin. It is a point. Details of the circuit will be described below.

  First, a local oscillator 12 that generates a local oscillation signal has a configuration in which a local oscillation signal (14.5 GHz) is obtained by a phase-locked oscillator (PLO) using a 10 MHz reference oscillator (crystal oscillator) 11 as a reference signal source. Yes. The local oscillation signal (14.5 GHz) thus obtained is divided into two by a distributor 13 such as a Wilkinson divider, and one is supplied to the first mixer 30 via the amplifier 14 and the BPF 15, and the other is amplified. 16 and the BPF 17 are supplied to the second mixer 34.

  The input frequency signal RFin (30.5 GHz to 31 GHz) input to the input terminal is amplified by the amplifier 28 and then amplified by the BPF 29 to generate a harmonic signal including unnecessary signals other than the input frequency signal RFin (30.5 GHz to 31 GHz). The spurious signal is removed. After the unnecessary signal is removed, the input frequency signal RFin is input to the first mixer 30. In the first mixer 30, the input frequency signal RFin (30.5 GHz to 31 GHz) and the local oscillation signal Lo (14.5 GHz) are mixed to generate a signal of 16 GHz to 16.5 GHz. In this process, a part of the local oscillation signal Lo (14.5 GHz) leaks to the output of the first mixer 30 and is mixed as an unnecessary signal, but this is reduced to some extent by the BPF 31 at the subsequent stage of the first mixer 30 ( (Since the necessary 16 GHz to 16.5 GHz signal and the frequency of the unnecessary spurious signal are close to each other, some unnecessary signals pass through the BPF 31). After the signal passing through the BPF 31 is amplified by the amplifier 32, unnecessary signals are removed by the BPF 33 and input to the second mixer 34.

  Subsequently, in the second mixer 34, the local oscillation signal Lo (14.5 GHz) is mixed again with the input frequency signal RFin−local oscillation signal Lo (16 GHz to 16.5 GHz), and the output intermediate frequency signal IFout = RFin−14. .5 GHz-14.5 GHz (1.5 GHz to 2 GHz) is obtained. The local oscillation signal Lo mixed in the first mixer 30 and the second mixer 34 is removed by the BPF 35 subsequent to the second stage mixer 34. The BPF 35 has a characteristic of allowing the vicinity of the output intermediate frequency signal IFout (1.5 GHz to 2 GHz) to pass therethrough. However, since the frequency deviates from the local oscillation signal Lo, the removal is easy and reliable. Thereafter, an output intermediate frequency signal IFout is obtained through an amplifier 36 and an LPF 37 that cuts off harmonics.

  As described above, even when the input frequency signal RFin is down-converted, it is possible to realize down-conversion by the double conversion method with one local oscillator without using a multiplier, and it is possible to down-convert without deteriorating C / N. The converted output intermediate frequency signal IFout can be obtained.

  In the first and second embodiments, the reference oscillator 11 is built in the frequency converter. However, the reference oscillation signal may be supplied from the outside. For example, as shown in FIG. 3, a signal obtained by superimposing a reference oscillation signal (10 MHz) on an input intermediate frequency signal IFin (1.5 GHz to 2 GHz) is input to an input terminal as an input signal, and only a 10 MHz signal is choke coil. The signal is separated by 38 and input to the local oscillator 12. The local oscillator 12 obtains a local oscillation signal (14.5 GHz) with a phase-locked oscillator (PLO) using the input 10 MHz signal as a reference signal source. Since the operation after obtaining the local oscillation signal (14.5 GHz) is the same as in the first and second embodiments, description thereof is omitted.

In the first to third embodiments, the double conversion method is used. However, the present invention may be applied to a triple conversion method in which there are three mixers. In this case, the difference between RF and IF is divided by three. A local oscillation signal is set so as to obtain a frequency output, and the signal is divided into three and supplied to each mixer. Although the circuit scale becomes large, the frequency of the local oscillation signal can be set lower than the double conversion method, and the frequency of the image signal and the local oscillation signal and the RF signal is more dissociated, so that the cutoff characteristic by BPF is improved An output signal with a good C / N ratio can be obtained.
When this is generalized, a local oscillation signal is set so that a frequency output is obtained by dividing the difference between RF and IF by n (n is a natural number equal to or greater than 2 = the number of mixers), and the signal is distributed n times. The present invention can also be realized by supplying each of the mixers and mixing them sequentially.

In the above embodiments, the present invention has been described as a transmitting device or a receiving device. However, the present invention is not limited to this, and the present invention can be applied to various electronic devices as a frequency converter for up-converting or down-converting. Is possible.
Moreover, although the reference frequency of PLO has been described as 10 MHz, the present invention is not limited to this, and 50 MHz, 100 MHz, or the like can be selected as appropriate.

  Further, when the present invention is used for an up-converter, for example, in the double conversion method, when the lower limit frequency of the frequency band of the input intermediate frequency signal IFin is f1, and the upper limit frequency is f2, f1 is satisfied so as to satisfy the relationship 2f1-f2> 0. , F2 can prevent the second harmonic generated in the second stage mixer from being generated in the frequency band of the output frequency signal RFout. Similarly, when mixing in n stages, the frequency of IFin can be set so as to prevent the generation of harmonics in the transmission band.

DESCRIPTION OF SYMBOLS 11 ... Reference oscillator, 12 ... Local oscillator, 13 ... Distributor, 14 ... Amplifier, 15 ... BPF (band pass filter), 16 ... Amplifier, 17 ... BPF, 18 ... Amplifier, 19 ... BPF, 20 ... First mixer 21 ... BPF, 22 ... amplifier, 23 ... BPF, 24 ... second mixer, 25 ... BPF, 26 ... amplifier, 27 ... LPF (low pass filter), 28 ... amplifier, 29 ... BPF, 30 ... first mixer 31 ... BPF, 32 ... Amplifier, 33 ... BPF, 34 ... Second mixer, 35 ... BPF, 36 ... Amplifier, 37 ... LPF, 38 ... Choke coil.

Claims (6)

  A transmission device that up-converts an input intermediate frequency signal into n stages by n (n is a natural number of 2 or more) mixers, converts the frequency into an output frequency signal, and transmits the output signal. A local oscillator that generates a local oscillation signal is provided. The local oscillation signal is divided into n and supplied to the n mixers, and the local oscillation signal is sequentially mixed in n stages with respect to the input intermediate frequency signal to obtain the output frequency signal. A transmission device characterized by that.   A transmitter that up-converts an input intermediate frequency signal in two stages by two mixers, converts the frequency into an output frequency signal, and transmits the output frequency signal. The transmitter includes a local oscillator that generates a local oscillation signal. The signal is divided into two and supplied to the two mixers, and the local oscillation signal is sequentially mixed in two stages with respect to the input intermediate frequency signal to obtain the output frequency signal. apparatus.   The frequency of the local oscillation signal is set to be a frequency obtained by dividing a frequency difference between an output frequency signal and the input intermediate frequency signal corresponding to the output frequency signal by the number of mixers. Item 3. The transmitter according to Item 1 or 2.   A receiving device that down-converts an input frequency signal into n stages by n (n is a natural number of 2 or more) mixers and converts the frequency to an output intermediate frequency signal, and includes a local oscillator that generates a local oscillation signal. The local oscillation signal is divided into n and supplied to the n mixers, and the local oscillation signal is sequentially mixed in n stages with respect to the input frequency signal to obtain the output intermediate frequency signal. A receiving device.   A receiving apparatus that down-converts an input frequency signal into two stages by two mixers and converts the frequency into an output intermediate frequency signal, and includes a local oscillator that generates a local oscillation signal. A receiving apparatus characterized in that the output intermediate frequency signal is obtained by distributing and supplying to the two mixers, and mixing the local oscillation signal sequentially in two stages with respect to the input frequency signal.   The frequency of the local oscillation signal is set to be a frequency obtained by dividing a frequency difference between the input frequency signal and the output intermediate frequency signal corresponding to the input frequency signal by the number of mixers. The receiving device according to claim 4 or 5.

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