JP2011146946A - Communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the scale of a circuit and the amount of data to be transmitted from being increased when reducing power consumption by controlling the degree of an LPF in accordance with a plurality of interference waves. <P>SOLUTION: An LPF 12 comprises three secondary LPFs having the same configuration, and outputs a main signal after canceling an adjacent ch signal or a next adjacent ch signal contained in a communication signal. A BPF 14 extracts the adjacent ch signal and the next adjacent ch signal from the communication signal, with a difference in bandwidth. A Power DET 15 outputs power of the adjacent ch signal and the next adjacent ch signal extracted in accordance with voltage values. Comparators 16, 17 compare the voltage values with reference voltages 18, 19 corresponding to the difference of the bandwidth, and detects the next adjacent ch signal and the adjacent ch signal. The LPF 12 automatically switches the secondary LPFs to serial connection in three stages based on the next adjacent ch signal and the adjacent ch signal. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a communication apparatus, and more particularly to a reception apparatus and a transmission apparatus suitable for reducing power consumption of an interference wave removing filter in OFDM (Orthogonal Frequency-Division Multiplexing) communication such as UWB (Ultra Wide Band) communication and BlueTooth communication. .

  In OFDM (Orthogonal Frequency-Division Multiplexing) communication such as UWB (Ultra Wide Band) communication and BlueTooth communication, a signal may exist at a frequency adjacent to the main signal frequency or at a frequency further adjacent to the adjacent frequency. These signals are referred to as an adjacent channel signal and a next adjacent channel signal. The adjacent channel signal and the next adjacent signal are unnecessary interference waves when viewed from the main signal, and it is determined to use a high-order LPF (Low Pass Filter) in order to remove them.

  However, the adjacent channel signal and the next adjacent channel signal are not always present, and when there is no adjacent channel signal or the next adjacent channel signal, a lower order LPF is sufficient. Therefore, if the LPF is made variable depending on the presence / absence of the adjacent channel signal and the next adjacent channel signal, power consumption can be reduced.

  As a conventional technology of this type, a BPF is provided for the adjacent channel, and an HPF is provided for the next adjacent channel, and the BPF output and the HPF output are compared with different reference voltages. Document 1) and a receiving circuit for a mobile phone (Patent Document 2) that powers off a filter portion that is not required among a plurality of filters having different pole positions for removing interference waves with a band selection signal are known. .

  However, in the above-described prior art, since the order of LPF is switched, if a filter is provided for ch, the circuit scale becomes large, and transmission with a band selection signal leads to an increase in the amount of data transmission. is there.

JP 2006-020238 A JP2007-300260

  The problem to be solved by the invention is that the circuit scale and the amount of data transmission increase when the order of the LPF is controlled and the power consumption is suppressed by the presence or absence of a plurality of interference waves.

  The most important aspect of the present invention is that a plurality of jamming waves are extracted from a communication signal with a difference in bandwidth between the jamming waves, and the presence / absence of each of the plurality of jamming waves can be known from the voltage value of each jamming wave. Features.

  According to the communication apparatus of the present invention, since the presence or absence of each of the plurality of interference waves can be known from the voltage value of each interference wave, one filter is sufficient for extracting the plurality of interference waves, and the plurality of interference waves Since there is no need to send information on the presence / absence of information in a communication signal, there is an advantage that the amount of transmission can be increased.

  Furthermore, since it is possible to automatically change the filter order from the power value of the disturbing wave component, it is not necessary to predetermine whether or not there are a plurality of disturbing waves as the specifications of the communication device, and the specifications can be changed later. It can cope with changes.

It is a block diagram of one Example of the receiver of this invention. It is a frequency characteristic figure of BPF in the receiver of the present invention. It is a figure which shows the power detection in the comparator in the receiver of this invention. It is a figure which shows the principal part of the LPF order automatic switching circuit in the receiver of this invention. FIG. 5 is a diagram for explaining the operation of the LPF order automatic switching circuit shown in FIG. 4. It is a block diagram of the other Example of the receiver of this invention.

  The communication device according to the present invention includes a filter for removing a plurality of interference waves included in a communication signal and outputting a main signal, and a plurality of interference waves with a bandwidth difference between the interference signals from the communication signal. Compare the bandpass filter to be extracted, the power detector that outputs the power of each extracted jamming wave as a voltage value, and compare the voltage value of each jamming wave with a reference voltage corresponding to the difference in bandwidth to determine whether each jamming wave exists. It is characterized in that the order of the filter is automatically switched based on the presence / absence of each interfering wave and a comparator corresponding to the interfering wave to be detected on a one-to-one basis.

  Embodiment 1 of the present invention will be described in detail with reference to FIG. FIG. 1 is a block diagram showing a receiving apparatus of the present invention. The wireless communication signal is captured by the antenna 20 and input from the antenna 20 to an LNA (low noise amplifier) 30 to be amplified. The output of the LNA 30 is input to a DEM (orthogonal demodulator) 40. The DEM 40 removes the RF frequency, which is the carrier frequency, from the radio communication signal, and the output of the DEM 40 is input to the LPF order automatic switching circuit 10. The LPF order automatic switching circuit 10 automatically removes the adjacent channel signal and the next adjacent channel signal from the wireless communication signal with low power consumption by automatically switching the LPF order only with the analog circuit depending on the strength of the interference wave component. Output only baseband signal.

  The LPF order automatic switching circuit 10 includes a VGA (variable gain amplifier) 11, LPF 12, VGA 13, BPF 14, PowerDET (power detector) 15, a comparator 16 and a comparator 17. First, the output of the DEM 40 is input to the VGA 11 whose gain can be adjusted, and the output of the VGA 11 includes the LPF 3 whose order can be switched and the power components of only the adjacent ch signal and the next adjacent ch signal that are interference wave components. Connected to BPF14 to pass.

  As shown by the solid line in FIG. 2, the BPF 14 passes the entire frequency band of the adjacent ch signal and the partial frequency band of the next adjacent ch signal. That is, the frequency components of the entire adjacent channel are extracted for the adjacent ch signal, but only a part of the frequency components are extracted for the next adjacent ch signal. The reason why the BPF 14 has such characteristics is to identify the presence / absence of the adjacent ch signal and the next adjacent ch signal based on the difference between the strengths thereof. Note that the dotted lines in FIG. 2 show the frequency bands of the main signal, adjacent channel signal, and next adjacent channel signal for reference.

  The PowerDET 15 outputs the output of the BPF 14, that is, the power of the disturbing wave as a voltage value. As a result, from the above characteristics of the BPF 14, a larger voltage value is generated when the adjacent channel signal is present than when the next adjacent channel signal is present. The output of PowerDET 15 is connected to one input terminal of the comparator 16 and one input terminal of the comparator 17. The comparator 16 compares the Ref voltage 18 connected to the other input terminal with the output of the PowerDET 15. The comparator 17 compares the Ref voltage 19 connected to the other input terminal with the output of the PowerDET 15.

  Here, Ref voltage 19 and Ref voltage 18 indicate that the output of PowerDET15 exceeds the Ref voltage 19 when there is an adjacent channel signal, and the output of PowerDET15 when there is no adjacent channel signal and the next adjacent channel signal exists. When the voltage value between the Ref voltage 18 and the Ref voltage 19 and both the adjacent channel signal and the next adjacent channel signal do not exist, the output of the PowerDET 15 is set to be less than the Ref voltage 18. Therefore, as shown in FIG. 3, the comparator 17 detects the presence / absence of an adjacent channel signal, and the comparator 16 detects the presence / absence of the next adjacent channel signal when there is no adjacent channel signal. The comparison results in the comparator 17 and the comparator 16 are supplied to the LPF 12, and are used for switching the order of the LPF 12.

  FIG. 4 shows a sixth-order LPF as an example of the LPF 12, and the LPF 12 is formed by connecting a second-order LPF 21, a second-order LPF 22, and a second-order LPF 23 in series in three stages. The secondary LPF21, the secondary LPF22, and the secondary LPF23 are LPFs each having a quadratic function cutoff characteristic, and their outputs are connected to the output of the LPF3 through the switch 24, the switch SW25, and the switch SW26. . The order control unit (not shown) of LPF 12 turns on a signal for turning ON / OFF secondary LPF 22 and secondary LPF 23, and switches 24, 25, and 26 based on the comparison results of comparator 16 and comparator 17. Generate a signal to turn OFF / OFF.

  In this embodiment, the LPF 12 is composed of a plurality of LPFs of the same order, and the order switching is realized by turning them ON / OFF, so there is no need to prepare a large number of LPFs having different orders, and the layout can be improved. There is an advantage that it can be reduced.

  FIG. 5 shows the filter characteristics of the LPF 12 when the order is switched. First, when the radio communication signal received by the antenna 20 includes an adjacent channel signal and a next adjacent channel signal (FIG. 5A), there are outputs of the comparator 16 and the comparator 17, and the order control unit of the LPF 12 The LPF 22 and the secondary LPF 23 are turned ON, the switches 24 and 25 are OPEN, and the switch 26 is SHORT. As a result, LPF12 becomes 6th-order LPF in which 2nd-order LPF21, 2nd-order LPF22 and 2nd-order LPF23 are connected in series, has a steep cut-off frequency characteristic, blocks adjacent channel signal and next adjacent channel signal, and only main signal Pass through. The same applies when the wireless communication signal includes the adjacent channel signal and does not include the next adjacent channel signal.

  Next, when the next adjacent channel signal is included in the radio communication signal received by the antenna 20 (FIG. 5B), the output of the comparator 16 is present, and the order control unit of the LPF 12 determines the secondary LPF 21 and the secondary LPF 22. ON, secondary LPF 23 is turned OFF, switch 24 and switch 26 are OPEN, and SW is SHORT. As a result, the LPF 12 becomes a fourth-order LPF in which the second-order LPF 21 and the second-order LPF 22 are connected in series, has a cut-off frequency characteristic of the middle, cuts off the next adjacent ch signal, and passes only the main signal. Since there is no adjacent channel signal, the frequency characteristic of the LPF 12 may extend to the frequency band of the adjacent channel.

  Finally, when the adjacent channel signal and the next adjacent channel signal are not included in the radio communication signal received by the antenna 20 (FIG. 5C), there is no output of the comparator 16 and the comparator 17, and the order control unit of the LPF 12 is 2 The next LPF 22 and the second LPF 23 are turned OFF, the switch 24 is set to SHORT, and the switch 25 and the switch 26 are set to OPEN. As a result, the LPF 12 becomes a secondary LPF having only the secondary LPF 21 and has a gentle cut-off frequency characteristic to pass only the main signal. Since neither the adjacent ch signal nor the next adjacent ch signal exists, the frequency characteristic of the LPF 12 may exceed the frequency band of the adjacent ch and reach the frequency band of the next adjacent ch signal.

  In this way, low power consumption is realized by automatically switching the order of the LPF 12 according to the presence / absence of the adjacent channel signal and the next adjacent channel signal. The presence / absence of the adjacent channel signal and the next adjacent channel signal is determined by extracting all the adjacent channel signals and partially extracting the next adjacent channel signal with the same filter. As a result, it is not necessary to provide a filter corresponding to the channel, so the circuit scale can be suppressed, and a band selection signal for notifying the presence / absence of the adjacent channel signal and the next adjacent channel signal is also unnecessary, thereby suppressing an increase in data transmission amount it can. Only the main signal is output from the LPF 12 from which the adjacent channel signal and the next adjacent channel signal are removed via the VGA 13.

  In the embodiment described above, the LPF order automatic switching is performed on the reception side, but it can also be performed on the transmission side. FIG. 6 is a block diagram of the receiving apparatus of the present invention when the LPF order automatic switching circuit 10 is provided on the transmitting side. In FIG. 6, the input data signal is input to the LPF order automatic switching circuit 10, the output of the LPF order automatic switching circuit 10 is input to the MOD (orthogonal modulator) 50, and the signal mixed with the RF frequency at the MOD 50 is PA. (Power amplifier) 60 is input, and the output of PA 42 is input to antenna 60 and output as a radio communication signal.

  The adjacent channel signal and the next adjacent channel signal in the embodiment described above can be broadly referred to as a second harmonic or a third harmonic generated from the data signal of the interference wave component. Moreover, although the wireless communication signal is targeted, a wired communication signal may be included in the target. Further, by making the number of comparators more than two, more detailed interference waves can be removed.

10 LPF order automatic switching circuit
11, 13 VGA (variable gain amplifier)
12 LPF (low pass filter)
14 BPF (band pass filter)
15 PowerDET (Power Detector)
16, 17 Comparator
18, 19 Ref voltage
20, 70 antenna
21-23 2nd order LPF
24-26 switch
30 LNA (Low Noise Amplifier)
40 DEM (Quadrature Demodulator)
50 MOD (Quadrature modulator)
60 PA (Power Amplifier)

Claims (3)

A filter for removing a plurality of interference waves included in a communication signal and outputting a main signal;
A band-pass filter that extracts the plurality of jamming waves from the communication signal with a difference in bandwidth between the jamming waves;
A power detector that outputs the power of each extracted jamming wave according to a voltage value;
A comparator that has a one-to-one correspondence with the disturbing wave that detects the presence or absence of each jamming wave by comparing the voltage value of each jamming wave with a reference voltage corresponding to the difference in the bandwidth;
A communication apparatus, wherein the order of the filter is automatically switched based on the presence / absence of each interference wave. The band pass filter passes the entire frequency band of the adjacent ch signal and the partial frequency band of the next adjacent ch signal with respect to the main signal,
The comparator includes a first comparator that compares the voltage value of the adjacent channel signal after the passage with a first reference voltage, and a second comparator that compares the voltage value of the next channel signal after the passage with a second reference voltage. The communication apparatus according to claim 1, wherein the communication apparatus is configured. The filter consists of three secondary low-pass filters of the same configuration,
The communication apparatus according to claim 2, wherein the second-order low-pass filter is switched from a three-stage to a one-stage series connection according to an output of the first comparator and an output of the second comparator.

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