JP2006100975A - Wireless communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize such temperature compensation as information can be transmitted accurately with no error by suppressing generation of signal distortion in a wireless communication apparatus. <P>SOLUTION: A baseband transmission signal is generated at a baseband signal processing section 11 and converted into a wireless frequency signal at a frequency converting section 32. Temperature characteristics of signal gain on the upstream side of the frequency converting section 32 including it are compensated at a temperature compensating section 20 and the wireless frequency signal is transmitted from a transmission antenna 17. With such an arrangement, distortion of the signal can be suppressed and information can be transmitted accurately with no error. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication apparatus that performs temperature compensation to ensure wireless performance.

  In recent years, the Internet has rapidly spread with the development of IT (Information Technology). As Internet usage forms, FTTH (Fiber To The Home) and ADSL (Asymmetric Digital Subscriber Line) occupy a large proportion, but there are users who cannot use FTTH or ADSL due to location conditions. There is a need for a wireless access system to provide such users with a stable communication line. Some wireless access systems use frequency bands such as 26 GHz, 5 GHz, and 2.4 GHz.Of these, wireless LAN (Local) for outdoor installation using each frequency band of 5 GHz and 2.4 GHz that can supply products at low cost. Area Network) communication devices are becoming popular. Many wireless LAN devices for outdoor installation are configured by wireless ICs (Integrated Circuits) intended for indoor use. Wireless ICs have individual variations, are not easily affected by temperature, and are relatively difficult to secure wireless performance at low cost.

  As a conventional wireless communication device, there is a wireless transmitter that compensates for increase / decrease in the amplification degree of an amplifier due to a change in ambient temperature by increasing / decreasing the level of a baseband signal (so-called temperature compensation) (for example, see Patent Document 1).

  In addition, there is a wireless receiver that performs temperature compensation in the interval of the intermediate frequency signal (for example, see Patent Document 2).

JP-A-10-190757 (paragraphs 0010 to 0012, FIG. 1) JP-A-10-256931 (paragraphs 0017 to 0018, FIG. 2)

  However, in the conventional wireless communication apparatus, since temperature compensation is performed in the baseband signal section or the intermediate frequency signal section, the amplifier provided in the baseband signal section or the intermediate frequency signal section is out of the dynamic range. A signal may be input. In this case, the signal is distorted by the amplifier, and the radio frequency signal including the distortion component is wirelessly transmitted, and there is a problem that the information before transmission cannot be accurately restored in the opposite receiver.

  An object of the present invention is to realize temperature compensation in a wireless communication apparatus that suppresses the occurrence of signal distortion and can accurately transmit information without error.

The present invention includes a baseband signal processing unit that generates a baseband transmission signal;
A frequency converter that converts the baseband signal output from the baseband signal processor to a radio frequency signal;
For the signal output from the frequency converter, a temperature compensator that compensates for the temperature characteristics of the signal gain on the upstream side of the frequency converter, including the frequency converter, and
A wireless communication apparatus comprising: a transmission antenna that wirelessly transmits a signal output from the temperature compensation unit.

  According to the present invention, since the temperature compensation is performed after the frequency conversion to the radio frequency signal, the input signal changes with respect to the amplifier provided in the section of the baseband signal or the section of the intermediate frequency signal to change the dynamic range. It is possible to avoid a situation that deviates from the above. Therefore, the occurrence of signal distortion can also be suppressed, and accurate information transmission without errors can be realized.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a wireless LAN communication apparatus according to Embodiment 1 of the present invention. The wireless LAN communication device is a communication device for outdoor installation that communicates by a wireless LAN method, and includes a baseband signal processing unit 10, a radio frequency signal processing unit 11, a band pass filter (BPF) 12, a first amplifier 13, and a second amplifier. An amplifier 14, a high-power amplifier 15, a low-pass filter (LPF) 16, a transmission antenna 17, and a temperature compensation unit 20 are provided.

  The baseband signal processing unit 10 is called an integrated circuit (IC) that generates a baseband (BB) transmission signal, so-called BBIC. The radio frequency signal processing unit 11 is an IC that converts a baseband signal output from the baseband signal processing unit 10 into a radio frequency (RF) signal, that is, an RFIC. The unit 32 is provided. The amplifier 31 has a predetermined dynamic range, and a signal within the range can be amplified without distortion. The frequency conversion unit 32 performs stepwise frequency conversion, that is, after converting a baseband signal into an intermediate frequency (IF) signal, further converts the intermediate frequency signal into a radio frequency signal. The band-pass filter (BPF) 12 is a filter that is arranged at a subsequent stage of the radio frequency signal processing 11 and passes a band sandwiched between two predetermined threshold values, and blocks the others. The first amplifier 13 is an amplifier (AMP) that amplifies the signal that has passed through the band pass filter 12, and the second amplifier 14 is an amplifier (AMP) that further amplifies the signal output from the first amplifier 13. The high-power amplifier 15 is a so-called HPA (High Power Amplifier), an amplifier that can further amplify the signal output from the second amplifier 14 and output a signal having a large gain and a high level. The low-pass filter 16 is a filter that is disposed at the subsequent stage of the high-power amplifier 15 and passes a signal having a frequency lower than a predetermined threshold, and blocks a signal having a frequency higher than the threshold. The transmission antenna 17 is an antenna that wirelessly transmits a signal that has passed through the low-pass filter 16.

  The temperature compensation unit 20 includes a plurality of stages of attenuators 21 and 22. The attenuator 21 is arranged so as to be interposed between the bandpass filter 12 and the first amplifier 13, and is a so-called active element in which the resistance elements R1, R2 and the thermistor (temperature sensitive resistance element) TH1 are connected in a π type. It is a passive π-type attenuator (ATT) not included. The resistance elements R1 and R2 are respectively disposed on two ground lines branched at two points on the signal line. The thermistor TH1 is disposed between two branch points on the ground line. The attenuator 22 is also disposed so as to be interposed between the first amplifier 13 and the second amplifier 14, and is a passive π type in which the resistance elements R3 and R4 and the thermistor (temperature sensitive resistance element) TH2 are connected to the π type. Attenuator (ATT). The resistance elements R3 and R4 are respectively arranged on two ground lines branched at two points on the signal line. The thermistor TH2 is disposed between two branch points on the ground line.

  Next, the operation of the wireless LAN communication device will be described.

  First, the baseband signal processing unit 10 generates a baseband transmission signal and outputs it to the radio frequency signal processing unit 11. The baseband signal is amplified with a predetermined gain by the amplifier 31 of the radio frequency signal processing unit 11 and frequency-converted to a radio frequency signal. Up to this point, that is, the signal gain in the section upstream of the frequency conversion unit 32 including the frequency conversion unit 32 has a predetermined temperature characteristic. In particular, the influence of the temperature characteristic due to the gain of the amplifier 31 is large and occupies the majority. Next, of the radio frequency signal output from the radio frequency signal processing unit 11, only a signal in a predetermined band passes through the band pass filter 12. The signal that has passed through the band-pass filter 12 is attenuated by the attenuator 21 with a gain corresponding to the ambient temperature at that time. The signal attenuated by the attenuator 21 is amplified by the first amplifier 13 with a predetermined gain. The signal amplified by the first amplifier 13 is attenuated by the attenuator 22 similarly to the attenuator 21 with a gain corresponding to the ambient temperature at that time. The signal attenuated by the attenuator 22 is amplified by the second amplifier 14 with a predetermined gain. The signal amplified by the second amplifier 14 is further amplified to a high output level by a high gain amplifier 15 with a predetermined gain. Of the signal amplified by the high-power amplifier 15, high-frequency components are blocked by the low-pass filter 16. A high-power signal that has passed through the low-pass filter 16 is wirelessly transmitted from the transmission antenna 17.

  FIG. 2 is a graph showing a characteristic of gain with respect to temperature. FIG. 2A shows characteristics relating to the amplifier in the RFIC 11, and FIG. 2B shows characteristics relating to the temperature compensation unit. Of the gains on the upstream side of the frequency conversion unit 32, the gain most likely to be affected by the temperature is the gain by the amplifier 31 in the RFIC 11. When the ambient temperature rises, the gain by the amplifier 31 in the RFIC 11 decreases as shown in FIG. On the other hand, the resistance value of the thermistors TH1 to TH4 is lowered due to the temperature rise, so that the gain by the temperature compensation unit 20 is raised and the gain reduction in FIG. 2A is compensated. Thereby, the gain change accompanying a temperature change is eliminated as the whole wireless LAN communication apparatus.

  As described above, in the present embodiment, since the temperature compensation unit 20 is arranged after the RFIC 11 that performs frequency conversion to a radio frequency, the amplifier of the RFIC 11 provided in the section of the baseband signal or the section of the intermediate frequency signal is used. The input signal is not changed and deviated from the dynamic range. For this reason, in the wireless LAN communication device, the occurrence of signal distortion can be suppressed, and accurate information transmission without errors can be realized.

  Further, since the temperature compensation unit 20 is configured by the passive attenuators 21 and 22, temperature compensation can be realized with a simple configuration.

  In addition, since the temperature compensation unit 20 is composed of a plurality of attenuators 21, 22, even a large temperature difference can be compensated.

  In particular, the wireless LAN communication device is manufactured on the assumption that it is used indoors. However, when this is used for outdoor installation, it is required to compensate for a large temperature difference. Is effective. Alternatively, it is possible to provide a wireless LAN communication apparatus that sufficiently satisfies the wireless performance by performing temperature compensation corresponding to the temperature characteristics of individual RFICs even for RFICs having large individual variations in temperature characteristics. This eliminates the need for selecting RFICs because of poor radio performance.

  In FIG. 1, the configuration of the attenuators 21 and 22 is a π-type attenuator including one each of the thermistors TH1 and TH2, but an attenuator of the type described in FIG. 3 can be substituted. .

  FIG. 3A to FIG. 3C are diagrams illustrating the configuration of the attenuator. The example of FIG. 3A is obtained by replacing the thermistor TH2 with the thermistors TH3 and TH4 connected in parallel in the attenuator 22 of FIG. 1, and is a π-type attenuator as in FIG. The example of FIG. 3B is one type of T-type attenuator, in which a resistance element R5 is disposed on the ground line, the thermistor TH5 is disposed upstream of the branch point on the signal line where the ground line branches, and the thermistor TH5 is disposed downstream. Each of the thermistors TH6 is arranged. The example of FIG. 3C is obtained by replacing the thermistor TH5 with thermistors TH7 and TH8 connected in parallel and thermistor TH6 with thermistors TH9 and TH10 connected in parallel in the attenuator of FIG. 3B.

  In this way, by configuring the attenuator with a plurality of thermistors, even a large temperature difference can be compensated.

  In order to increase the temperature range that can be compensated, it is necessary to use a thermistor having a large B constant. The B constant is an index indicating how much the resistance value varies depending on the temperature. The larger the B constant, the larger the temperature change of the resistance value. A thermistor having a small resistance value generally has a small B constant, and it may be difficult to increase the temperature difference that can be compensated. Therefore, by connecting a plurality of thermistors in parallel as shown in FIGS. 3A and 3C, it is possible to compensate for a large temperature difference while keeping the resistance value of the attenuator low. .

  Further, by connecting the thermistors having standard resistance values in parallel, resistance values other than the standard resistance values can be realized as combined resistance values by a plurality of thermistors, so that the attenuation amount of the attenuator can be set finely.

Embodiment 2. FIG.
FIG. 4 is a diagram showing an attenuator of the wireless LAN communication apparatus according to Embodiment 2 of the present invention. The wireless LAN communication apparatus according to the second embodiment is obtained by replacing the passive attenuators 21 and 22 of the wireless LAN communication apparatus (see FIG. 1) according to the first embodiment with the active attenuator shown in FIG. It is. Hereinafter, the configuration of the active attenuator will be described, and the other configurations are the same as those in the first embodiment, and thus the description thereof will be omitted.

  The attenuator is a so-called active type attenuator including active elements. The attenuator includes a diode D1 as an active element, and also includes resistance elements R6, R7, and R8, capacitive elements C1, C2, C3, and C4 and an inductive element L1 as passive elements. The diode D1 is a PIN diode. On the signal line, a capacitive element C1, a diode D1, and a capacitive element C4 are arranged in this order from the upstream side. Ground lines extend from two branch points on the signal line. On one ground line extending from a branch point located between the capacitive element C1 and the diode D1, a resistive element R7 and a capacitive element C2 are arranged. On the other hand, a resistance element R8 is arranged on a ground line extending from a branch point located between the diode D1 and the capacitive element C4. In addition, a voltage application line is provided from a position closer to the downstream side between the capacitive element C1 and the diode D1 on the signal line. An inductive element L1 and a resistance element R6 are arranged on the voltage application line, and a voltage V is applied to an end portion of the resistance element R6 facing the signal line. On the voltage application line, two ground lines extend from a branch point located between the induction element L1 and the resistance element R6. The capacitive element C3 is disposed on one ground line, and the thermistor TH11 is disposed on the other ground line.

The voltage V applied to the attenuator is divided by the resistance element R6 and the thermistor TH11. The resistance value of the thermistor TH11 by temperature change is changed, the voltage V ₀ which between the resistive element R6 and the thermistor TH11 also varies with temperature changes. Therefore, the attenuation amount of the entire attenuator also changes with temperature change. This attenuator is adjusted so that the temperature characteristic of the gain becomes the same as that shown in FIG.

  Therefore, even in the second embodiment using an active attenuator, as in the first embodiment using a passive attenuator, the occurrence of signal distortion can be suppressed and accurate information transmission can be realized without error. be able to.

  Further, in the second embodiment, by using an active attenuator, the gain change of the thermistor accompanying the temperature change is expanded by the active element, so that a larger temperature difference can be compensated.

It is a figure which shows the structure of the wireless LAN communication apparatus which concerns on Embodiment 1 of this invention. FIG. 2A shows the temperature characteristic of the amplifier in the RFIC, and FIG. 2B shows the temperature characteristic of the temperature compensation unit. FIG. 3A to FIG. 3C are diagrams illustrating the configuration of the attenuator. It is a figure which shows the attenuator of the wireless LAN communication apparatus which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Baseband signal processing part 11 Radio frequency signal processing part 12 Band pass filter 13 1st amplifier 14 2nd amplifier 15 High output amplifier 16 Low pass filter 17 Transmitting antenna 20 Temperature compensation part 21 and 22 Attenuator R1-R8 Resistive element TH1 to TH11 Temperature sensitive resistance elements C1 to C4 Capacitance element L1 Inductive element D1 Diodes V and V ₀ voltage

Claims (5)

A baseband signal processing unit for generating a baseband transmission signal;
A frequency converter that converts the baseband signal output from the baseband signal processor to a radio frequency signal;
For the signal output from the frequency converter, a temperature compensator that compensates for the temperature characteristics of the signal gain on the upstream side of the frequency converter, including the frequency converter, and
A wireless communication apparatus, comprising: a transmission antenna that wirelessly transmits a signal output from the temperature compensation unit. The wireless communication apparatus according to claim 1, wherein the temperature compensation unit includes a passive attenuator. The wireless communication apparatus according to claim 2, wherein the passive attenuator includes a plurality of temperature sensitive resistance elements. The wireless communication apparatus according to claim 3, wherein the plurality of temperature sensitive resistance elements are connected to each other in parallel. The wireless communication apparatus according to claim 1, wherein the temperature compensation unit includes an active attenuator.

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