JP2009100049A - Negative feedback amplifying circuit and radio communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a range in which radio communication is possible from being narrowed when radio communication is performed as modulation parameters are switched, while securing the linearity of signal distortion characteristic as necessary, and to reduce energy losses to extend battery life. <P>SOLUTION: A negative feedback amplifying circuit is used in a radio communication device that can switch a plurality of modulation parameters. An amplifier 12 amplifies the power of signals transmitted. A phase circuit unit 16 reverses the phase of an output signal of the amplifier 12. An amplifying circuit unit 15 attenuates the amplitude of a signal after phase reversal. A control signal input terminal 11 is supplied with a negative feedback control signal for controlling the amplifying circuit unit 15 with an amount of attenuation (amount of negative feedback) optimized for the modulation parameter that the radio communication device uses among the plurality of modulation parameters. In this way, the amplifying circuit unit 15 attenuates signal amplitude with an amount of attenuation corresponding to the negative feedback signal, and a signal after the attenuation is fed back to the amplifier 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a negative feedback amplifier circuit that amplifies a transmission signal during wireless communication and a wireless communication apparatus including the negative feedback amplifier circuit.

  2. Description of the Related Art Conventionally, in a wireless communication apparatus typified by a mobile phone terminal using so-called WCDMA (Wideband Code Division Multiple Access) modulation, an ACLR (Adjacent Channel Leakage Ratio: adjacent) related to a distortion amount of a transmission wave at the time of wireless transmission It is required to satisfy the characteristics of channel leakage power ratio).

  As a conventional technique related to improvement of distortion characteristics at the time of wireless transmission, for example, a high-frequency amplification device described in Japanese Patent Application Laid-Open No. 2007-60635 (Patent Document 1) is known. That is, the high-frequency amplifier includes a configuration that feeds back the intermodulation distortion output from the final stage amplifier to the interstage control circuit via the first and second control circuits. In the first and second control circuits, the first stage Mutual feedback from the final stage amplifier to the interstage matching circuit so that the combined amplitude of the intermodulation distortion input from the amplifier to the final stage amplifier and amplified and the intermodulation distortion newly generated in the final stage amplifier is small. The distortion characteristics are improved by controlling the amplitude and phase of the modulation distortion.

  Further, for example, in Japanese Patent Application Laid-Open No. 2007-28473 (Patent Document 2), an input signal is modulated with a carrier signal, the modulated signal is amplified and output, and the amplified output is the same as the carrier signal. Demodulate with a demodulation auxiliary signal whose frequency is shifted in phase, subtract the demodulated signal from the modulated signal to obtain a difference signal, and perform feedback by limiting the band of the difference signal using a filter with a variable cutoff frequency A negative feedback amplification device is disclosed that generates a signal and adds the feedback signal to the modulated signal. In this negative feedback amplifying device, by controlling the cutoff frequency of the filter in accordance with the amplitude of the difference signal, negative feedback amplification that is stable with respect to a change in transmission bandwidth and environmental fluctuation and less distorted is realized. ing.

  In addition, for example, in Japanese Patent Application Laid-Open No. 2006-245843 (Patent Document 3), gain control is performed in a variable gain amplifier having a configuration in which an input terminal and an output terminal of a main amplifier are connected by a variable resistance element. At the time, by controlling the gain control voltage of the main amplifier and the control voltage of the variable resistance element at the same time so that the input impedance and the output impedance of the variable gain amplifier are kept constant, the input terminal and the output terminal at the time of gain control. There is disclosed a technique that makes it possible to reduce the deterioration of reflection characteristics in the above-mentioned.

Japanese Patent Laying-Open No. 2007-60635 (FIG. 1) JP 2007-28473 A (FIG. 1) Japanese Patent Laying-Open No. 2006-245843 (FIG. 1)

  By the way, it is known that the above-mentioned ACLR characteristics generally depend on the magnitude of output power (transmission power) during wireless communication. That is, when the output power decreases, the ACLR characteristic improves, and conversely, when the output power increases, the ACLR characteristic deteriorates. Note that the technique described in the published patent publication of the above-mentioned Japanese Patent Application Laid-Open No. 2007-60635 can improve the distortion characteristics to some extent, but, for example, an HSDPA (High Speed Downlink Packet Access) system developed from a WCDMA modulation system. Is not necessarily sufficient.

  In addition, in the case of the WCDMA system corresponding to the HSDPA system, an adaptive modulation technique that changes the modulation system in accordance with the state of radio waves (transmission path conditions) is employed. For example, when the HSDPA system can be used, the HSDPA system is In other cases, the normal WCDMA system is used. For example, when the HSDPA system is used, the value of the modulation parameter is switched every moment. For this reason, in a wireless communication apparatus using a WCDMA modulation method corresponding to the HSDPA method, the ACLR characteristics are always satisfied regardless of whether the modulation method is switched or the modulation parameter is changed. In other words, the transmission power amplifier (power amplifier) is set so that an ACLR characteristic of a certain level or more is always obtained in all cases.

  Hereinafter, the setting of the transmission power amplifier will be described using a wireless communication apparatus that performs wireless communication by the HSDPA method as an example.

  A transmission power amplifier provided in a general transmission system of a wireless communication apparatus mainly includes an AGC (Automatic Gain Control) circuit for adjusting a gain of a transmission signal, and a linearity of transmission power control and distortion characteristics. The negative feedback amplifier has a linearity of the distortion characteristic when using a modulation parameter (in particular, expressed as a modulation parameter βm) in which the distortion characteristic of the transmission signal is most deteriorated. Is set to satisfy the above. That is, in the conventional negative feedback amplifier, the set value for maintaining the linearity of the distortion characteristic is matched with the value when the modulation parameter βm is used, and the set value is a modulation parameter other than the modulation parameter βm. Is also used as it is. In other words, for the modulation parameters other than the modulation parameter βm where the distortion characteristics are most deteriorated, a margin more than necessary is taken for the distortion characteristics.

  Further, in the conventional transmission power amplifier, in order to ensure the linearity of the distortion characteristic with respect to the modulation parameter βm, the output power (transmission power) is set to be low as described above. As a result, the communicable range of the wireless communication device is narrowed, which is undesirable for the user. Further, keeping output power low to ensure the linearity of distortion characteristics means that the hardware performance inherent in the transmission power amplifier cannot be fully exhibited.

  Further, for example, in order to maintain the linearity of the distortion characteristic with respect to the modulation parameter βm, a certain amount of bias power is always required, resulting in a large energy loss. As a result, for example, in a battery-driven wireless communication device There arises a problem that the maintenance of the battery is deteriorated.

  Of course, the above-described phenomenon also occurs when wireless communication is performed by switching between the HSDPA method and the normal WCDMA method, for example.

  In addition, for example, a wireless communication apparatus that has both second-generation (2G system) and third-generation (3G system) communication functions and uses them by switching them is the same, and the 2G system is used. The transmission power amplifier is set so as to meet the most severe distortion characteristics of both cases even though the case where the 3G system is used differs in the demand for distortion of the transmission power amplifier (power amplifier). Therefore, the communicable range is narrowed or energy loss occurs.

  The present invention has been proposed in view of such circumstances, and when performing wireless communication by switching the modulation method and modulation parameters, while ensuring the linearity of the distortion characteristics of the transmission signal as necessary, It is possible to obtain the maximum transmission output that can be realized for each modulation method and modulation parameter used by switching, preventing the communication range during wireless communication from becoming narrower, and reducing the loss of energy by reducing energy loss. It is an object of the present invention to provide a negative feedback amplifier circuit and a wireless communication device that can improve the maintenance.

  The negative feedback amplifier circuit according to the present invention is a circuit provided in a wireless communication device that switches between a plurality of modulation parameters and amplifies the power of the modulated signal, and inverts the phase of the output signal of the amplifier A phase inverting unit to be amplified, an amplitude attenuating unit for attenuating the amplitude of the output signal of the amplifying unit, and an attenuation amount optimized for the modulation parameter used by the wireless communication device among a plurality of modulation parameters, By having an attenuation control unit that causes the amplitude attenuation unit to attenuate the amplitude by the attenuation amount, and a feedback path that feeds back the signal via the phase inversion unit and the amplitude attenuation unit to the amplification unit, the above-described problem is solved. To do.

  In addition, the wireless communication device of the present invention includes a modulation unit that modulates a signal using a modulation parameter that is selectively set from among a plurality of modulation parameters, and amplifies the power of the signal that is modulated by the modulation unit An amplifying unit, a phase inverting unit for inverting the phase of the output signal of the amplifying unit, an amplitude attenuating unit for attenuating the amplitude of the output signal of the amplifying unit, and a modulation parameter used by the modulating unit among a plurality of modulation parameters An attenuation amount optimized for the attenuation is determined, and an attenuation control unit that causes the amplitude attenuation unit to attenuate the amplitude based on the attenuation amount, and a signal through the phase inversion unit and the amplitude attenuation unit are fed back to the amplification unit. The problem described above is solved by including a feedback path and a transmission unit that wirelessly transmits at least a signal amplified by the amplification unit.

  That is, according to the present invention, attenuations optimized for a plurality of modulation parameters used for modulation are prepared, and attenuations corresponding to the modulation parameters actually used for modulation among them are prepared. Is used to adjust the amplitude of the negative feedback signal. That is, in the present invention, the amount of negative feedback to the negative feedback amplifier circuit is adjusted according to the modulation parameter used.

  In the present invention, by adjusting the amount of negative feedback to the negative feedback amplifier circuit to an optimum value according to the modulation parameter to be used, when performing wireless communication by switching the modulation method and modulation parameter, The linearity of the distortion characteristics can be ensured as necessary, and the maximum transmission output that can be realized for each modulation method and modulation parameter used by switching can be obtained to prevent the communication range from being narrowed during wireless communication. In addition, it is possible to reduce the loss of energy and improve battery maintenance.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In the following embodiments, a mobile phone terminal is cited as an application example of the negative feedback amplifier circuit and the wireless communication device of the present invention.

  In addition, the mobile phone terminal according to the present embodiment can switch the modulation method or change the modulation parameter within a predetermined modulation method. In this embodiment, as an example of switching of the modulation system, for example, switching of so-called second generation (2G system) and third generation (3G system) is given, and switching of the modulation parameter within a predetermined modulation system As an example, switching of modulation parameters at the time of adaptive modulation in the WCDMA HSDPA system is cited. Note that switching between 2G and 3G modulation methods is actually performed by switching, for example, a modulation parameter defined in the 2G method to a modulation parameter defined in the 3G method, or vice versa. Is switched to a 2G modulation parameter. In the following description, the switching of the modulation method by switching the modulation parameter and the switching of the modulation parameter within the predetermined modulation method are expressed as “switching of the modulation parameter” unless otherwise distinguished. In the following embodiments, a terminal that switches between 2G and 3G modulation schemes and a terminal that switches modulation parameters in the HSDPA scheme are described separately, but the present invention describes those 2G scheme and 3G scheme. The present invention can also be applied to a terminal having both functions of system switching and HSDPA modulation parameter switching.

  Of course, the content described here is merely an example, and it goes without saying that the present invention is not limited to this example.

[Configuration of main part of negative feedback amplifier circuit]
FIG. 1 shows a schematic configuration of a negative feedback amplifier circuit provided in the mobile phone terminal of the embodiment of the present invention.

  In FIG. 1, the transmission signal input terminal 10 is connected to the input terminal of the amplifier 12. The output terminal of the amplifier 12 is connected to the transmission signal output terminal 13 and also to the input terminal of the feedback circuit 14. The output terminal of the feedback circuit 14 is connected to a common connection point between the transmission signal input terminal 10 and the input terminal of the amplifier 12. That is, the negative feedback amplifier circuit of FIG. 1 is configured to feed back the output signal of the feedback circuit 14 to the input terminal of the amplifier 12 through the feedback path having the common connection point.

  The feedback circuit 14 includes a phase circuit unit 16 and an amplitude circuit unit 15. The phase circuit unit 16 is a phase inverting circuit set so that the phase difference between the signal supplied to the input terminal and the signal output from the output terminal is 180 degrees. The amplitude circuit unit 15 is a variable attenuation circuit capable of attenuating and outputting the amplitude of the input signal and changing the attenuation amount. In the negative feedback amplifier circuit of this embodiment, the attenuation amount when the amplitude of the input signal is attenuated by the amplitude circuit unit 15 is from the table reference unit 25 of FIG. 2 described later via the control signal input terminal 11. The amplitude circuit 15 is variably controlled by the supplied negative feedback control signal, and the amplitude circuit unit 15 attenuates the amplitude of the input signal by the variably controlled attenuation amount and outputs the attenuated signal.

  As the simplest example, the phase circuit unit 16 of the feedback circuit 14 can use a transmission line having a predetermined length that only inverts the phase of the input signal (180-degree phase shift). Further, as a specific configuration example of the amplitude circuit unit 15, for example, a plurality of resistors each having a different resistance value, and a selector switch that switches and selects any of the plurality of resistors according to the negative feedback control signal. By passing the input signal of the input terminal to the resistor selected by the changeover switch, or by sending the output signal of the resistor selected by the changeover switch to the output terminal, A resistor bank configuration that attenuates the amplitude of the input signal to the amplitude circuit unit 15 can be given. Of course, the phase circuit unit 16 may have other configurations, and the amplitude circuit unit 15 is also a variable attenuator configured by a variable resistor whose resistance value is changed and controlled according to the control voltage, for example. Also good.

  As described above, in the negative feedback amplifier circuit of the present embodiment, the transmission signal supplied to the transmission signal input terminal 10 is amplified by the amplifier 12 and output from the transmission signal output terminal 13, and at the same time, the output signal of the amplifier 12 is output. A negative feedback amplification process is performed in which the phase is inverted (180-degree phase shift) by the phase circuit unit 16 and further attenuated by the amplitude circuit unit 15 and fed back to the input terminal of the amplifier 12.

[Relationship between negative feedback amount of negative feedback amplifier circuit and distortion characteristics of signal, and switching of modulation parameter and control of negative feedback amount]
Here, in the negative feedback amplifier circuit having the configuration shown in FIG. 1, when the attenuation amount of the amplitude circuit unit 15 is variably controlled, for example, a large attenuation amount that makes the amplitude of the input signal substantially zero is used. When the control is performed, the amount of negative feedback to the amplifier 12 becomes substantially zero, and the negative feedback amplifier circuit in this case operates as a circuit consisting of only the amplifier 12. On the other hand, when the attenuation amount variable control of the amplitude circuit unit 15 is performed, for example, when the control for reducing the attenuation amount is performed, the negative feedback amount to the amplifier 12 is increased, and strong negative feedback is applied. Become. That is, in the negative feedback amplifier circuit, as the amount of negative feedback to the amplifier 12 increases, the degree of amplification in the entire negative feedback amplifier circuit decreases.

  As described above, the distortion characteristic (ACLR characteristic) of the transmission signal depends on the magnitude of the output power (that is, transmission power). For example, when the output power decreases, the distortion characteristic improves, and conversely, when the output power increases. The distortion characteristics deteriorate. Therefore, in the negative feedback amplifier circuit, for example, if the degree of amplification in the entire negative feedback amplifier circuit is lowered by increasing the amount of negative feedback, the distortion characteristic of the transmission signal is improved.

  On the other hand, in the case of a terminal that can be used by appropriately switching between the 2G system and the 3G system, such as the mobile phone terminal of the present embodiment, the transmission power amplifier of the transmission system is used when the 2G system is used and when the 3G system is used. Different requirements for distortion of (power amplifier). Similarly, when switching the modulation parameter of the HSDPA system, the request for distortion of the transmission power amplifier is different for each modulation parameter.

  Here, as an example, in the case of the HSDPA system, for example, the control channel signal and the data channel signal are mixed and modulated, and the ratio of the amplitude when the control channel signal amplitude and the data channel signal amplitude are mixed, Switching is performed every moment depending on the communication status (the state of radio waves and the status of transmission lines). That is, in the HSDPA method, a modulation parameter βc for the control channel and a modulation parameter βd for the data channel are defined as modulation parameters relating to the ratio of the signal amplitude of the control channel and the data channel. In this case, the ratio (βc / βd) of the modulation parameters βc and βd is switched every moment according to the communication status. In the HSDPA system, the requirement for the distortion characteristic for the transmission power amplifier varies depending on the combination of the modulation parameters βc and βd. In other combinations, the demand for distortion characteristics may be relaxed.

  For these reasons, in the present embodiment, for example, when switching the modulation parameters of the 2G and 3G methods is performed in order to meet the demand for distortion characteristics that change due to the switching of the modulation parameters of the 2G method and the 3G method. Is a negative feedback amount (that is, an attenuation amount) prepared in advance by optimizing the modulation parameters for each of the 2G and 3G modulation schemes, in accordance with the modulation parameter switched by the 2G and 3G modulation schemes. By selecting the negative feedback amount (attenuation amount) and performing the negative feedback amplification process using the selected negative feedback amount, the optimum distortion characteristic can be obtained for the modulation parameter of the switched modulation method, As much transmission power as possible is obtained. Similarly, in the present embodiment, when the modulation parameter combination is switched in order to meet the demand for distortion characteristics that change due to switching of the modulation parameter (particularly βc / βd) combination in the HSDPA system. Selects a negative feedback amount (attenuation amount) corresponding to each combination of modulation parameters from negative feedback amounts (attenuation amounts) optimized and prepared in advance for each combination of modulation parameters of the HSDPA system, By performing a negative feedback amplification process using the selected negative feedback amount, an optimum distortion characteristic can be obtained for the switched modulation parameter, and at the same time, as much transmission power as possible can be obtained.

  That is, in the present embodiment, the negative feedback amount (attenuation amount) prepared by optimizing each modulation parameter is reduced in linearity to some extent for, for example, a modulation parameter that does not require so severe distortion characteristics. The amount of negative feedback that becomes distortion characteristics is reduced, so that energy loss during signal transmission at the desired transmission power is reduced, while linearity is ensured for modulation parameters that require strict distortion characteristics, for example. Thus, the amount of negative feedback resulting in the distortion characteristics is set, so that the quality of the transmission signal can be maintained.

  In this embodiment, in order to realize this, for each modulation parameter that can be switched, a negative feedback amount that provides an optimum distortion characteristic for each transmission power is obtained in advance, and each of the modulation parameters and a negative value are obtained. A table in which the feedback amount is associated with each transmission power is prepared and prepared in advance. In this embodiment, when the modulation parameter is switched, a negative feedback amount (attenuation amount) corresponding to the switched modulation parameter is selected from the table, and the negative feedback using the selected negative feedback amount is selected. Amplification processing is performed.

  The control signal input terminal 11 shown in FIG. 1 is supplied with a negative feedback control signal for setting a negative feedback amount that provides optimum distortion characteristics for the modulation parameter to be switched. In the circuit, the attenuation amount of the amplitude circuit unit 15 of the feedback circuit 14 (that is, the negative feedback amount to the amplifier 12) is variably controlled by the negative feedback control signal. Thereby, in the negative feedback amplifier circuit shown in FIG. 1, when signal transmission is performed with a desired transmission power, a transmission signal having optimum distortion characteristics with respect to the switched modulation parameter can be obtained.

[Configuration example for switching modulation parameter and controlling negative feedback amount and table example of negative feedback amount control data]
FIG. 2 shows a schematic configuration of a main part for switching the modulation parameter and controlling the negative feedback amount in the mobile phone terminal of the present embodiment. Note that the mobile phone terminal of the present embodiment naturally includes components included in a general mobile phone terminal, but FIG. 2 shows only the components of the main part related to the present invention.

  In FIG. 2, the data processing unit 21 outputs at least modulation parameter data used for modulation of a transmission signal and transmission power information indicating the transmission power of the transmission signal. The modulation parameter data used for modulating the transmission signal is sent to the modulation unit 22 and the table reference unit 25, and the transmission power information is sent to the table reference unit 25.

  Here, when the mobile phone terminal of the present embodiment is a terminal that can switch between 2G and 3G modulation schemes, for example, when switching between these modulation schemes, the data processing unit 21 performs modulation using, for example, the 2G scheme. In this case, the modulation parameter data defined in the 2G system is selected and output to the modulation unit 22 and also to the table reference unit 25. Further, for example, when modulation by the 3G system is performed, the data processing unit 21 selects and outputs the modulation parameter data defined in the 3G system to the modulation unit 22 and also to the table reference unit 25. On the other hand, when the mobile phone terminal of the present embodiment is a terminal capable of switching modulation parameters by, for example, adaptive modulation of the HSDPA method, and when switching the modulation parameter of the HSDPA method, the data processing unit 21 uses the HSDPA method. The modulation parameter data to be switched is selected and output to the modulation unit 22 and also output to the table reference unit 25.

  When a transmission signal is supplied from a previous configuration (not shown), the modulation unit 22 performs quadrature modulation of the transmission signal using the modulation parameter supplied from the data processing unit 21 to center on a desired transmission channel frequency. A modulated signal (modulated transmission signal) having a frequency is output. The modulated transmission signal is sent to the AGC unit 23 of the signal amplification unit 20.

  The AGC unit 23 adjusts the gain of the transmission signal based on AGC adjustment value data supplied from a table reference unit 25 described later. The transmission signal whose gain has been adjusted by the AGC unit 23 is sent to the negative feedback amplification unit 24.

  The table reference unit 25 includes transmission power information of a transmission signal output from the signal amplification unit 20 to the front end and the antenna unit 26, AGC adjustment value data when the AGC unit 23 performs AGC adjustment, and 2G and 3G modulation schemes Modulation parameter data or HSDPA modulation parameter data and the transmission signal modulated by the modulation unit 22 sets the negative feedback amount necessary and optimum for the negative feedback amplification unit 24 to satisfy the ACLLR distortion characteristic standard. The table data associated with the negative feedback control data for each is stored. Then, the table reference unit 25 refers to the table using the transmission power information and the modulation parameter supplied from the data processing unit 21, and AGC adjustment value data and negative feedback associated with them in the table. The control data is extracted, AGC adjustment value data is output to the AGC unit 23, and negative feedback control data is output to the negative feedback amplification unit 24 of the signal amplification unit 20. A specific example of the table held in the table reference unit 25 will be described later.

  The front end and antenna unit 26 radiates the transmission signal transmitted from the negative feedback amplification unit 24 to the outside as a radio wave.

  Here, examples of the table held by the table reference unit 25 include tables as shown in FIGS.

  FIG. 3 shows an example of a table held in the table reference unit 25 when the mobile phone terminal of the present embodiment is a terminal that can switch between the 2G and 3G modulation schemes. FIG. 4 shows an example of a table held in the table reference unit 25 when the mobile phone terminal of the present embodiment is a terminal capable of switching modulation parameters by, for example, the HSDPA method. Similarly, FIG. 5 shows another example of a table held in the table reference unit 25 when the mobile phone terminal of the present embodiment is a terminal capable of switching modulation parameters by the HSDPA method. .

  The table shown in FIG. 3 includes items indicating modulation schemes (in this example, items corresponding to the modulation schemes 2G and 3G) and items of power information of transmission signals output from the signal amplification unit 20 to the front end and the antenna unit 26. Necessary for Pout and its transmission power value, AGC adjustment value item AGC and its AGC adjustment value of AGC unit 23 and its AGC adjustment value, and the transmission signal modulated by 2G or 3G method to satisfy the standard of distortion characteristics of ACLR In addition, the negative feedback control item FB for setting the optimum negative feedback amount in the negative feedback amplification unit 24 and the value of the negative feedback amount are tables associated with each other. 3, A1, B2, C3,... And A11, B12, C13,... In the item AGC are, for example, numerical values representing AGC adjustment values, and a1, b2, c3,. ..., A11, b12, c13,... Are numerical values representing negative feedback amounts (attenuation amounts), for example. In addition, in the item 2G representing the modulation method, data of the modulation parameter actually used in the 2G modulation method is described, and in the item 3G, data of the modulation parameter used in the 3G modulation method is described.

  In the example of FIG. 3, when the modulation parameter data is supplied from the data processing unit 21, the table reference unit 25 receives the supplied modulation parameter data and the modulation parameter described in the items 2G and 3G. Data matching is performed, and it is determined whether the modulation parameter supplied from the data processing unit 21 is of 2G modulation system or 3G modulation system. For example, when 2G modulation parameter data is supplied from the data processing unit 21 to the table reference unit 25 and, for example, data indicating 23 dBm is supplied as transmission power information, the table reference unit 25 By the reference processing based on them, negative feedback control data indicating the value of “a1” is output and sent to the negative feedback amplifier 24, and data indicating the value of “A1” is output as the AGC adjustment value And sent to the AGC unit 23. Also, for example, when 3G modulation parameter data is supplied from the data processing unit 21 to the table reference unit 25 and, for example, data indicating 19 dBm is supplied as transmission power information, the table reference unit 25 By reference processing based on them, negative feedback control data indicating the value of “c13” is output and sent to the negative feedback amplifier 24, and data indicating the value of “C13” is output as the AGC adjustment value. And sent to the AGC unit 23.

  Next, the table shown in FIG. 4 includes items βc / βd indicating modulation parameters of the control channel and data channel of the HSDPA system, items R1, R2, R3,... Indicating the modulation parameter ratio (βc / βd), The transmission power information item Pout and its transmission power value, the AGC adjustment value item AGC and its AGC adjustment value, and the transmission signal modulated by the HSDPA method are necessary and optimal for satisfying the ACLR distortion characteristics standard. The negative feedback control item FB for setting the negative feedback amount in the negative feedback amplification unit 24 and the value of the negative feedback amount are tables associated with each other. 4, A21, B22, C23,... And A31, B32, C33,... In the item AGC are numerical values representing AGC adjustment values, for example, and a21, b22, c23,. ..., A31, b32, c33,... Are numerical values representing negative feedback amounts (attenuation amounts), for example. Further, items R1, R2, R3,... Describe data representing the ratio (βc / βd) of the modulation parameter βc of the control channel and the modulation parameter βd of the data channel. Further, in the item βc / βd, data of the modulation parameter βc of the control channel (control channel) that has a great influence on the deterioration of the distortion characteristic among the modulation parameters of the HSDPA system and data of the modulation parameter βd of the data channel are described. Has been.

  In the example of FIG. 4, when the modulation parameter data is supplied from the data processing unit 21, the table reference unit 25 receives the modulation parameter data and the modulation parameter described in the item βc / βd. Data matching is performed, and it is determined whether the modulation parameters supplied from the data processing unit 21 are the control channel modulation parameter βc and the data channel modulation parameter βc. For example, data of the control channel modulation parameter βc and the data channel modulation parameter βc is supplied from the data processing unit 21 to the table reference unit 25, and the ratio of the parameters βc and βd is R1, for example. When data indicating, for example, 22 dBm is supplied as transmission power information, negative feedback control data indicating the value of “b22” is output from the table reference unit 25 by the reference processing based on the data, thereby negative feedback amplification The data indicating the value of B22 is output as the AGC adjustment value and sent to the AGC unit 23. For example, the modulation parameter βc and the table reference unit 25 are sent from the data processing unit 21 to the table reference unit 25. βd data is supplied, and the ratio of these modulation parameters is R2, for example. For example, when data indicating 23 dBm is supplied as the word information, negative feedback control data indicating the value of “a31” is output from the table reference unit 25 by reference processing based on them, and the negative feedback amplification unit 24, and data indicating the value of “A31” as an AGC adjustment value is output and sent to the AGC unit 23. The modulation parameters βc and βd supplied from the data processing unit 21 The calculation for obtaining the ratio (βc / βd) may be performed by the table reference unit 25, or is performed by the data processing unit 21 and data of the ratio (βc / βd) is supplied from the data processing unit 21. Also good.

  Next, as in the example of FIG. 4, the table shown in FIG. 5 includes items βc / βd of modulation parameter data in the HSDPA system, items R1, R2, R3,. This is a table in which information items Pout and transmission power values, AGC adjustment value items AGC and AGC adjustment values, negative feedback control items FB and negative feedback amount values are associated with each other.

  However, in the example of FIG. 5, the data A21, B22, C23,... Of the item AGC in the column of the item R1 are respectively numerical values indicating the AGC adjustment values, and the data a21, b22, c23,. Although it is a numerical value representing the negative feedback amount, the offset value (for example, +3) from each data value in the item AGC in the column of the item R1 is described in the data of the item AGC in the column of the item R2 or the item R3. Has been. Therefore, for example, when the item AGC in the column of the item R2 is referred to, a value obtained by adding the offset value (+3) to each numerical value (A21, B22, C23,...) Of the item AGC in the column of the item R1. Similarly, when the item FB in the column of the item R2 is referred to, an offset value (+3) is added to each numerical value (a21, b22, c23,...) Of the item FB in the column of the item R1. ) Will be used.

  That is, in the case of the example in FIG. 5, the data of the modulation parameters βc and βd is supplied from the data processing unit 21 to the table reference unit 25, the ratio thereof is, for example, R1, and the transmission power information indicates, for example, 21 dBm When data is supplied, negative feedback control data indicating the value of “c23” is output from the table reference unit 25 by reference processing based on them, and is sent to the negative feedback amplification unit 24. The data indicating the value of C23 is output as the AGC adjustment value and is sent to the AGC unit 23. For example, the data of the modulation parameters βc and βd are supplied from the data processing unit 21 to the table reference unit 25, If the ratio is R2, for example, and data indicating, for example, 22 dBm is supplied as transmission power information, the table reference unit 25 Are referred to the AGC adjustment value data of B22 + 3 from the item AGC in the column of the item R2, based on the value of “B22” which is the AGC adjustment value in the column of the item R1, and the AGC adjustment value data is AGC. Further, based on the value of “b22” which is the negative feedback control data in the column of the item R1, the negative feedback control data of b22 + 3 is referred to from the item FB in the column of the item R2, Negative feedback control data is sent to the negative feedback amplifier 24.

  As described above, according to the configuration of the present embodiment, the table reference unit 25 requires the transmission signal to satisfy the ACLLR distortion characteristic standard for each of the usable modulation processing and transmission power. Optimal negative feedback control data and AGC adjustment value data are stored, and negative feedback control data and AGC adjustment value data corresponding to the modulation processing and transmission power in the modulation unit 22 are read from the table reference unit 25. . In the negative feedback amplifying unit 24 of the present embodiment, since negative feedback amplification processing is performed using the negative feedback control data, for example, when linearity is required for distortion characteristics, the linearity can be ensured, When the distortion characteristic may have non-linearity, sufficient transmission power can be ensured and power can be saved by using the distortion characteristic.

[Example of creating table data]
The table data held in the table reference unit 25 described above is data created in advance, for example, at the time of designing and manufacturing the negative feedback amplifier circuit of this embodiment (the mobile phone terminal of this embodiment).

  The table data is modulated using both 2G and 3G modulation parameters and HSDPA modulation parameters, the output of the negative feedback amplifier circuit of this embodiment is detected by the detector, and the detected signal is To obtain signal distortion characteristics for each AGC adjustment value and each transmission power used in actual wireless communication, satisfy the linearity required for each distortion characteristic, and vice versa. It is created by measuring the amount of negative feedback that allows some degree of nonlinearity. For the table data created in this way, for example, the negative feedback amplifier circuit shown in FIG. 1 operates as an amplifier including only the amplifier 12 and has the modulation parameter that is the least required from the viewpoint of the ACLR standard. Make calibration in the set state. In addition, an optimum negative feedback amount for a certain AGC adjustment value and transmission power is obtained for some typical values of the modulation parameter, and other AGC adjustment values and transmission power are negative. By setting the offset value of the feedback amount, it is not necessary to obtain the total AGC adjustment value used for each modulation parameter and the negative feedback amount for the total transmission power using the detection signal from the detection unit.

[Summary]
As described above, according to the present embodiment, in the case of performing wireless communication by switching the modulation parameter, only when strict distortion characteristics are required, a negative value for ensuring linearity in the distortion characteristics of the transmission signal is required. When feedback control is performed and, on the other hand, loose distortion characteristics are acceptable, transmission power may be reduced more than necessary by performing negative feedback control that makes the distortion characteristics of the transmission signal nonlinear to some extent. As a result, the maximum transmission output that can be realized in each case can be obtained for the modulation parameters that are switched and used, and as a result, it is possible to prevent the occurrence of a situation where the communicable range becomes narrow during wireless communication. Further, according to the present embodiment, when a gentle distortion characteristic is acceptable, the distortion characteristic is allowed to be somewhat nonlinear, for example, the energy characteristic is higher than that in the case where the linearity of the distortion characteristic is always maintained. Loss can be reduced, and as a result, it is possible to improve the maintenance of a battery such as a mobile phone terminal. Further, according to the present embodiment, the transmission power is not suppressed to be unnecessarily low, so that the hardware performance originally provided in the transmission power amplifier can be sufficiently exhibited.

  The negative feedback amplifier circuit of the present invention is used in the final stage of the transmission unit of a wireless communication device such as a mobile phone terminal, and the band of the signal amplified by the negative feedback amplifier circuit is wireless communication. It is defined in the communication band of the device. That is, the negative feedback amplifier circuit changes only the amplitude characteristic in the desired communication band according to the modulation parameter, and is designed to have no cutoff in the communication band. Therefore, the negative feedback amplifier circuit of the present invention has a configuration that does not require control of the cut-off frequency as in the technique described in the published patent publication (Patent Document 2) of the aforementioned Japanese Patent Application Laid-Open No. 2007-28473. .

  Also, in the above-mentioned published patent document (Patent Document 3) of Japanese Patent Application Laid-Open No. 2006-245843, the control of the main amplifier is made so that the input impedance and the output impedance of the variable gain amplifier are constant during the gain control. In the present invention, the control voltage for controlling the main amplifier is not necessarily required, and the impedance is made constant. There is no need.

  The above description of the embodiments of the present invention is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made according to the design or the like as long as the technical idea according to the present invention is not deviated.

  The present invention is not limited to a mobile phone terminal, and can be applied to various communication devices having a wireless communication function for performing negative feedback amplification.

It is a block circuit diagram which shows schematic structure of the negative feedback amplifier circuit with which the mobile telephone terminal of this invention embodiment is equipped. It is a block circuit diagram which shows schematic structure of the principal part for performing switching of a modulation parameter and control of the amount of negative feedback among the structures of the mobile telephone terminal of this embodiment. It is a figure which shows an example of the table hold | maintained at a table reference part, when the mobile telephone terminal of this embodiment is a terminal which can switch the modulation system of 2G system and 3G system. It is a figure which shows an example of the table hold | maintained at a table reference part, when the mobile telephone terminal of this embodiment is a terminal which can switch a modulation parameter by a HSDPA system. It is a figure which shows the other example of the table hold | maintained at a table reference part, when the mobile telephone terminal of this embodiment is a terminal which can switch a modulation parameter by a HSDPA system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Transmission signal input terminal, 11 Control signal input terminal, 12 Amplifier, 13 Transmission signal output terminal, 14 Feedback circuit, 15 Amplitude circuit part, 16 Phase circuit part, 20 Signal amplification part, 21 Data processing part, 22 Modulation part, 23 AGC section, 24 negative feedback amplification section, 25 table reference section, 26 front end & antenna section

Claims (6)

A negative feedback amplifier circuit provided in a wireless communication device that uses a plurality of modulation parameters by switching,
An amplifier for amplifying the power of the modulated signal;
A phase inversion unit for inverting the phase of the output signal of the amplification unit;
An amplitude attenuation unit for attenuating the amplitude of the output signal of the amplification unit;
Attenuation control that determines an attenuation amount optimized for the modulation parameter used by the wireless communication apparatus among the plurality of modulation parameters, and causes the amplitude attenuation unit to attenuate the amplitude based on the attenuation amount And
A feedback path for feeding back the signal via the phase inversion unit and the amplitude attenuation unit to the amplification unit,
A negative feedback amplifier circuit. The attenuation control unit
The wireless communication device has a table in which a plurality of modulation parameters that can be used by switching, and a plurality of attenuation values optimized in advance for each modulation parameter are associated with each other,
2. The negative feedback amplifier circuit according to claim 1, wherein an attenuation amount corresponding to a modulation parameter used by the wireless communication apparatus is selected from the table and determined as the optimized attenuation amount. The attenuation control unit
Correspondence between a modulation parameter predetermined as a representative among a plurality of modulation parameters that can be switched and used by the wireless communication device and an attenuation amount optimized in advance for the representative modulation parameter, and the representative A table in which the offset value of the attenuation optimized for the representative modulation parameter is associated with a modulation parameter other than
When the wireless communication apparatus uses the representative modulation parameter, the attenuation corresponding to the representative modulation parameter is selected from the table and determined as the optimized attenuation,
When the wireless communication apparatus uses a modulation parameter other than the representative, the offset corresponding to the modulation parameter other than the representative is added to the attenuation optimized for the representative modulation parameter. 2. The negative feedback amplifier circuit according to claim 1, wherein the negative feedback amplifier circuit is determined as an attenuation amount. A modulation unit that modulates a signal using a modulation parameter selectively set from a plurality of modulation parameters;
An amplifying unit for amplifying the power of the signal modulated by the modulating unit;
A phase inversion unit for inverting the phase of the output signal of the amplification unit;
An amplitude attenuation unit for attenuating the amplitude of the output signal of the amplification unit;
An attenuation control unit that determines an attenuation amount optimized for a modulation parameter used by the modulation unit among a plurality of modulation parameters, and causes the amplitude attenuation unit to attenuate the amplitude based on the attenuation amount; ,
A feedback path for feeding back the signal through the phase inversion unit and the amplitude attenuation unit to the amplification unit;
A transmitter that wirelessly transmits at least the signal amplified by the amplifier,
A wireless communication apparatus. The attenuation control unit
The modulation unit has a table in which a plurality of modulation parameters that can be used for signal modulation and a plurality of attenuation amounts optimized in advance for each modulation parameter are associated with each other,
5. The wireless communication apparatus according to claim 4, wherein an attenuation amount corresponding to a modulation parameter used by the modulation unit is selected from the table and determined as the optimized attenuation amount. The attenuation control unit
Correspondence between a modulation parameter predetermined as a representative among a plurality of modulation parameters that can be used for signal modulation by the modulation unit and an attenuation amount optimized in advance for the representative modulation parameter, and the representative A table in which the offset value of the attenuation optimized for the representative modulation parameter is associated with a modulation parameter other than
When the modulation unit uses the representative modulation parameter, the attenuation corresponding to the representative modulation parameter is selected from the table and determined as the optimized attenuation,
When the modulation unit uses a modulation parameter other than the representative, the attenuation corresponding to the modulation parameter other than the representative is the attenuation obtained by adding the offset value to the attenuation optimized for the representative modulation parameter. The wireless communication apparatus according to claim 4, wherein the wireless communication apparatus is determined as a quantity.

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