JP2010130207A - Wireless communication apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and method for attaining reduction in power consumption of a power amplifier that is linearly operated during transmission of a low output power signal. <P>SOLUTION: The apparatus includes a power amplifier 2 to be linearly operated to amplify the electrical power of transmitting signal. During transmission of signal in the power equal to or lower than the predetermined level, a bias voltage of the power amplifier 2 is set to the value lower than that for transmission of signal in the electrical power higher than the predetermined level. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus and method.

  In wireless communication devices (terminals) such as mobile phone terminals (cellular terminals), not only voice calls but also high-speed data communication are often used as devices become more functional and faster.

  In the GSM (Global System for Mobile Communications) communication system, since the circuit configuration and control are simple as a general transmitter architecture, the direct conversion system is RFIC (Radio Frequency Integrated Circuit: simply “transceiver” Is often used in the design.

  Since GMSK (Gaussian minimum phase keying modulation) modulation used in the GSM communication system is a constant envelope modulation system, the power amplifier (power amplifier) can be operated in saturation. By saturating the power amplifier, current consumption of the power amplifier can be reduced. Increasing the efficiency of the power amplifier and transmitter also increases battery life.

  However, GSM packet data communication using the GMSK modulation method has a maximum throughput of 171.2 kbps and does not satisfy the needs for high-speed data communication.

  In the GSM communication system, a linear modulation system such as 8-phase shift keying (8PSK) has been used as a digital modulation system. By using 8-phase shift keying (8PSK), the transfer rate reaches a maximum throughput of 473.6 kbps, which is suitable for high-speed data communication.

  Regarding bias voltage control of a power amplifier, Patent Document 1 discloses a gain variable circuit (AGC) that variably controls a transmission power amplification gain of a transmission signal, a power amplifier that power-amplifies the transmission signal, and transmission power control. A bias for applying a bias voltage to the power amplifier as a first control system for forming a feedback loop for the power amplifier and a second control system for reducing the power consumption by controlling the bias voltage of the power amplifier at the time of low output A configuration including a voltage generation unit and a gain variation compensation unit is disclosed. In Patent Document 2, a change amount of the bias control signal corresponding to the transmission power control information before and after the update is obtained, and when the change amount is less than the threshold, the bias generation unit is selected, and the bias control signal corresponding to the transmission power information is obtained. In addition to the input to the bias generator, the gain control signal is input to the variable gain amplifier, and when the amount of change is equal to or greater than the threshold value, the amount of change in the bias voltage is calculated from the bias control signal and the DC voltage of the DC power supply. The gain correction value is calculated and added to the gain control signal, the DC power supply is selected, input to the power amplifier, the bias control signal is input to the bias generator, and the gain control signal is input to the variable gain amplifier. In Patent Document 3, a variable attenuator varies the level of a transmission signal for controlling transmission power. The linear power amplifier amplifies in the linear region or quasi-linear region, and the bias control circuit controls the bias voltage of the linear amplifier according to the attenuation amount from the attenuation control circuit that controls the attenuation amount of the variable attenuator, An apparatus configuration that achieves high accuracy, a wide dynamic range, low distortion, and reduced power consumption is disclosed.

JP 2000-201089 A JP 2004-221737 A JP-A-6-252797

  The following is an analysis of the related art according to the present invention.

  When 8-phase shift keying (8PSK) is used for the GSM communication system, there are the following problems. 8-phase shift keying (8PSK) suitable for high-speed communication includes phase information and amplitude information. In 8-phase shift keying (8PSK), the amplitude changes by about 17 dB, unlike the GMSK constant envelope modulation method. Due to the fluctuation in amplitude, non-linearity of the amplitude transfer function of the amplifier causes spectrum regrowth, which is a component of adjacent channel leakage power, and distortion occurs in the transfer signal.

  For this reason, a transmitter using 8-phase shift keying (8PSK) direct conversion cannot use a power amplifier that operates in saturation, and must operate in a linear region of the power amplifier.

  A power amplifier that operates linearly consumes more current than a power amplifier that operates in saturation, the efficiency of the transmitter is low, and the battery life is short.

  In the GSM communication system, the mobile terminal does not always transmit at the maximum power, but the mobile transmitter transmits only the necessary transmission power according to the radio field strength information (electric field strength) of the base station. In the GSM communication system, the transmission power of the mobile terminal is controlled by the base station according to the distance between the mobile terminal and the base station. When the mobile terminal approaches the base station and the distance becomes small, the mobile terminal reduces the transmission power to the optimum transmission power based on the signal strength information from the base station. Such power control is performed when operating in 8-phase shift keying (8PSK).

  Reduction of the current consumption of a power amplifier that operates linearly at low power transmission in the operation of 8-phase shift keying modulation (8PSK) is one issue for transmitters of linear modulation methods such as 8-phase shift keying modulation (8PSK). Become.

  An object of the present invention is to provide an apparatus and a method that can reduce the power consumption of a linearly operating power amplifier during low power transmission.

  In order to solve the above problems, the invention disclosed in the present application is generally configured as follows.

  In the present invention, the bias voltage of the linearly operating power amplifier is set to a lower value than when transmitting at a power higher than the predetermined level at the time of transmission at a power lower than a predetermined level. .

  According to the present invention, the power consumption of a linearly operating power amplifier can be reduced at the time of low power transmission of a linear modulation system transmitter such as an 8-phase shift keying modulation (8PSK) system, the power efficiency of the transmitter is improved, and the battery You can extend your time.

  In the present invention, when the transmission power requested from the base station becomes lower than a predetermined level at the time of transmission by 8-phase shift keying modulation (8PSK) in the wireless communication apparatus, the bias voltage of the linear operation power amplifier is lowered. As a result, the current consumption of the power amplifier is suppressed and the current consumption at the time of low output of the power amplifier is reduced.

  Examples of the present invention will be described. FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. FIG. 1 shows the configuration of a direct conversion type transmitter.

  The transmitter of the present embodiment includes a transmitter of a transceiver (RFIC) 1 and a power amplifier (power amplifier) 2 that operates linearly. By setting the bias voltage of the power amplifier 2 high / low, the gain of the power amplifier 2 is set high / low. The transmission signal amplified by the power amplifier 2 is wirelessly transmitted from the antenna 11. The transmitter of the transceiver (RFIC) 1 has a direct conversion architecture using an 8-phase shift keying (8PSK) system. In-phase component (I) and quadrature component (Q) of the baseband analog signal are input to multipliers (mixers) 10-1 and 10-2 via low-pass filters 6 and 7, respectively. Multipliers (mixers) 10-1 and 10-2 receive the oscillation output from the local oscillator 8 and a signal obtained by shifting the oscillation output by 90 ° by the phase shifter 9, respectively, and multiply (up) the I and Q signals. Convert). The outputs of the multipliers (mixers) 10-1 and 10-2 are added (combined) and input to the variable gain amplifier 3. The output amplified (voltage amplified) by the variable gain amplifier 3 is amplified by the power amplifier 2 and supplied to the antenna 11. The in-phase component (I) and the quadrature component (Q) are differentially input to the multipliers 10-1 and 10-2, respectively, and the variable gain amplifier 3 adds the outputs of the multipliers 10-1 and 10-2. It is good also as a structure which inputs a result differentially.

  The transceiver (RFIC) 1 analyzes power control information from a base station received by a receiving unit (not shown) and supplies a control command to the power control unit 4 and the bias control unit 5. A signal from the base station is decoded by a decoding process (software or hardware process) (not shown), and a control command corresponding to the requested transmission level is supplied to the power controller 4 and the bias controller 5 to the transmitter.

  The power control unit 4 has a variable gain and controls the output power of the amplifier 3 according to a power control command. The bias controller 5 controls the bias voltage of the power amplifier 2 according to a bias control command. The base station determines necessary transmission output power based on the distance between the mobile terminal and the base station, and transmits the information to the mobile terminal.

  The mobile terminal receives transmission output power information from the base station, and performs a linear operation via the bias control unit 5 of the mobile terminal when the requested transmission power is lower than a predetermined level (threshold). The bias voltage of the power amplifier 2 is lowered. When the mobile terminal has low output power, the current consumption of the linearly operating power amplifier 2 can be suppressed, the efficiency of the transmitter can be improved, and the battery life can be extended. This transmitter is based on a certain value of transmission power level A.

  Case 1: The RFIC 1 sets the bias voltage of the power amplifier 2 high when it is requested by the power control information transmitted from the base station that the transmission power reaches the reference transmission power level A or higher. By setting the bias voltage of the power amplifier 2 high, the gain of the power amplifier is set high. The power control unit 4 that receives a control command based on the power control information sent from the base station controls the output power of the variable gain amplifier 3 so as to reach the transmission power requested from the base station.

  Case 2: When the RFIC 1 is requested to transmit power that does not reach the reference transmission power level A by the power control information transmitted from the base station, the bias voltage of the power amplifier 2 is set to a low level by the control command. To do. By setting the bias voltage of the power amplifier 2 low, the gain of the power amplifier 2 is also set low. The power control unit 4 that receives a control command based on the power control information sent from the base station controls the output power of the amplifier 3 so as to reach the transmission power requested from the base station. The reference transmission power level A is set between 10 dBm and 18 dBm. In Case 2, the current consumption of the power amplifier is reduced by 40% compared to Case 1.

  In case 2, when a low output power is requested from the base station, the current consumption of the power amplifier at the time of low power output is set by setting the bias voltage of the power amplifier 2 low so that the power amplifier 2 operates linearly. Can be suppressed, the power efficiency of the transmitter can be improved, and the battery life can be extended.

  Next, examples of the present invention will be described. FIG. 2 is a flowchart for explaining the operation of this embodiment. Information such as position and signal strength sent from the base station is received (step S1), decoded by software or hardware (step S2), and the control command is transmitted to the power control unit 4 and the bias control unit 5. . The transmitter is based on a reference transmission power level A.

  Information such as position and signal strength sent from the base station is decoded by software or hardware to determine whether or not the transmission power required by the transmitter has reached the reference level A. If the transmission power exceeds the reference level A (required transmission power in step S3> A branch), the bias voltage of the power amplifier 2 is set high (step S5). By setting the bias voltage of the power amplifier 2 high, the gain of the power amplifier 2 is set high. In accordance with the power control information sent from the base station, the power control unit 4 controls the output power of the amplifier 3 so as to reach the requested transmission power.

  When the transmission power required for the transmitter is smaller than the reference level A (required transmission power in step S3 ≦ A branch), the bias voltage of the power amplifier is set low (step S4).

  By setting the bias voltage of the power amplifier 2 low, the gain of the power amplifier 2 is set low. Further, according to the power control information sent from the base station, the power control unit 4 controls the output power of the amplifier 3 so as to reach the requested transmission power. By setting the bias voltage of the power amplifier 2 low, the current consumption of the power amplifier 2 at the time of low power output of the transmitter is suppressed as compared with the setting of case 1, improving the power efficiency and extending the battery life. Can do.

  According to the present embodiment, in a GSM transmitter that uses a linear modulation scheme such as 8PSK, the current consumption of the power amplifier can be suppressed by setting the bias voltage of the power amplifier that operates linearly at the time of low output transmission, The power efficiency of the transmitter can be improved and the battery life can be extended. The present invention is applied to a wireless communication device, a mobile phone, 8PSK, 16QAM (Quadrature Amplitude Modulation), and a 32QAM linear modulation transmission device.

  It should be noted that the disclosures of the above patent documents are incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Various combinations and selections of various disclosed elements are possible within the scope of the claims of the present invention. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea.

It is a figure which shows the structure of one Example of this invention. It is a flowchart which shows operation | movement of one Example of this invention.

Explanation of symbols

1 RFIC
2 Power amplifier
3 Amplifier (variable gain amplifier)
4 Power control unit 5 Bias control unit 6, 7 Low pass filter (LPF)
8 Local oscillator 9 Phase shifter 10 Mixer device 10-1, 10-2 Mixer 11 Antenna

Claims (10)

A power amplifier that amplifies the transmission signal and operates in the linear region;
Control means for setting the bias voltage of the power amplifier to a lower value than when transmitting at a power larger than the predetermined level at the time of transmission at a power below a predetermined level set in advance. A wireless transmitter characterized by the above.   A wireless communication apparatus that performs modulation using a linear modulation method.   A power control information wirelessly transmitted from a base station is received and analyzed by a receiver, and a control unit is provided that variably controls the bias voltage of the power amplifier and the gain of the variable gain amplifier in the previous stage of the power amplifier. The wireless communication apparatus according to claim 2.   The wireless communication apparatus according to claim 2 or 3, wherein the predetermined level is set between 10 dBm and 18 dBm.   The radio | wireless communication apparatus of any one of the Claims 2 thru | or 4 which uses a GSM (Global System for Mobile communications) communication system.   A bias voltage of a linearly operating power amplifier is set to a lower value than when transmitting at a power equal to or lower than the predetermined level when transmitting at a power equal to or lower than a predetermined level. Wireless transmission method.   The wireless communication method according to claim 6, wherein modulation is performed by a linear modulation method.   The power control information transmitted from the communication partner station is received and analyzed, and the bias voltage of the power amplifier and the gain of the gain variable amplifier in the previous stage of the power amplifier are variably controlled. Wireless communication method.   The wireless communication method according to claim 7 or 8, wherein the predetermined level is set between 10 dBm and 18 dBm.   The wireless communication method according to claim 6, wherein a GSM (Global System for Mobile communications) communication system is used.

Images