JP2006166161A - Radio communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide radio communication equipment capable of preventing the degradation of spurious emission characteristics due to the decline of a power supply voltage. <P>SOLUTION: The sound signals of an RF band are amplified by a power amplifier circuit 30, an antenna multicoupler 14 emits the amplified sound signals from an antenna 12, and the emitted sound signals reach the portable telephone set of a communicating party through a plurality of radio base stations. In the meantime, a power supply voltage value is detected by a CPU 32. The CPU 32 reduces the gain of the power amplifier circuit 30 when the detected power supply voltage value is below a threshold (=3.7V). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication apparatus, and more particularly to a wireless communication apparatus that is applied to, for example, a portable communication terminal and emits a high-frequency signal amplified by an amplifier from an antenna.

  An example of a conventional device of this type is disclosed in Patent Document 1. According to this prior art, when the digital mode is selected, the gain of the RF variable power amplifier is fixed, and the gain of the IF-AGC amplifier is variably controlled. On the other hand, when the analog mode is selected, the gain of the IF-AGC amplifier is fixed, and the gain of the RF variable power amplifier is variably controlled.

As a result, the spurious emission characteristic in the digital mode requiring strict transmission quality is improved, and the power added efficiency characteristic of the RF variable power amplifier in the analog mode with high power consumption is improved.
JP 2001-186555 A [H04Q 7/32]

    However, when the power supply voltage is lowered, the dynamic range of the RF variable power amplifier is lowered, thereby deteriorating spurious emission characteristics. The prior art does not take any measures against such a problem.

  Therefore, a main object of the present invention is to provide a wireless communication apparatus that can prevent deterioration of spurious emission characteristics due to a decrease in power supply voltage.

  The wireless communication apparatus according to the invention of claim 1 is detected by an amplifying means for amplifying a high-frequency signal, a launching means for emitting a high-frequency signal amplified by the amplifying means from an antenna, a detecting means for detecting a power supply voltage value, and a detecting means. And a reducing means for reducing the gain of the amplifying means when the power supply voltage value falls below the threshold value.

  The high frequency signal is amplified by the amplifying means. The launching means launches the amplified high frequency signal from the antenna. On the other hand, the power supply voltage is detected by the detection means. The reduction means reduces the gain of the amplification means when the detected power supply voltage value falls below the threshold value. By reducing the gain of the amplification means in accordance with the reduction of the power supply voltage value, deterioration of the spurious emission characteristics is prevented.

  The wireless communication device according to the invention of claim 2 is dependent on claim 1, and further comprises control means for controlling the gain of the amplifying means so that the DC level of the high-frequency signal amplified by the amplifying means matches the reference level, The reduction means reduces the reference level. Thereby, stabilization of the direct current level of the high-frequency signal and prevention of deterioration of the spurious emission characteristics are realized at the same time.

  A wireless communication device according to a third aspect of the present invention is dependent on the first or second aspect, and the emitting means emits a high-frequency signal toward the repeater. As a result, the high frequency signal reaches the destination via the repeater. The power shortage of the high frequency signal due to the reduction of the gain of the amplification means is compensated by the repeater.

  According to a fourth aspect of the present invention, there is provided a wireless communication apparatus according to any one of the first to third aspects, further comprising conversion means for converting a terminal voltage of the battery into a power supply voltage.

  According to a fifth aspect of the present invention, there is provided a gain control program comprising: a detection step of detecting a power supply voltage value in a wireless communication device that emits a high-frequency signal amplified by an amplification means; and a power supply voltage value detected by the detection means is a threshold value. A reduction step for reducing the gain of the amplification means is executed when the value is below. As in the first aspect, the spurious emission characteristics are prevented from being deteriorated.

  According to the present invention, since the gain of the amplification means is reduced according to the reduction of the power supply voltage value, it is possible to prevent the spurious emission characteristics from being deteriorated.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

  Referring to FIG. 1, a mobile phone 10 of this embodiment corresponds to a GSM (Global System for Mobile Communications) system and includes a battery 42. The power supply circuit 40 converts the voltage of the battery 42 into a power supply voltage having a rating of 3.7 V, and drives the entire system by the converted power supply voltage.

  When a call operation for a call is performed by the key input device 38, the CPU 32 instructs the baseband signal processing circuit 20 to output a call signal. The baseband signal processing circuit 20 supplies a baseband call signal to the modulator 26, and the modulator 26 converts the supplied call signal into an IF band call signal.

  The IF band call signal is converted into an RF band call signal by the orthogonal transform / DA converter 28. The converted call signal is amplified by the power amplifier circuit 30 and then emitted from the antenna 12 via the antenna duplexer 14. The emitted call signal reaches the other party's mobile phone via a plurality of radio base stations (repeaters). When the other party performs an incoming call operation in response to the call signal, a call state is established.

  When the call state is established, the baseband signal processing circuit 20 performs predetermined processing on the audio signal captured by the microphone 24. The processed audio signal band is converted to an IF band by the modulator 26 and converted to an RF band by the orthogonal transform / DA converter 28. The RF band audio signal is amplified by the power amplifier 30 and then emitted from the antenna 12 via the antenna duplexer 14. The audio signal also reaches the other party's mobile phone via a plurality of radio base stations.

  On the other hand, the audio signal from the other party is captured by the antenna 12 and is provided to the orthogonal transform / AD converter 16 via the antenna duplexer 14. The band of the audio signal is converted from the RF band to the IF band by the orthogonal transform / AD converter 16 and converted from the IF band to the baseband by the demodulator 18. The baseband audio signal is given to the speaker 22 through the processing of the baseband signal processing circuit 20. As a result, the voice of the other party is output from the speaker 22.

  When a call end operation is performed by the key input device 38 during such a call, the CPU 32 controls the baseband signal processing circuit 20 and transmits a call end signal to the other party. After transmitting the call end signal, the CPU 32 ends the call process. Also when the call end signal is received from the other party first, the CPU 32 ends the call process.

  The power amplifier circuit 30 is configured as shown in FIG. The audio signal in the RF band given from the orthogonal transform / DA converter 28 is amplified by the amplifier 30a. The gain of the amplifier 30a increases when the output of the comparator 30b is H level, and decreases when the output of the comparator 30b is L level. The amplifier 30a outputs the audio signal amplified according to such a gain to the antenna duplexer 14.

  The LPF 30b detects the DC level of the audio signal output from the amplifier 30a, and applies the detected DC level to one input terminal of the comparator 30b. The D / A converter 30c performs D / A conversion on the RF control voltage input from the CPU 32, and applies the converted RF control voltage to the other input terminal of the comparator 30b. The comparator 30b sets the output to the H level when the DC level is lower than the RF control voltage value, and sets the output to the L level when the DC level is equal to or higher than the RF control voltage value.

  As a result, the input / output characteristics of the amplifier 30a, that is, the RF transmission power characteristics fluctuate as shown in FIG. That is, the relationship between the power level of the audio signal input to the amplifier 30a and the power level of the audio signal output from the amplifier 30a slightly moves within a range of ± ΔG with the solid line L as a reference. The DC level value of the audio signal output from the amplifier 30a is adjusted to the RF control voltage value by such a gain adjustment operation.

  However, the CPU 32 decreases the RF control voltage in accordance with the decrease in the power supply voltage. At this time, the CPU 32 executes processing according to the interrupt routine shown in FIG. A control program corresponding to this interrupt routine is stored in the flash memory 36.

  Referring to FIG. 3, in step S1, the RF control voltage value is initialized. In step S3, the power supply voltage value Vbattery is detected, and in step S5, it is determined whether or not the detected power supply voltage value Vbattery is below a threshold value (= 3.7V). If “NO” here, the process is terminated as it is, but if “YES”, the process is terminated through steps S7 and S9.

In step S7, a voltage correction value ΔV is calculated according to Equation 1. According to Equation 1, the difference value between the threshold value “3.7 V” and the power supply voltage value Vbattery is divided by the difference value between the threshold value “3.7 V” and the minimum voltage value “3.2 V”, and a division value obtained thereby. Is multiplied by a constant PW (= −0.5).
[Equation 1]
ΔV = (3.7−Vbattery) / (3.7−3.2) * PW
Therefore, the voltage correction value ΔV has the relationship shown in FIG. 5 with the power supply voltage value Vbattery. Note that the threshold value “3.7 V” matches the rated voltage value. The minimum voltage value is a minimum voltage value at which the mobile phone 10 operates.

  In step S9, the RF control voltage value is reduced using the voltage correction value ΔV thus obtained. Specifically, the voltage correction value ΔV is added to the initial value of the RF control voltage. The updated RF control voltage is applied to the D / A converter 30d shown in FIG. Therefore, the gain of the amplifier 30a decreases as the power supply voltage value Vbattery decreases.

  Referring to FIG. 6, the power level of the audio signal input to amplifier 30a is always Pin (dBm). When the power supply voltage value Vbattery satisfies the rated 3.7V, the RF transmission power characteristic of the amplifier 30a is defined by the curve Cp1. The amplifier 30a outputs an audio signal having a power level of Pout1 (dBm).

  When attention is paid to the curve Cp1, the RF transmission power level increases in proportion to the increase of the input power level in the range where the input power level is not more than Pin (dBm). However, when the input power level exceeds Pin (dBm), the RF transmit power level is saturated. The spurious emission characteristic is defined by the curve Cs1 corresponding to the change of the curve Cp1. That is, the spurious emission level maintains SEL1 (dBc) in the range where the input power level is not more than Pin (dBm). However, in the range where the input power level exceeds Pin (dBm), the spurious emission level increases as the input power level increases.

  As described above, the power level of the audio signal input to the amplifier 30a is always Pin (dBm). For this reason, when the power supply voltage value Vbattery satisfies the rating, the spurious emission level is suppressed to SEL1.

  When the power supply voltage value Vbattery falls below 3.7V, the saturation level of the RF transmission power, that is, the dynamic range decreases. If the RF control voltage remains at the initial value, the curve defining the RF transmission power characteristic transitions from Cp1 to Cp2, and the power level of the audio signal output from the amplifier 30a decreases to Pout2. The spurious emission characteristic is defined by the curve Cs2 corresponding to the curve Cp2. As a result, the spurious emission level increases from SEL1 to SEL2.

  However, the RF control voltage value decreases as the power supply voltage value Vbattery decreases due to the execution of the interrupt routine shown in FIG. As a result, the RF transmission power characteristic is defined by the curve Cp3, and the spurious emission characteristic is defined by the curve Cs1 corresponding to the curve Cp3. Therefore, the spurious emission level maintains SEL1 regardless of the decrease in the power supply voltage value Vbattery.

  Note that the fluctuation range of the RF transmission power characteristic curve due to the decrease in the RF control voltage value is much larger than the fluctuation range ΔG shown in FIG.

  As can be seen from the above description, the audio signal in the RF band is amplified by the amplifier 30a. The antenna duplexer 14 emits the amplified audio signal from the antenna 12. The emitted audio signal reaches the other party's mobile phone via a plurality of radio base stations. On the other hand, the power supply voltage value Vbattery is detected by the CPU 32 (S3). When the detected power supply voltage value Vbattery falls below a threshold value (= 3.7 V), the CPU 32 reduces the RF control voltage (S7, S9). The RF control voltage is compared with the DC level of the audio signal by the comparator 30c, and the gain of the amplifier 30a is controlled by the comparison result of the comparator 30c.

  Thus, the gain of amplifier 30a is reduced by reducing the RF control voltage. The DC level of the audio signal is fine tuned to match the reduced RF control voltage. As a result, deterioration of spurious emission characteristics and stabilization of the direct current level of the audio signal are realized at the same time.

  The audio signal emitted from the antenna 12 is relayed by the radio base station. Therefore, the shortage of power of the audio signal due to the reduction in the gain of the amplifier 30a is compensated by the radio base station. As a result, quality that does not hinder calls is ensured.

  In this embodiment, a mobile phone is used for explanation, but it goes without saying that the present invention can also be applied to a wireless communication apparatus that transmits and receives contents other than voice such as data communication.

It is a block diagram which shows the structure of one Example of this invention. It is a block diagram which shows an example of a structure of the power amplifier circuit shown in FIG. It is a flowchart which shows a part of operation | movement of this invention. FIG. 3 is an illustrative view showing one portion of a gain control operation of the power amplifier circuit shown in FIG. 1. It is an illustration figure which shows a part of correction | amendment operation | movement of RF control voltage. FIG. 10 is an illustrative view showing another portion of gain control operation of the power amplifier circuit shown in FIG. 1;

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Mobile phone 12 ... Antenna 14 ... Duplexer 20 ... Baseband signal processing circuit 26 ... Modulator 28 ... Orthogonal transformation / DA converter 30 ... Power amplifier 32 ... CPU

Claims (5)

Amplifying means for amplifying a high-frequency signal;
Launching means for launching a high-frequency signal amplified by the amplification means from an antenna;
A wireless communication apparatus comprising: a detecting unit that detects a power supply voltage value; and a reducing unit that reduces a gain of the amplifying unit when a power supply voltage value detected by the detecting unit falls below a threshold value. Control means for controlling the gain of the amplifying means so that the direct current level of the high-frequency signal amplified by the amplifying means matches a reference level;
The wireless communication apparatus according to claim 1, wherein the reduction unit reduces the reference level.   The wireless communication apparatus according to claim 1, wherein the emitting unit emits the high-frequency signal toward a repeater.   The wireless communication apparatus according to claim 1, further comprising conversion means for converting a terminal voltage of the battery into a power supply voltage. To a wireless communication device that emits a high-frequency signal amplified by an amplification means from an antenna,
A gain control program for executing a detection step of detecting a power supply voltage value, and a reduction step of reducing the gain of the amplification means when the power supply voltage value detected by the detection means falls below a threshold value.

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