JP3700337B2 - Mobile phone equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile phone device, and more particularly to a mobile phone device including means for changing a reception band of a receiving circuit.
[0002]
[Prior art]
A receiving circuit in a cellular phone device is required to have contradictory characteristics such as low intermodulation distortion and low power consumption.
[0003]
Intermodulation distortion of the receiver circuit is the sum and difference of frequency components that are integral multiples of two or more component frequencies present in the input wave, and depends on the non-linear characteristics of the amplifier and frequency converter. Is.
[0004]
Therefore, in the amplifier and frequency converter of the receiving circuit, if the level of the received signal increases, it is necessary to expand the dynamic range accordingly and reduce the intermodulation distortion. However, in order to expand the dynamic range, it is necessary to increase the operating voltage and operating current of the amplifier and frequency converter of the receiving circuit.
[0005]
In the dual mode method that shares the code division multiple access method and the analog method, the conventional technology has sufficient intermodulation distortion characteristics so that a signal due to the intermodulation distortion does not occur for a strong analog signal in the reception band. Therefore, it is difficult to reduce power consumption.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a mobile phone device capable of changing the reception band of a receiving circuit of a mobile phone.
[0008]
[Means for Solving the Problems]
The cellular phone device according to the present invention includes a receiving unit that receives a radio signal from a base station, a transmitting unit that transmits a radio signal to the base station, a baseband signal that is modulated into the radio signal, and a base that uses the radio signal as a base. Modulating / demodulating means for demodulating the signal into a band signal, coding / decoding means for encoding the speech signal and the control signal into the baseband signal, and decoding the baseband signal into the speech signal and the control signal, and converting speech into the speech signal A transmitter and a voice encoding means, a receiver and a voice decoding means for converting the call signal into voice, and controls the operation of the apparatus by the control signal, and sends necessary information to the base station as the control signal. Control means and means for varying the reception band of the receiving circuit .
The reception means includes reception signal strength detection means for detecting a radio signal level of a reception channel or a radio signal level of all reception channels, and the means for changing the reception band is obtained by the reception signal strength detection means. Operating in relation to received signal strength and received pilot strength.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0014]
FIG. 1 is a configuration diagram of a mobile phone device according to a first embodiment of the present invention.
[0015]
First, in the receiving system, a radio communication signal transmitted from a base station (not shown) is input to the duplexer 2 via the antenna 1. Here, the reception frequency (all reception channels) band is limited, and the signal is guided to the low noise amplifier 11. The signal amplified by the low noise amplifier 11 is further limited in the reception frequency (all reception channels) band by the high frequency band pass filter 12 and converted to an intermediate frequency by the frequency mixer 13. The received intermediate frequency signal is limited in signal band by the intermediate frequency band pass filter 14, amplified to a necessary level by the variable gain amplifier 15, and demodulated by the demodulator 16. The demodulated baseband signal is decoded by the baseband signal processing circuit 6. Here, the decoded and output signals include a digital control signal and a digital call signal. Among these signals, the digital control signal is supplied to the control circuit 5 and identified. On the other hand, the digital call signal is returned from the handset 7 after being returned to the analog call signal.
[0016]
The variable gain amplifier 15 has a function of measuring received signal strength (RSSI), and this received signal strength signal is also supplied to the control circuit 5 and identified.
[0017]
On the other hand, in the transmission system, the transmission voice is converted into a transmission signal by the transmitter 8 and then converted into a digital transmission signal by the baseband signal processing circuit 6. This digital transmission signal is encoded by the baseband signal processing circuit 6 together with the digital control signal generated by the control circuit 5, and then input to the modulator 26 and modulated into a quadrature modulation signal. The modulation signal is adjusted so that the signal band is limited by the intermediate frequency band filter 24 and the output level required by the base station is adjusted by the variable gain amplifier 25, and converted to a high frequency signal of a predetermined frequency channel by the frequency mixer 23. Is done. Then, unnecessary spurious signals are removed by the high-frequency bandpass filter 22, amplified to a required output level by the power amplifier 21, and then transmitted from the antenna 1 to the base station via the duplexer 2.
[0018]
In the local oscillation system, the local oscillation frequency is oscillated by the variable frequency oscillator 31 controlled by the control circuit 5. The local oscillation signal is amplified by the buffer amplifier 32 and then distributed by the signal distributor 33 so that the frequency does not change due to the fluctuation of the load of the oscillator, and the local oscillation signal is distributed between the frequency mixer 13 of the reception system and the transmission system. Simultaneously supplied to the frequency mixer 23.
[0019]
Further, the control circuit 5 includes a microcomputer as a main control unit, and adjusts the gain of the variable gain amplifier 15 so that the frequency setting of the variable frequency oscillator 31 and the input level of the demodulator 16 become appropriate. In addition to adjusting the gain of the variable gain amplifier 25 so that the transmission output level is appropriate, it has a function of controlling each part.
[0020]
Next, reception intermodulation distortion in the embodiment of the present invention will be described. FIG. 2 is an explanatory diagram of reception intermodulation distortion in the embodiment of the present invention.
[0021]
In FIG. 2, since the mobile phone supports the dual mode of the CDMA (Code Division Multiple Access) method and the analog method, the frequency band fd for communicating with the base station is the frequency band fc of the CDMA method and the frequency of the analog method. The band fa is included. Now, when communication is performed using a CDMA channel signal 41, there are two analog channel signals 42 in the analog frequency band fa, and these signals are simultaneously input to the receiver of the mobile phone. Then, a signal 43 due to third-order intermodulation distortion is generated due to nonlinear distortion of the receiving unit. Normally, the receiver is designed to have a sufficiently large dynamic range so that the signal 43 due to the third-order intermodulation distortion does not occur. However, since the performance is contradictory in terms of downsizing and low power consumption, it is naturally limited. Therefore, it is difficult to satisfy the performance in a place where the antenna of the base station can be seen or in a place very close to the base station. As shown in FIG. 2, when the signal 43 due to the third-order intermodulation distortion overlaps the signal of the signal 41 of the CDMA channel, the quality of the received signal is deteriorated.
[0022]
Therefore, the input signal level at the current receiver input is known from the received signal strength signal obtained by the variable gain amplifier 15. On the other hand, since the signal strength of the CDMA signal can be determined by measuring the received pilot strength in the baseband signal processing circuit 6, if the pilot signal strength of the CDMA signal is compared with the received signal strength signal, the signal 43 due to third-order intermodulation distortion is obtained. Can be known. Alternatively, it is also possible to simply compare the pilot signal strength of the CDMA signal with the code error rate.
[0023]
If the generation of the signal 43 due to the third-order intermodulation distortion can be known, the filter selector switch 3 between the duplexer 2 and the low noise amplifier 11 is controlled to connect the analog system band filter 4 in parallel. By doing so, the signal 42 of the analog channel can be shunted and attenuated, so that the signal 43 due to third-order intermodulation distortion can be reduced.
[0024]
Furthermore, as another embodiment, a configuration diagram of a mobile phone device in the second embodiment of the present invention in FIG. 3 will be described.
[0025]
The received signal enters the filter changeover switch 3 directly from the antenna 1 and a filter suitable for either the CDMA band filter 17 or the analog band filter 4 is selected. The method of controlling the filter changeover switch 3 for selecting the filter is as described in the first embodiment. Here, since an appropriate filter is selected for each method and a reception band is determined, interference caused by unnecessary waves can be significantly reduced.
[0026]
The transmission signal is amplified to a required output level by the power amplifier 21 and then transmitted from the antenna 1 via the transmission band filter 27.
[0027]
Furthermore, according to the second embodiment, it is possible to divide the antenna 1 into a receiving antenna and a transmitting antenna and use two independent antennas. In this case, a filter for a CDMA system band 17. The attenuation band characteristics of the analog band filter 4 and the transmission band filter 27 can be relaxed, and there is an advantage that the filter can be easily manufactured.
[0028]
In the above two embodiments, the mobile station apparatus of the CDMA automobile mobile phone system has been described. However, the present invention is not necessarily limited to this method, and can be considered to achieve the object of the present invention. Other configurations are also included. Furthermore, the configuration and means of the apparatus described in the embodiments are not limited to those shown in the embodiments.
[0029]
As described above, mobile telephone apparatus according to this embodiment, by varying the reception band of the receiving circuit, so always be necessary and sufficient operating current, reducing power consumption, long Can stand by. Furthermore, according to the present invention, when an unwanted wave is input to the receiving circuit of the mobile phone, an intermodulation distortion wave generated by an amplifier or a frequency converter can be detected and automatically reduced.
[0030]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the mobile telephone apparatus which can make the receiving band of the receiving circuit of a mobile telephone variable can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a mobile phone device according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of reception intermodulation distortion in the first embodiment of the present invention.
FIG. 3 is a configuration diagram of a mobile phone device according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Antenna 2 Duplexer 3 Filter change-over switch 4 Analog system band filter 5 Control circuit 6 Baseband signal processing circuit 7 Handset 8 Transmitter 11 Low noise amplifier 12 High frequency band pass filter (receiving system)
13 Frequency mixer (receiving system)
14 Intermediate frequency bandpass filter (Reception system)
15 Variable gain amplifier (receiving system)
16 Demodulator 17 CDMA band filter 21 Power amplifier 22 High frequency band pass filter (transmission system)
23 Frequency mixer (transmission system)
24 Intermediate frequency bandpass filter (transmission system)
25 Variable gain amplifier (transmission system)
26 Modulator 27 Transmission band filter 31 Variable frequency oscillator 32 Buffer amplifier 33 Signal distributor 41 CDMA channel signal 42 Analog channel signal 43 Third-order intermodulation distortion signal

Claims (3)

Receiving means for receiving a radio signal from a base station; transmitting means for transmitting a radio signal to the base station; modulating / demodulating means for modulating a baseband signal into the radio signal and demodulating the radio signal into a baseband signal; A code decoding means for encoding a call signal and a control signal into the baseband signal, and decoding the baseband signal into a call signal and a control signal; and a transmitter and a voice encoding means for converting speech into the call signal A receiver and a voice decoding means for converting the call signal into voice, a control means for controlling the operation of the own apparatus by the control signal and sending necessary information to the base station as the control signal , and reception by a receiving circuit Means for varying the bandwidth ,
The reception means includes a reception signal strength detection means for detecting a radio signal level of a reception channel or a radio signal level of all reception channels,
The mobile phone apparatus characterized in that the means for changing the reception band operates in relation to the received signal strength obtained by the received signal strength detecting means and the received pilot strength . The receiving means comprises means for detecting a code error rate of a received signal;
The mobile telephone apparatus according to claim 1, wherein the means for changing the reception band operates in association with a code error rate of a reception signal.   2. The code division multiple access method and the analog method are selected, and the means for changing the reception band operates when communication is performed in the code division multiple access method. 2. The mobile phone device according to 2.

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