Electronic device having an AGC loop

Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part

Reexamination Certificate

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Details

C455S127500

Reexamination Certificate

active

06178309

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic device having an AGC loop, and more particularly to a portable radio device which compensates errors caused by accuracy in manufacturing electronic parts, etc.
2. Description of the Related Art
Up to now, in a portable radio device such as a cordless telephone, etc., the respective circuits in the device are driven by a battery. For that reason, when a porter (user) uses the portable radio device for a long period, a battery voltage drops, thereby coming to an unusable state.
To eliminate the above defect, a technique in which upon detection of the battery voltage that drops lower than a predetermined voltage, the fact that the voltage has dropped is announced to the user, has been disclosed in, for example, Japanese Patent Unexamined Publication No. Hei 4-200140.
According to the disclosure in the publication, there are provided a primary battery and an auxiliary battery, and when a voltage of the primary battery drops, the battery in use is switched from the primary battery to the auxiliary battery while the fact that the voltage has dropped is announced to the user.
However, in the above conventional portable radio device, a predetermined voltage is compared with an output voltage of the battery, and when the output voltage of the battery is lower than the predetermined voltage, an alarm is given to the user. Under this circumstance, for example, if a transmission power depending on the characteristic of a power amplifier is different between the respective devices, that is, if the transmission power relative to the voltage is different between the respective devices, the following problems occur because the same predetermined voltage is set in all the radio devices. There occurs such a disadvantage that in a radio device, the user is alarmed although the device is still in a communicatable state, and in another radio device, the user is not alarmed even though the communication quality is poor.
Also, when the battery in use is switched from the primary battery to the auxiliary battery, the communication quality is improved in a short period. However, the provision of the auxiliary battery makes it difficult to downsize the device.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems, and therefore an object of the present invention is to provide a portable radio device which is capable of setting a voltage which is compared with an output voltage of a battery, individually.
Another object of the present invention is to provide a portable radio device which improves in reliability such as the transmission efficiency, the uniformity of the communication quality, etc.
Still another object of the present invention is to provide a portable radio device which is capable of being downsized while improving in reliability such as the transmission efficiency, the uniformity of the communication quality, etc.
In order to achieve the above objects, according to the present invention, there is provided a portable radio device which includes a power amplifier for amplifying a radio frequency signal, an antenna for sending the radio frequency signal, a switch connected between the power amplifier and the antenna, a gain controller for controlling the radio frequency signal which is sent from the antenna to a predetermined power, a converter for converting a transmission power value of the power amplifier into a voltage corresponding to the transmission voltage value, a memory in which a predetermined comparison voltage is stored, and a comparator for comparing the voltage with the comparison voltage.
It is preferable that the switch is a three-point switch having a movable contact which is connected to one of a first contact which is connected to the antenna and a second contact which sets the comparison voltage.
It is preferable that the converter includes a directional coupler for taking out a given power according to the transmission power value, and a detector for detecting said voltage according to the power from the directional coupler.
Also, according to the present invention, there is provided a portable radio device which includes a converter for converting a transmission power from a power amplifier into a d.c. voltage, a memory for storing a supply voltage obtained when the transmission power becomes a predetermined power as a comparison voltage, and a circuit for comparing the d.c. voltage with the comparison voltage to generate an alarm when the d.c. voltage is lower than the comparison voltage.
Further, according to the present invention, there is provided a portable radio device which includes a power amplifier for amplifying a radio frequency signal, an antenna for sending said radio frequency signal, a switch connected between the power amplifier and the antenna, a gain controller for controlling the radio frequency signal which is sent from the antenna to a predetermined power, a memory in which a predetermined voltage is stored, and a comparator for comparing a supply voltage with the voltage.
It is preferable that the portable radio device further includes a notification circuit for announcing the drop of the supply voltage to a user when the comparator judges that the supply voltage is lower than the voltage.
With the above structure of the present invention, the difference of a timing when the user is notified to the voltage drop between the respective devices can be eliminated.


REFERENCES:
patent: 4521912 (1985-06-01), Franke et al.
patent: 5126688 (1992-06-01), Nakanishi et al.
patent: 5175875 (1992-12-01), Yokoya et al.
patent: 5551067 (1996-08-01), Hulkko et al.
patent: 5663692 (1997-09-01), Swope
patent: 5828953 (1998-10-01), Kawase
patent: 60-261228 (1985-12-01), None
patent: 4-200140 (1992-07-01), None
patent: 4-372227 (1992-12-01), None
patent: 8-8769 (1996-01-01), None
patent: 8-265210 (1996-10-01), None
patent: 10-22757 (1998-01-01), None

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