JPH05344057A - Radio telephone set - Google Patents

Abstract

PURPOSE:To provide a small sized, light weight and inexpensive telephone set while the circuit scale is reduced. CONSTITUTION:A telephone set is provided with a PLL synthesizer 1 generating a cellular telephone transmission frequency band and a wireless telephone transmission frequency band, a cellular transmission means 3 receiving a signal at a cellular telephone transmission frequency band and amplifying the signal to a required power level for a cellular telephone call and outputting the amplified signal to an antenna 12, a wireless transmission means 4 receiving a signal at a wireless telephone transmission frequency band and amplifying the signal to a required power level for a wireless telephone call and outputting the amplified signal to the antenna 12, a respectively means 8 amplifying and demodulating the cellular telephone reception signal and the wireless telephone reception signal received by the antenna, and a control means 9 connecting to the cellular transmission means 3, the wireless transmission means 4 and the reception means 8 and a loop filter of the PLL synthesizer 1 is selected for the cellular telephone band and the wireless telephone band.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a cellular telephone, and more particularly to a wireless telephone device which can be used as a cordless telephone within the coverage area of a cordless telephone base unit and as a cellular telephone within the coverage area of a cellular telephone.

[0002]

2. Description of the Related Art In recent years, a cellular telephone device capable of making a call anytime, anywhere and a cordless telephone using a radio have been used instead of a cord between a telephone body and a handset.

In the prior art, a cordless telephone has a master unit connected to a wired telephone line, and the master unit and the slave unit communicate wirelessly. A user can make and receive a call using a cordless telephone slave unit around a master unit installed in a home (generally, within a radius of several hundred meters). Calls using cordless telephones use the subscriber's subscribed telephone line, so call charges are the same as ordinary wireline charges.

In addition, a cellular telephone is a cell
The cellular phone base station is placed in each cell and the user uses a cellular mobile device to find the surroundings of the base station (generally, several kilometers to several tens of kilometers) in any cell. You can make and receive calls from anywhere in (range). This cellular telephone call is made by the cellular base station and the cellular switching device, and the call charge is much higher than that of a general wire telephone.

Therefore, there is a cellular / cordless telephone that can make both a cellular call and a cordless call and that automatically operates as a cordless telephone when it is within the call range of the corresponding cordless telephone base unit. It is described in Japanese Unexamined Patent Publication No. 3-1621.

[0006]

However, the above-mentioned conventional cellular / cordless telephone device is composed of a cellular transmitter / receiver and a cordless transmitter / receiver, and each transceiver further comprises a bandpass filter. Therefore, the size of the device becomes large, and there is a serious problem for the wireless telephone device, which is important to be small and easy to carry.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a compact, lightweight and inexpensive radiotelephone device with a reduced circuit scale.

[0008]

In order to solve the above problems and achieve the object, the present invention inputs a PLL synthesizer for generating a cellular telephone transmission frequency band and a cordless telephone transmission frequency band, and a signal in the cellular telephone transmission frequency band. Cellular transmitting means for amplifying to the required power level of the cellular telephone and outputting to the antenna, cordless transmitting means for inputting the signal of the cordless telephone transmission frequency band and amplifying to the required power level of the cordless telephone and outputting to the antenna, to the antenna And a receiving means for amplifying and demodulating a cellular telephone reception signal and a cordless telephone reception signal, the cellular transmission means, the cordless transmission means, and a control means connected to the reception means, and the loop filter of the PLL synthesizer is a cellular filter. Switchable between telephone band and cordless telephone band Sea urchin made.

[0009]

According to the present invention, the transmission signal of the cellular telephone and the transmission signal of the cordless telephone can be generated by one PLL synthesizer, so that the circuit scale can be reduced.
It is possible to provide a smaller, lighter, and cheaper wireless telephone device.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a radio telephone apparatus of the present invention. In FIG. 1, 1 is a PLL synthesizer, 2 is a high frequency switch (SW), and 3 is a cellular transmitting means.
(CEL T _X ), 4 is a cordless transmission means (CORD T _X )
_X ), 5, 6, 7 are bandpass filters (BPF), 8 is cellular
Cordless receiving means (R _X ), 9 is a control circuit (CONT), 1
0 is a microphone (MIC), 11 is a speaker (SPK), 12
Is an antenna.

Here, in the embodiment, the cellular transmission frequency is 824 to 849 MHz (hereinafter referred to as F1), the cellular reception frequency is 869 to 894 MHz (hereinafter referred to as F2), and the cordless transmission frequency is 926 to 928 MHz (hereinafter referred to as F4). The cordless reception frequency is 902 to 904 MHz (hereinafter referred to as F3), and the channel interval is 30 kHz for both the cellular phone and the cordless phone.

The cellular cordless telephone of FIG. 1 is controlled by the control circuit 9 in the vicinity of the cordless telephone base unit.
The cordless receiving means 8 has a cordless receiving channel F3.
In the operating state, the PLL synthesizer 1 generates a signal of the cordless transmission frequency F4, and the cordless transmission means 4 outputs F.
It becomes an operation state in 4, and a cordless telephone base unit and an antenna
Communicate via 12 At this time, the cellular transmission means 3 is in a non-operating state.

On the other hand, when the cordless telephone master unit is separated from the periphery of the cordless telephone unit and is out of the communication range of the parent unit, the control circuit 9 controls the cellular cordless receiving means 8 to operate in the cellular reception channel F2 and the PLL synthesizer 1 to the cellular telephone. A signal of the transmission frequency F1 is generated, the cellular transmission means 3 is activated in F1, and communicates with the cellular base station via the antenna 12. Cordless transmission means 4 at this time
Becomes inactive.

FIG. 2 shows typical characteristics of a voltage controlled oscillator (hereinafter abbreviated as VCO) used in the PLL synthesizer 1 shown in FIG. In FIG. 2, the vertical axis indicates the VCO oscillation frequency.
(MHz), the horizontal axis is the control voltage (V) of the VCO, point A is the lowest frequency in the cellular transmission band, point B is the highest frequency in the cellular transmission band, point C is the lowest frequency in the cordless transmission band, and point D is It is the highest frequency in the cordless transmission band. As shown in FIG. 2, the control voltage sensitivity of the cellular transmission band, that is, the slope (MHz / V) of the line AB and the control voltage sensitivity of the cordless transmission band, that is, the slope (MHz / V) of the line CD are due to different frequency bands. They are not the same, and as a result, the characteristics (for example, lockup time) of the PLL synthesizer 1 also differ. A block diagram of FIG. 3 shows an example of the configuration of a PLL synthesizer that prevents this characteristic change.

In FIG. 3, reference numeral 21 is a reference signal generator (OS).
C), 22 is a phase comparator (PD), 23 is a loop filter (LP
F), 24 are VCOs, 25 is a variable frequency divider (1 / N), and the output signal f _r of the reference signal generator 21 and the output signal f of the variable frequency divider 25
/ By synchronizing the N outputs a signal f = N · f _r. The VCO 24 has a modulation input terminal MOD, and a frequency (or phase) modulated signal can be obtained by inputting the modulation signal f ₁ (eg, audio signal) to this terminal. Further, the loop filter 23 has a control terminal CONT, and a band switching signal f indicating whether the frequency is a cellular telephone frequency or a cordless telephone frequency.
The band of the loop filter is switched by ₂ so that the characteristic change due to the band of the PLL synthesizer can be minimized. Further, the variable frequency divider 25 outputs an output signal f / N when the control signal f ₃ is input.

FIG. 4 shows an example of a circuit of the loop filter 23 capable of switching the band. In FIG.
231, 232, and 233 are resistors, 234 is a capacitor, and 235 is an analog switch. Now, when the control terminal (CONT) of the analog switch 235 is logic H, the analog switch 235 is in the ON state, the resistor 232 is bypassed, and the capacitor 234
Is charged and discharged through resistors 231 and 233. On the other hand, when the control terminal (CONT) of the analog switch 235 is logic L, the analog switch 235 is in the off state, the resistor 232 is not bypassed, and the capacitor 234 is charged / discharged through the resistors 231, 232, 233. As a result, the band of the loop filter can be switched.

[0018]

As described above, since the radio telephone device of the present invention can generate the transmission signal of the cellular telephone and the transmission signal of the cordless telephone with one PLL synthesizer, the circuit scale can be reduced and the size can be reduced. It is possible to provide a lightweight and inexpensive wireless telephone device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless telephone device according to an embodiment of the present invention.

FIG. 2 is a diagram showing typical characteristics of the VCO shown in FIG.

FIG. 3 is a block diagram showing a configuration example of the PLL synthesizer of FIG.

FIG. 4 is a block diagram showing a circuit example of the loop filter of FIG.

[Explanation of symbols]

1 ... PLL synthesizer, 2 ... high-frequency switch, 3
... cellular transmission means, 4 ... cordless transmission means, 5,
6, 7 ... Bandpass filter, 8 ... Cellular cordless receiving means, 9 ... Control circuit, 10 ... Microphone, 11 ... Speaker, 12 ... Antenna, 21 ... Reference signal generator, 22
… Phase comparator, 23… Loop filter, 24… Voltage controlled oscillator (VCO), 25… Variable divider, 231, 232, 233…
Resistor, 234 ... Capacitor, 235 ... Analog switch.

Claims (1)

[Claims] 1. A PLL synthesizer for generating a cellular telephone transmission frequency band and a cordless telephone transmission frequency band, a cellular transmission means for inputting a signal in the cellular telephone transmission frequency band, amplifying it to a required power level of the cellular telephone, and outputting it to an antenna, Cordless transmission means for inputting a signal in the cordless telephone transmission frequency band, amplifying it to the required power level of the cordless telephone and outputting it to the antenna, reception for amplifying and demodulating the cellular telephone reception signal and the cordless telephone reception signal received by the antenna Means, said cellular transmission means,
A radiotelephone device comprising a control means connected to the cordless transmission means and the reception means, wherein the loop filter of the PLL synthesizer is configured to be switched between a cellular telephone band and a cordless telephone band.