JPH0474027A - Cordless telephone system - Google Patents

Abstract

PURPOSE:To reduce power consumption and to attain the standby for a long time by using a local frequency obtained from a self-running frequency of a VCO of a frequency synthesizer circuit so as to implement a reception of a control channel in the standby state. CONSTITUTION:Changeover switches 20,21 of a frequency synthesizer circuit 17 are thrown respectively to the position (a) in the standby operation and a VCO 14 is free-running-oscillated by a voltage obtained from a bias circuit 22 and a 1st local frequency is generated to select a control channel. The control channel is turned by a mixer circuit 6 and an intermediate frequency BPF 7 by using the frequency and the input of a reception frequency is awaited. When a radio wave is inputted from an antenna 1, a high frequency signal tuned by the 1st local frequency is demodulated by a detection circuit 12 to be a low frequency signal, a control data is demodulated and outputted, and a discrimination output of the presence of a carrier is informed to a control circuit. When talking is finished and the standby operation is transited again, the changeover switches 20,21 are thrown to the position (a) to stop power supply of a PLL 15 and a crystal oscillation circuit 16 so as to reduce the current consumption of the reception circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cordless telephone device comprising a base station connected to a telephone line and a mobile station wirelessly connected to the base station, and particularly relates to a wireless This relates to the configuration of a receiving circuit.

BACKGROUND OF THE INVENTION FIG. 2 shows the configuration of a radio receiving circuit in a mobile station of a conventional cordless telephone device. In Figure 2, 1 is an antenna, 2 is a DPX (antenna duplexer) for distinguishing between transmitting and receiving frequencies, 3.5 is a bandpass filter that passes only the receiving frequency, and 4.8.10 is a high-frequency amplification 6 is a mixer circuit for the 10th Cull frequency and reception frequency, 7 is a first intermediate frequency band pass filter, 9 is a mixer circuit for the 20th Cull frequency and intermediate frequency, 11
is a second intermediate frequency band pass filter, 12 is a detection circuit,
13 is a low frequency amplifier circuit, 14 is a VCO (voltage controlled oscillation circuit) that oscillates the 10th-cal frequency, and 15 is a 10th-
16 is a reference crystal oscillation circuit including a crystal oscillator for obtaining the reference frequency of the PLL 15; 17 is a reference crystal oscillation circuit including these VCOs 14, PPLI
5 and a reference crystal oscillation circuit 16; 18 is a second frequency synthesizer circuit for obtaining the 20th-cal frequency;
0-Cal oscillation circuit, 19 is a crystal resonator.

Next, the operation of the conventional example will be explained. If the cordless phone is unused and in standby mode, the second
The receiving circuit shown in the figure generally turns on and off the power intermittently to reduce power consumption. When the power is intermittently turned on, a frequency synthesizer circuit 17 consisting of a VCO 14, a PLL 15, and a reference crystal oscillation circuit 16 performs reception on a control channel and waits for an incoming call from a base station. At this time, when a transmission wave from the base station is received, this receiving circuit is switched to continuous power supply, demodulates the control data for the incoming call operation, and shifts to the designated communication channel.

Setting of the channel is performed by a frequency synthesizer 17 which generates the 10th-cal frequency.

Problems to be Solved by the Invention However, in the conventional cordless telephone device, the entire receiving circuit including the frequency synthesizer circuit 17 is intermittently supplied with power during the reception standby operation, so that the power consumption is only There is a problem that the number of frequency synthesizer circuits is larger than that of a one-channel receiving circuit, and the effective power during standby, which is determined by the intermittent period and the power consumption of all receiving circuits, cannot be reduced very much. For this reason, the standby time determined by the capacity of a rechargeable battery, which is a power source built into the mobile station, is limited, and there is a limit to realizing a long standby operation.

SUMMARY OF THE INVENTION The present invention solves these conventional problems, and aims to provide a cordless telephone device that reduces power consumption and enables long standby operation.

Means for Solving the Problems In order to achieve the above object, the present invention provides that in order to set the 10th-cal frequency on the control channel, the free running frequency of the voltage controlled oscillator circuit (vCO) of the frequency synthesizer circuit is The 10th-cal frequency required for reception of the control channel is set so that standby operation can be performed without feeding power to the PLL and the reference crystal oscillation circuit.

According to the present invention, with the above configuration, the 10th cull frequency for setting the channel during the intermittent reception operation on the control channel during the standby operation is set to the PL of the frequency synthesizer circuit.
It is not locked by L and the reference crystal oscillation circuit (because it is obtained by the own running frequency of the voltage controlled oscillation circuit, the PLL
and the reference crystal oscillation circuit remains stopped. Control channel reception may be enabled.

Therefore, the power required for the PLL and the reference crystal oscillator circuit can be saved, so that when configured with batteries of the same capacity, a longer standby time can be achieved. Further, in order to obtain the same standby time, a smaller capacity battery can be used, so the device can be made smaller and lighter.

Embodiment FIG. 1 is a block diagram of a radio reception circuit in a mobile station of a cordless telephone device showing an embodiment of the present invention.
Elements similar to those of the conventional example shown in the figure are given the same reference numerals. That is, in Fig. 1, ■ is an antenna, 2 is a DPX (antenna duplexer) for discriminating between transmitting and receiving frequencies, 3.5 is a bandpass filter that passes only the receiving frequency, and 4, 8.10 are high frequencies. Amplification circuit, 6 is the first
0 - mixer circuit for the cull frequency and reception frequency, 7 is the first
9 is a mixer circuit for the 20th-cal frequency and intermediate frequency; 11 is the second intermediate frequency band-pass filter; 12 is a detection circuit; 13 is a low-frequency amplification circuit; 14 is a 10th-cal frequency mixer circuit; a VCO (voltage controlled oscillator circuit) for oscillation, 15 a PLL (phase locked circuit) for controlling the 10th-cal frequency, 16 a PLL, a reference crystal oscillation circuit including a crystal resonator for obtaining the reference frequency of 15, 17 18 is a frequency synthesizer circuit consisting of the VCO 14, PPL 15 and reference crystal oscillation circuit 16; 18 is a 20th-cal oscillation circuit for obtaining the 20th-cal frequency; and 19 is a crystal oscillator. Reference numeral 20 denotes a changeover switch for cutting off power supply to the PLL 15 other than vC014 of the frequency synthesizer circuit 17 and the reference crystal oscillation circuit 16. 21 is interlocked with the changeover switch 20, and PLL1
This is a changeover switch for cutting off the control voltage path from VCO 5 to VCO 14. 22 is a bias circuit for causing the VCO 14 to oscillate at a constant free-running frequency.

Next, the operation of the above embodiment will be explained. During standby operation, the changeover switches 20 and 21 are switched to the a side, and the voltage obtained from the bias circuit 22 is used to
O14 is caused to free-run oscillate to generate a 10th cull frequency for selecting a control channel. The mixer circuit 6 and the intermediate frequency bandpass filter 7 are tuned to the control channel using this 10th-cal frequency, and are waiting for input of the reception frequency.

When radio waves in the control channel are input from the antenna 1, the high-frequency signal tuned by the 10th-cal frequency is demodulated by the detection circuit 12 through the subsequent stages to become a low-frequency signal, and the control data to be sent is It demodulates and outputs the signal, and notifies a control circuit (not shown) of the carrier presence determination output.

When reception is completed on the control channel and you want to move on to connection operation, switch the selector switches 20 and 21 to the b side, and switch the PLL
15 and the reference crystal oscillation circuit 16, the frequency synthesizer circuit 17 operates, and the PLL 15
A 10th-Cull frequency corresponding to the channel set to is generated.

Thereafter, the transition to the speech channel is performed by rewriting the channel data set in the PLL 15, as in the conventional cordless telephone device.

When the call ends and the mode returns to standby operation, the changeover switches 20 and 21 are switched to the a side to stop the power supply to the PLL 15 and the reference crystal oscillation circuit 16, thereby reducing the current consumption of the receiving circuit.

Effects of the Invention As is clear from the embodiments described above, the present invention allows the 10th-cal frequency of the reception circuit during standby to be determined automatically by operating only the voltage controlled oscillation circuit without operating the entire frequency synthesizer circuit. Since reception is performed in synchronization with the control channel using the running frequency, power consumption during reception standby can be reduced. Therefore, it is possible to extend the standby time, and there is no need for the user to charge the battery frequently. In addition, in order to obtain the same continuous standby time, the mobile station can be configured with a smaller capacity battery, making it possible to make the mobile station smaller and lighter, which improves the user's usability. This has the effect of improving the

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a wireless receiving circuit of a cordless telephone device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a wireless receiving circuit of a conventional cordless telephone device. 1... Antenna, 2... D that discriminates between transmitting and receiving frequencies
PX (antenna duplexer), 3.5... Reception frequency band pass filter, 4.8.10... High frequency amplification circuit, 6... First mixer circuit, ? . . . first intermediate frequency band pass filter, 9 . . . second mixer circuit, 11.
...Second intermediate frequency band pass filter, 12...Detection circuit, 13...Low frequency amplification circuit, 14...VC○(
voltage controlled oscillation circuit), 15... PLL (phase locked loop), 16... reference crystal oscillation circuit, I7... frequency synthesizer circuit, 18... 20th-cal oscillation circuit, 1
9...Crystal resonator, 20...PLL reference crystal oscillation circuit changeover switch, 21...VC○ control voltage input changeover switch, 22...V for control channel reception
Bias circuit for CO free running frequency setting.

Claims (1)

[Claims] It consists of a base station connected to a telephone line and a mobile station wirelessly connected to this base station, and uses a multi-channel radio receiving circuit that uses a frequency synthesizer method to enable transmission and reception on multiple radio channels. In the cordless telephone device, the wireless receiving circuit performs a receiving operation on a control channel during standby using a local frequency obtained from a free-running frequency of a voltage-controlled oscillator circuit of a frequency synthesizer circuit. Cordless telephone equipment.