JPH0514231A - Receiver circuit - Google Patents

Abstract

PURPOSE:To lengthen the battery life of a portable radio communication equipment or the like, and to lengthen the continuous utilizing time of the device by arranging a synthesizer and a crystal oscillator at a local oscillation circuit, and turning the synthesizer side ON at the time of calling or getting a call CONSTITUTION:When a radio communication equipment 2 is in a reception waiting state at a control channel, the power source of a synthesizer 16 is turned OFF, and switches 19 and 20 are switched to a multiplier 18 side, in a local oscillation circuit 1. At that time, a received frequency is held to be the frequency of a local oscillation signal decided by both the oscillation frequency of a crystal oscillator 17, and the multiplication number of the multiplier 18. When the request for calling or getting a call is made, the power source of the synthesizer 16 is turned ON, and the switches 19 and 20 are switched to the synthesizer 16 side. Then, the local oscillation signal prepared by the synthesizer 16 is inputted to a mixer 13, and the receiving state at a speed channel is obtained. Thus, the power consumption of a receiving circuit can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving circuit of a wireless communication device.

[0002]

2. Description of the Related Art Conventionally, a receiving circuit for receiving a plurality of frequencies has been as shown in FIG. That is, the antenna 11
The incoming radio wave is amplified by the high frequency amplifier 12, and the amplified radio wave is mixed by the mixer 13 with the local oscillation signal generated by the synthesizer 16 to have an intermediate frequency. The local oscillation frequency is the difference between the reception frequency and the intermediate frequency. Therefore, when selecting the reception frequency, the frequency of the local oscillation signal is changed. The intermediate frequency is amplified by the intermediate frequency amplifier 14 and detected by the wave detector 15 to be a reception output. The crystal oscillator 17 is the reference frequency of the synthesizer.

[0003]

Recently, the demand for portable wireless devices has been rapidly increasing. Most of these devices use a battery as a power source, and the continuous usable time of the device is limited to the battery life. In the circuit configuration as described above, the power source of the synthesizer 16 is always supplied during reception operation. It is an indispensable task to reduce the power consumption of the device itself, including the fact that the power is turned on and power is consumed.

[0004]

In the present invention, a synthesizer and a crystal oscillator are arranged in the local oscillation circuit, and either the synthesizer or the crystal oscillator can be selected for the local oscillation signal.

[0005]

According to the above construction, when the reception time of the specific reception frequency is long, the power consumption can be reduced in the standby state in the control channel of the MCA system, for example.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of a wireless communication device using the receiving circuit of the present invention. In FIG. 1, reference numeral 2 denotes the entire wireless communication device, and 1 denotes a local oscillation circuit. The incoming radio wave is received by the antenna 11, amplified by the high frequency amplifier 12, and input to the mixer 13. Here, it is mixed with the local oscillation signal generated by the local oscillation circuit 1 to generate an intermediate frequency signal, which is amplified by the intermediate frequency amplifier 14 and detected by the detector 1.
It is detected at 5 and becomes the reception output.

The transmitting section 30 is composed of a modulator, a transmission output amplifier and the like. The control unit 40 includes a CPU and the like, and controls the entire wireless communication device 2. Next, the local oscillator circuit 1 will be described. The synthesizer 16 includes a VCO 51, a variable frequency divider 52, and a variable frequency divider 52, as shown in FIG.
It is composed of a phase comparator 53 and a low-pass filter 54. In the figure, the synthesizer can generate a local oscillation signal of any frequency by inputting the reference frequency to the phase comparator 53 and setting the frequency division ratio of the variable frequency divider 52.

In FIG. 1, the crystal oscillator 17 can be switched by a switch 20 to either the synthesizer 16 side or the multiplier 18 side. The multiplier 18 doubles the oscillation frequency of the crystal oscillator, and the multiplication factor may be arbitrarily determined according to the reception frequency. The switch 19 is a crystal oscillator 1 which produces a local oscillation signal by the synthesizer 16.
7 and that generated by the multiplier 18 are switched and input to the mixer 13. Switch 19
The switch 20 is configured to switch in conjunction with each other.

Next, the operation of the present invention will be described when the receiving circuit is used in a wireless communication apparatus of the MCA system having at least one control channel and a plurality of communication channels. When the wireless communication device 2 is in the standby reception state on the control channel, the power of the synthesizer in the local oscillation circuit 1 is turned off, and the switches 19 and 20 are switched to the multiplier side. In this case, the reception frequency of the wireless communication device 2 is the oscillation frequency of the crystal oscillator 17 and the multiplier 1
It depends on the frequency of the local oscillation signal determined by a multiple of 8. If there is a call request or call request next,
The synthesizer 16 is powered on, switch 19,
The switch 20 is switched to the synthesizer 16 side, and the local oscillation signal generated by the synthesizer 16 is mixed by the mixer 13.
Is input to, and the reception state on the call channel is set. In this case, the frequency of the local oscillation signal can be arbitrarily set by changing the variable frequency divider 52 in the synthesizer 1 and the reference frequency. FIG. 3 shows a state transition diagram of the synthesizer 16 from OFF to ON and from ON to OFF.

[0010]

According to the present invention, by reducing the power consumption of the receiving circuit, it is possible to extend the battery life of a wireless communication device or the like using a battery as a power source and to extend the continuous usable time of the device.

[Brief description of drawings]

FIG. 1 is a block diagram of a wireless communication device including a receiving circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram of a synthesizer unit in FIG.

FIG. 3 is a state transition diagram illustrating a switching state.

FIG. 4 is a block diagram of a conventional wireless communication device.

[Explanation of symbols]

1 local oscillator 2 wireless communication device 11 antenna 12 High frequency amplifier 13 Mixer 14 Intermediate frequency amplifier 15 Detector 16 Synthesizer 17 Crystal oscillator 18 doubler 19, 20 switch 30 transmitter 40 control unit 51 VCO 52 Variable frequency divider 53 Phase comparator 54 Low-pass filter

Claims (2)

[Claims] 1. In a wireless communication device for receiving a plurality of frequencies, a synthesizer and a crystal oscillator are arranged in a circuit for generating a local oscillation signal of a receiving circuit, and when a call or an incoming call is made, the synthesizer side is provided. A receiving circuit in a wireless communication device, which is switched on. 2. The receiving circuit according to claim 1, wherein a frequency of the oscillator is used as a reference frequency of a synthesizer arranged in a circuit for generating a local oscillation signal.