Portable telephone apparatus and stablly supplying method of reference frequency

A portable telephone apparatus comprises:

• reference frequency generating means capable of changing an output frequency for communication with a base station by means of a voltage control signal;
• high-accurate reference frequency generating means in which frequency accuracy always meets a prescribed value;
• comparison means for comparing an output signal after an AFC operation of said reference frequency generating means with an output signal from said high-accurate reference frequency generating means;
• determination means for determining whether or not frequency accuracy of an output signal after an AFC operation of said reference frequency generating means meets a said prescribed value, based on a comparison result of said comparison means;
• selection means for selecting an output signal from said reference frequency generating means in case that a determination result of said determination means meets said prescribed value, and for selecting an output signal from said high-accurate reference frequency generating means in case that a determination result of said determination means does not meet said prescribed value;
• and
• power supply controlling means for turning off a power supply of said high-accurate reference frequency generating means in case that an output signal from said high-accurate reference frequency generating means is used for a reference frequency and other than a case in which an output signal from said high-accurate reference frequency generating means is used in said comparison, and for turning off a power supply of said reference frequency generating means in case that an output signal from said high-accurate reference frequency generating means is used for a reference frequency and other than a time period during which an AFC operation is conducted.

A stably supplying method of a reference frequency in a portable telephone apparatus comprises steps-of:

• providing reference frequency generating means capable of changing an output frequency for communication with a base station by means of a voltage control signal, and high-accurate reference frequency generating means in which frequency accuracy always meets a prescribed value;
• determining whether or not frequency accuracy of an output signal from said reference frequency generating means meets said prescribed value;
• and
• selecting an output signal from said reference frequency generating means in case that a result of said determination meets said prescribed value, and for selecting an output signal from said high-accurate reference frequency generating means in case that a determination result of said determination means does not meet said prescribed value.

A stably supplying method of a reference frequency in a portable telephone apparatus characterized in that said method comprises:

• providing reference frequency generating means capable of changing an output frequency for communication with a base station by means of a voltage control signal, and high-accurate reference frequency generating means in which frequency accuracy always meets a prescribed value;
• comparing an output signal after an AFC operation of said reference frequency generating means with an output signal from said high-accurate reference frequency generating means;
• determining whether or not frequency accuracy of an output signal after an AFC operation of said reference frequency generating means meets said prescribed value, based on a result of said comparison;
• selecting an output signal from said reference frequency generating means in case that a result of said determination meets said prescribed value, and selecting an output signal from said high-accurate reference frequency generating means in case that a determination result of said determination means does not meet said prescribed value;
• turning off a power supply of said high-accurate reference frequency generating means in case that an output signal from said high-accurate reference frequency generating means is used for a reference frequency and other than a case in which an output signal from said high-accurate reference frequency generating means is used in said comparison;
• and
• turning off a power supply of said reference frequency generating means in case that an output signal from said high-accurate reference frequency generating means is used for a reference frequency and other than a time period during which an AFC operation is conducted.