| 摘要 |
PROBLEM TO BE SOLVED: To provide a filter automatic adjusting circuit, a filter adjusting method, and a mobile telephone system for enabling the variation correction having high adjusting accuracy and to be easily obtained low power consumption relating to a filter having an adjusting function about the characteristic frequency, and capable of securely suppressing a filter adjusting error. SOLUTION: In order to detect variations of a reference filter 103, the phase difference before and after the reference filter 103 is counted by a counter 106 not only by using one kind of reference signal but also by using a plurality number of reference signals to be produced by a variable phase shifter 110 when being counted by a phase difference detector 104. All operation of members relating to filter adjustment is stopped after adjustment about variations of the main filter 103 is performed by holding signals acquired from the counting results to a resister 108 as control signals 116(1) to 116(n) of the main filter 109. COPYRIGHT: (C)2007,JPO&INPIT
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