DIGITALLY CONTROLLED OSCILLATOR CIRCUIT, FREQUENCY SYNTHESIZER, RADIO COMMUNICATION DEVICE USING THE SAME AND ITS CONTROLLING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a digital oscillator circuit which changes its frequency linearly in a wide range and occupies a small area. SOLUTION: A digitally controlled oscillator circuit 10 has a variable capacity portion 12 including a first capacitive element group 14 consisting of a plurality of first variable capacitive elements and a second capacitive element group 15 consisting of a plurality of second variable capacitive elements, and also has an oscillating portion for generating a signal having an oscillation frequency corresponding to the capacity value of the variable capacity portion 12. A first change amount of capacity of the first variable capacitive elements is a value equal to a second change amount of capacity of the second variable capacitive elements multiplied by an integer of 2 or above. The number of the second variable capacitive elements is an integer of 2 or above with one subtracted therefrom. COPYRIGHT: (C)2009,JPO&INPIT