| 摘要 |
PROBLEM TO BE SOLVED: To prevent the resolution of an entire digital variable capacitor from deteriorating by connecting n pieces of switches to each capacity means and connecting a control means to each of the n pieces of switches, and making the weighting value of each capacitance value smaller than 2 and larger than 1. SOLUTION: In a digital variable capacity circuit, n pieces of switches Sn are connected to each capacity row that has been designed to a binary-coded weighted capacitance value Cbn, and a binary counter circuit 5 as a control means is connected to each of the n pieces of switches Sn (n: integer). Then, the values Cbn/Cbn-1 of the weighting of the capacitance value of the capacity row are made smaller than 2 and larger than 1, thus preventing the resolution of a digital variable capacity from becoming larger than the amount of allowable variable step of the capacitance value due to manufacturing scattering or the like and eliminating accuracy deterioration and hence simplifying layout and reducing area.
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