ADJUSTABLE CAPACITOR, DIGITALLY CONTROLLED OSCILLATOR, AND ALL-DIGITAL PHASE LOCKED LOOP

摘要

PURPOSE: A variable capacitor, a digitally controlled oscillator, and a digital phase locked loop are provided to minimize the size of capacitance by connection a plurality of capacitor groups in parallel. CONSTITUTION: A capacitor unit(110) includes a plurality of capacitor groups which are arranged in a matrix shape. Based on line/ row selection signal with respect to the matrix, a switch unit(120) connects the capacitor groups in parallel and adjusts capacitance. A first capacitor sub-group has a first capacitance. A second capacitor sub-group has other capacitance which is different from the first capacitance. An adjust unit(130) selects the capacitor groups based on the size of the capacitances.