SEMICONDUCTOR DEVICE AND VOLTAGE CONTROLLED OSCILLATION CIRCUIT

摘要

A voltage controlled oscillation circuit (15) comprising a plurality of independent ring oscillation circuits having a different number of stages, and a selector (22) selecting any one of the independent ring oscillation circuits delivering a feedback clock signal (FB). Since an independent ring oscillation circuit delivers the feedback clock signal at all times, the feedback clock signal can be delivered while keeping a duty ratio even if the operating speed is high and the delay time before an input signal (DLL1) is delivered can be adjusted arbitrarily.