Patent ID: 7659785
Filing Date: 2010-02-09
Classification: H03K,H03L

Abstract:
1. A voltage controlled oscillator (VCO), comprising: a plurality of oscillation units connected in cascade to form a chain; and a plurality of current source sections operatively connected to the oscillation units, the current source sections each being configured to control current provided to the oscillation units, wherein each of the current source sections includes: wherein the fixed voltage is a reference direct-current voltage corresponding to a reference clock frequency of a phase locked loop (PLL) that includes the VCO, wherein the reference direct-current voltage is generated through a switching operation of a voltage divider, the switching operation being based on a control bit provided to the voltage divider, and wherein the VCO is configured to receive the reference direct-current voltage from a comparator, the comparator being configured to determine whether or not an output clock frequency of the VCO is within a normal range by comparing an output clock frequency range of the VCO with the reference clock frequency on the condition that the fixed voltage is inputted to the VCO.