Patent ID: 7453970
Filing Date: 2008-11-18
Classification: G06F,H03K,H03L

Abstract:
1. A clock signal selecting apparatus that guarantees the continuity of an output clock signal, the clock signal selecting apparatus comprising: N phase comparators, each of which compares the phase of one of N phase-controlled clock signals with the phase of a second one of said N phase controlled clock signals, which is an active clock signal, and generates one of N control signals that control the phase of one of N clock signals to follow the phase of a predetermined clock signal; N phase controllers, which control the phases of the N clock signals in response to the N control signals and generate the N phase-controlled clock signals; and a selector, which selects one of the N phase-controlled clock signals corresponding to the active clock signal, wherein if each of the N phase-controlled clock signals corresponds to the active clock signal, each of the N phase controllers generates a phase-controlled clock signal having a constant phase difference with an input clock signal, and N is an integer greater than one.