Patent ID: 8970312
Filing Date: 2015-03-03
Classification: H03K,H03L

Abstract:
1. A differential ring oscillation circuit comprising: a differential ring oscillation unit in which delay circuits, to which signals of 2 phases are input, and which delay and output the input signals of 2 phases, are connected at even stages in a ring form; a first common-mode level detection unit that detects that the input signals of 2 phases of one delay circuit at an even stage of the differential ring oscillation unit are at a same predetermined level; a first switch that sets, to a specific potential, one of the output signals of 2 phases of the delay circuit delaying the input signals of 2 phases, when the first common-mode level detection unit detects the same predetermined level; a second common-mode level detection unit that detects that the input signals of 2 phases of one delay circuit at an odd stage of the differential ring oscillation unit are at the same predetermined level; and a second switch that sets, to the specific potential, one of the output signals of 2 phases of the delay circuit delaying the input signals of 2 phases, when the second common-mode level detection unit detects the same predetermined level.