Patent ID: 7876166

Claim:
A coupled ring oscillator comprising: n ring oscillators each including m inverter circuits and wires connecting the m inverter circuits arranged so that the m inverter circuits and the wires constitute n loop circuits each having a loop shape in a plan view; and a phase-coupling loop in which m×n phase-coupling circuits, each of which couples signal phases at two points in a certain phase mode, are connected with each other in a ring configuration in a plan view, wherein connection points at which the inverter circuits are connected with each other and connection points at which the phase-coupling circuits are connected with each other are connected bijectively, each of the inverter circuits is connected between two points that divide the phase-coupling circuits into two parts at a certain ratio, each of the n loop circuits of the ring oscillators does not include any of the m×n phase-coupling circuits, and encloses at least one common phase-coupling circuit in a plan view, each of the phase-coupling circuits couples signal phases at two points in a common mode; and each of the inverter circuits is connected between two points that divide the phase-coupling circuits into n×(m−1)/2 phase-coupling circuits and n×(m+1)/2 phase-coupling circuits.