Oscillation frequency analysis of N-stage CMOS ring oscillator with wired-OR connections

Quadrature oscillators are effective in applications such as clock-recovery circuits and complex signal processing. In this paper, the oscillation frequency of the CMOS inverter-type N-stage ring oscillator with wired-OR connections is analyzed. The analysis is applied to a quadrature oscillator proposed in 2008, called the ORIGAMI oscillator, and the extended N-stage ring oscillators. To verify the oscillation frequency analysis, the formulated oscillation frequency is compared with simulated frequency using HSPICE assuming 0.18 μm CMOS processes.