Energy-Efficient Cyclic-Coupled Ring Oscillator With Delay-Based Injection Locking

This paper presents a new tristate-based delay cell to realize the recently proposed delay-based injection locking in ring oscillators. The circuit is then applied to implement a cyclic-coupled ring oscillator (CCRO). Compared to an inverter-based CCRO with multi-drive injection, the proposed circuit eliminates the static short-circuit current drawn from the supply when drive circuits are in conflicting logic states, thus reducing the power consumption of the CCRO. The functionality and improved energy efficiency of the proposed circuit is demonstrated with circuit simulations of a CCRO implemented in a 28-nm CMOS process. The CCRO employing the proposed technique achieves up to 25% lower power consumption and over 20% lower power-delay product (PDP) compared to the inverter-based CCRO.