Wide Frequency Multiphase Oscillator Designed by Coupling Two Identical Ring Voltage Controlled Oscillators

ABSTRACT This work presents a novel wide tuning range ring voltage controlled oscillator (RVCO) designed to generate six‐phase signals. The proposed circuit is realized by coupling two identical three‐stage single‐ended inverter‐based RVCOs. The coupling network injects the common mode signals from one RVCO to the other one and vice versa in a cross‐connected manner. Three‐stage RVCOs used for coupling have been configured by modifying the conventional current‐starved RVCO. The proposed six‐phase RVCO is optimized using an improved version of non‐dominated Sorting Genetic Algorithm III (NSGAIII). In this algorithm, the sigma scaling method is used to control selection pressure and enhance the algorithm's performance. The proposed RVCO oscillates at 3.46 GHz. It can operate from 970 MHz to 4 GHz with a supply voltage of 1.5 V, demonstrating a wide frequency tuning range of 120%. Additionally, another six‐phase oscillator is proposed, achieved by capacitively coupling two identical three‐stage RVCOs. Both proposed oscillators are designed in TSMC 0.18 μm CMOS technology.