Process Variation Sensitivities of Rotary Traveling Wave and Mobius Standing Wave Oscillators

Resonant clocking technologies have been gaining increased attention due to high clock frequencies and low power dissipation. Two of the resonant clocking technologies, rotary traveling wave oscillator (RTWO) and Mobius standing wave oscillator (SWO) are considered in this work. The Mobius implementation of resonant clocking technologies requires long interconnects with varying geometric shape segments on the chip, which are modeled by transmission lines. With the fabrication of these transmission line based resonant clocking schemes in lower process node, the on-chip variations are critical and if not accounted for can have a detrimental effect on the functionality. To this end, the process variations sensitivity analysis is presented for the Mobius traveling wave and standing wave technologies. The analysis is centered on the effects of supply voltage variations, temperature variations and multiple process corners on the frequency and power of the resonant clocking technologies. Further, Monte Carlo based analysis is presented to analyze the exhaustive effects of process parameter variations. The SPICE simulations demonstrate that the traveling wave based clocking scheme has better tolerance to variations (especially to voltage and process variations) as compared to the Mobius standing wave technology.